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Building PCRE without using autotools
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-------------------------------------
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NOTE: This document relates to PCRE releases that use the original API, with
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library names libpcre, libpcre16, and libpcre32. January 2015 saw the first
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release of a new API, known as PCRE2, with release numbers starting at 10.00
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and library names libpcre2-8, libpcre2-16, and libpcre2-32. The old libraries
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(now called PCRE1) are still being maintained for bug fixes, but there will be
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no new development. New projects are advised to use the new PCRE2 libraries.
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This document contains the following sections:
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General
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Generic instructions for the PCRE C library
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The C++ wrapper functions
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Building for virtual Pascal
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Stack size in Windows environments
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Linking programs in Windows environments
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Calling conventions in Windows environments
|
||||
Comments about Win32 builds
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Building PCRE on Windows with CMake
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Use of relative paths with CMake on Windows
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Testing with RunTest.bat
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Building under Windows CE with Visual Studio 200x
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Building under Windows with BCC5.5
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Building using Borland C++ Builder 2007 (CB2007) and higher
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Building PCRE on OpenVMS
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Building PCRE on Stratus OpenVOS
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Building PCRE on native z/OS and z/VM
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GENERAL
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I (Philip Hazel) have no experience of Windows or VMS sytems and how their
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libraries work. The items in the PCRE distribution and Makefile that relate to
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anything other than Linux systems are untested by me.
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There are some other comments and files (including some documentation in CHM
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format) in the Contrib directory on the FTP site:
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ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/Contrib
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The basic PCRE library consists entirely of code written in Standard C, and so
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should compile successfully on any system that has a Standard C compiler and
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library. The C++ wrapper functions are a separate issue (see below).
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The PCRE distribution includes a "configure" file for use by the configure/make
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(autotools) build system, as found in many Unix-like environments. The README
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file contains information about the options for "configure".
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There is also support for CMake, which some users prefer, especially in Windows
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environments, though it can also be run in Unix-like environments. See the
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section entitled "Building PCRE on Windows with CMake" below.
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Versions of config.h and pcre.h are distributed in the PCRE tarballs under the
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names config.h.generic and pcre.h.generic. These are provided for those who
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build PCRE without using "configure" or CMake. If you use "configure" or CMake,
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the .generic versions are not used.
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GENERIC INSTRUCTIONS FOR THE PCRE C LIBRARY
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The following are generic instructions for building the PCRE C library "by
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hand". If you are going to use CMake, this section does not apply to you; you
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can skip ahead to the CMake section.
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(1) Copy or rename the file config.h.generic as config.h, and edit the macro
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settings that it contains to whatever is appropriate for your environment.
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In particular, you can alter the definition of the NEWLINE macro to
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specify what character(s) you want to be interpreted as line terminators.
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In an EBCDIC environment, you MUST change NEWLINE, because its default
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value is 10, an ASCII LF. The usual EBCDIC newline character is 21 (0x15,
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NL), though in some cases it may be 37 (0x25).
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When you compile any of the PCRE modules, you must specify -DHAVE_CONFIG_H
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to your compiler so that config.h is included in the sources.
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An alternative approach is not to edit config.h, but to use -D on the
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compiler command line to make any changes that you need to the
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configuration options. In this case -DHAVE_CONFIG_H must not be set.
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NOTE: There have been occasions when the way in which certain parameters
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in config.h are used has changed between releases. (In the configure/make
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world, this is handled automatically.) When upgrading to a new release,
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you are strongly advised to review config.h.generic before re-using what
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you had previously.
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(2) Copy or rename the file pcre.h.generic as pcre.h.
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(3) EITHER:
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Copy or rename file pcre_chartables.c.dist as pcre_chartables.c.
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OR:
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Compile dftables.c as a stand-alone program (using -DHAVE_CONFIG_H if
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you have set up config.h), and then run it with the single argument
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"pcre_chartables.c". This generates a set of standard character tables
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and writes them to that file. The tables are generated using the default
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C locale for your system. If you want to use a locale that is specified
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by LC_xxx environment variables, add the -L option to the dftables
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command. You must use this method if you are building on a system that
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uses EBCDIC code.
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The tables in pcre_chartables.c are defaults. The caller of PCRE can
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specify alternative tables at run time.
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(4) Ensure that you have the following header files:
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pcre_internal.h
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ucp.h
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(5) For an 8-bit library, compile the following source files, setting
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-DHAVE_CONFIG_H as a compiler option if you have set up config.h with your
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configuration, or else use other -D settings to change the configuration
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as required.
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pcre_byte_order.c
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pcre_chartables.c
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pcre_compile.c
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pcre_config.c
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pcre_dfa_exec.c
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pcre_exec.c
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pcre_fullinfo.c
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pcre_get.c
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pcre_globals.c
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pcre_jit_compile.c
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pcre_maketables.c
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pcre_newline.c
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pcre_ord2utf8.c
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pcre_refcount.c
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pcre_string_utils.c
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pcre_study.c
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pcre_tables.c
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pcre_ucd.c
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pcre_valid_utf8.c
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pcre_version.c
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pcre_xclass.c
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Make sure that you include -I. in the compiler command (or equivalent for
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an unusual compiler) so that all included PCRE header files are first
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sought in the current directory. Otherwise you run the risk of picking up
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a previously-installed file from somewhere else.
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Note that you must still compile pcre_jit_compile.c, even if you have not
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defined SUPPORT_JIT in config.h, because when JIT support is not
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configured, dummy functions are compiled. When JIT support IS configured,
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pcre_jit_compile.c #includes sources from the sljit subdirectory, where
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there should be 16 files, all of whose names begin with "sljit".
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(6) Now link all the compiled code into an object library in whichever form
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your system keeps such libraries. This is the basic PCRE C 8-bit library.
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If your system has static and shared libraries, you may have to do this
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once for each type.
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(7) If you want to build a 16-bit library (as well as, or instead of the 8-bit
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or 32-bit libraries) repeat steps 5-6 with the following files:
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pcre16_byte_order.c
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pcre16_chartables.c
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pcre16_compile.c
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pcre16_config.c
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pcre16_dfa_exec.c
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pcre16_exec.c
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pcre16_fullinfo.c
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pcre16_get.c
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pcre16_globals.c
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pcre16_jit_compile.c
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pcre16_maketables.c
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pcre16_newline.c
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pcre16_ord2utf16.c
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pcre16_refcount.c
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pcre16_string_utils.c
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pcre16_study.c
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pcre16_tables.c
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pcre16_ucd.c
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pcre16_utf16_utils.c
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pcre16_valid_utf16.c
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pcre16_version.c
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pcre16_xclass.c
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(8) If you want to build a 32-bit library (as well as, or instead of the 8-bit
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or 16-bit libraries) repeat steps 5-6 with the following files:
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pcre32_byte_order.c
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pcre32_chartables.c
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pcre32_compile.c
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pcre32_config.c
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pcre32_dfa_exec.c
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pcre32_exec.c
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pcre32_fullinfo.c
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||||
pcre32_get.c
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||||
pcre32_globals.c
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||||
pcre32_jit_compile.c
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pcre32_maketables.c
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||||
pcre32_newline.c
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||||
pcre32_ord2utf32.c
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pcre32_refcount.c
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||||
pcre32_string_utils.c
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pcre32_study.c
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pcre32_tables.c
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||||
pcre32_ucd.c
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||||
pcre32_utf32_utils.c
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pcre32_valid_utf32.c
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pcre32_version.c
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pcre32_xclass.c
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(9) If you want to build the POSIX wrapper functions (which apply only to the
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8-bit library), ensure that you have the pcreposix.h file and then compile
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pcreposix.c (remembering -DHAVE_CONFIG_H if necessary). Link the result
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(on its own) as the pcreposix library.
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(10) The pcretest program can be linked with any combination of the 8-bit,
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16-bit and 32-bit libraries (depending on what you selected in config.h).
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Compile pcretest.c and pcre_printint.c (again, don't forget
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-DHAVE_CONFIG_H) and link them together with the appropriate library/ies.
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If you compiled an 8-bit library, pcretest also needs the pcreposix
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wrapper library unless you compiled it with -DNOPOSIX.
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(11) Run pcretest on the testinput files in the testdata directory, and check
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that the output matches the corresponding testoutput files. There are
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||||
comments about what each test does in the section entitled "Testing PCRE"
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in the README file. If you compiled more than one of the 8-bit, 16-bit and
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32-bit libraries, you need to run pcretest with the -16 option to do
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16-bit tests and with the -32 option to do 32-bit tests.
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Some tests are relevant only when certain build-time options are selected.
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||||
For example, test 4 is for UTF-8/UTF-16/UTF-32 support, and will not run
|
||||
if you have built PCRE without it. See the comments at the start of each
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testinput file. If you have a suitable Unix-like shell, the RunTest script
|
||||
will run the appropriate tests for you. The command "RunTest list" will
|
||||
output a list of all the tests.
|
||||
|
||||
Note that the supplied files are in Unix format, with just LF characters
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||||
as line terminators. You may need to edit them to change this if your
|
||||
system uses a different convention. If you are using Windows, you probably
|
||||
should use the wintestinput3 file instead of testinput3 (and the
|
||||
corresponding output file). This is a locale test; wintestinput3 sets the
|
||||
locale to "french" rather than "fr_FR", and there some minor output
|
||||
differences.
|
||||
|
||||
(12) If you have built PCRE with SUPPORT_JIT, the JIT features will be tested
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||||
by the testdata files. However, you might also like to build and run
|
||||
the freestanding JIT test program, pcre_jit_test.c.
|
||||
|
||||
(13) If you want to use the pcregrep command, compile and link pcregrep.c; it
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||||
uses only the basic 8-bit PCRE library (it does not need the pcreposix
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||||
library).
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||||
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||||
|
||||
THE C++ WRAPPER FUNCTIONS
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||||
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||||
The PCRE distribution also contains some C++ wrapper functions and tests,
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||||
applicable to the 8-bit library, which were contributed by Google Inc. On a
|
||||
system that can use "configure" and "make", the functions are automatically
|
||||
built into a library called pcrecpp. It should be straightforward to compile
|
||||
the .cc files manually on other systems. The files called xxx_unittest.cc are
|
||||
test programs for each of the corresponding xxx.cc files.
|
||||
|
||||
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||||
BUILDING FOR VIRTUAL PASCAL
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A script for building PCRE using Borland's C++ compiler for use with VPASCAL
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||||
was contributed by Alexander Tokarev. Stefan Weber updated the script and added
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||||
additional files. The following files in the distribution are for building PCRE
|
||||
for use with VP/Borland: makevp_c.txt, makevp_l.txt, makevp.bat, pcregexp.pas.
|
||||
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||||
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||||
STACK SIZE IN WINDOWS ENVIRONMENTS
|
||||
|
||||
The default processor stack size of 1Mb in some Windows environments is too
|
||||
small for matching patterns that need much recursion. In particular, test 2 may
|
||||
fail because of this. Normally, running out of stack causes a crash, but there
|
||||
have been cases where the test program has just died silently. See your linker
|
||||
documentation for how to increase stack size if you experience problems. The
|
||||
Linux default of 8Mb is a reasonable choice for the stack, though even that can
|
||||
be too small for some pattern/subject combinations.
|
||||
|
||||
PCRE has a compile configuration option to disable the use of stack for
|
||||
recursion so that heap is used instead. However, pattern matching is
|
||||
significantly slower when this is done. There is more about stack usage in the
|
||||
"pcrestack" documentation.
|
||||
|
||||
|
||||
LINKING PROGRAMS IN WINDOWS ENVIRONMENTS
|
||||
|
||||
If you want to statically link a program against a PCRE library in the form of
|
||||
a non-dll .a file, you must define PCRE_STATIC before including pcre.h or
|
||||
pcrecpp.h, otherwise the pcre_malloc() and pcre_free() exported functions will
|
||||
be declared __declspec(dllimport), with unwanted results.
|
||||
|
||||
|
||||
CALLING CONVENTIONS IN WINDOWS ENVIRONMENTS
|
||||
|
||||
It is possible to compile programs to use different calling conventions using
|
||||
MSVC. Search the web for "calling conventions" for more information. To make it
|
||||
easier to change the calling convention for the exported functions in the
|
||||
PCRE library, the macro PCRE_CALL_CONVENTION is present in all the external
|
||||
definitions. It can be set externally when compiling (e.g. in CFLAGS). If it is
|
||||
not set, it defaults to empty; the default calling convention is then used
|
||||
(which is what is wanted most of the time).
|
||||
|
||||
|
||||
COMMENTS ABOUT WIN32 BUILDS (see also "BUILDING PCRE ON WINDOWS WITH CMAKE")
|
||||
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||||
There are two ways of building PCRE using the "configure, make, make install"
|
||||
paradigm on Windows systems: using MinGW or using Cygwin. These are not at all
|
||||
the same thing; they are completely different from each other. There is also
|
||||
support for building using CMake, which some users find a more straightforward
|
||||
way of building PCRE under Windows.
|
||||
|
||||
The MinGW home page (http://www.mingw.org/) says this:
|
||||
|
||||
MinGW: A collection of freely available and freely distributable Windows
|
||||
specific header files and import libraries combined with GNU toolsets that
|
||||
allow one to produce native Windows programs that do not rely on any
|
||||
3rd-party C runtime DLLs.
|
||||
|
||||
The Cygwin home page (http://www.cygwin.com/) says this:
|
||||
|
||||
Cygwin is a Linux-like environment for Windows. It consists of two parts:
|
||||
|
||||
. A DLL (cygwin1.dll) which acts as a Linux API emulation layer providing
|
||||
substantial Linux API functionality
|
||||
|
||||
. A collection of tools which provide Linux look and feel.
|
||||
|
||||
The Cygwin DLL currently works with all recent, commercially released x86 32
|
||||
bit and 64 bit versions of Windows, with the exception of Windows CE.
|
||||
|
||||
On both MinGW and Cygwin, PCRE should build correctly using:
|
||||
|
||||
./configure && make && make install
|
||||
|
||||
This should create two libraries called libpcre and libpcreposix, and, if you
|
||||
have enabled building the C++ wrapper, a third one called libpcrecpp. These are
|
||||
independent libraries: when you link with libpcreposix or libpcrecpp you must
|
||||
also link with libpcre, which contains the basic functions. (Some earlier
|
||||
releases of PCRE included the basic libpcre functions in libpcreposix. This no
|
||||
longer happens.)
|
||||
|
||||
A user submitted a special-purpose patch that makes it easy to create
|
||||
"pcre.dll" under mingw32 using the "msys" environment. It provides "pcre.dll"
|
||||
as a special target. If you use this target, no other files are built, and in
|
||||
particular, the pcretest and pcregrep programs are not built. An example of how
|
||||
this might be used is:
|
||||
|
||||
./configure --enable-utf --disable-cpp CFLAGS="-03 -s"; make pcre.dll
|
||||
|
||||
Using Cygwin's compiler generates libraries and executables that depend on
|
||||
cygwin1.dll. If a library that is generated this way is distributed,
|
||||
cygwin1.dll has to be distributed as well. Since cygwin1.dll is under the GPL
|
||||
licence, this forces not only PCRE to be under the GPL, but also the entire
|
||||
application. A distributor who wants to keep their own code proprietary must
|
||||
purchase an appropriate Cygwin licence.
|
||||
|
||||
MinGW has no such restrictions. The MinGW compiler generates a library or
|
||||
executable that can run standalone on Windows without any third party dll or
|
||||
licensing issues.
|
||||
|
||||
But there is more complication:
|
||||
|
||||
If a Cygwin user uses the -mno-cygwin Cygwin gcc flag, what that really does is
|
||||
to tell Cygwin's gcc to use the MinGW gcc. Cygwin's gcc is only acting as a
|
||||
front end to MinGW's gcc (if you install Cygwin's gcc, you get both Cygwin's
|
||||
gcc and MinGW's gcc). So, a user can:
|
||||
|
||||
. Build native binaries by using MinGW or by getting Cygwin and using
|
||||
-mno-cygwin.
|
||||
|
||||
. Build binaries that depend on cygwin1.dll by using Cygwin with the normal
|
||||
compiler flags.
|
||||
|
||||
The test files that are supplied with PCRE are in UNIX format, with LF
|
||||
characters as line terminators. Unless your PCRE library uses a default newline
|
||||
option that includes LF as a valid newline, it may be necessary to change the
|
||||
line terminators in the test files to get some of the tests to work.
|
||||
|
||||
|
||||
BUILDING PCRE ON WINDOWS WITH CMAKE
|
||||
|
||||
CMake is an alternative configuration facility that can be used instead of
|
||||
"configure". CMake creates project files (make files, solution files, etc.)
|
||||
tailored to numerous development environments, including Visual Studio,
|
||||
Borland, Msys, MinGW, NMake, and Unix. If possible, use short paths with no
|
||||
spaces in the names for your CMake installation and your PCRE source and build
|
||||
directories.
|
||||
|
||||
The following instructions were contributed by a PCRE user. If they are not
|
||||
followed exactly, errors may occur. In the event that errors do occur, it is
|
||||
recommended that you delete the CMake cache before attempting to repeat the
|
||||
CMake build process. In the CMake GUI, the cache can be deleted by selecting
|
||||
"File > Delete Cache".
|
||||
|
||||
1. Install the latest CMake version available from http://www.cmake.org/, and
|
||||
ensure that cmake\bin is on your path.
|
||||
|
||||
2. Unzip (retaining folder structure) the PCRE source tree into a source
|
||||
directory such as C:\pcre. You should ensure your local date and time
|
||||
is not earlier than the file dates in your source dir if the release is
|
||||
very new.
|
||||
|
||||
3. Create a new, empty build directory, preferably a subdirectory of the
|
||||
source dir. For example, C:\pcre\pcre-xx\build.
|
||||
|
||||
4. Run cmake-gui from the Shell envirornment of your build tool, for example,
|
||||
Msys for Msys/MinGW or Visual Studio Command Prompt for VC/VC++. Do not try
|
||||
to start Cmake from the Windows Start menu, as this can lead to errors.
|
||||
|
||||
5. Enter C:\pcre\pcre-xx and C:\pcre\pcre-xx\build for the source and build
|
||||
directories, respectively.
|
||||
|
||||
6. Hit the "Configure" button.
|
||||
|
||||
7. Select the particular IDE / build tool that you are using (Visual
|
||||
Studio, MSYS makefiles, MinGW makefiles, etc.)
|
||||
|
||||
8. The GUI will then list several configuration options. This is where
|
||||
you can enable UTF-8 support or other PCRE optional features.
|
||||
|
||||
9. Hit "Configure" again. The adjacent "Generate" button should now be
|
||||
active.
|
||||
|
||||
10. Hit "Generate".
|
||||
|
||||
11. The build directory should now contain a usable build system, be it a
|
||||
solution file for Visual Studio, makefiles for MinGW, etc. Exit from
|
||||
cmake-gui and use the generated build system with your compiler or IDE.
|
||||
E.g., for MinGW you can run "make", or for Visual Studio, open the PCRE
|
||||
solution, select the desired configuration (Debug, or Release, etc.) and
|
||||
build the ALL_BUILD project.
|
||||
|
||||
12. If during configuration with cmake-gui you've elected to build the test
|
||||
programs, you can execute them by building the test project. E.g., for
|
||||
MinGW: "make test"; for Visual Studio build the RUN_TESTS project. The
|
||||
most recent build configuration is targeted by the tests. A summary of
|
||||
test results is presented. Complete test output is subsequently
|
||||
available for review in Testing\Temporary under your build dir.
|
||||
|
||||
|
||||
USE OF RELATIVE PATHS WITH CMAKE ON WINDOWS
|
||||
|
||||
A PCRE user comments as follows: I thought that others may want to know the
|
||||
current state of CMAKE_USE_RELATIVE_PATHS support on Windows. Here it is:
|
||||
|
||||
-- AdditionalIncludeDirectories is only partially modified (only the
|
||||
first path - see below)
|
||||
-- Only some of the contained file paths are modified - shown below for
|
||||
pcre.vcproj
|
||||
-- It properly modifies
|
||||
|
||||
I am sure CMake people can fix that if they want to. Until then one will
|
||||
need to replace existing absolute paths in project files with relative
|
||||
paths manually (e.g. from VS) - relative to project file location. I did
|
||||
just that before being told to try CMAKE_USE_RELATIVE_PATHS. Not a big
|
||||
deal.
|
||||
|
||||
AdditionalIncludeDirectories="E:\builds\pcre\build;E:\builds\pcre\pcre-7.5;"
|
||||
AdditionalIncludeDirectories=".;E:\builds\pcre\pcre-7.5;"
|
||||
|
||||
RelativePath="pcre.h"
|
||||
RelativePath="pcre_chartables.c"
|
||||
RelativePath="pcre_chartables.c.rule"
|
||||
|
||||
|
||||
TESTING WITH RUNTEST.BAT
|
||||
|
||||
If configured with CMake, building the test project ("make test" or building
|
||||
ALL_TESTS in Visual Studio) creates (and runs) pcre_test.bat (and depending
|
||||
on your configuration options, possibly other test programs) in the build
|
||||
directory. Pcre_test.bat runs RunTest.Bat with correct source and exe paths.
|
||||
|
||||
For manual testing with RunTest.bat, provided the build dir is a subdirectory
|
||||
of the source directory: Open command shell window. Chdir to the location
|
||||
of your pcretest.exe and pcregrep.exe programs. Call RunTest.bat with
|
||||
"..\RunTest.Bat" or "..\..\RunTest.bat" as appropriate.
|
||||
|
||||
To run only a particular test with RunTest.Bat provide a test number argument.
|
||||
|
||||
Otherwise:
|
||||
|
||||
1. Copy RunTest.bat into the directory where pcretest.exe and pcregrep.exe
|
||||
have been created.
|
||||
|
||||
2. Edit RunTest.bat to indentify the full or relative location of
|
||||
the pcre source (wherein which the testdata folder resides), e.g.:
|
||||
|
||||
set srcdir=C:\pcre\pcre-8.20
|
||||
|
||||
3. In a Windows command environment, chdir to the location of your bat and
|
||||
exe programs.
|
||||
|
||||
4. Run RunTest.bat. Test outputs will automatically be compared to expected
|
||||
results, and discrepancies will be identified in the console output.
|
||||
|
||||
To independently test the just-in-time compiler, run pcre_jit_test.exe.
|
||||
To test pcrecpp, run pcrecpp_unittest.exe, pcre_stringpiece_unittest.exe and
|
||||
pcre_scanner_unittest.exe.
|
||||
|
||||
|
||||
BUILDING UNDER WINDOWS CE WITH VISUAL STUDIO 200x
|
||||
|
||||
Vincent Richomme sent a zip archive of files to help with this process. They
|
||||
can be found in the file "pcre-vsbuild.zip" in the Contrib directory of the FTP
|
||||
site.
|
||||
|
||||
|
||||
BUILDING UNDER WINDOWS WITH BCC5.5
|
||||
|
||||
Michael Roy sent these comments about building PCRE under Windows with BCC5.5:
|
||||
|
||||
Some of the core BCC libraries have a version of PCRE from 1998 built in, which
|
||||
can lead to pcre_exec() giving an erroneous PCRE_ERROR_NULL from a version
|
||||
mismatch. I'm including an easy workaround below, if you'd like to include it
|
||||
in the non-unix instructions:
|
||||
|
||||
When linking a project with BCC5.5, pcre.lib must be included before any of the
|
||||
libraries cw32.lib, cw32i.lib, cw32mt.lib, and cw32mti.lib on the command line.
|
||||
|
||||
|
||||
BUILDING USING BORLAND C++ BUILDER 2007 (CB2007) AND HIGHER
|
||||
|
||||
A PCRE user sent these comments about this environment (see also the comment
|
||||
from another user that follows them):
|
||||
|
||||
The XE versions of C++ Builder come with a RegularExpressionsCore class which
|
||||
contain a version of TPerlRegEx. However, direct use of the C PCRE library may
|
||||
be desirable.
|
||||
|
||||
The default makevp.bat, however, supplied with PCRE builds a version of PCRE
|
||||
that is not usable with any version of C++ Builder because the compiler ships
|
||||
with an embedded version of PCRE, version 2.01 from 1998! [See also the note
|
||||
about BCC5.5 above.] If you want to use PCRE you'll need to rename the
|
||||
functions (pcre_compile to pcre_compile_bcc, etc) or do as I have done and just
|
||||
use the 16 bit versions. I'm using std::wstring everywhere anyway. Since the
|
||||
embedded version of PCRE does not have the 16 bit function names, there is no
|
||||
conflict.
|
||||
|
||||
Building PCRE using a C++ Builder static library project file (recommended):
|
||||
|
||||
1. Rename or remove pcre.h, pcreposi.h, and pcreposix.h from your C++ Builder
|
||||
original include path.
|
||||
|
||||
2. Download PCRE from pcre.org and extract to a directory.
|
||||
|
||||
3. Rename pcre_chartables.c.dist to pcre_chartables.c, pcre.h.generic to
|
||||
pcre.h, and config.h.generic to config.h.
|
||||
|
||||
4. Edit pcre.h and pcre_config.c so that they include config.h.
|
||||
|
||||
5. Edit config.h like so:
|
||||
|
||||
Comment out the following lines:
|
||||
#define PACKAGE "pcre"
|
||||
#define PACKAGE_BUGREPORT ""
|
||||
#define PACKAGE_NAME "PCRE"
|
||||
#define PACKAGE_STRING "PCRE 8.32"
|
||||
#define PACKAGE_TARNAME "pcre"
|
||||
#define PACKAGE_URL ""
|
||||
#define PACKAGE_VERSION "8.32"
|
||||
|
||||
Add the following lines:
|
||||
#ifndef SUPPORT_UTF
|
||||
#define SUPPORT_UTF 100 // any value is fine
|
||||
#endif
|
||||
|
||||
#ifndef SUPPORT_UCP
|
||||
#define SUPPORT_UCP 101 // any value is fine
|
||||
#endif
|
||||
|
||||
#ifndef SUPPORT_UCP
|
||||
#define SUPPORT_PCRE16 102 // any value is fine
|
||||
#endif
|
||||
|
||||
#ifndef SUPPORT_UTF8
|
||||
#define SUPPORT_UTF8 103 // any value is fine
|
||||
#endif
|
||||
|
||||
6. Build a C++ Builder project using the IDE. Go to File / New / Other and
|
||||
choose Static Library. You can name it pcre.cbproj or whatever. Now set your
|
||||
paths by going to Project / Options. Set the Include path. Do this from the
|
||||
"Base" option to apply to both Release and Debug builds. Now add the following
|
||||
files to the project:
|
||||
|
||||
pcre.h
|
||||
pcre16_byte_order.c
|
||||
pcre16_chartables.c
|
||||
pcre16_compile.c
|
||||
pcre16_config.c
|
||||
pcre16_dfa_exec.c
|
||||
pcre16_exec.c
|
||||
pcre16_fullinfo.c
|
||||
pcre16_get.c
|
||||
pcre16_globals.c
|
||||
pcre16_maketables.c
|
||||
pcre16_newline.c
|
||||
pcre16_ord2utf16.c
|
||||
pcre16_printint.c
|
||||
pcre16_refcount.c
|
||||
pcre16_string_utils.c
|
||||
pcre16_study.c
|
||||
pcre16_tables.c
|
||||
pcre16_ucd.c
|
||||
pcre16_utf16_utils.c
|
||||
pcre16_valid_utf16.c
|
||||
pcre16_version.c
|
||||
pcre16_xclass.c
|
||||
|
||||
//Optional
|
||||
pcre_version.c
|
||||
|
||||
7. After compiling the .lib file, copy the .lib and header files to a project
|
||||
you want to use PCRE with. Enjoy.
|
||||
|
||||
Optional ... Building PCRE using the makevp.bat file:
|
||||
|
||||
1. Edit makevp_c.txt and makevp_l.txt and change all the names to the 16 bit
|
||||
versions.
|
||||
|
||||
2. Edit makevp.bat and set the path to C++ Builder. Run makevp.bat.
|
||||
|
||||
Another PCRE user added this comment:
|
||||
|
||||
Another approach I successfully used for some years with BCB 5 and 6 was to
|
||||
make sure that include and library paths of PCRE are configured before the
|
||||
default paths of the IDE in the dialogs where one can manage those paths.
|
||||
Afterwards one can open the project files using a text editor and manually add
|
||||
the self created library for pcre itself, pcrecpp doesn't ship with the IDE, in
|
||||
the library nodes where the IDE manages its own libraries to link against in
|
||||
front of the IDE-own libraries. This way one can use the default PCRE function
|
||||
names without getting access violations on runtime.
|
||||
|
||||
<ALLLIB value="libpcre.lib $(LIBFILES) $(LIBRARIES) import32.lib cp32mt.lib"/>
|
||||
|
||||
|
||||
BUILDING PCRE ON OPENVMS
|
||||
|
||||
Stephen Hoffman sent the following, in December 2012:
|
||||
|
||||
"Here <http://labs.hoffmanlabs.com/node/1847> is a very short write-up on the
|
||||
OpenVMS port and here
|
||||
|
||||
<http://labs.hoffmanlabs.com/labsnotes/pcre-vms-8_32.zip>
|
||||
|
||||
is a zip with the OpenVMS files, and with one modified testing-related PCRE
|
||||
file." This is a port of PCRE 8.32.
|
||||
|
||||
Earlier, Dan Mooney sent the following comments about building PCRE on OpenVMS.
|
||||
They relate to an older version of PCRE that used fewer source files, so the
|
||||
exact commands will need changing. See the current list of source files above.
|
||||
|
||||
"It was quite easy to compile and link the library. I don't have a formal
|
||||
make file but the attached file [reproduced below] contains the OpenVMS DCL
|
||||
commands I used to build the library. I had to add #define
|
||||
POSIX_MALLOC_THRESHOLD 10 to pcre.h since it was not defined anywhere.
|
||||
|
||||
The library was built on:
|
||||
O/S: HP OpenVMS v7.3-1
|
||||
Compiler: Compaq C v6.5-001-48BCD
|
||||
Linker: vA13-01
|
||||
|
||||
The test results did not match 100% due to the issues you mention in your
|
||||
documentation regarding isprint(), iscntrl(), isgraph() and ispunct(). I
|
||||
modified some of the character tables temporarily and was able to get the
|
||||
results to match. Tests using the fr locale did not match since I don't have
|
||||
that locale loaded. The study size was always reported to be 3 less than the
|
||||
value in the standard test output files."
|
||||
|
||||
=========================
|
||||
$! This DCL procedure builds PCRE on OpenVMS
|
||||
$!
|
||||
$! I followed the instructions in the non-unix-use file in the distribution.
|
||||
$!
|
||||
$ COMPILE == "CC/LIST/NOMEMBER_ALIGNMENT/PREFIX_LIBRARY_ENTRIES=ALL_ENTRIES
|
||||
$ COMPILE DFTABLES.C
|
||||
$ LINK/EXE=DFTABLES.EXE DFTABLES.OBJ
|
||||
$ RUN DFTABLES.EXE/OUTPUT=CHARTABLES.C
|
||||
$ COMPILE MAKETABLES.C
|
||||
$ COMPILE GET.C
|
||||
$ COMPILE STUDY.C
|
||||
$! I had to set POSIX_MALLOC_THRESHOLD to 10 in PCRE.H since the symbol
|
||||
$! did not seem to be defined anywhere.
|
||||
$! I edited pcre.h and added #DEFINE SUPPORT_UTF8 to enable UTF8 support.
|
||||
$ COMPILE PCRE.C
|
||||
$ LIB/CREATE PCRE MAKETABLES.OBJ, GET.OBJ, STUDY.OBJ, PCRE.OBJ
|
||||
$! I had to set POSIX_MALLOC_THRESHOLD to 10 in PCRE.H since the symbol
|
||||
$! did not seem to be defined anywhere.
|
||||
$ COMPILE PCREPOSIX.C
|
||||
$ LIB/CREATE PCREPOSIX PCREPOSIX.OBJ
|
||||
$ COMPILE PCRETEST.C
|
||||
$ LINK/EXE=PCRETEST.EXE PCRETEST.OBJ, PCRE/LIB, PCREPOSIX/LIB
|
||||
$! C programs that want access to command line arguments must be
|
||||
$! defined as a symbol
|
||||
$ PCRETEST :== "$ SYS$ROADSUSERS:[DMOONEY.REGEXP]PCRETEST.EXE"
|
||||
$! Arguments must be enclosed in quotes.
|
||||
$ PCRETEST "-C"
|
||||
$! Test results:
|
||||
$!
|
||||
$! The test results did not match 100%. The functions isprint(), iscntrl(),
|
||||
$! isgraph() and ispunct() on OpenVMS must not produce the same results
|
||||
$! as the system that built the test output files provided with the
|
||||
$! distribution.
|
||||
$!
|
||||
$! The study size did not match and was always 3 less on OpenVMS.
|
||||
$!
|
||||
$! Locale could not be set to fr
|
||||
$!
|
||||
=========================
|
||||
|
||||
|
||||
BUILDING PCRE ON STRATUS OPENVOS
|
||||
|
||||
These notes on the port of PCRE to VOS (lightly edited) were supplied by
|
||||
Ashutosh Warikoo, whose email address has the local part awarikoo and the
|
||||
domain nse.co.in. The port was for version 7.9 in August 2009.
|
||||
|
||||
1. Building PCRE
|
||||
|
||||
I built pcre on OpenVOS Release 17.0.1at using GNU Tools 3.4a without any
|
||||
problems. I used the following packages to build PCRE:
|
||||
|
||||
ftp://ftp.stratus.com/pub/vos/posix/ga/posix.save.evf.gz
|
||||
|
||||
Please read and follow the instructions that come with these packages. To start
|
||||
the build of pcre, from the root of the package type:
|
||||
|
||||
./build.sh
|
||||
|
||||
2. Installing PCRE
|
||||
|
||||
Once you have successfully built PCRE, login to the SysAdmin group, switch to
|
||||
the root user, and type
|
||||
|
||||
[ !create_dir (master_disk)>usr --if needed ]
|
||||
[ !create_dir (master_disk)>usr>local --if needed ]
|
||||
!gmake install
|
||||
|
||||
This installs PCRE and its man pages into /usr/local. You can add
|
||||
(master_disk)>usr>local>bin to your command search paths, or if you are in
|
||||
BASH, add /usr/local/bin to the PATH environment variable.
|
||||
|
||||
4. Restrictions
|
||||
|
||||
This port requires readline library optionally. However during the build I
|
||||
faced some yet unexplored errors while linking with readline. As it was an
|
||||
optional component I chose to disable it.
|
||||
|
||||
5. Known Problems
|
||||
|
||||
I ran the test suite, but you will have to be your own judge of whether this
|
||||
command, and this port, suits your purposes. If you find any problems that
|
||||
appear to be related to the port itself, please let me know. Please see the
|
||||
build.log file in the root of the package also.
|
||||
|
||||
|
||||
BUILDING PCRE ON NATIVE Z/OS AND Z/VM
|
||||
|
||||
z/OS and z/VM are operating systems for mainframe computers, produced by IBM.
|
||||
The character code used is EBCDIC, not ASCII or Unicode. In z/OS, UNIX APIs and
|
||||
applications can be supported through UNIX System Services, and in such an
|
||||
environment PCRE can be built in the same way as in other systems. However, in
|
||||
native z/OS (without UNIX System Services) and in z/VM, special ports are
|
||||
required. For details, please see this web site:
|
||||
|
||||
http://www.zaconsultants.net
|
||||
|
||||
You may download PCRE from WWW.CBTTAPE.ORG, file 882. Everything, source and
|
||||
executable, is in EBCDIC and native z/OS file formats and this is the
|
||||
recommended download site.
|
||||
|
||||
==========================
|
||||
Last Updated: 25 June 2015
|
||||
@@ -0,0 +1,1002 @@
|
||||
README file for PCRE (Perl-compatible regular expression library)
|
||||
-----------------------------------------------------------------
|
||||
|
||||
NOTE: This set of files relates to PCRE releases that use the original API,
|
||||
with library names libpcre, libpcre16, and libpcre32. January 2015 saw the
|
||||
first release of a new API, known as PCRE2, with release numbers starting at
|
||||
10.00 and library names libpcre2-8, libpcre2-16, and libpcre2-32. The old
|
||||
libraries (now called PCRE1) are still being maintained for bug fixes, but
|
||||
there will be no new development. New projects are advised to use the new PCRE2
|
||||
libraries.
|
||||
|
||||
|
||||
The latest release of PCRE1 is always available in three alternative formats
|
||||
from:
|
||||
|
||||
ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-xxx.tar.gz
|
||||
ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-xxx.tar.bz2
|
||||
ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-xxx.zip
|
||||
|
||||
There is a mailing list for discussion about the development of PCRE at
|
||||
pcre-dev@exim.org. You can access the archives and subscribe or manage your
|
||||
subscription here:
|
||||
|
||||
https://lists.exim.org/mailman/listinfo/pcre-dev
|
||||
|
||||
Please read the NEWS file if you are upgrading from a previous release.
|
||||
The contents of this README file are:
|
||||
|
||||
The PCRE APIs
|
||||
Documentation for PCRE
|
||||
Contributions by users of PCRE
|
||||
Building PCRE on non-Unix-like systems
|
||||
Building PCRE without using autotools
|
||||
Building PCRE using autotools
|
||||
Retrieving configuration information
|
||||
Shared libraries
|
||||
Cross-compiling using autotools
|
||||
Using HP's ANSI C++ compiler (aCC)
|
||||
Compiling in Tru64 using native compilers
|
||||
Using Sun's compilers for Solaris
|
||||
Using PCRE from MySQL
|
||||
Making new tarballs
|
||||
Testing PCRE
|
||||
Character tables
|
||||
File manifest
|
||||
|
||||
|
||||
The PCRE APIs
|
||||
-------------
|
||||
|
||||
PCRE is written in C, and it has its own API. There are three sets of
|
||||
functions, one for the 8-bit library, which processes strings of bytes, one for
|
||||
the 16-bit library, which processes strings of 16-bit values, and one for the
|
||||
32-bit library, which processes strings of 32-bit values. The distribution also
|
||||
includes a set of C++ wrapper functions (see the pcrecpp man page for details),
|
||||
courtesy of Google Inc., which can be used to call the 8-bit PCRE library from
|
||||
C++. Other C++ wrappers have been created from time to time. See, for example:
|
||||
https://github.com/YasserAsmi/regexp, which aims to be simple and similar in
|
||||
style to the C API.
|
||||
|
||||
The distribution also contains a set of C wrapper functions (again, just for
|
||||
the 8-bit library) that are based on the POSIX regular expression API (see the
|
||||
pcreposix man page). These end up in the library called libpcreposix. Note that
|
||||
this just provides a POSIX calling interface to PCRE; the regular expressions
|
||||
themselves still follow Perl syntax and semantics. The POSIX API is restricted,
|
||||
and does not give full access to all of PCRE's facilities.
|
||||
|
||||
The header file for the POSIX-style functions is called pcreposix.h. The
|
||||
official POSIX name is regex.h, but I did not want to risk possible problems
|
||||
with existing files of that name by distributing it that way. To use PCRE with
|
||||
an existing program that uses the POSIX API, pcreposix.h will have to be
|
||||
renamed or pointed at by a link.
|
||||
|
||||
If you are using the POSIX interface to PCRE and there is already a POSIX regex
|
||||
library installed on your system, as well as worrying about the regex.h header
|
||||
file (as mentioned above), you must also take care when linking programs to
|
||||
ensure that they link with PCRE's libpcreposix library. Otherwise they may pick
|
||||
up the POSIX functions of the same name from the other library.
|
||||
|
||||
One way of avoiding this confusion is to compile PCRE with the addition of
|
||||
-Dregcomp=PCREregcomp (and similarly for the other POSIX functions) to the
|
||||
compiler flags (CFLAGS if you are using "configure" -- see below). This has the
|
||||
effect of renaming the functions so that the names no longer clash. Of course,
|
||||
you have to do the same thing for your applications, or write them using the
|
||||
new names.
|
||||
|
||||
|
||||
Documentation for PCRE
|
||||
----------------------
|
||||
|
||||
If you install PCRE in the normal way on a Unix-like system, you will end up
|
||||
with a set of man pages whose names all start with "pcre". The one that is just
|
||||
called "pcre" lists all the others. In addition to these man pages, the PCRE
|
||||
documentation is supplied in two other forms:
|
||||
|
||||
1. There are files called doc/pcre.txt, doc/pcregrep.txt, and
|
||||
doc/pcretest.txt in the source distribution. The first of these is a
|
||||
concatenation of the text forms of all the section 3 man pages except
|
||||
the listing of pcredemo.c and those that summarize individual functions.
|
||||
The other two are the text forms of the section 1 man pages for the
|
||||
pcregrep and pcretest commands. These text forms are provided for ease of
|
||||
scanning with text editors or similar tools. They are installed in
|
||||
<prefix>/share/doc/pcre, where <prefix> is the installation prefix
|
||||
(defaulting to /usr/local).
|
||||
|
||||
2. A set of files containing all the documentation in HTML form, hyperlinked
|
||||
in various ways, and rooted in a file called index.html, is distributed in
|
||||
doc/html and installed in <prefix>/share/doc/pcre/html.
|
||||
|
||||
Users of PCRE have contributed files containing the documentation for various
|
||||
releases in CHM format. These can be found in the Contrib directory of the FTP
|
||||
site (see next section).
|
||||
|
||||
|
||||
Contributions by users of PCRE
|
||||
------------------------------
|
||||
|
||||
You can find contributions from PCRE users in the directory
|
||||
|
||||
ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/Contrib
|
||||
|
||||
There is a README file giving brief descriptions of what they are. Some are
|
||||
complete in themselves; others are pointers to URLs containing relevant files.
|
||||
Some of this material is likely to be well out-of-date. Several of the earlier
|
||||
contributions provided support for compiling PCRE on various flavours of
|
||||
Windows (I myself do not use Windows). Nowadays there is more Windows support
|
||||
in the standard distribution, so these contibutions have been archived.
|
||||
|
||||
A PCRE user maintains downloadable Windows binaries of the pcregrep and
|
||||
pcretest programs here:
|
||||
|
||||
http://www.rexegg.com/pcregrep-pcretest.html
|
||||
|
||||
|
||||
Building PCRE on non-Unix-like systems
|
||||
--------------------------------------
|
||||
|
||||
For a non-Unix-like system, please read the comments in the file
|
||||
NON-AUTOTOOLS-BUILD, though if your system supports the use of "configure" and
|
||||
"make" you may be able to build PCRE using autotools in the same way as for
|
||||
many Unix-like systems.
|
||||
|
||||
PCRE can also be configured using the GUI facility provided by CMake's
|
||||
cmake-gui command. This creates Makefiles, solution files, etc. The file
|
||||
NON-AUTOTOOLS-BUILD has information about CMake.
|
||||
|
||||
PCRE has been compiled on many different operating systems. It should be
|
||||
straightforward to build PCRE on any system that has a Standard C compiler and
|
||||
library, because it uses only Standard C functions.
|
||||
|
||||
|
||||
Building PCRE without using autotools
|
||||
-------------------------------------
|
||||
|
||||
The use of autotools (in particular, libtool) is problematic in some
|
||||
environments, even some that are Unix or Unix-like. See the NON-AUTOTOOLS-BUILD
|
||||
file for ways of building PCRE without using autotools.
|
||||
|
||||
|
||||
Building PCRE using autotools
|
||||
-----------------------------
|
||||
|
||||
If you are using HP's ANSI C++ compiler (aCC), please see the special note
|
||||
in the section entitled "Using HP's ANSI C++ compiler (aCC)" below.
|
||||
|
||||
The following instructions assume the use of the widely used "configure; make;
|
||||
make install" (autotools) process.
|
||||
|
||||
To build PCRE on system that supports autotools, first run the "configure"
|
||||
command from the PCRE distribution directory, with your current directory set
|
||||
to the directory where you want the files to be created. This command is a
|
||||
standard GNU "autoconf" configuration script, for which generic instructions
|
||||
are supplied in the file INSTALL.
|
||||
|
||||
Most commonly, people build PCRE within its own distribution directory, and in
|
||||
this case, on many systems, just running "./configure" is sufficient. However,
|
||||
the usual methods of changing standard defaults are available. For example:
|
||||
|
||||
CFLAGS='-O2 -Wall' ./configure --prefix=/opt/local
|
||||
|
||||
This command specifies that the C compiler should be run with the flags '-O2
|
||||
-Wall' instead of the default, and that "make install" should install PCRE
|
||||
under /opt/local instead of the default /usr/local.
|
||||
|
||||
If you want to build in a different directory, just run "configure" with that
|
||||
directory as current. For example, suppose you have unpacked the PCRE source
|
||||
into /source/pcre/pcre-xxx, but you want to build it in /build/pcre/pcre-xxx:
|
||||
|
||||
cd /build/pcre/pcre-xxx
|
||||
/source/pcre/pcre-xxx/configure
|
||||
|
||||
PCRE is written in C and is normally compiled as a C library. However, it is
|
||||
possible to build it as a C++ library, though the provided building apparatus
|
||||
does not have any features to support this.
|
||||
|
||||
There are some optional features that can be included or omitted from the PCRE
|
||||
library. They are also documented in the pcrebuild man page.
|
||||
|
||||
. By default, both shared and static libraries are built. You can change this
|
||||
by adding one of these options to the "configure" command:
|
||||
|
||||
--disable-shared
|
||||
--disable-static
|
||||
|
||||
(See also "Shared libraries on Unix-like systems" below.)
|
||||
|
||||
. By default, only the 8-bit library is built. If you add --enable-pcre16 to
|
||||
the "configure" command, the 16-bit library is also built. If you add
|
||||
--enable-pcre32 to the "configure" command, the 32-bit library is also built.
|
||||
If you want only the 16-bit or 32-bit library, use --disable-pcre8 to disable
|
||||
building the 8-bit library.
|
||||
|
||||
. If you are building the 8-bit library and want to suppress the building of
|
||||
the C++ wrapper library, you can add --disable-cpp to the "configure"
|
||||
command. Otherwise, when "configure" is run without --disable-pcre8, it will
|
||||
try to find a C++ compiler and C++ header files, and if it succeeds, it will
|
||||
try to build the C++ wrapper.
|
||||
|
||||
. If you want to include support for just-in-time compiling, which can give
|
||||
large performance improvements on certain platforms, add --enable-jit to the
|
||||
"configure" command. This support is available only for certain hardware
|
||||
architectures. If you try to enable it on an unsupported architecture, there
|
||||
will be a compile time error.
|
||||
|
||||
. When JIT support is enabled, pcregrep automatically makes use of it, unless
|
||||
you add --disable-pcregrep-jit to the "configure" command.
|
||||
|
||||
. If you want to make use of the support for UTF-8 Unicode character strings in
|
||||
the 8-bit library, or UTF-16 Unicode character strings in the 16-bit library,
|
||||
or UTF-32 Unicode character strings in the 32-bit library, you must add
|
||||
--enable-utf to the "configure" command. Without it, the code for handling
|
||||
UTF-8, UTF-16 and UTF-8 is not included in the relevant library. Even
|
||||
when --enable-utf is included, the use of a UTF encoding still has to be
|
||||
enabled by an option at run time. When PCRE is compiled with this option, its
|
||||
input can only either be ASCII or UTF-8/16/32, even when running on EBCDIC
|
||||
platforms. It is not possible to use both --enable-utf and --enable-ebcdic at
|
||||
the same time.
|
||||
|
||||
. There are no separate options for enabling UTF-8, UTF-16 and UTF-32
|
||||
independently because that would allow ridiculous settings such as requesting
|
||||
UTF-16 support while building only the 8-bit library. However, the option
|
||||
--enable-utf8 is retained for backwards compatibility with earlier releases
|
||||
that did not support 16-bit or 32-bit character strings. It is synonymous with
|
||||
--enable-utf. It is not possible to configure one library with UTF support
|
||||
and the other without in the same configuration.
|
||||
|
||||
. If, in addition to support for UTF-8/16/32 character strings, you want to
|
||||
include support for the \P, \p, and \X sequences that recognize Unicode
|
||||
character properties, you must add --enable-unicode-properties to the
|
||||
"configure" command. This adds about 30K to the size of the library (in the
|
||||
form of a property table); only the basic two-letter properties such as Lu
|
||||
are supported.
|
||||
|
||||
. You can build PCRE to recognize either CR or LF or the sequence CRLF or any
|
||||
of the preceding, or any of the Unicode newline sequences as indicating the
|
||||
end of a line. Whatever you specify at build time is the default; the caller
|
||||
of PCRE can change the selection at run time. The default newline indicator
|
||||
is a single LF character (the Unix standard). You can specify the default
|
||||
newline indicator by adding --enable-newline-is-cr or --enable-newline-is-lf
|
||||
or --enable-newline-is-crlf or --enable-newline-is-anycrlf or
|
||||
--enable-newline-is-any to the "configure" command, respectively.
|
||||
|
||||
If you specify --enable-newline-is-cr or --enable-newline-is-crlf, some of
|
||||
the standard tests will fail, because the lines in the test files end with
|
||||
LF. Even if the files are edited to change the line endings, there are likely
|
||||
to be some failures. With --enable-newline-is-anycrlf or
|
||||
--enable-newline-is-any, many tests should succeed, but there may be some
|
||||
failures.
|
||||
|
||||
. By default, the sequence \R in a pattern matches any Unicode line ending
|
||||
sequence. This is independent of the option specifying what PCRE considers to
|
||||
be the end of a line (see above). However, the caller of PCRE can restrict \R
|
||||
to match only CR, LF, or CRLF. You can make this the default by adding
|
||||
--enable-bsr-anycrlf to the "configure" command (bsr = "backslash R").
|
||||
|
||||
. When called via the POSIX interface, PCRE uses malloc() to get additional
|
||||
storage for processing capturing parentheses if there are more than 10 of
|
||||
them in a pattern. You can increase this threshold by setting, for example,
|
||||
|
||||
--with-posix-malloc-threshold=20
|
||||
|
||||
on the "configure" command.
|
||||
|
||||
. PCRE has a counter that limits the depth of nesting of parentheses in a
|
||||
pattern. This limits the amount of system stack that a pattern uses when it
|
||||
is compiled. The default is 250, but you can change it by setting, for
|
||||
example,
|
||||
|
||||
--with-parens-nest-limit=500
|
||||
|
||||
. PCRE has a counter that can be set to limit the amount of resources it uses
|
||||
when matching a pattern. If the limit is exceeded during a match, the match
|
||||
fails. The default is ten million. You can change the default by setting, for
|
||||
example,
|
||||
|
||||
--with-match-limit=500000
|
||||
|
||||
on the "configure" command. This is just the default; individual calls to
|
||||
pcre_exec() can supply their own value. There is more discussion on the
|
||||
pcreapi man page.
|
||||
|
||||
. There is a separate counter that limits the depth of recursive function calls
|
||||
during a matching process. This also has a default of ten million, which is
|
||||
essentially "unlimited". You can change the default by setting, for example,
|
||||
|
||||
--with-match-limit-recursion=500000
|
||||
|
||||
Recursive function calls use up the runtime stack; running out of stack can
|
||||
cause programs to crash in strange ways. There is a discussion about stack
|
||||
sizes in the pcrestack man page.
|
||||
|
||||
. The default maximum compiled pattern size is around 64K. You can increase
|
||||
this by adding --with-link-size=3 to the "configure" command. In the 8-bit
|
||||
library, PCRE then uses three bytes instead of two for offsets to different
|
||||
parts of the compiled pattern. In the 16-bit library, --with-link-size=3 is
|
||||
the same as --with-link-size=4, which (in both libraries) uses four-byte
|
||||
offsets. Increasing the internal link size reduces performance. In the 32-bit
|
||||
library, the only supported link size is 4.
|
||||
|
||||
. You can build PCRE so that its internal match() function that is called from
|
||||
pcre_exec() does not call itself recursively. Instead, it uses memory blocks
|
||||
obtained from the heap via the special functions pcre_stack_malloc() and
|
||||
pcre_stack_free() to save data that would otherwise be saved on the stack. To
|
||||
build PCRE like this, use
|
||||
|
||||
--disable-stack-for-recursion
|
||||
|
||||
on the "configure" command. PCRE runs more slowly in this mode, but it may be
|
||||
necessary in environments with limited stack sizes. This applies only to the
|
||||
normal execution of the pcre_exec() function; if JIT support is being
|
||||
successfully used, it is not relevant. Equally, it does not apply to
|
||||
pcre_dfa_exec(), which does not use deeply nested recursion. There is a
|
||||
discussion about stack sizes in the pcrestack man page.
|
||||
|
||||
. For speed, PCRE uses four tables for manipulating and identifying characters
|
||||
whose code point values are less than 256. By default, it uses a set of
|
||||
tables for ASCII encoding that is part of the distribution. If you specify
|
||||
|
||||
--enable-rebuild-chartables
|
||||
|
||||
a program called dftables is compiled and run in the default C locale when
|
||||
you obey "make". It builds a source file called pcre_chartables.c. If you do
|
||||
not specify this option, pcre_chartables.c is created as a copy of
|
||||
pcre_chartables.c.dist. See "Character tables" below for further information.
|
||||
|
||||
. It is possible to compile PCRE for use on systems that use EBCDIC as their
|
||||
character code (as opposed to ASCII/Unicode) by specifying
|
||||
|
||||
--enable-ebcdic
|
||||
|
||||
This automatically implies --enable-rebuild-chartables (see above). However,
|
||||
when PCRE is built this way, it always operates in EBCDIC. It cannot support
|
||||
both EBCDIC and UTF-8/16/32. There is a second option, --enable-ebcdic-nl25,
|
||||
which specifies that the code value for the EBCDIC NL character is 0x25
|
||||
instead of the default 0x15.
|
||||
|
||||
. In environments where valgrind is installed, if you specify
|
||||
|
||||
--enable-valgrind
|
||||
|
||||
PCRE will use valgrind annotations to mark certain memory regions as
|
||||
unaddressable. This allows it to detect invalid memory accesses, and is
|
||||
mostly useful for debugging PCRE itself.
|
||||
|
||||
. In environments where the gcc compiler is used and lcov version 1.6 or above
|
||||
is installed, if you specify
|
||||
|
||||
--enable-coverage
|
||||
|
||||
the build process implements a code coverage report for the test suite. The
|
||||
report is generated by running "make coverage". If ccache is installed on
|
||||
your system, it must be disabled when building PCRE for coverage reporting.
|
||||
You can do this by setting the environment variable CCACHE_DISABLE=1 before
|
||||
running "make" to build PCRE. There is more information about coverage
|
||||
reporting in the "pcrebuild" documentation.
|
||||
|
||||
. The pcregrep program currently supports only 8-bit data files, and so
|
||||
requires the 8-bit PCRE library. It is possible to compile pcregrep to use
|
||||
libz and/or libbz2, in order to read .gz and .bz2 files (respectively), by
|
||||
specifying one or both of
|
||||
|
||||
--enable-pcregrep-libz
|
||||
--enable-pcregrep-libbz2
|
||||
|
||||
Of course, the relevant libraries must be installed on your system.
|
||||
|
||||
. The default size (in bytes) of the internal buffer used by pcregrep can be
|
||||
set by, for example:
|
||||
|
||||
--with-pcregrep-bufsize=51200
|
||||
|
||||
The value must be a plain integer. The default is 20480.
|
||||
|
||||
. It is possible to compile pcretest so that it links with the libreadline
|
||||
or libedit libraries, by specifying, respectively,
|
||||
|
||||
--enable-pcretest-libreadline or --enable-pcretest-libedit
|
||||
|
||||
If this is done, when pcretest's input is from a terminal, it reads it using
|
||||
the readline() function. This provides line-editing and history facilities.
|
||||
Note that libreadline is GPL-licenced, so if you distribute a binary of
|
||||
pcretest linked in this way, there may be licensing issues. These can be
|
||||
avoided by linking with libedit (which has a BSD licence) instead.
|
||||
|
||||
Enabling libreadline causes the -lreadline option to be added to the pcretest
|
||||
build. In many operating environments with a sytem-installed readline
|
||||
library this is sufficient. However, in some environments (e.g. if an
|
||||
unmodified distribution version of readline is in use), it may be necessary
|
||||
to specify something like LIBS="-lncurses" as well. This is because, to quote
|
||||
the readline INSTALL, "Readline uses the termcap functions, but does not link
|
||||
with the termcap or curses library itself, allowing applications which link
|
||||
with readline the to choose an appropriate library." If you get error
|
||||
messages about missing functions tgetstr, tgetent, tputs, tgetflag, or tgoto,
|
||||
this is the problem, and linking with the ncurses library should fix it.
|
||||
|
||||
The "configure" script builds the following files for the basic C library:
|
||||
|
||||
. Makefile the makefile that builds the library
|
||||
. config.h build-time configuration options for the library
|
||||
. pcre.h the public PCRE header file
|
||||
. pcre-config script that shows the building settings such as CFLAGS
|
||||
that were set for "configure"
|
||||
. libpcre.pc ) data for the pkg-config command
|
||||
. libpcre16.pc )
|
||||
. libpcre32.pc )
|
||||
. libpcreposix.pc )
|
||||
. libtool script that builds shared and/or static libraries
|
||||
|
||||
Versions of config.h and pcre.h are distributed in the PCRE tarballs under the
|
||||
names config.h.generic and pcre.h.generic. These are provided for those who
|
||||
have to built PCRE without using "configure" or CMake. If you use "configure"
|
||||
or CMake, the .generic versions are not used.
|
||||
|
||||
When building the 8-bit library, if a C++ compiler is found, the following
|
||||
files are also built:
|
||||
|
||||
. libpcrecpp.pc data for the pkg-config command
|
||||
. pcrecpparg.h header file for calling PCRE via the C++ wrapper
|
||||
. pcre_stringpiece.h header for the C++ "stringpiece" functions
|
||||
|
||||
The "configure" script also creates config.status, which is an executable
|
||||
script that can be run to recreate the configuration, and config.log, which
|
||||
contains compiler output from tests that "configure" runs.
|
||||
|
||||
Once "configure" has run, you can run "make". This builds the the libraries
|
||||
libpcre, libpcre16 and/or libpcre32, and a test program called pcretest. If you
|
||||
enabled JIT support with --enable-jit, a test program called pcre_jit_test is
|
||||
built as well.
|
||||
|
||||
If the 8-bit library is built, libpcreposix and the pcregrep command are also
|
||||
built, and if a C++ compiler was found on your system, and you did not disable
|
||||
it with --disable-cpp, "make" builds the C++ wrapper library, which is called
|
||||
libpcrecpp, as well as some test programs called pcrecpp_unittest,
|
||||
pcre_scanner_unittest, and pcre_stringpiece_unittest.
|
||||
|
||||
The command "make check" runs all the appropriate tests. Details of the PCRE
|
||||
tests are given below in a separate section of this document.
|
||||
|
||||
You can use "make install" to install PCRE into live directories on your
|
||||
system. The following are installed (file names are all relative to the
|
||||
<prefix> that is set when "configure" is run):
|
||||
|
||||
Commands (bin):
|
||||
pcretest
|
||||
pcregrep (if 8-bit support is enabled)
|
||||
pcre-config
|
||||
|
||||
Libraries (lib):
|
||||
libpcre16 (if 16-bit support is enabled)
|
||||
libpcre32 (if 32-bit support is enabled)
|
||||
libpcre (if 8-bit support is enabled)
|
||||
libpcreposix (if 8-bit support is enabled)
|
||||
libpcrecpp (if 8-bit and C++ support is enabled)
|
||||
|
||||
Configuration information (lib/pkgconfig):
|
||||
libpcre16.pc
|
||||
libpcre32.pc
|
||||
libpcre.pc
|
||||
libpcreposix.pc
|
||||
libpcrecpp.pc (if C++ support is enabled)
|
||||
|
||||
Header files (include):
|
||||
pcre.h
|
||||
pcreposix.h
|
||||
pcre_scanner.h )
|
||||
pcre_stringpiece.h ) if C++ support is enabled
|
||||
pcrecpp.h )
|
||||
pcrecpparg.h )
|
||||
|
||||
Man pages (share/man/man{1,3}):
|
||||
pcregrep.1
|
||||
pcretest.1
|
||||
pcre-config.1
|
||||
pcre.3
|
||||
pcre*.3 (lots more pages, all starting "pcre")
|
||||
|
||||
HTML documentation (share/doc/pcre/html):
|
||||
index.html
|
||||
*.html (lots more pages, hyperlinked from index.html)
|
||||
|
||||
Text file documentation (share/doc/pcre):
|
||||
AUTHORS
|
||||
COPYING
|
||||
ChangeLog
|
||||
LICENCE
|
||||
NEWS
|
||||
README
|
||||
pcre.txt (a concatenation of the man(3) pages)
|
||||
pcretest.txt the pcretest man page
|
||||
pcregrep.txt the pcregrep man page
|
||||
pcre-config.txt the pcre-config man page
|
||||
|
||||
If you want to remove PCRE from your system, you can run "make uninstall".
|
||||
This removes all the files that "make install" installed. However, it does not
|
||||
remove any directories, because these are often shared with other programs.
|
||||
|
||||
|
||||
Retrieving configuration information
|
||||
------------------------------------
|
||||
|
||||
Running "make install" installs the command pcre-config, which can be used to
|
||||
recall information about the PCRE configuration and installation. For example:
|
||||
|
||||
pcre-config --version
|
||||
|
||||
prints the version number, and
|
||||
|
||||
pcre-config --libs
|
||||
|
||||
outputs information about where the library is installed. This command can be
|
||||
included in makefiles for programs that use PCRE, saving the programmer from
|
||||
having to remember too many details.
|
||||
|
||||
The pkg-config command is another system for saving and retrieving information
|
||||
about installed libraries. Instead of separate commands for each library, a
|
||||
single command is used. For example:
|
||||
|
||||
pkg-config --cflags pcre
|
||||
|
||||
The data is held in *.pc files that are installed in a directory called
|
||||
<prefix>/lib/pkgconfig.
|
||||
|
||||
|
||||
Shared libraries
|
||||
----------------
|
||||
|
||||
The default distribution builds PCRE as shared libraries and static libraries,
|
||||
as long as the operating system supports shared libraries. Shared library
|
||||
support relies on the "libtool" script which is built as part of the
|
||||
"configure" process.
|
||||
|
||||
The libtool script is used to compile and link both shared and static
|
||||
libraries. They are placed in a subdirectory called .libs when they are newly
|
||||
built. The programs pcretest and pcregrep are built to use these uninstalled
|
||||
libraries (by means of wrapper scripts in the case of shared libraries). When
|
||||
you use "make install" to install shared libraries, pcregrep and pcretest are
|
||||
automatically re-built to use the newly installed shared libraries before being
|
||||
installed themselves. However, the versions left in the build directory still
|
||||
use the uninstalled libraries.
|
||||
|
||||
To build PCRE using static libraries only you must use --disable-shared when
|
||||
configuring it. For example:
|
||||
|
||||
./configure --prefix=/usr/gnu --disable-shared
|
||||
|
||||
Then run "make" in the usual way. Similarly, you can use --disable-static to
|
||||
build only shared libraries.
|
||||
|
||||
|
||||
Cross-compiling using autotools
|
||||
-------------------------------
|
||||
|
||||
You can specify CC and CFLAGS in the normal way to the "configure" command, in
|
||||
order to cross-compile PCRE for some other host. However, you should NOT
|
||||
specify --enable-rebuild-chartables, because if you do, the dftables.c source
|
||||
file is compiled and run on the local host, in order to generate the inbuilt
|
||||
character tables (the pcre_chartables.c file). This will probably not work,
|
||||
because dftables.c needs to be compiled with the local compiler, not the cross
|
||||
compiler.
|
||||
|
||||
When --enable-rebuild-chartables is not specified, pcre_chartables.c is created
|
||||
by making a copy of pcre_chartables.c.dist, which is a default set of tables
|
||||
that assumes ASCII code. Cross-compiling with the default tables should not be
|
||||
a problem.
|
||||
|
||||
If you need to modify the character tables when cross-compiling, you should
|
||||
move pcre_chartables.c.dist out of the way, then compile dftables.c by hand and
|
||||
run it on the local host to make a new version of pcre_chartables.c.dist.
|
||||
Then when you cross-compile PCRE this new version of the tables will be used.
|
||||
|
||||
|
||||
Using HP's ANSI C++ compiler (aCC)
|
||||
----------------------------------
|
||||
|
||||
Unless C++ support is disabled by specifying the "--disable-cpp" option of the
|
||||
"configure" script, you must include the "-AA" option in the CXXFLAGS
|
||||
environment variable in order for the C++ components to compile correctly.
|
||||
|
||||
Also, note that the aCC compiler on PA-RISC platforms may have a defect whereby
|
||||
needed libraries fail to get included when specifying the "-AA" compiler
|
||||
option. If you experience unresolved symbols when linking the C++ programs,
|
||||
use the workaround of specifying the following environment variable prior to
|
||||
running the "configure" script:
|
||||
|
||||
CXXLDFLAGS="-lstd_v2 -lCsup_v2"
|
||||
|
||||
|
||||
Compiling in Tru64 using native compilers
|
||||
-----------------------------------------
|
||||
|
||||
The following error may occur when compiling with native compilers in the Tru64
|
||||
operating system:
|
||||
|
||||
CXX libpcrecpp_la-pcrecpp.lo
|
||||
cxx: Error: /usr/lib/cmplrs/cxx/V7.1-006/include/cxx/iosfwd, line 58: #error
|
||||
directive: "cannot include iosfwd -- define __USE_STD_IOSTREAM to
|
||||
override default - see section 7.1.2 of the C++ Using Guide"
|
||||
#error "cannot include iosfwd -- define __USE_STD_IOSTREAM to override default
|
||||
- see section 7.1.2 of the C++ Using Guide"
|
||||
|
||||
This may be followed by other errors, complaining that 'namespace "std" has no
|
||||
member'. The solution to this is to add the line
|
||||
|
||||
#define __USE_STD_IOSTREAM 1
|
||||
|
||||
to the config.h file.
|
||||
|
||||
|
||||
Using Sun's compilers for Solaris
|
||||
---------------------------------
|
||||
|
||||
A user reports that the following configurations work on Solaris 9 sparcv9 and
|
||||
Solaris 9 x86 (32-bit):
|
||||
|
||||
Solaris 9 sparcv9: ./configure --disable-cpp CC=/bin/cc CFLAGS="-m64 -g"
|
||||
Solaris 9 x86: ./configure --disable-cpp CC=/bin/cc CFLAGS="-g"
|
||||
|
||||
|
||||
Using PCRE from MySQL
|
||||
---------------------
|
||||
|
||||
On systems where both PCRE and MySQL are installed, it is possible to make use
|
||||
of PCRE from within MySQL, as an alternative to the built-in pattern matching.
|
||||
There is a web page that tells you how to do this:
|
||||
|
||||
http://www.mysqludf.org/lib_mysqludf_preg/index.php
|
||||
|
||||
|
||||
Making new tarballs
|
||||
-------------------
|
||||
|
||||
The command "make dist" creates three PCRE tarballs, in tar.gz, tar.bz2, and
|
||||
zip formats. The command "make distcheck" does the same, but then does a trial
|
||||
build of the new distribution to ensure that it works.
|
||||
|
||||
If you have modified any of the man page sources in the doc directory, you
|
||||
should first run the PrepareRelease script before making a distribution. This
|
||||
script creates the .txt and HTML forms of the documentation from the man pages.
|
||||
|
||||
|
||||
Testing PCRE
|
||||
------------
|
||||
|
||||
To test the basic PCRE library on a Unix-like system, run the RunTest script.
|
||||
There is another script called RunGrepTest that tests the options of the
|
||||
pcregrep command. If the C++ wrapper library is built, three test programs
|
||||
called pcrecpp_unittest, pcre_scanner_unittest, and pcre_stringpiece_unittest
|
||||
are also built. When JIT support is enabled, another test program called
|
||||
pcre_jit_test is built.
|
||||
|
||||
Both the scripts and all the program tests are run if you obey "make check" or
|
||||
"make test". For other environments, see the instructions in
|
||||
NON-AUTOTOOLS-BUILD.
|
||||
|
||||
The RunTest script runs the pcretest test program (which is documented in its
|
||||
own man page) on each of the relevant testinput files in the testdata
|
||||
directory, and compares the output with the contents of the corresponding
|
||||
testoutput files. RunTest uses a file called testtry to hold the main output
|
||||
from pcretest. Other files whose names begin with "test" are used as working
|
||||
files in some tests.
|
||||
|
||||
Some tests are relevant only when certain build-time options were selected. For
|
||||
example, the tests for UTF-8/16/32 support are run only if --enable-utf was
|
||||
used. RunTest outputs a comment when it skips a test.
|
||||
|
||||
Many of the tests that are not skipped are run up to three times. The second
|
||||
run forces pcre_study() to be called for all patterns except for a few in some
|
||||
tests that are marked "never study" (see the pcretest program for how this is
|
||||
done). If JIT support is available, the non-DFA tests are run a third time,
|
||||
this time with a forced pcre_study() with the PCRE_STUDY_JIT_COMPILE option.
|
||||
This testing can be suppressed by putting "nojit" on the RunTest command line.
|
||||
|
||||
The entire set of tests is run once for each of the 8-bit, 16-bit and 32-bit
|
||||
libraries that are enabled. If you want to run just one set of tests, call
|
||||
RunTest with either the -8, -16 or -32 option.
|
||||
|
||||
If valgrind is installed, you can run the tests under it by putting "valgrind"
|
||||
on the RunTest command line. To run pcretest on just one or more specific test
|
||||
files, give their numbers as arguments to RunTest, for example:
|
||||
|
||||
RunTest 2 7 11
|
||||
|
||||
You can also specify ranges of tests such as 3-6 or 3- (meaning 3 to the
|
||||
end), or a number preceded by ~ to exclude a test. For example:
|
||||
|
||||
Runtest 3-15 ~10
|
||||
|
||||
This runs tests 3 to 15, excluding test 10, and just ~13 runs all the tests
|
||||
except test 13. Whatever order the arguments are in, the tests are always run
|
||||
in numerical order.
|
||||
|
||||
You can also call RunTest with the single argument "list" to cause it to output
|
||||
a list of tests.
|
||||
|
||||
The first test file can be fed directly into the perltest.pl script to check
|
||||
that Perl gives the same results. The only difference you should see is in the
|
||||
first few lines, where the Perl version is given instead of the PCRE version.
|
||||
|
||||
The second set of tests check pcre_fullinfo(), pcre_study(),
|
||||
pcre_copy_substring(), pcre_get_substring(), pcre_get_substring_list(), error
|
||||
detection, and run-time flags that are specific to PCRE, as well as the POSIX
|
||||
wrapper API. It also uses the debugging flags to check some of the internals of
|
||||
pcre_compile().
|
||||
|
||||
If you build PCRE with a locale setting that is not the standard C locale, the
|
||||
character tables may be different (see next paragraph). In some cases, this may
|
||||
cause failures in the second set of tests. For example, in a locale where the
|
||||
isprint() function yields TRUE for characters in the range 128-255, the use of
|
||||
[:isascii:] inside a character class defines a different set of characters, and
|
||||
this shows up in this test as a difference in the compiled code, which is being
|
||||
listed for checking. Where the comparison test output contains [\x00-\x7f] the
|
||||
test will contain [\x00-\xff], and similarly in some other cases. This is not a
|
||||
bug in PCRE.
|
||||
|
||||
The third set of tests checks pcre_maketables(), the facility for building a
|
||||
set of character tables for a specific locale and using them instead of the
|
||||
default tables. The tests make use of the "fr_FR" (French) locale. Before
|
||||
running the test, the script checks for the presence of this locale by running
|
||||
the "locale" command. If that command fails, or if it doesn't include "fr_FR"
|
||||
in the list of available locales, the third test cannot be run, and a comment
|
||||
is output to say why. If running this test produces instances of the error
|
||||
|
||||
** Failed to set locale "fr_FR"
|
||||
|
||||
in the comparison output, it means that locale is not available on your system,
|
||||
despite being listed by "locale". This does not mean that PCRE is broken.
|
||||
|
||||
[If you are trying to run this test on Windows, you may be able to get it to
|
||||
work by changing "fr_FR" to "french" everywhere it occurs. Alternatively, use
|
||||
RunTest.bat. The version of RunTest.bat included with PCRE 7.4 and above uses
|
||||
Windows versions of test 2. More info on using RunTest.bat is included in the
|
||||
document entitled NON-UNIX-USE.]
|
||||
|
||||
The fourth and fifth tests check the UTF-8/16/32 support and error handling and
|
||||
internal UTF features of PCRE that are not relevant to Perl, respectively. The
|
||||
sixth and seventh tests do the same for Unicode character properties support.
|
||||
|
||||
The eighth, ninth, and tenth tests check the pcre_dfa_exec() alternative
|
||||
matching function, in non-UTF-8/16/32 mode, UTF-8/16/32 mode, and UTF-8/16/32
|
||||
mode with Unicode property support, respectively.
|
||||
|
||||
The eleventh test checks some internal offsets and code size features; it is
|
||||
run only when the default "link size" of 2 is set (in other cases the sizes
|
||||
change) and when Unicode property support is enabled.
|
||||
|
||||
The twelfth test is run only when JIT support is available, and the thirteenth
|
||||
test is run only when JIT support is not available. They test some JIT-specific
|
||||
features such as information output from pcretest about JIT compilation.
|
||||
|
||||
The fourteenth, fifteenth, and sixteenth tests are run only in 8-bit mode, and
|
||||
the seventeenth, eighteenth, and nineteenth tests are run only in 16/32-bit
|
||||
mode. These are tests that generate different output in the two modes. They are
|
||||
for general cases, UTF-8/16/32 support, and Unicode property support,
|
||||
respectively.
|
||||
|
||||
The twentieth test is run only in 16/32-bit mode. It tests some specific
|
||||
16/32-bit features of the DFA matching engine.
|
||||
|
||||
The twenty-first and twenty-second tests are run only in 16/32-bit mode, when
|
||||
the link size is set to 2 for the 16-bit library. They test reloading
|
||||
pre-compiled patterns.
|
||||
|
||||
The twenty-third and twenty-fourth tests are run only in 16-bit mode. They are
|
||||
for general cases, and UTF-16 support, respectively.
|
||||
|
||||
The twenty-fifth and twenty-sixth tests are run only in 32-bit mode. They are
|
||||
for general cases, and UTF-32 support, respectively.
|
||||
|
||||
|
||||
Character tables
|
||||
----------------
|
||||
|
||||
For speed, PCRE uses four tables for manipulating and identifying characters
|
||||
whose code point values are less than 256. The final argument of the
|
||||
pcre_compile() function is a pointer to a block of memory containing the
|
||||
concatenated tables. A call to pcre_maketables() can be used to generate a set
|
||||
of tables in the current locale. If the final argument for pcre_compile() is
|
||||
passed as NULL, a set of default tables that is built into the binary is used.
|
||||
|
||||
The source file called pcre_chartables.c contains the default set of tables. By
|
||||
default, this is created as a copy of pcre_chartables.c.dist, which contains
|
||||
tables for ASCII coding. However, if --enable-rebuild-chartables is specified
|
||||
for ./configure, a different version of pcre_chartables.c is built by the
|
||||
program dftables (compiled from dftables.c), which uses the ANSI C character
|
||||
handling functions such as isalnum(), isalpha(), isupper(), islower(), etc. to
|
||||
build the table sources. This means that the default C locale which is set for
|
||||
your system will control the contents of these default tables. You can change
|
||||
the default tables by editing pcre_chartables.c and then re-building PCRE. If
|
||||
you do this, you should take care to ensure that the file does not get
|
||||
automatically re-generated. The best way to do this is to move
|
||||
pcre_chartables.c.dist out of the way and replace it with your customized
|
||||
tables.
|
||||
|
||||
When the dftables program is run as a result of --enable-rebuild-chartables,
|
||||
it uses the default C locale that is set on your system. It does not pay
|
||||
attention to the LC_xxx environment variables. In other words, it uses the
|
||||
system's default locale rather than whatever the compiling user happens to have
|
||||
set. If you really do want to build a source set of character tables in a
|
||||
locale that is specified by the LC_xxx variables, you can run the dftables
|
||||
program by hand with the -L option. For example:
|
||||
|
||||
./dftables -L pcre_chartables.c.special
|
||||
|
||||
The first two 256-byte tables provide lower casing and case flipping functions,
|
||||
respectively. The next table consists of three 32-byte bit maps which identify
|
||||
digits, "word" characters, and white space, respectively. These are used when
|
||||
building 32-byte bit maps that represent character classes for code points less
|
||||
than 256.
|
||||
|
||||
The final 256-byte table has bits indicating various character types, as
|
||||
follows:
|
||||
|
||||
1 white space character
|
||||
2 letter
|
||||
4 decimal digit
|
||||
8 hexadecimal digit
|
||||
16 alphanumeric or '_'
|
||||
128 regular expression metacharacter or binary zero
|
||||
|
||||
You should not alter the set of characters that contain the 128 bit, as that
|
||||
will cause PCRE to malfunction.
|
||||
|
||||
|
||||
File manifest
|
||||
-------------
|
||||
|
||||
The distribution should contain the files listed below. Where a file name is
|
||||
given as pcre[16|32]_xxx it means that there are three files, one with the name
|
||||
pcre_xxx, one with the name pcre16_xx, and a third with the name pcre32_xxx.
|
||||
|
||||
(A) Source files of the PCRE library functions and their headers:
|
||||
|
||||
dftables.c auxiliary program for building pcre_chartables.c
|
||||
when --enable-rebuild-chartables is specified
|
||||
|
||||
pcre_chartables.c.dist a default set of character tables that assume ASCII
|
||||
coding; used, unless --enable-rebuild-chartables is
|
||||
specified, by copying to pcre[16]_chartables.c
|
||||
|
||||
pcreposix.c )
|
||||
pcre[16|32]_byte_order.c )
|
||||
pcre[16|32]_compile.c )
|
||||
pcre[16|32]_config.c )
|
||||
pcre[16|32]_dfa_exec.c )
|
||||
pcre[16|32]_exec.c )
|
||||
pcre[16|32]_fullinfo.c )
|
||||
pcre[16|32]_get.c ) sources for the functions in the library,
|
||||
pcre[16|32]_globals.c ) and some internal functions that they use
|
||||
pcre[16|32]_jit_compile.c )
|
||||
pcre[16|32]_maketables.c )
|
||||
pcre[16|32]_newline.c )
|
||||
pcre[16|32]_refcount.c )
|
||||
pcre[16|32]_string_utils.c )
|
||||
pcre[16|32]_study.c )
|
||||
pcre[16|32]_tables.c )
|
||||
pcre[16|32]_ucd.c )
|
||||
pcre[16|32]_version.c )
|
||||
pcre[16|32]_xclass.c )
|
||||
pcre_ord2utf8.c )
|
||||
pcre_valid_utf8.c )
|
||||
pcre16_ord2utf16.c )
|
||||
pcre16_utf16_utils.c )
|
||||
pcre16_valid_utf16.c )
|
||||
pcre32_utf32_utils.c )
|
||||
pcre32_valid_utf32.c )
|
||||
|
||||
pcre[16|32]_printint.c ) debugging function that is used by pcretest,
|
||||
) and can also be #included in pcre_compile()
|
||||
|
||||
pcre.h.in template for pcre.h when built by "configure"
|
||||
pcreposix.h header for the external POSIX wrapper API
|
||||
pcre_internal.h header for internal use
|
||||
sljit/* 16 files that make up the JIT compiler
|
||||
ucp.h header for Unicode property handling
|
||||
|
||||
config.h.in template for config.h, which is built by "configure"
|
||||
|
||||
pcrecpp.h public header file for the C++ wrapper
|
||||
pcrecpparg.h.in template for another C++ header file
|
||||
pcre_scanner.h public header file for C++ scanner functions
|
||||
pcrecpp.cc )
|
||||
pcre_scanner.cc ) source for the C++ wrapper library
|
||||
|
||||
pcre_stringpiece.h.in template for pcre_stringpiece.h, the header for the
|
||||
C++ stringpiece functions
|
||||
pcre_stringpiece.cc source for the C++ stringpiece functions
|
||||
|
||||
(B) Source files for programs that use PCRE:
|
||||
|
||||
pcredemo.c simple demonstration of coding calls to PCRE
|
||||
pcregrep.c source of a grep utility that uses PCRE
|
||||
pcretest.c comprehensive test program
|
||||
|
||||
(C) Auxiliary files:
|
||||
|
||||
132html script to turn "man" pages into HTML
|
||||
AUTHORS information about the author of PCRE
|
||||
ChangeLog log of changes to the code
|
||||
CleanTxt script to clean nroff output for txt man pages
|
||||
Detrail script to remove trailing spaces
|
||||
HACKING some notes about the internals of PCRE
|
||||
INSTALL generic installation instructions
|
||||
LICENCE conditions for the use of PCRE
|
||||
COPYING the same, using GNU's standard name
|
||||
Makefile.in ) template for Unix Makefile, which is built by
|
||||
) "configure"
|
||||
Makefile.am ) the automake input that was used to create
|
||||
) Makefile.in
|
||||
NEWS important changes in this release
|
||||
NON-UNIX-USE the previous name for NON-AUTOTOOLS-BUILD
|
||||
NON-AUTOTOOLS-BUILD notes on building PCRE without using autotools
|
||||
PrepareRelease script to make preparations for "make dist"
|
||||
README this file
|
||||
RunTest a Unix shell script for running tests
|
||||
RunGrepTest a Unix shell script for pcregrep tests
|
||||
aclocal.m4 m4 macros (generated by "aclocal")
|
||||
config.guess ) files used by libtool,
|
||||
config.sub ) used only when building a shared library
|
||||
configure a configuring shell script (built by autoconf)
|
||||
configure.ac ) the autoconf input that was used to build
|
||||
) "configure" and config.h
|
||||
depcomp ) script to find program dependencies, generated by
|
||||
) automake
|
||||
doc/*.3 man page sources for PCRE
|
||||
doc/*.1 man page sources for pcregrep and pcretest
|
||||
doc/index.html.src the base HTML page
|
||||
doc/html/* HTML documentation
|
||||
doc/pcre.txt plain text version of the man pages
|
||||
doc/pcretest.txt plain text documentation of test program
|
||||
doc/perltest.txt plain text documentation of Perl test program
|
||||
install-sh a shell script for installing files
|
||||
libpcre16.pc.in template for libpcre16.pc for pkg-config
|
||||
libpcre32.pc.in template for libpcre32.pc for pkg-config
|
||||
libpcre.pc.in template for libpcre.pc for pkg-config
|
||||
libpcreposix.pc.in template for libpcreposix.pc for pkg-config
|
||||
libpcrecpp.pc.in template for libpcrecpp.pc for pkg-config
|
||||
ltmain.sh file used to build a libtool script
|
||||
missing ) common stub for a few missing GNU programs while
|
||||
) installing, generated by automake
|
||||
mkinstalldirs script for making install directories
|
||||
perltest.pl Perl test program
|
||||
pcre-config.in source of script which retains PCRE information
|
||||
pcre_jit_test.c test program for the JIT compiler
|
||||
pcrecpp_unittest.cc )
|
||||
pcre_scanner_unittest.cc ) test programs for the C++ wrapper
|
||||
pcre_stringpiece_unittest.cc )
|
||||
testdata/testinput* test data for main library tests
|
||||
testdata/testoutput* expected test results
|
||||
testdata/grep* input and output for pcregrep tests
|
||||
testdata/* other supporting test files
|
||||
|
||||
(D) Auxiliary files for cmake support
|
||||
|
||||
cmake/COPYING-CMAKE-SCRIPTS
|
||||
cmake/FindPackageHandleStandardArgs.cmake
|
||||
cmake/FindEditline.cmake
|
||||
cmake/FindReadline.cmake
|
||||
CMakeLists.txt
|
||||
config-cmake.h.in
|
||||
|
||||
(E) Auxiliary files for VPASCAL
|
||||
|
||||
makevp.bat
|
||||
makevp_c.txt
|
||||
makevp_l.txt
|
||||
pcregexp.pas
|
||||
|
||||
(F) Auxiliary files for building PCRE "by hand"
|
||||
|
||||
pcre.h.generic ) a version of the public PCRE header file
|
||||
) for use in non-"configure" environments
|
||||
config.h.generic ) a version of config.h for use in non-"configure"
|
||||
) environments
|
||||
|
||||
(F) Miscellaneous
|
||||
|
||||
RunTest.bat a script for running tests under Windows
|
||||
|
||||
Philip Hazel
|
||||
Email local part: ph10
|
||||
Email domain: cam.ac.uk
|
||||
Last updated: 10 February 2015
|
||||
@@ -0,0 +1,185 @@
|
||||
<html>
|
||||
<!-- This is a manually maintained file that is the root of the HTML version of
|
||||
the PCRE documentation. When the HTML documents are built from the man
|
||||
page versions, the entire doc/html directory is emptied, this file is then
|
||||
copied into doc/html/index.html, and the remaining files therein are
|
||||
created by the 132html script.
|
||||
-->
|
||||
<head>
|
||||
<title>PCRE specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>Perl-compatible Regular Expressions (PCRE)</h1>
|
||||
<p>
|
||||
The HTML documentation for PCRE consists of a number of pages that are listed
|
||||
below in alphabetical order. If you are new to PCRE, please read the first one
|
||||
first.
|
||||
</p>
|
||||
|
||||
<table>
|
||||
<tr><td><a href="pcre.html">pcre</a></td>
|
||||
<td> Introductory page</td></tr>
|
||||
|
||||
<tr><td><a href="pcre-config.html">pcre-config</a></td>
|
||||
<td> Information about the installation configuration</td></tr>
|
||||
|
||||
<tr><td><a href="pcre16.html">pcre16</a></td>
|
||||
<td> Discussion of the 16-bit PCRE library</td></tr>
|
||||
|
||||
<tr><td><a href="pcre32.html">pcre32</a></td>
|
||||
<td> Discussion of the 32-bit PCRE library</td></tr>
|
||||
|
||||
<tr><td><a href="pcreapi.html">pcreapi</a></td>
|
||||
<td> PCRE's native API</td></tr>
|
||||
|
||||
<tr><td><a href="pcrebuild.html">pcrebuild</a></td>
|
||||
<td> Building PCRE</td></tr>
|
||||
|
||||
<tr><td><a href="pcrecallout.html">pcrecallout</a></td>
|
||||
<td> The <i>callout</i> facility</td></tr>
|
||||
|
||||
<tr><td><a href="pcrecompat.html">pcrecompat</a></td>
|
||||
<td> Compability with Perl</td></tr>
|
||||
|
||||
<tr><td><a href="pcrecpp.html">pcrecpp</a></td>
|
||||
<td> The C++ wrapper for the PCRE library</td></tr>
|
||||
|
||||
<tr><td><a href="pcredemo.html">pcredemo</a></td>
|
||||
<td> A demonstration C program that uses the PCRE library</td></tr>
|
||||
|
||||
<tr><td><a href="pcregrep.html">pcregrep</a></td>
|
||||
<td> The <b>pcregrep</b> command</td></tr>
|
||||
|
||||
<tr><td><a href="pcrejit.html">pcrejit</a></td>
|
||||
<td> Discussion of the just-in-time optimization support</td></tr>
|
||||
|
||||
<tr><td><a href="pcrelimits.html">pcrelimits</a></td>
|
||||
<td> Details of size and other limits</td></tr>
|
||||
|
||||
<tr><td><a href="pcrematching.html">pcrematching</a></td>
|
||||
<td> Discussion of the two matching algorithms</td></tr>
|
||||
|
||||
<tr><td><a href="pcrepartial.html">pcrepartial</a></td>
|
||||
<td> Using PCRE for partial matching</td></tr>
|
||||
|
||||
<tr><td><a href="pcrepattern.html">pcrepattern</a></td>
|
||||
<td> Specification of the regular expressions supported by PCRE</td></tr>
|
||||
|
||||
<tr><td><a href="pcreperform.html">pcreperform</a></td>
|
||||
<td> Some comments on performance</td></tr>
|
||||
|
||||
<tr><td><a href="pcreposix.html">pcreposix</a></td>
|
||||
<td> The POSIX API to the PCRE 8-bit library</td></tr>
|
||||
|
||||
<tr><td><a href="pcreprecompile.html">pcreprecompile</a></td>
|
||||
<td> How to save and re-use compiled patterns</td></tr>
|
||||
|
||||
<tr><td><a href="pcresample.html">pcresample</a></td>
|
||||
<td> Discussion of the pcredemo program</td></tr>
|
||||
|
||||
<tr><td><a href="pcrestack.html">pcrestack</a></td>
|
||||
<td> Discussion of PCRE's stack usage</td></tr>
|
||||
|
||||
<tr><td><a href="pcresyntax.html">pcresyntax</a></td>
|
||||
<td> Syntax quick-reference summary</td></tr>
|
||||
|
||||
<tr><td><a href="pcretest.html">pcretest</a></td>
|
||||
<td> The <b>pcretest</b> command for testing PCRE</td></tr>
|
||||
|
||||
<tr><td><a href="pcreunicode.html">pcreunicode</a></td>
|
||||
<td> Discussion of Unicode and UTF-8/UTF-16/UTF-32 support</td></tr>
|
||||
</table>
|
||||
|
||||
<p>
|
||||
There are also individual pages that summarize the interface for each function
|
||||
in the library. There is a single page for each triple of 8-bit/16-bit/32-bit
|
||||
functions.
|
||||
</p>
|
||||
|
||||
<table>
|
||||
|
||||
<tr><td><a href="pcre_assign_jit_stack.html">pcre_assign_jit_stack</a></td>
|
||||
<td> Assign stack for JIT matching</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_compile.html">pcre_compile</a></td>
|
||||
<td> Compile a regular expression</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_compile2.html">pcre_compile2</a></td>
|
||||
<td> Compile a regular expression (alternate interface)</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_config.html">pcre_config</a></td>
|
||||
<td> Show build-time configuration options</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_copy_named_substring.html">pcre_copy_named_substring</a></td>
|
||||
<td> Extract named substring into given buffer</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_copy_substring.html">pcre_copy_substring</a></td>
|
||||
<td> Extract numbered substring into given buffer</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_dfa_exec.html">pcre_dfa_exec</a></td>
|
||||
<td> Match a compiled pattern to a subject string
|
||||
(DFA algorithm; <i>not</i> Perl compatible)</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_exec.html">pcre_exec</a></td>
|
||||
<td> Match a compiled pattern to a subject string
|
||||
(Perl compatible)</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_free_study.html">pcre_free_study</a></td>
|
||||
<td> Free study data</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_free_substring.html">pcre_free_substring</a></td>
|
||||
<td> Free extracted substring</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_free_substring_list.html">pcre_free_substring_list</a></td>
|
||||
<td> Free list of extracted substrings</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_fullinfo.html">pcre_fullinfo</a></td>
|
||||
<td> Extract information about a pattern</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_get_named_substring.html">pcre_get_named_substring</a></td>
|
||||
<td> Extract named substring into new memory</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_get_stringnumber.html">pcre_get_stringnumber</a></td>
|
||||
<td> Convert captured string name to number</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_get_stringtable_entries.html">pcre_get_stringtable_entries</a></td>
|
||||
<td> Find table entries for given string name</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_get_substring.html">pcre_get_substring</a></td>
|
||||
<td> Extract numbered substring into new memory</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_get_substring_list.html">pcre_get_substring_list</a></td>
|
||||
<td> Extract all substrings into new memory</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_jit_exec.html">pcre_jit_exec</a></td>
|
||||
<td> Fast path interface to JIT matching</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_jit_stack_alloc.html">pcre_jit_stack_alloc</a></td>
|
||||
<td> Create a stack for JIT matching</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_jit_stack_free.html">pcre_jit_stack_free</a></td>
|
||||
<td> Free a JIT matching stack</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_maketables.html">pcre_maketables</a></td>
|
||||
<td> Build character tables in current locale</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_pattern_to_host_byte_order.html">pcre_pattern_to_host_byte_order</a></td>
|
||||
<td> Convert compiled pattern to host byte order if necessary</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_refcount.html">pcre_refcount</a></td>
|
||||
<td> Maintain reference count in compiled pattern</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_study.html">pcre_study</a></td>
|
||||
<td> Study a compiled pattern</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_utf16_to_host_byte_order.html">pcre_utf16_to_host_byte_order</a></td>
|
||||
<td> Convert UTF-16 string to host byte order if necessary</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_utf32_to_host_byte_order.html">pcre_utf32_to_host_byte_order</a></td>
|
||||
<td> Convert UTF-32 string to host byte order if necessary</td></tr>
|
||||
|
||||
<tr><td><a href="pcre_version.html">pcre_version</a></td>
|
||||
<td> Return PCRE version and release date</td></tr>
|
||||
</table>
|
||||
|
||||
</html>
|
||||
@@ -0,0 +1,109 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre-config specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre-config man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
|
||||
<li><a name="TOC2" href="#SEC2">DESCRIPTION</a>
|
||||
<li><a name="TOC3" href="#SEC3">OPTIONS</a>
|
||||
<li><a name="TOC4" href="#SEC4">SEE ALSO</a>
|
||||
<li><a name="TOC5" href="#SEC5">AUTHOR</a>
|
||||
<li><a name="TOC6" href="#SEC6">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
|
||||
<P>
|
||||
<b>pcre-config [--prefix] [--exec-prefix] [--version] [--libs]</b>
|
||||
<b> [--libs16] [--libs32] [--libs-cpp] [--libs-posix]</b>
|
||||
<b> [--cflags] [--cflags-posix]</b>
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">DESCRIPTION</a><br>
|
||||
<P>
|
||||
<b>pcre-config</b> returns the configuration of the installed PCRE
|
||||
libraries and the options required to compile a program to use them. Some of
|
||||
the options apply only to the 8-bit, or 16-bit, or 32-bit libraries,
|
||||
respectively, and are
|
||||
not available if only one of those libraries has been built. If an unavailable
|
||||
option is encountered, the "usage" information is output.
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">OPTIONS</a><br>
|
||||
<P>
|
||||
<b>--prefix</b>
|
||||
Writes the directory prefix used in the PCRE installation for architecture
|
||||
independent files (<i>/usr</i> on many systems, <i>/usr/local</i> on some
|
||||
systems) to the standard output.
|
||||
</P>
|
||||
<P>
|
||||
<b>--exec-prefix</b>
|
||||
Writes the directory prefix used in the PCRE installation for architecture
|
||||
dependent files (normally the same as <b>--prefix</b>) to the standard output.
|
||||
</P>
|
||||
<P>
|
||||
<b>--version</b>
|
||||
Writes the version number of the installed PCRE libraries to the standard
|
||||
output.
|
||||
</P>
|
||||
<P>
|
||||
<b>--libs</b>
|
||||
Writes to the standard output the command line options required to link
|
||||
with the 8-bit PCRE library (<b>-lpcre</b> on many systems).
|
||||
</P>
|
||||
<P>
|
||||
<b>--libs16</b>
|
||||
Writes to the standard output the command line options required to link
|
||||
with the 16-bit PCRE library (<b>-lpcre16</b> on many systems).
|
||||
</P>
|
||||
<P>
|
||||
<b>--libs32</b>
|
||||
Writes to the standard output the command line options required to link
|
||||
with the 32-bit PCRE library (<b>-lpcre32</b> on many systems).
|
||||
</P>
|
||||
<P>
|
||||
<b>--libs-cpp</b>
|
||||
Writes to the standard output the command line options required to link with
|
||||
PCRE's C++ wrapper library (<b>-lpcrecpp</b> <b>-lpcre</b> on many
|
||||
systems).
|
||||
</P>
|
||||
<P>
|
||||
<b>--libs-posix</b>
|
||||
Writes to the standard output the command line options required to link with
|
||||
PCRE's POSIX API wrapper library (<b>-lpcreposix</b> <b>-lpcre</b> on many
|
||||
systems).
|
||||
</P>
|
||||
<P>
|
||||
<b>--cflags</b>
|
||||
Writes to the standard output the command line options required to compile
|
||||
files that use PCRE (this may include some <b>-I</b> options, but is blank on
|
||||
many systems).
|
||||
</P>
|
||||
<P>
|
||||
<b>--cflags-posix</b>
|
||||
Writes to the standard output the command line options required to compile
|
||||
files that use PCRE's POSIX API wrapper library (this may include some <b>-I</b>
|
||||
options, but is blank on many systems).
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">SEE ALSO</a><br>
|
||||
<P>
|
||||
<b>pcre(3)</b>
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
This manual page was originally written by Mark Baker for the Debian GNU/Linux
|
||||
system. It has been subsequently revised as a generic PCRE man page.
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 24 June 2012
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,224 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">PLEASE TAKE NOTE</a>
|
||||
<li><a name="TOC2" href="#SEC2">INTRODUCTION</a>
|
||||
<li><a name="TOC3" href="#SEC3">SECURITY CONSIDERATIONS</a>
|
||||
<li><a name="TOC4" href="#SEC4">USER DOCUMENTATION</a>
|
||||
<li><a name="TOC5" href="#SEC5">AUTHOR</a>
|
||||
<li><a name="TOC6" href="#SEC6">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">PLEASE TAKE NOTE</a><br>
|
||||
<P>
|
||||
This document relates to PCRE releases that use the original API,
|
||||
with library names libpcre, libpcre16, and libpcre32. January 2015 saw the
|
||||
first release of a new API, known as PCRE2, with release numbers starting at
|
||||
10.00 and library names libpcre2-8, libpcre2-16, and libpcre2-32. The old
|
||||
libraries (now called PCRE1) are still being maintained for bug fixes, but
|
||||
there will be no new development. New projects are advised to use the new PCRE2
|
||||
libraries.
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">INTRODUCTION</a><br>
|
||||
<P>
|
||||
The PCRE library is a set of functions that implement regular expression
|
||||
pattern matching using the same syntax and semantics as Perl, with just a few
|
||||
differences. Some features that appeared in Python and PCRE before they
|
||||
appeared in Perl are also available using the Python syntax, there is some
|
||||
support for one or two .NET and Oniguruma syntax items, and there is an option
|
||||
for requesting some minor changes that give better JavaScript compatibility.
|
||||
</P>
|
||||
<P>
|
||||
Starting with release 8.30, it is possible to compile two separate PCRE
|
||||
libraries: the original, which supports 8-bit character strings (including
|
||||
UTF-8 strings), and a second library that supports 16-bit character strings
|
||||
(including UTF-16 strings). The build process allows either one or both to be
|
||||
built. The majority of the work to make this possible was done by Zoltan
|
||||
Herczeg.
|
||||
</P>
|
||||
<P>
|
||||
Starting with release 8.32 it is possible to compile a third separate PCRE
|
||||
library that supports 32-bit character strings (including UTF-32 strings). The
|
||||
build process allows any combination of the 8-, 16- and 32-bit libraries. The
|
||||
work to make this possible was done by Christian Persch.
|
||||
</P>
|
||||
<P>
|
||||
The three libraries contain identical sets of functions, except that the names
|
||||
in the 16-bit library start with <b>pcre16_</b> instead of <b>pcre_</b>, and the
|
||||
names in the 32-bit library start with <b>pcre32_</b> instead of <b>pcre_</b>. To
|
||||
avoid over-complication and reduce the documentation maintenance load, most of
|
||||
the documentation describes the 8-bit library, with the differences for the
|
||||
16-bit and 32-bit libraries described separately in the
|
||||
<a href="pcre16.html"><b>pcre16</b></a>
|
||||
and
|
||||
<a href="pcre32.html"><b>pcre32</b></a>
|
||||
pages. References to functions or structures of the form <i>pcre[16|32]_xxx</i>
|
||||
should be read as meaning "<i>pcre_xxx</i> when using the 8-bit library,
|
||||
<i>pcre16_xxx</i> when using the 16-bit library, or <i>pcre32_xxx</i> when using
|
||||
the 32-bit library".
|
||||
</P>
|
||||
<P>
|
||||
The current implementation of PCRE corresponds approximately with Perl 5.12,
|
||||
including support for UTF-8/16/32 encoded strings and Unicode general category
|
||||
properties. However, UTF-8/16/32 and Unicode support has to be explicitly
|
||||
enabled; it is not the default. The Unicode tables correspond to Unicode
|
||||
release 6.3.0.
|
||||
</P>
|
||||
<P>
|
||||
In addition to the Perl-compatible matching function, PCRE contains an
|
||||
alternative function that matches the same compiled patterns in a different
|
||||
way. In certain circumstances, the alternative function has some advantages.
|
||||
For a discussion of the two matching algorithms, see the
|
||||
<a href="pcrematching.html"><b>pcrematching</b></a>
|
||||
page.
|
||||
</P>
|
||||
<P>
|
||||
PCRE is written in C and released as a C library. A number of people have
|
||||
written wrappers and interfaces of various kinds. In particular, Google Inc.
|
||||
have provided a comprehensive C++ wrapper for the 8-bit library. This is now
|
||||
included as part of the PCRE distribution. The
|
||||
<a href="pcrecpp.html"><b>pcrecpp</b></a>
|
||||
page has details of this interface. Other people's contributions can be found
|
||||
in the <i>Contrib</i> directory at the primary FTP site, which is:
|
||||
<a href="ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre">ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre</a>
|
||||
</P>
|
||||
<P>
|
||||
Details of exactly which Perl regular expression features are and are not
|
||||
supported by PCRE are given in separate documents. See the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
and
|
||||
<a href="pcrecompat.html"><b>pcrecompat</b></a>
|
||||
pages. There is a syntax summary in the
|
||||
<a href="pcresyntax.html"><b>pcresyntax</b></a>
|
||||
page.
|
||||
</P>
|
||||
<P>
|
||||
Some features of PCRE can be included, excluded, or changed when the library is
|
||||
built. The
|
||||
<a href="pcre_config.html"><b>pcre_config()</b></a>
|
||||
function makes it possible for a client to discover which features are
|
||||
available. The features themselves are described in the
|
||||
<a href="pcrebuild.html"><b>pcrebuild</b></a>
|
||||
page. Documentation about building PCRE for various operating systems can be
|
||||
found in the
|
||||
<a href="README.txt"><b>README</b></a>
|
||||
and
|
||||
<a href="NON-AUTOTOOLS-BUILD.txt"><b>NON-AUTOTOOLS_BUILD</b></a>
|
||||
files in the source distribution.
|
||||
</P>
|
||||
<P>
|
||||
The libraries contains a number of undocumented internal functions and data
|
||||
tables that are used by more than one of the exported external functions, but
|
||||
which are not intended for use by external callers. Their names all begin with
|
||||
"_pcre_" or "_pcre16_" or "_pcre32_", which hopefully will not provoke any name
|
||||
clashes. In some environments, it is possible to control which external symbols
|
||||
are exported when a shared library is built, and in these cases the
|
||||
undocumented symbols are not exported.
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">SECURITY CONSIDERATIONS</a><br>
|
||||
<P>
|
||||
If you are using PCRE in a non-UTF application that permits users to supply
|
||||
arbitrary patterns for compilation, you should be aware of a feature that
|
||||
allows users to turn on UTF support from within a pattern, provided that PCRE
|
||||
was built with UTF support. For example, an 8-bit pattern that begins with
|
||||
"(*UTF8)" or "(*UTF)" turns on UTF-8 mode, which interprets patterns and
|
||||
subjects as strings of UTF-8 characters instead of individual 8-bit characters.
|
||||
This causes both the pattern and any data against which it is matched to be
|
||||
checked for UTF-8 validity. If the data string is very long, such a check might
|
||||
use sufficiently many resources as to cause your application to lose
|
||||
performance.
|
||||
</P>
|
||||
<P>
|
||||
One way of guarding against this possibility is to use the
|
||||
<b>pcre_fullinfo()</b> function to check the compiled pattern's options for UTF.
|
||||
Alternatively, from release 8.33, you can set the PCRE_NEVER_UTF option at
|
||||
compile time. This causes an compile time error if a pattern contains a
|
||||
UTF-setting sequence.
|
||||
</P>
|
||||
<P>
|
||||
If your application is one that supports UTF, be aware that validity checking
|
||||
can take time. If the same data string is to be matched many times, you can use
|
||||
the PCRE_NO_UTF[8|16|32]_CHECK option for the second and subsequent matches to
|
||||
save redundant checks.
|
||||
</P>
|
||||
<P>
|
||||
Another way that performance can be hit is by running a pattern that has a very
|
||||
large search tree against a string that will never match. Nested unlimited
|
||||
repeats in a pattern are a common example. PCRE provides some protection
|
||||
against this: see the PCRE_EXTRA_MATCH_LIMIT feature in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page.
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">USER DOCUMENTATION</a><br>
|
||||
<P>
|
||||
The user documentation for PCRE comprises a number of different sections. In
|
||||
the "man" format, each of these is a separate "man page". In the HTML format,
|
||||
each is a separate page, linked from the index page. In the plain text format,
|
||||
the descriptions of the <b>pcregrep</b> and <b>pcretest</b> programs are in files
|
||||
called <b>pcregrep.txt</b> and <b>pcretest.txt</b>, respectively. The remaining
|
||||
sections, except for the <b>pcredemo</b> section (which is a program listing),
|
||||
are concatenated in <b>pcre.txt</b>, for ease of searching. The sections are as
|
||||
follows:
|
||||
<pre>
|
||||
pcre this document
|
||||
pcre-config show PCRE installation configuration information
|
||||
pcre16 details of the 16-bit library
|
||||
pcre32 details of the 32-bit library
|
||||
pcreapi details of PCRE's native C API
|
||||
pcrebuild building PCRE
|
||||
pcrecallout details of the callout feature
|
||||
pcrecompat discussion of Perl compatibility
|
||||
pcrecpp details of the C++ wrapper for the 8-bit library
|
||||
pcredemo a demonstration C program that uses PCRE
|
||||
pcregrep description of the <b>pcregrep</b> command (8-bit only)
|
||||
pcrejit discussion of the just-in-time optimization support
|
||||
pcrelimits details of size and other limits
|
||||
pcrematching discussion of the two matching algorithms
|
||||
pcrepartial details of the partial matching facility
|
||||
pcrepattern syntax and semantics of supported regular expressions
|
||||
pcreperform discussion of performance issues
|
||||
pcreposix the POSIX-compatible C API for the 8-bit library
|
||||
pcreprecompile details of saving and re-using precompiled patterns
|
||||
pcresample discussion of the pcredemo program
|
||||
pcrestack discussion of stack usage
|
||||
pcresyntax quick syntax reference
|
||||
pcretest description of the <b>pcretest</b> testing command
|
||||
pcreunicode discussion of Unicode and UTF-8/16/32 support
|
||||
</pre>
|
||||
In the "man" and HTML formats, there is also a short page for each C library
|
||||
function, listing its arguments and results.
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<P>
|
||||
Putting an actual email address here seems to have been a spam magnet, so I've
|
||||
taken it away. If you want to email me, use my two initials, followed by the
|
||||
two digits 10, at the domain cam.ac.uk.
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 10 February 2015
|
||||
<br>
|
||||
Copyright © 1997-2015 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,384 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre16 specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre16 man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">PCRE 16-BIT API BASIC FUNCTIONS</a>
|
||||
<li><a name="TOC2" href="#SEC2">PCRE 16-BIT API STRING EXTRACTION FUNCTIONS</a>
|
||||
<li><a name="TOC3" href="#SEC3">PCRE 16-BIT API AUXILIARY FUNCTIONS</a>
|
||||
<li><a name="TOC4" href="#SEC4">PCRE 16-BIT API INDIRECTED FUNCTIONS</a>
|
||||
<li><a name="TOC5" href="#SEC5">PCRE 16-BIT API 16-BIT-ONLY FUNCTION</a>
|
||||
<li><a name="TOC6" href="#SEC6">THE PCRE 16-BIT LIBRARY</a>
|
||||
<li><a name="TOC7" href="#SEC7">THE HEADER FILE</a>
|
||||
<li><a name="TOC8" href="#SEC8">THE LIBRARY NAME</a>
|
||||
<li><a name="TOC9" href="#SEC9">STRING TYPES</a>
|
||||
<li><a name="TOC10" href="#SEC10">STRUCTURE TYPES</a>
|
||||
<li><a name="TOC11" href="#SEC11">16-BIT FUNCTIONS</a>
|
||||
<li><a name="TOC12" href="#SEC12">SUBJECT STRING OFFSETS</a>
|
||||
<li><a name="TOC13" href="#SEC13">NAMED SUBPATTERNS</a>
|
||||
<li><a name="TOC14" href="#SEC14">OPTION NAMES</a>
|
||||
<li><a name="TOC15" href="#SEC15">CHARACTER CODES</a>
|
||||
<li><a name="TOC16" href="#SEC16">ERROR NAMES</a>
|
||||
<li><a name="TOC17" href="#SEC17">ERROR TEXTS</a>
|
||||
<li><a name="TOC18" href="#SEC18">CALLOUTS</a>
|
||||
<li><a name="TOC19" href="#SEC19">TESTING</a>
|
||||
<li><a name="TOC20" href="#SEC20">NOT SUPPORTED IN 16-BIT MODE</a>
|
||||
<li><a name="TOC21" href="#SEC21">AUTHOR</a>
|
||||
<li><a name="TOC22" href="#SEC22">REVISION</a>
|
||||
</ul>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<br><a name="SEC1" href="#TOC1">PCRE 16-BIT API BASIC FUNCTIONS</a><br>
|
||||
<P>
|
||||
<b>pcre16 *pcre16_compile(PCRE_SPTR16 <i>pattern</i>, int <i>options</i>,</b>
|
||||
<b> const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
|
||||
<b> const unsigned char *<i>tableptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre16 *pcre16_compile2(PCRE_SPTR16 <i>pattern</i>, int <i>options</i>,</b>
|
||||
<b> int *<i>errorcodeptr</i>,</b>
|
||||
<b> const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
|
||||
<b> const unsigned char *<i>tableptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre16_extra *pcre16_study(const pcre16 *<i>code</i>, int <i>options</i>,</b>
|
||||
<b> const char **<i>errptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre16_free_study(pcre16_extra *<i>extra</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_exec(const pcre16 *<i>code</i>, const pcre16_extra *<i>extra</i>,</b>
|
||||
<b> PCRE_SPTR16 <i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_dfa_exec(const pcre16 *<i>code</i>, const pcre16_extra *<i>extra</i>,</b>
|
||||
<b> PCRE_SPTR16 <i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
|
||||
<b> int *<i>workspace</i>, int <i>wscount</i>);</b>
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">PCRE 16-BIT API STRING EXTRACTION FUNCTIONS</a><br>
|
||||
<P>
|
||||
<b>int pcre16_copy_named_substring(const pcre16 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR16 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, PCRE_SPTR16 <i>stringname</i>,</b>
|
||||
<b> PCRE_UCHAR16 *<i>buffer</i>, int <i>buffersize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_copy_substring(PCRE_SPTR16 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, int <i>stringnumber</i>, PCRE_UCHAR16 *<i>buffer</i>,</b>
|
||||
<b> int <i>buffersize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_get_named_substring(const pcre16 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR16 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, PCRE_SPTR16 <i>stringname</i>,</b>
|
||||
<b> PCRE_SPTR16 *<i>stringptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_get_stringnumber(const pcre16 *<i>code</i>,</b>
|
||||
<b>" PCRE_SPTR16 <i>name</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_get_stringtable_entries(const pcre16 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR16 <i>name</i>, PCRE_UCHAR16 **<i>first</i>, PCRE_UCHAR16 **<i>last</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_get_substring(PCRE_SPTR16 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, int <i>stringnumber</i>,</b>
|
||||
<b> PCRE_SPTR16 *<i>stringptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_get_substring_list(PCRE_SPTR16 <i>subject</i>,</b>
|
||||
<b> int *<i>ovector</i>, int <i>stringcount</i>, PCRE_SPTR16 **<i>listptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre16_free_substring(PCRE_SPTR16 <i>stringptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre16_free_substring_list(PCRE_SPTR16 *<i>stringptr</i>);</b>
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">PCRE 16-BIT API AUXILIARY FUNCTIONS</a><br>
|
||||
<P>
|
||||
<b>pcre16_jit_stack *pcre16_jit_stack_alloc(int <i>startsize</i>, int <i>maxsize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre16_jit_stack_free(pcre16_jit_stack *<i>stack</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre16_assign_jit_stack(pcre16_extra *<i>extra</i>,</b>
|
||||
<b> pcre16_jit_callback <i>callback</i>, void *<i>data</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>const unsigned char *pcre16_maketables(void);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_fullinfo(const pcre16 *<i>code</i>, const pcre16_extra *<i>extra</i>,</b>
|
||||
<b> int <i>what</i>, void *<i>where</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_refcount(pcre16 *<i>code</i>, int <i>adjust</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_config(int <i>what</i>, void *<i>where</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>const char *pcre16_version(void);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_pattern_to_host_byte_order(pcre16 *<i>code</i>,</b>
|
||||
<b> pcre16_extra *<i>extra</i>, const unsigned char *<i>tables</i>);</b>
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">PCRE 16-BIT API INDIRECTED FUNCTIONS</a><br>
|
||||
<P>
|
||||
<b>void *(*pcre16_malloc)(size_t);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void (*pcre16_free)(void *);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void *(*pcre16_stack_malloc)(size_t);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void (*pcre16_stack_free)(void *);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int (*pcre16_callout)(pcre16_callout_block *);</b>
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">PCRE 16-BIT API 16-BIT-ONLY FUNCTION</a><br>
|
||||
<P>
|
||||
<b>int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *<i>output</i>,</b>
|
||||
<b> PCRE_SPTR16 <i>input</i>, int <i>length</i>, int *<i>byte_order</i>,</b>
|
||||
<b> int <i>keep_boms</i>);</b>
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">THE PCRE 16-BIT LIBRARY</a><br>
|
||||
<P>
|
||||
Starting with release 8.30, it is possible to compile a PCRE library that
|
||||
supports 16-bit character strings, including UTF-16 strings, as well as or
|
||||
instead of the original 8-bit library. The majority of the work to make this
|
||||
possible was done by Zoltan Herczeg. The two libraries contain identical sets
|
||||
of functions, used in exactly the same way. Only the names of the functions and
|
||||
the data types of their arguments and results are different. To avoid
|
||||
over-complication and reduce the documentation maintenance load, most of the
|
||||
PCRE documentation describes the 8-bit library, with only occasional references
|
||||
to the 16-bit library. This page describes what is different when you use the
|
||||
16-bit library.
|
||||
</P>
|
||||
<P>
|
||||
WARNING: A single application can be linked with both libraries, but you must
|
||||
take care when processing any particular pattern to use functions from just one
|
||||
library. For example, if you want to study a pattern that was compiled with
|
||||
<b>pcre16_compile()</b>, you must do so with <b>pcre16_study()</b>, not
|
||||
<b>pcre_study()</b>, and you must free the study data with
|
||||
<b>pcre16_free_study()</b>.
|
||||
</P>
|
||||
<br><a name="SEC7" href="#TOC1">THE HEADER FILE</a><br>
|
||||
<P>
|
||||
There is only one header file, <b>pcre.h</b>. It contains prototypes for all the
|
||||
functions in all libraries, as well as definitions of flags, structures, error
|
||||
codes, etc.
|
||||
</P>
|
||||
<br><a name="SEC8" href="#TOC1">THE LIBRARY NAME</a><br>
|
||||
<P>
|
||||
In Unix-like systems, the 16-bit library is called <b>libpcre16</b>, and can
|
||||
normally be accesss by adding <b>-lpcre16</b> to the command for linking an
|
||||
application that uses PCRE.
|
||||
</P>
|
||||
<br><a name="SEC9" href="#TOC1">STRING TYPES</a><br>
|
||||
<P>
|
||||
In the 8-bit library, strings are passed to PCRE library functions as vectors
|
||||
of bytes with the C type "char *". In the 16-bit library, strings are passed as
|
||||
vectors of unsigned 16-bit quantities. The macro PCRE_UCHAR16 specifies an
|
||||
appropriate data type, and PCRE_SPTR16 is defined as "const PCRE_UCHAR16 *". In
|
||||
very many environments, "short int" is a 16-bit data type. When PCRE is built,
|
||||
it defines PCRE_UCHAR16 as "unsigned short int", but checks that it really is a
|
||||
16-bit data type. If it is not, the build fails with an error message telling
|
||||
the maintainer to modify the definition appropriately.
|
||||
</P>
|
||||
<br><a name="SEC10" href="#TOC1">STRUCTURE TYPES</a><br>
|
||||
<P>
|
||||
The types of the opaque structures that are used for compiled 16-bit patterns
|
||||
and JIT stacks are <b>pcre16</b> and <b>pcre16_jit_stack</b> respectively. The
|
||||
type of the user-accessible structure that is returned by <b>pcre16_study()</b>
|
||||
is <b>pcre16_extra</b>, and the type of the structure that is used for passing
|
||||
data to a callout function is <b>pcre16_callout_block</b>. These structures
|
||||
contain the same fields, with the same names, as their 8-bit counterparts. The
|
||||
only difference is that pointers to character strings are 16-bit instead of
|
||||
8-bit types.
|
||||
</P>
|
||||
<br><a name="SEC11" href="#TOC1">16-BIT FUNCTIONS</a><br>
|
||||
<P>
|
||||
For every function in the 8-bit library there is a corresponding function in
|
||||
the 16-bit library with a name that starts with <b>pcre16_</b> instead of
|
||||
<b>pcre_</b>. The prototypes are listed above. In addition, there is one extra
|
||||
function, <b>pcre16_utf16_to_host_byte_order()</b>. This is a utility function
|
||||
that converts a UTF-16 character string to host byte order if necessary. The
|
||||
other 16-bit functions expect the strings they are passed to be in host byte
|
||||
order.
|
||||
</P>
|
||||
<P>
|
||||
The <i>input</i> and <i>output</i> arguments of
|
||||
<b>pcre16_utf16_to_host_byte_order()</b> may point to the same address, that is,
|
||||
conversion in place is supported. The output buffer must be at least as long as
|
||||
the input.
|
||||
</P>
|
||||
<P>
|
||||
The <i>length</i> argument specifies the number of 16-bit data units in the
|
||||
input string; a negative value specifies a zero-terminated string.
|
||||
</P>
|
||||
<P>
|
||||
If <i>byte_order</i> is NULL, it is assumed that the string starts off in host
|
||||
byte order. This may be changed by byte-order marks (BOMs) anywhere in the
|
||||
string (commonly as the first character).
|
||||
</P>
|
||||
<P>
|
||||
If <i>byte_order</i> is not NULL, a non-zero value of the integer to which it
|
||||
points means that the input starts off in host byte order, otherwise the
|
||||
opposite order is assumed. Again, BOMs in the string can change this. The final
|
||||
byte order is passed back at the end of processing.
|
||||
</P>
|
||||
<P>
|
||||
If <i>keep_boms</i> is not zero, byte-order mark characters (0xfeff) are copied
|
||||
into the output string. Otherwise they are discarded.
|
||||
</P>
|
||||
<P>
|
||||
The result of the function is the number of 16-bit units placed into the output
|
||||
buffer, including the zero terminator if the string was zero-terminated.
|
||||
</P>
|
||||
<br><a name="SEC12" href="#TOC1">SUBJECT STRING OFFSETS</a><br>
|
||||
<P>
|
||||
The lengths and starting offsets of subject strings must be specified in 16-bit
|
||||
data units, and the offsets within subject strings that are returned by the
|
||||
matching functions are in also 16-bit units rather than bytes.
|
||||
</P>
|
||||
<br><a name="SEC13" href="#TOC1">NAMED SUBPATTERNS</a><br>
|
||||
<P>
|
||||
The name-to-number translation table that is maintained for named subpatterns
|
||||
uses 16-bit characters. The <b>pcre16_get_stringtable_entries()</b> function
|
||||
returns the length of each entry in the table as the number of 16-bit data
|
||||
units.
|
||||
</P>
|
||||
<br><a name="SEC14" href="#TOC1">OPTION NAMES</a><br>
|
||||
<P>
|
||||
There are two new general option names, PCRE_UTF16 and PCRE_NO_UTF16_CHECK,
|
||||
which correspond to PCRE_UTF8 and PCRE_NO_UTF8_CHECK in the 8-bit library. In
|
||||
fact, these new options define the same bits in the options word. There is a
|
||||
discussion about the
|
||||
<a href="pcreunicode.html#utf16strings">validity of UTF-16 strings</a>
|
||||
in the
|
||||
<a href="pcreunicode.html"><b>pcreunicode</b></a>
|
||||
page.
|
||||
</P>
|
||||
<P>
|
||||
For the <b>pcre16_config()</b> function there is an option PCRE_CONFIG_UTF16
|
||||
that returns 1 if UTF-16 support is configured, otherwise 0. If this option is
|
||||
given to <b>pcre_config()</b> or <b>pcre32_config()</b>, or if the
|
||||
PCRE_CONFIG_UTF8 or PCRE_CONFIG_UTF32 option is given to <b>pcre16_config()</b>,
|
||||
the result is the PCRE_ERROR_BADOPTION error.
|
||||
</P>
|
||||
<br><a name="SEC15" href="#TOC1">CHARACTER CODES</a><br>
|
||||
<P>
|
||||
In 16-bit mode, when PCRE_UTF16 is not set, character values are treated in the
|
||||
same way as in 8-bit, non UTF-8 mode, except, of course, that they can range
|
||||
from 0 to 0xffff instead of 0 to 0xff. Character types for characters less than
|
||||
0xff can therefore be influenced by the locale in the same way as before.
|
||||
Characters greater than 0xff have only one case, and no "type" (such as letter
|
||||
or digit).
|
||||
</P>
|
||||
<P>
|
||||
In UTF-16 mode, the character code is Unicode, in the range 0 to 0x10ffff, with
|
||||
the exception of values in the range 0xd800 to 0xdfff because those are
|
||||
"surrogate" values that are used in pairs to encode values greater than 0xffff.
|
||||
</P>
|
||||
<P>
|
||||
A UTF-16 string can indicate its endianness by special code knows as a
|
||||
byte-order mark (BOM). The PCRE functions do not handle this, expecting strings
|
||||
to be in host byte order. A utility function called
|
||||
<b>pcre16_utf16_to_host_byte_order()</b> is provided to help with this (see
|
||||
above).
|
||||
</P>
|
||||
<br><a name="SEC16" href="#TOC1">ERROR NAMES</a><br>
|
||||
<P>
|
||||
The errors PCRE_ERROR_BADUTF16_OFFSET and PCRE_ERROR_SHORTUTF16 correspond to
|
||||
their 8-bit counterparts. The error PCRE_ERROR_BADMODE is given when a compiled
|
||||
pattern is passed to a function that processes patterns in the other
|
||||
mode, for example, if a pattern compiled with <b>pcre_compile()</b> is passed to
|
||||
<b>pcre16_exec()</b>.
|
||||
</P>
|
||||
<P>
|
||||
There are new error codes whose names begin with PCRE_UTF16_ERR for invalid
|
||||
UTF-16 strings, corresponding to the PCRE_UTF8_ERR codes for UTF-8 strings that
|
||||
are described in the section entitled
|
||||
<a href="pcreapi.html#badutf8reasons">"Reason codes for invalid UTF-8 strings"</a>
|
||||
in the main
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page. The UTF-16 errors are:
|
||||
<pre>
|
||||
PCRE_UTF16_ERR1 Missing low surrogate at end of string
|
||||
PCRE_UTF16_ERR2 Invalid low surrogate follows high surrogate
|
||||
PCRE_UTF16_ERR3 Isolated low surrogate
|
||||
PCRE_UTF16_ERR4 Non-character
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC17" href="#TOC1">ERROR TEXTS</a><br>
|
||||
<P>
|
||||
If there is an error while compiling a pattern, the error text that is passed
|
||||
back by <b>pcre16_compile()</b> or <b>pcre16_compile2()</b> is still an 8-bit
|
||||
character string, zero-terminated.
|
||||
</P>
|
||||
<br><a name="SEC18" href="#TOC1">CALLOUTS</a><br>
|
||||
<P>
|
||||
The <i>subject</i> and <i>mark</i> fields in the callout block that is passed to
|
||||
a callout function point to 16-bit vectors.
|
||||
</P>
|
||||
<br><a name="SEC19" href="#TOC1">TESTING</a><br>
|
||||
<P>
|
||||
The <b>pcretest</b> program continues to operate with 8-bit input and output
|
||||
files, but it can be used for testing the 16-bit library. If it is run with the
|
||||
command line option <b>-16</b>, patterns and subject strings are converted from
|
||||
8-bit to 16-bit before being passed to PCRE, and the 16-bit library functions
|
||||
are used instead of the 8-bit ones. Returned 16-bit strings are converted to
|
||||
8-bit for output. If both the 8-bit and the 32-bit libraries were not compiled,
|
||||
<b>pcretest</b> defaults to 16-bit and the <b>-16</b> option is ignored.
|
||||
</P>
|
||||
<P>
|
||||
When PCRE is being built, the <b>RunTest</b> script that is called by "make
|
||||
check" uses the <b>pcretest</b> <b>-C</b> option to discover which of the 8-bit,
|
||||
16-bit and 32-bit libraries has been built, and runs the tests appropriately.
|
||||
</P>
|
||||
<br><a name="SEC20" href="#TOC1">NOT SUPPORTED IN 16-BIT MODE</a><br>
|
||||
<P>
|
||||
Not all the features of the 8-bit library are available with the 16-bit
|
||||
library. The C++ and POSIX wrapper functions support only the 8-bit library,
|
||||
and the <b>pcregrep</b> program is at present 8-bit only.
|
||||
</P>
|
||||
<br><a name="SEC21" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC22" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 12 May 2013
|
||||
<br>
|
||||
Copyright © 1997-2013 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,382 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre32 specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre32 man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">PCRE 32-BIT API BASIC FUNCTIONS</a>
|
||||
<li><a name="TOC2" href="#SEC2">PCRE 32-BIT API STRING EXTRACTION FUNCTIONS</a>
|
||||
<li><a name="TOC3" href="#SEC3">PCRE 32-BIT API AUXILIARY FUNCTIONS</a>
|
||||
<li><a name="TOC4" href="#SEC4">PCRE 32-BIT API INDIRECTED FUNCTIONS</a>
|
||||
<li><a name="TOC5" href="#SEC5">PCRE 32-BIT API 32-BIT-ONLY FUNCTION</a>
|
||||
<li><a name="TOC6" href="#SEC6">THE PCRE 32-BIT LIBRARY</a>
|
||||
<li><a name="TOC7" href="#SEC7">THE HEADER FILE</a>
|
||||
<li><a name="TOC8" href="#SEC8">THE LIBRARY NAME</a>
|
||||
<li><a name="TOC9" href="#SEC9">STRING TYPES</a>
|
||||
<li><a name="TOC10" href="#SEC10">STRUCTURE TYPES</a>
|
||||
<li><a name="TOC11" href="#SEC11">32-BIT FUNCTIONS</a>
|
||||
<li><a name="TOC12" href="#SEC12">SUBJECT STRING OFFSETS</a>
|
||||
<li><a name="TOC13" href="#SEC13">NAMED SUBPATTERNS</a>
|
||||
<li><a name="TOC14" href="#SEC14">OPTION NAMES</a>
|
||||
<li><a name="TOC15" href="#SEC15">CHARACTER CODES</a>
|
||||
<li><a name="TOC16" href="#SEC16">ERROR NAMES</a>
|
||||
<li><a name="TOC17" href="#SEC17">ERROR TEXTS</a>
|
||||
<li><a name="TOC18" href="#SEC18">CALLOUTS</a>
|
||||
<li><a name="TOC19" href="#SEC19">TESTING</a>
|
||||
<li><a name="TOC20" href="#SEC20">NOT SUPPORTED IN 32-BIT MODE</a>
|
||||
<li><a name="TOC21" href="#SEC21">AUTHOR</a>
|
||||
<li><a name="TOC22" href="#SEC22">REVISION</a>
|
||||
</ul>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<br><a name="SEC1" href="#TOC1">PCRE 32-BIT API BASIC FUNCTIONS</a><br>
|
||||
<P>
|
||||
<b>pcre32 *pcre32_compile(PCRE_SPTR32 <i>pattern</i>, int <i>options</i>,</b>
|
||||
<b> const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
|
||||
<b> const unsigned char *<i>tableptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre32 *pcre32_compile2(PCRE_SPTR32 <i>pattern</i>, int <i>options</i>,</b>
|
||||
<b> int *<i>errorcodeptr</i>,</b>
|
||||
<b> const unsigned char *<i>tableptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre32_extra *pcre32_study(const pcre32 *<i>code</i>, int <i>options</i>,</b>
|
||||
<b> const char **<i>errptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre32_free_study(pcre32_extra *<i>extra</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_exec(const pcre32 *<i>code</i>, const pcre32_extra *<i>extra</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_dfa_exec(const pcre32 *<i>code</i>, const pcre32_extra *<i>extra</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
|
||||
<b> int *<i>workspace</i>, int <i>wscount</i>);</b>
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">PCRE 32-BIT API STRING EXTRACTION FUNCTIONS</a><br>
|
||||
<P>
|
||||
<b>int pcre32_copy_named_substring(const pcre32 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, PCRE_SPTR32 <i>stringname</i>,</b>
|
||||
<b> PCRE_UCHAR32 *<i>buffer</i>, int <i>buffersize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_copy_substring(PCRE_SPTR32 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, int <i>stringnumber</i>, PCRE_UCHAR32 *<i>buffer</i>,</b>
|
||||
<b> int <i>buffersize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_get_named_substring(const pcre32 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, PCRE_SPTR32 <i>stringname</i>,</b>
|
||||
<b> PCRE_SPTR32 *<i>stringptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_get_stringnumber(const pcre32 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>name</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_get_stringtable_entries(const pcre32 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>name</i>, PCRE_UCHAR32 **<i>first</i>, PCRE_UCHAR32 **<i>last</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_get_substring(PCRE_SPTR32 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, int <i>stringnumber</i>,</b>
|
||||
<b> PCRE_SPTR32 *<i>stringptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_get_substring_list(PCRE_SPTR32 <i>subject</i>,</b>
|
||||
<b> int *<i>ovector</i>, int <i>stringcount</i>, PCRE_SPTR32 **<i>listptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre32_free_substring(PCRE_SPTR32 <i>stringptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre32_free_substring_list(PCRE_SPTR32 *<i>stringptr</i>);</b>
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">PCRE 32-BIT API AUXILIARY FUNCTIONS</a><br>
|
||||
<P>
|
||||
<b>pcre32_jit_stack *pcre32_jit_stack_alloc(int <i>startsize</i>, int <i>maxsize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre32_jit_stack_free(pcre32_jit_stack *<i>stack</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre32_assign_jit_stack(pcre32_extra *<i>extra</i>,</b>
|
||||
<b> pcre32_jit_callback <i>callback</i>, void *<i>data</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>const unsigned char *pcre32_maketables(void);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_fullinfo(const pcre32 *<i>code</i>, const pcre32_extra *<i>extra</i>,</b>
|
||||
<b> int <i>what</i>, void *<i>where</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_refcount(pcre32 *<i>code</i>, int <i>adjust</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_config(int <i>what</i>, void *<i>where</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>const char *pcre32_version(void);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_pattern_to_host_byte_order(pcre32 *<i>code</i>,</b>
|
||||
<b> pcre32_extra *<i>extra</i>, const unsigned char *<i>tables</i>);</b>
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">PCRE 32-BIT API INDIRECTED FUNCTIONS</a><br>
|
||||
<P>
|
||||
<b>void *(*pcre32_malloc)(size_t);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void (*pcre32_free)(void *);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void *(*pcre32_stack_malloc)(size_t);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void (*pcre32_stack_free)(void *);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int (*pcre32_callout)(pcre32_callout_block *);</b>
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">PCRE 32-BIT API 32-BIT-ONLY FUNCTION</a><br>
|
||||
<P>
|
||||
<b>int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *<i>output</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>input</i>, int <i>length</i>, int *<i>byte_order</i>,</b>
|
||||
<b> int <i>keep_boms</i>);</b>
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">THE PCRE 32-BIT LIBRARY</a><br>
|
||||
<P>
|
||||
Starting with release 8.32, it is possible to compile a PCRE library that
|
||||
supports 32-bit character strings, including UTF-32 strings, as well as or
|
||||
instead of the original 8-bit library. This work was done by Christian Persch,
|
||||
based on the work done by Zoltan Herczeg for the 16-bit library. All three
|
||||
libraries contain identical sets of functions, used in exactly the same way.
|
||||
Only the names of the functions and the data types of their arguments and
|
||||
results are different. To avoid over-complication and reduce the documentation
|
||||
maintenance load, most of the PCRE documentation describes the 8-bit library,
|
||||
with only occasional references to the 16-bit and 32-bit libraries. This page
|
||||
describes what is different when you use the 32-bit library.
|
||||
</P>
|
||||
<P>
|
||||
WARNING: A single application can be linked with all or any of the three
|
||||
libraries, but you must take care when processing any particular pattern
|
||||
to use functions from just one library. For example, if you want to study
|
||||
a pattern that was compiled with <b>pcre32_compile()</b>, you must do so
|
||||
with <b>pcre32_study()</b>, not <b>pcre_study()</b>, and you must free the
|
||||
study data with <b>pcre32_free_study()</b>.
|
||||
</P>
|
||||
<br><a name="SEC7" href="#TOC1">THE HEADER FILE</a><br>
|
||||
<P>
|
||||
There is only one header file, <b>pcre.h</b>. It contains prototypes for all the
|
||||
functions in all libraries, as well as definitions of flags, structures, error
|
||||
codes, etc.
|
||||
</P>
|
||||
<br><a name="SEC8" href="#TOC1">THE LIBRARY NAME</a><br>
|
||||
<P>
|
||||
In Unix-like systems, the 32-bit library is called <b>libpcre32</b>, and can
|
||||
normally be accesss by adding <b>-lpcre32</b> to the command for linking an
|
||||
application that uses PCRE.
|
||||
</P>
|
||||
<br><a name="SEC9" href="#TOC1">STRING TYPES</a><br>
|
||||
<P>
|
||||
In the 8-bit library, strings are passed to PCRE library functions as vectors
|
||||
of bytes with the C type "char *". In the 32-bit library, strings are passed as
|
||||
vectors of unsigned 32-bit quantities. The macro PCRE_UCHAR32 specifies an
|
||||
appropriate data type, and PCRE_SPTR32 is defined as "const PCRE_UCHAR32 *". In
|
||||
very many environments, "unsigned int" is a 32-bit data type. When PCRE is
|
||||
built, it defines PCRE_UCHAR32 as "unsigned int", but checks that it really is
|
||||
a 32-bit data type. If it is not, the build fails with an error message telling
|
||||
the maintainer to modify the definition appropriately.
|
||||
</P>
|
||||
<br><a name="SEC10" href="#TOC1">STRUCTURE TYPES</a><br>
|
||||
<P>
|
||||
The types of the opaque structures that are used for compiled 32-bit patterns
|
||||
and JIT stacks are <b>pcre32</b> and <b>pcre32_jit_stack</b> respectively. The
|
||||
type of the user-accessible structure that is returned by <b>pcre32_study()</b>
|
||||
is <b>pcre32_extra</b>, and the type of the structure that is used for passing
|
||||
data to a callout function is <b>pcre32_callout_block</b>. These structures
|
||||
contain the same fields, with the same names, as their 8-bit counterparts. The
|
||||
only difference is that pointers to character strings are 32-bit instead of
|
||||
8-bit types.
|
||||
</P>
|
||||
<br><a name="SEC11" href="#TOC1">32-BIT FUNCTIONS</a><br>
|
||||
<P>
|
||||
For every function in the 8-bit library there is a corresponding function in
|
||||
the 32-bit library with a name that starts with <b>pcre32_</b> instead of
|
||||
<b>pcre_</b>. The prototypes are listed above. In addition, there is one extra
|
||||
function, <b>pcre32_utf32_to_host_byte_order()</b>. This is a utility function
|
||||
that converts a UTF-32 character string to host byte order if necessary. The
|
||||
other 32-bit functions expect the strings they are passed to be in host byte
|
||||
order.
|
||||
</P>
|
||||
<P>
|
||||
The <i>input</i> and <i>output</i> arguments of
|
||||
<b>pcre32_utf32_to_host_byte_order()</b> may point to the same address, that is,
|
||||
conversion in place is supported. The output buffer must be at least as long as
|
||||
the input.
|
||||
</P>
|
||||
<P>
|
||||
The <i>length</i> argument specifies the number of 32-bit data units in the
|
||||
input string; a negative value specifies a zero-terminated string.
|
||||
</P>
|
||||
<P>
|
||||
If <i>byte_order</i> is NULL, it is assumed that the string starts off in host
|
||||
byte order. This may be changed by byte-order marks (BOMs) anywhere in the
|
||||
string (commonly as the first character).
|
||||
</P>
|
||||
<P>
|
||||
If <i>byte_order</i> is not NULL, a non-zero value of the integer to which it
|
||||
points means that the input starts off in host byte order, otherwise the
|
||||
opposite order is assumed. Again, BOMs in the string can change this. The final
|
||||
byte order is passed back at the end of processing.
|
||||
</P>
|
||||
<P>
|
||||
If <i>keep_boms</i> is not zero, byte-order mark characters (0xfeff) are copied
|
||||
into the output string. Otherwise they are discarded.
|
||||
</P>
|
||||
<P>
|
||||
The result of the function is the number of 32-bit units placed into the output
|
||||
buffer, including the zero terminator if the string was zero-terminated.
|
||||
</P>
|
||||
<br><a name="SEC12" href="#TOC1">SUBJECT STRING OFFSETS</a><br>
|
||||
<P>
|
||||
The lengths and starting offsets of subject strings must be specified in 32-bit
|
||||
data units, and the offsets within subject strings that are returned by the
|
||||
matching functions are in also 32-bit units rather than bytes.
|
||||
</P>
|
||||
<br><a name="SEC13" href="#TOC1">NAMED SUBPATTERNS</a><br>
|
||||
<P>
|
||||
The name-to-number translation table that is maintained for named subpatterns
|
||||
uses 32-bit characters. The <b>pcre32_get_stringtable_entries()</b> function
|
||||
returns the length of each entry in the table as the number of 32-bit data
|
||||
units.
|
||||
</P>
|
||||
<br><a name="SEC14" href="#TOC1">OPTION NAMES</a><br>
|
||||
<P>
|
||||
There are two new general option names, PCRE_UTF32 and PCRE_NO_UTF32_CHECK,
|
||||
which correspond to PCRE_UTF8 and PCRE_NO_UTF8_CHECK in the 8-bit library. In
|
||||
fact, these new options define the same bits in the options word. There is a
|
||||
discussion about the
|
||||
<a href="pcreunicode.html#utf32strings">validity of UTF-32 strings</a>
|
||||
in the
|
||||
<a href="pcreunicode.html"><b>pcreunicode</b></a>
|
||||
page.
|
||||
</P>
|
||||
<P>
|
||||
For the <b>pcre32_config()</b> function there is an option PCRE_CONFIG_UTF32
|
||||
that returns 1 if UTF-32 support is configured, otherwise 0. If this option is
|
||||
given to <b>pcre_config()</b> or <b>pcre16_config()</b>, or if the
|
||||
PCRE_CONFIG_UTF8 or PCRE_CONFIG_UTF16 option is given to <b>pcre32_config()</b>,
|
||||
the result is the PCRE_ERROR_BADOPTION error.
|
||||
</P>
|
||||
<br><a name="SEC15" href="#TOC1">CHARACTER CODES</a><br>
|
||||
<P>
|
||||
In 32-bit mode, when PCRE_UTF32 is not set, character values are treated in the
|
||||
same way as in 8-bit, non UTF-8 mode, except, of course, that they can range
|
||||
from 0 to 0x7fffffff instead of 0 to 0xff. Character types for characters less
|
||||
than 0xff can therefore be influenced by the locale in the same way as before.
|
||||
Characters greater than 0xff have only one case, and no "type" (such as letter
|
||||
or digit).
|
||||
</P>
|
||||
<P>
|
||||
In UTF-32 mode, the character code is Unicode, in the range 0 to 0x10ffff, with
|
||||
the exception of values in the range 0xd800 to 0xdfff because those are
|
||||
"surrogate" values that are ill-formed in UTF-32.
|
||||
</P>
|
||||
<P>
|
||||
A UTF-32 string can indicate its endianness by special code knows as a
|
||||
byte-order mark (BOM). The PCRE functions do not handle this, expecting strings
|
||||
to be in host byte order. A utility function called
|
||||
<b>pcre32_utf32_to_host_byte_order()</b> is provided to help with this (see
|
||||
above).
|
||||
</P>
|
||||
<br><a name="SEC16" href="#TOC1">ERROR NAMES</a><br>
|
||||
<P>
|
||||
The error PCRE_ERROR_BADUTF32 corresponds to its 8-bit counterpart.
|
||||
The error PCRE_ERROR_BADMODE is given when a compiled
|
||||
pattern is passed to a function that processes patterns in the other
|
||||
mode, for example, if a pattern compiled with <b>pcre_compile()</b> is passed to
|
||||
<b>pcre32_exec()</b>.
|
||||
</P>
|
||||
<P>
|
||||
There are new error codes whose names begin with PCRE_UTF32_ERR for invalid
|
||||
UTF-32 strings, corresponding to the PCRE_UTF8_ERR codes for UTF-8 strings that
|
||||
are described in the section entitled
|
||||
<a href="pcreapi.html#badutf8reasons">"Reason codes for invalid UTF-8 strings"</a>
|
||||
in the main
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page. The UTF-32 errors are:
|
||||
<pre>
|
||||
PCRE_UTF32_ERR1 Surrogate character (range from 0xd800 to 0xdfff)
|
||||
PCRE_UTF32_ERR2 Non-character
|
||||
PCRE_UTF32_ERR3 Character > 0x10ffff
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC17" href="#TOC1">ERROR TEXTS</a><br>
|
||||
<P>
|
||||
If there is an error while compiling a pattern, the error text that is passed
|
||||
back by <b>pcre32_compile()</b> or <b>pcre32_compile2()</b> is still an 8-bit
|
||||
character string, zero-terminated.
|
||||
</P>
|
||||
<br><a name="SEC18" href="#TOC1">CALLOUTS</a><br>
|
||||
<P>
|
||||
The <i>subject</i> and <i>mark</i> fields in the callout block that is passed to
|
||||
a callout function point to 32-bit vectors.
|
||||
</P>
|
||||
<br><a name="SEC19" href="#TOC1">TESTING</a><br>
|
||||
<P>
|
||||
The <b>pcretest</b> program continues to operate with 8-bit input and output
|
||||
files, but it can be used for testing the 32-bit library. If it is run with the
|
||||
command line option <b>-32</b>, patterns and subject strings are converted from
|
||||
8-bit to 32-bit before being passed to PCRE, and the 32-bit library functions
|
||||
are used instead of the 8-bit ones. Returned 32-bit strings are converted to
|
||||
8-bit for output. If both the 8-bit and the 16-bit libraries were not compiled,
|
||||
<b>pcretest</b> defaults to 32-bit and the <b>-32</b> option is ignored.
|
||||
</P>
|
||||
<P>
|
||||
When PCRE is being built, the <b>RunTest</b> script that is called by "make
|
||||
check" uses the <b>pcretest</b> <b>-C</b> option to discover which of the 8-bit,
|
||||
16-bit and 32-bit libraries has been built, and runs the tests appropriately.
|
||||
</P>
|
||||
<br><a name="SEC20" href="#TOC1">NOT SUPPORTED IN 32-BIT MODE</a><br>
|
||||
<P>
|
||||
Not all the features of the 8-bit library are available with the 32-bit
|
||||
library. The C++ and POSIX wrapper functions support only the 8-bit library,
|
||||
and the <b>pcregrep</b> program is at present 8-bit only.
|
||||
</P>
|
||||
<br><a name="SEC21" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC22" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 12 May 2013
|
||||
<br>
|
||||
Copyright © 1997-2013 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,76 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_assign_jit_stack specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_assign_jit_stack man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>void pcre_assign_jit_stack(pcre_extra *<i>extra</i>,</b>
|
||||
<b> pcre_jit_callback <i>callback</i>, void *<i>data</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre16_assign_jit_stack(pcre16_extra *<i>extra</i>,</b>
|
||||
<b> pcre16_jit_callback <i>callback</i>, void *<i>data</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre32_assign_jit_stack(pcre32_extra *<i>extra</i>,</b>
|
||||
<b> pcre32_jit_callback <i>callback</i>, void *<i>data</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function provides control over the memory used as a stack at run-time by a
|
||||
call to <b>pcre[16|32]_exec()</b> with a pattern that has been successfully
|
||||
compiled with JIT optimization. The arguments are:
|
||||
<pre>
|
||||
extra the data pointer returned by <b>pcre[16|32]_study()</b>
|
||||
callback a callback function
|
||||
data a JIT stack or a value to be passed to the callback
|
||||
function
|
||||
</PRE>
|
||||
</P>
|
||||
<P>
|
||||
If <i>callback</i> is NULL and <i>data</i> is NULL, an internal 32K block on
|
||||
the machine stack is used.
|
||||
</P>
|
||||
<P>
|
||||
If <i>callback</i> is NULL and <i>data</i> is not NULL, <i>data</i> must
|
||||
be a valid JIT stack, the result of calling <b>pcre[16|32]_jit_stack_alloc()</b>.
|
||||
</P>
|
||||
<P>
|
||||
If <i>callback</i> not NULL, it is called with <i>data</i> as an argument at
|
||||
the start of matching, in order to set up a JIT stack. If the result is NULL,
|
||||
the internal 32K stack is used; otherwise the return value must be a valid JIT
|
||||
stack, the result of calling <b>pcre[16|32]_jit_stack_alloc()</b>.
|
||||
</P>
|
||||
<P>
|
||||
You may safely assign the same JIT stack to multiple patterns, as long as they
|
||||
are all matched in the same thread. In a multithread application, each thread
|
||||
must use its own JIT stack. For more details, see the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
page.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,111 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_compile specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_compile man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>pcre *pcre_compile(const char *<i>pattern</i>, int <i>options</i>,</b>
|
||||
<b> const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
|
||||
<b> const unsigned char *<i>tableptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre16 *pcre16_compile(PCRE_SPTR16 <i>pattern</i>, int <i>options</i>,</b>
|
||||
<b> const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
|
||||
<b> const unsigned char *<i>tableptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre32 *pcre32_compile(PCRE_SPTR32 <i>pattern</i>, int <i>options</i>,</b>
|
||||
<b> const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
|
||||
<b> const unsigned char *<i>tableptr</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function compiles a regular expression into an internal form. It is the
|
||||
same as <b>pcre[16|32]_compile2()</b>, except for the absence of the
|
||||
<i>errorcodeptr</i> argument. Its arguments are:
|
||||
<pre>
|
||||
<i>pattern</i> A zero-terminated string containing the
|
||||
regular expression to be compiled
|
||||
<i>options</i> Zero or more option bits
|
||||
<i>errptr</i> Where to put an error message
|
||||
<i>erroffset</i> Offset in pattern where error was found
|
||||
<i>tableptr</i> Pointer to character tables, or NULL to
|
||||
use the built-in default
|
||||
</pre>
|
||||
The option bits are:
|
||||
<pre>
|
||||
PCRE_ANCHORED Force pattern anchoring
|
||||
PCRE_AUTO_CALLOUT Compile automatic callouts
|
||||
PCRE_BSR_ANYCRLF \R matches only CR, LF, or CRLF
|
||||
PCRE_BSR_UNICODE \R matches all Unicode line endings
|
||||
PCRE_CASELESS Do caseless matching
|
||||
PCRE_DOLLAR_ENDONLY $ not to match newline at end
|
||||
PCRE_DOTALL . matches anything including NL
|
||||
PCRE_DUPNAMES Allow duplicate names for subpatterns
|
||||
PCRE_EXTENDED Ignore white space and # comments
|
||||
PCRE_EXTRA PCRE extra features
|
||||
(not much use currently)
|
||||
PCRE_FIRSTLINE Force matching to be before newline
|
||||
PCRE_JAVASCRIPT_COMPAT JavaScript compatibility
|
||||
PCRE_MULTILINE ^ and $ match newlines within data
|
||||
PCRE_NEVER_UTF Lock out UTF, e.g. via (*UTF)
|
||||
PCRE_NEWLINE_ANY Recognize any Unicode newline sequence
|
||||
PCRE_NEWLINE_ANYCRLF Recognize CR, LF, and CRLF as newline
|
||||
sequences
|
||||
PCRE_NEWLINE_CR Set CR as the newline sequence
|
||||
PCRE_NEWLINE_CRLF Set CRLF as the newline sequence
|
||||
PCRE_NEWLINE_LF Set LF as the newline sequence
|
||||
PCRE_NO_AUTO_CAPTURE Disable numbered capturing paren-
|
||||
theses (named ones available)
|
||||
PCRE_NO_AUTO_POSSESS Disable auto-possessification
|
||||
PCRE_NO_START_OPTIMIZE Disable match-time start optimizations
|
||||
PCRE_NO_UTF16_CHECK Do not check the pattern for UTF-16
|
||||
validity (only relevant if
|
||||
PCRE_UTF16 is set)
|
||||
PCRE_NO_UTF32_CHECK Do not check the pattern for UTF-32
|
||||
validity (only relevant if
|
||||
PCRE_UTF32 is set)
|
||||
PCRE_NO_UTF8_CHECK Do not check the pattern for UTF-8
|
||||
validity (only relevant if
|
||||
PCRE_UTF8 is set)
|
||||
PCRE_UCP Use Unicode properties for \d, \w, etc.
|
||||
PCRE_UNGREEDY Invert greediness of quantifiers
|
||||
PCRE_UTF16 Run in <b>pcre16_compile()</b> UTF-16 mode
|
||||
PCRE_UTF32 Run in <b>pcre32_compile()</b> UTF-32 mode
|
||||
PCRE_UTF8 Run in <b>pcre_compile()</b> UTF-8 mode
|
||||
</pre>
|
||||
PCRE must be built with UTF support in order to use PCRE_UTF8/16/32 and
|
||||
PCRE_NO_UTF8/16/32_CHECK, and with UCP support if PCRE_UCP is used.
|
||||
</P>
|
||||
<P>
|
||||
The yield of the function is a pointer to a private data structure that
|
||||
contains the compiled pattern, or NULL if an error was detected. Note that
|
||||
compiling regular expressions with one version of PCRE for use with a different
|
||||
version is not guaranteed to work and may cause crashes.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,115 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_compile2 specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_compile2 man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>pcre *pcre_compile2(const char *<i>pattern</i>, int <i>options</i>,</b>
|
||||
<b> int *<i>errorcodeptr</i>,</b>
|
||||
<b> const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
|
||||
<b> const unsigned char *<i>tableptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre16 *pcre16_compile2(PCRE_SPTR16 <i>pattern</i>, int <i>options</i>,</b>
|
||||
<b> int *<i>errorcodeptr</i>,</b>
|
||||
<b> const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
|
||||
<b> const unsigned char *<i>tableptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre32 *pcre32_compile2(PCRE_SPTR32 <i>pattern</i>, int <i>options</i>,</b>
|
||||
<b>" int *<i>errorcodeptr</i>,£</b>
|
||||
<b> const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
|
||||
<b> const unsigned char *<i>tableptr</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function compiles a regular expression into an internal form. It is the
|
||||
same as <b>pcre[16|32]_compile()</b>, except for the addition of the
|
||||
<i>errorcodeptr</i> argument. The arguments are:
|
||||
<pre>
|
||||
<i>pattern</i> A zero-terminated string containing the
|
||||
regular expression to be compiled
|
||||
<i>options</i> Zero or more option bits
|
||||
<i>errorcodeptr</i> Where to put an error code
|
||||
<i>errptr</i> Where to put an error message
|
||||
<i>erroffset</i> Offset in pattern where error was found
|
||||
<i>tableptr</i> Pointer to character tables, or NULL to
|
||||
use the built-in default
|
||||
</pre>
|
||||
The option bits are:
|
||||
<pre>
|
||||
PCRE_ANCHORED Force pattern anchoring
|
||||
PCRE_AUTO_CALLOUT Compile automatic callouts
|
||||
PCRE_BSR_ANYCRLF \R matches only CR, LF, or CRLF
|
||||
PCRE_BSR_UNICODE \R matches all Unicode line endings
|
||||
PCRE_CASELESS Do caseless matching
|
||||
PCRE_DOLLAR_ENDONLY $ not to match newline at end
|
||||
PCRE_DOTALL . matches anything including NL
|
||||
PCRE_DUPNAMES Allow duplicate names for subpatterns
|
||||
PCRE_EXTENDED Ignore white space and # comments
|
||||
PCRE_EXTRA PCRE extra features
|
||||
(not much use currently)
|
||||
PCRE_FIRSTLINE Force matching to be before newline
|
||||
PCRE_JAVASCRIPT_COMPAT JavaScript compatibility
|
||||
PCRE_MULTILINE ^ and $ match newlines within data
|
||||
PCRE_NEVER_UTF Lock out UTF, e.g. via (*UTF)
|
||||
PCRE_NEWLINE_ANY Recognize any Unicode newline sequence
|
||||
PCRE_NEWLINE_ANYCRLF Recognize CR, LF, and CRLF as newline
|
||||
sequences
|
||||
PCRE_NEWLINE_CR Set CR as the newline sequence
|
||||
PCRE_NEWLINE_CRLF Set CRLF as the newline sequence
|
||||
PCRE_NEWLINE_LF Set LF as the newline sequence
|
||||
PCRE_NO_AUTO_CAPTURE Disable numbered capturing paren-
|
||||
theses (named ones available)
|
||||
PCRE_NO_AUTO_POSSESS Disable auto-possessification
|
||||
PCRE_NO_START_OPTIMIZE Disable match-time start optimizations
|
||||
PCRE_NO_UTF16_CHECK Do not check the pattern for UTF-16
|
||||
validity (only relevant if
|
||||
PCRE_UTF16 is set)
|
||||
PCRE_NO_UTF32_CHECK Do not check the pattern for UTF-32
|
||||
validity (only relevant if
|
||||
PCRE_UTF32 is set)
|
||||
PCRE_NO_UTF8_CHECK Do not check the pattern for UTF-8
|
||||
validity (only relevant if
|
||||
PCRE_UTF8 is set)
|
||||
PCRE_UCP Use Unicode properties for \d, \w, etc.
|
||||
PCRE_UNGREEDY Invert greediness of quantifiers
|
||||
PCRE_UTF16 Run <b>pcre16_compile()</b> in UTF-16 mode
|
||||
PCRE_UTF32 Run <b>pcre32_compile()</b> in UTF-32 mode
|
||||
PCRE_UTF8 Run <b>pcre_compile()</b> in UTF-8 mode
|
||||
</pre>
|
||||
PCRE must be built with UTF support in order to use PCRE_UTF8/16/32 and
|
||||
PCRE_NO_UTF8/16/32_CHECK, and with UCP support if PCRE_UCP is used.
|
||||
</P>
|
||||
<P>
|
||||
The yield of the function is a pointer to a private data structure that
|
||||
contains the compiled pattern, or NULL if an error was detected. Note that
|
||||
compiling regular expressions with one version of PCRE for use with a different
|
||||
version is not guaranteed to work and may cause crashes.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,94 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_config specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_config man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre_config(int <i>what</i>, void *<i>where</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre16_config(int <i>what</i>, void *<i>where</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre32_config(int <i>what</i>, void *<i>where</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function makes it possible for a client program to find out which optional
|
||||
features are available in the version of the PCRE library it is using. The
|
||||
arguments are as follows:
|
||||
<pre>
|
||||
<i>what</i> A code specifying what information is required
|
||||
<i>where</i> Points to where to put the data
|
||||
</pre>
|
||||
The <i>where</i> argument must point to an integer variable, except for
|
||||
PCRE_CONFIG_MATCH_LIMIT, PCRE_CONFIG_MATCH_LIMIT_RECURSION, and
|
||||
PCRE_CONFIG_PARENS_LIMIT, when it must point to an unsigned long integer,
|
||||
and for PCRE_CONFIG_JITTARGET, when it must point to a const char*.
|
||||
The available codes are:
|
||||
<pre>
|
||||
PCRE_CONFIG_JIT Availability of just-in-time compiler
|
||||
support (1=yes 0=no)
|
||||
PCRE_CONFIG_JITTARGET String containing information about the
|
||||
target architecture for the JIT compiler,
|
||||
or NULL if there is no JIT support
|
||||
PCRE_CONFIG_LINK_SIZE Internal link size: 2, 3, or 4
|
||||
PCRE_CONFIG_PARENS_LIMIT Parentheses nesting limit
|
||||
PCRE_CONFIG_MATCH_LIMIT Internal resource limit
|
||||
PCRE_CONFIG_MATCH_LIMIT_RECURSION
|
||||
Internal recursion depth limit
|
||||
PCRE_CONFIG_NEWLINE Value of the default newline sequence:
|
||||
13 (0x000d) for CR
|
||||
10 (0x000a) for LF
|
||||
3338 (0x0d0a) for CRLF
|
||||
-2 for ANYCRLF
|
||||
-1 for ANY
|
||||
PCRE_CONFIG_BSR Indicates what \R matches by default:
|
||||
0 all Unicode line endings
|
||||
1 CR, LF, or CRLF only
|
||||
PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
|
||||
Threshold of return slots, above which
|
||||
<b>malloc()</b> is used by the POSIX API
|
||||
PCRE_CONFIG_STACKRECURSE Recursion implementation (1=stack 0=heap)
|
||||
PCRE_CONFIG_UTF16 Availability of UTF-16 support (1=yes
|
||||
0=no); option for <b>pcre16_config()</b>
|
||||
PCRE_CONFIG_UTF32 Availability of UTF-32 support (1=yes
|
||||
0=no); option for <b>pcre32_config()</b>
|
||||
PCRE_CONFIG_UTF8 Availability of UTF-8 support (1=yes 0=no);
|
||||
option for <b>pcre_config()</b>
|
||||
PCRE_CONFIG_UNICODE_PROPERTIES
|
||||
Availability of Unicode property support
|
||||
(1=yes 0=no)
|
||||
</pre>
|
||||
The function yields 0 on success or PCRE_ERROR_BADOPTION otherwise. That error
|
||||
is also given if PCRE_CONFIG_UTF16 or PCRE_CONFIG_UTF32 is passed to
|
||||
<b>pcre_config()</b>, if PCRE_CONFIG_UTF8 or PCRE_CONFIG_UTF32 is passed to
|
||||
<b>pcre16_config()</b>, or if PCRE_CONFIG_UTF8 or PCRE_CONFIG_UTF16 is passed to
|
||||
<b>pcre32_config()</b>.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,65 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_copy_named_substring specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_copy_named_substring man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b>
|
||||
<b> const char *<i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, const char *<i>stringname</i>,</b>
|
||||
<b> char *<i>buffer</i>, int <i>buffersize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_copy_named_substring(const pcre16 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR16 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, PCRE_SPTR16 <i>stringname</i>,</b>
|
||||
<b> PCRE_UCHAR16 *<i>buffer</i>, int <i>buffersize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_copy_named_substring(const pcre32 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, PCRE_SPTR32 <i>stringname</i>,</b>
|
||||
<b> PCRE_UCHAR32 *<i>buffer</i>, int <i>buffersize</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This is a convenience function for extracting a captured substring, identified
|
||||
by name, into a given buffer. The arguments are:
|
||||
<pre>
|
||||
<i>code</i> Pattern that was successfully matched
|
||||
<i>subject</i> Subject that has been successfully matched
|
||||
<i>ovector</i> Offset vector that <b>pcre[16|32]_exec()</b> used
|
||||
<i>stringcount</i> Value returned by <b>pcre[16|32]_exec()</b>
|
||||
<i>stringname</i> Name of the required substring
|
||||
<i>buffer</i> Buffer to receive the string
|
||||
<i>buffersize</i> Size of buffer
|
||||
</pre>
|
||||
The yield is the length of the substring, PCRE_ERROR_NOMEMORY if the buffer was
|
||||
too small, or PCRE_ERROR_NOSUBSTRING if the string name is invalid.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,61 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_copy_substring specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_copy_substring man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre_copy_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, int <i>stringnumber</i>, char *<i>buffer</i>,</b>
|
||||
<b> int <i>buffersize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_copy_substring(PCRE_SPTR16 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, int <i>stringnumber</i>, PCRE_UCHAR16 *<i>buffer</i>,</b>
|
||||
<b> int <i>buffersize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_copy_substring(PCRE_SPTR32 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, int <i>stringnumber</i>, PCRE_UCHAR32 *<i>buffer</i>,</b>
|
||||
<b> int <i>buffersize</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This is a convenience function for extracting a captured substring into a given
|
||||
buffer. The arguments are:
|
||||
<pre>
|
||||
<i>subject</i> Subject that has been successfully matched
|
||||
<i>ovector</i> Offset vector that <b>pcre[16|32]_exec()</b> used
|
||||
<i>stringcount</i> Value returned by <b>pcre[16|32]_exec()</b>
|
||||
<i>stringnumber</i> Number of the required substring
|
||||
<i>buffer</i> Buffer to receive the string
|
||||
<i>buffersize</i> Size of buffer
|
||||
</pre>
|
||||
The yield is the length of the string, PCRE_ERROR_NOMEMORY if the buffer was
|
||||
too small, or PCRE_ERROR_NOSUBSTRING if the string number is invalid.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,129 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_dfa_exec specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_dfa_exec man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre_dfa_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
|
||||
<b> const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
|
||||
<b> int *<i>workspace</i>, int <i>wscount</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_dfa_exec(const pcre16 *<i>code</i>, const pcre16_extra *<i>extra</i>,</b>
|
||||
<b> PCRE_SPTR16 <i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
|
||||
<b> int *<i>workspace</i>, int <i>wscount</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_dfa_exec(const pcre32 *<i>code</i>, const pcre32_extra *<i>extra</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
|
||||
<b> int *<i>workspace</i>, int <i>wscount</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function matches a compiled regular expression against a given subject
|
||||
string, using an alternative matching algorithm that scans the subject string
|
||||
just once (<i>not</i> Perl-compatible). Note that the main, Perl-compatible,
|
||||
matching function is <b>pcre[16|32]_exec()</b>. The arguments for this function
|
||||
are:
|
||||
<pre>
|
||||
<i>code</i> Points to the compiled pattern
|
||||
<i>extra</i> Points to an associated <b>pcre[16|32]_extra</b> structure,
|
||||
or is NULL
|
||||
<i>subject</i> Points to the subject string
|
||||
<i>length</i> Length of the subject string
|
||||
<i>startoffset</i> Offset in the subject at which to start matching
|
||||
<i>options</i> Option bits
|
||||
<i>ovector</i> Points to a vector of ints for result offsets
|
||||
<i>ovecsize</i> Number of elements in the vector
|
||||
<i>workspace</i> Points to a vector of ints used as working space
|
||||
<i>wscount</i> Number of elements in the vector
|
||||
</pre>
|
||||
The units for <i>length</i> and <i>startoffset</i> are bytes for
|
||||
<b>pcre_exec()</b>, 16-bit data items for <b>pcre16_exec()</b>, and 32-bit items
|
||||
for <b>pcre32_exec()</b>. The options are:
|
||||
<pre>
|
||||
PCRE_ANCHORED Match only at the first position
|
||||
PCRE_BSR_ANYCRLF \R matches only CR, LF, or CRLF
|
||||
PCRE_BSR_UNICODE \R matches all Unicode line endings
|
||||
PCRE_NEWLINE_ANY Recognize any Unicode newline sequence
|
||||
PCRE_NEWLINE_ANYCRLF Recognize CR, LF, & CRLF as newline sequences
|
||||
PCRE_NEWLINE_CR Recognize CR as the only newline sequence
|
||||
PCRE_NEWLINE_CRLF Recognize CRLF as the only newline sequence
|
||||
PCRE_NEWLINE_LF Recognize LF as the only newline sequence
|
||||
PCRE_NOTBOL Subject is not the beginning of a line
|
||||
PCRE_NOTEOL Subject is not the end of a line
|
||||
PCRE_NOTEMPTY An empty string is not a valid match
|
||||
PCRE_NOTEMPTY_ATSTART An empty string at the start of the subject
|
||||
is not a valid match
|
||||
PCRE_NO_START_OPTIMIZE Do not do "start-match" optimizations
|
||||
PCRE_NO_UTF16_CHECK Do not check the subject for UTF-16
|
||||
validity (only relevant if PCRE_UTF16
|
||||
was set at compile time)
|
||||
PCRE_NO_UTF32_CHECK Do not check the subject for UTF-32
|
||||
validity (only relevant if PCRE_UTF32
|
||||
was set at compile time)
|
||||
PCRE_NO_UTF8_CHECK Do not check the subject for UTF-8
|
||||
validity (only relevant if PCRE_UTF8
|
||||
was set at compile time)
|
||||
PCRE_PARTIAL ) Return PCRE_ERROR_PARTIAL for a partial
|
||||
PCRE_PARTIAL_SOFT ) match if no full matches are found
|
||||
PCRE_PARTIAL_HARD Return PCRE_ERROR_PARTIAL for a partial match
|
||||
even if there is a full match as well
|
||||
PCRE_DFA_SHORTEST Return only the shortest match
|
||||
PCRE_DFA_RESTART Restart after a partial match
|
||||
</pre>
|
||||
There are restrictions on what may appear in a pattern when using this matching
|
||||
function. Details are given in the
|
||||
<a href="pcrematching.html"><b>pcrematching</b></a>
|
||||
documentation. For details of partial matching, see the
|
||||
<a href="pcrepartial.html"><b>pcrepartial</b></a>
|
||||
page.
|
||||
</P>
|
||||
<P>
|
||||
A <b>pcre[16|32]_extra</b> structure contains the following fields:
|
||||
<pre>
|
||||
<i>flags</i> Bits indicating which fields are set
|
||||
<i>study_data</i> Opaque data from <b>pcre[16|32]_study()</b>
|
||||
<i>match_limit</i> Limit on internal resource use
|
||||
<i>match_limit_recursion</i> Limit on internal recursion depth
|
||||
<i>callout_data</i> Opaque data passed back to callouts
|
||||
<i>tables</i> Points to character tables or is NULL
|
||||
<i>mark</i> For passing back a *MARK pointer
|
||||
<i>executable_jit</i> Opaque data from JIT compilation
|
||||
</pre>
|
||||
The flag bits are PCRE_EXTRA_STUDY_DATA, PCRE_EXTRA_MATCH_LIMIT,
|
||||
PCRE_EXTRA_MATCH_LIMIT_RECURSION, PCRE_EXTRA_CALLOUT_DATA,
|
||||
PCRE_EXTRA_TABLES, PCRE_EXTRA_MARK and PCRE_EXTRA_EXECUTABLE_JIT. For this
|
||||
matching function, the <i>match_limit</i> and <i>match_limit_recursion</i> fields
|
||||
are not used, and must not be set. The PCRE_EXTRA_EXECUTABLE_JIT flag and
|
||||
the corresponding variable are ignored.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,111 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_exec specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_exec man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
|
||||
<b> const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_exec(const pcre16 *<i>code</i>, const pcre16_extra *<i>extra</i>,</b>
|
||||
<b> PCRE_SPTR16 <i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_exec(const pcre32 *<i>code</i>, const pcre32_extra *<i>extra</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function matches a compiled regular expression against a given subject
|
||||
string, using a matching algorithm that is similar to Perl's. It returns
|
||||
offsets to captured substrings. Its arguments are:
|
||||
<pre>
|
||||
<i>code</i> Points to the compiled pattern
|
||||
<i>extra</i> Points to an associated <b>pcre[16|32]_extra</b> structure,
|
||||
or is NULL
|
||||
<i>subject</i> Points to the subject string
|
||||
<i>length</i> Length of the subject string
|
||||
<i>startoffset</i> Offset in the subject at which to start matching
|
||||
<i>options</i> Option bits
|
||||
<i>ovector</i> Points to a vector of ints for result offsets
|
||||
<i>ovecsize</i> Number of elements in the vector (a multiple of 3)
|
||||
</pre>
|
||||
The units for <i>length</i> and <i>startoffset</i> are bytes for
|
||||
<b>pcre_exec()</b>, 16-bit data items for <b>pcre16_exec()</b>, and 32-bit items
|
||||
for <b>pcre32_exec()</b>. The options are:
|
||||
<pre>
|
||||
PCRE_ANCHORED Match only at the first position
|
||||
PCRE_BSR_ANYCRLF \R matches only CR, LF, or CRLF
|
||||
PCRE_BSR_UNICODE \R matches all Unicode line endings
|
||||
PCRE_NEWLINE_ANY Recognize any Unicode newline sequence
|
||||
PCRE_NEWLINE_ANYCRLF Recognize CR, LF, & CRLF as newline sequences
|
||||
PCRE_NEWLINE_CR Recognize CR as the only newline sequence
|
||||
PCRE_NEWLINE_CRLF Recognize CRLF as the only newline sequence
|
||||
PCRE_NEWLINE_LF Recognize LF as the only newline sequence
|
||||
PCRE_NOTBOL Subject string is not the beginning of a line
|
||||
PCRE_NOTEOL Subject string is not the end of a line
|
||||
PCRE_NOTEMPTY An empty string is not a valid match
|
||||
PCRE_NOTEMPTY_ATSTART An empty string at the start of the subject
|
||||
is not a valid match
|
||||
PCRE_NO_START_OPTIMIZE Do not do "start-match" optimizations
|
||||
PCRE_NO_UTF16_CHECK Do not check the subject for UTF-16
|
||||
validity (only relevant if PCRE_UTF16
|
||||
was set at compile time)
|
||||
PCRE_NO_UTF32_CHECK Do not check the subject for UTF-32
|
||||
validity (only relevant if PCRE_UTF32
|
||||
was set at compile time)
|
||||
PCRE_NO_UTF8_CHECK Do not check the subject for UTF-8
|
||||
validity (only relevant if PCRE_UTF8
|
||||
was set at compile time)
|
||||
PCRE_PARTIAL ) Return PCRE_ERROR_PARTIAL for a partial
|
||||
PCRE_PARTIAL_SOFT ) match if no full matches are found
|
||||
PCRE_PARTIAL_HARD Return PCRE_ERROR_PARTIAL for a partial match
|
||||
if that is found before a full match
|
||||
</pre>
|
||||
For details of partial matching, see the
|
||||
<a href="pcrepartial.html"><b>pcrepartial</b></a>
|
||||
page. A <b>pcre_extra</b> structure contains the following fields:
|
||||
<pre>
|
||||
<i>flags</i> Bits indicating which fields are set
|
||||
<i>study_data</i> Opaque data from <b>pcre[16|32]_study()</b>
|
||||
<i>match_limit</i> Limit on internal resource use
|
||||
<i>match_limit_recursion</i> Limit on internal recursion depth
|
||||
<i>callout_data</i> Opaque data passed back to callouts
|
||||
<i>tables</i> Points to character tables or is NULL
|
||||
<i>mark</i> For passing back a *MARK pointer
|
||||
<i>executable_jit</i> Opaque data from JIT compilation
|
||||
</pre>
|
||||
The flag bits are PCRE_EXTRA_STUDY_DATA, PCRE_EXTRA_MATCH_LIMIT,
|
||||
PCRE_EXTRA_MATCH_LIMIT_RECURSION, PCRE_EXTRA_CALLOUT_DATA,
|
||||
PCRE_EXTRA_TABLES, PCRE_EXTRA_MARK and PCRE_EXTRA_EXECUTABLE_JIT.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,46 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_free_study specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_free_study man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>void pcre_free_study(pcre_extra *<i>extra</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>void pcre16_free_study(pcre16_extra *<i>extra</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>void pcre32_free_study(pcre32_extra *<i>extra</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function is used to free the memory used for the data generated by a call
|
||||
to <b>pcre[16|32]_study()</b> when it is no longer needed. The argument must be the
|
||||
result of such a call.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,46 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_free_substring specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_free_substring man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>void pcre_free_substring(const char *<i>stringptr</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>void pcre16_free_substring(PCRE_SPTR16 <i>stringptr</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>void pcre32_free_substring(PCRE_SPTR32 <i>stringptr</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This is a convenience function for freeing the store obtained by a previous
|
||||
call to <b>pcre[16|32]_get_substring()</b> or <b>pcre[16|32]_get_named_substring()</b>.
|
||||
Its only argument is a pointer to the string.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,46 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_free_substring_list specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_free_substring_list man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>void pcre_free_substring_list(const char **<i>stringptr</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>void pcre16_free_substring_list(PCRE_SPTR16 *<i>stringptr</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>void pcre32_free_substring_list(PCRE_SPTR32 *<i>stringptr</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This is a convenience function for freeing the store obtained by a previous
|
||||
call to <b>pcre[16|32]_get_substring_list()</b>. Its only argument is a pointer to
|
||||
the list of string pointers.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,118 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_fullinfo specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_fullinfo man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre_fullinfo(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
|
||||
<b> int <i>what</i>, void *<i>where</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_fullinfo(const pcre16 *<i>code</i>, const pcre16_extra *<i>extra</i>,</b>
|
||||
<b> int <i>what</i>, void *<i>where</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_fullinfo(const pcre32 *<i>code</i>, const pcre32_extra *<i>extra</i>,</b>
|
||||
<b> int <i>what</i>, void *<i>where</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function returns information about a compiled pattern. Its arguments are:
|
||||
<pre>
|
||||
<i>code</i> Compiled regular expression
|
||||
<i>extra</i> Result of <b>pcre[16|32]_study()</b> or NULL
|
||||
<i>what</i> What information is required
|
||||
<i>where</i> Where to put the information
|
||||
</pre>
|
||||
The following information is available:
|
||||
<pre>
|
||||
PCRE_INFO_BACKREFMAX Number of highest back reference
|
||||
PCRE_INFO_CAPTURECOUNT Number of capturing subpatterns
|
||||
PCRE_INFO_DEFAULT_TABLES Pointer to default tables
|
||||
PCRE_INFO_FIRSTBYTE Fixed first data unit for a match, or
|
||||
-1 for start of string
|
||||
or after newline, or
|
||||
-2 otherwise
|
||||
PCRE_INFO_FIRSTTABLE Table of first data units (after studying)
|
||||
PCRE_INFO_HASCRORLF Return 1 if explicit CR or LF matches exist
|
||||
PCRE_INFO_JCHANGED Return 1 if (?J) or (?-J) was used
|
||||
PCRE_INFO_JIT Return 1 after successful JIT compilation
|
||||
PCRE_INFO_JITSIZE Size of JIT compiled code
|
||||
PCRE_INFO_LASTLITERAL Literal last data unit required
|
||||
PCRE_INFO_MINLENGTH Lower bound length of matching strings
|
||||
PCRE_INFO_MATCHEMPTY Return 1 if the pattern can match an empty string,
|
||||
0 otherwise
|
||||
PCRE_INFO_MATCHLIMIT Match limit if set, otherwise PCRE_RROR_UNSET
|
||||
PCRE_INFO_MAXLOOKBEHIND Length (in characters) of the longest lookbehind assertion
|
||||
PCRE_INFO_NAMECOUNT Number of named subpatterns
|
||||
PCRE_INFO_NAMEENTRYSIZE Size of name table entry
|
||||
PCRE_INFO_NAMETABLE Pointer to name table
|
||||
PCRE_INFO_OKPARTIAL Return 1 if partial matching can be tried
|
||||
(always returns 1 after release 8.00)
|
||||
PCRE_INFO_OPTIONS Option bits used for compilation
|
||||
PCRE_INFO_SIZE Size of compiled pattern
|
||||
PCRE_INFO_STUDYSIZE Size of study data
|
||||
PCRE_INFO_FIRSTCHARACTER Fixed first data unit for a match
|
||||
PCRE_INFO_FIRSTCHARACTERFLAGS Returns
|
||||
1 if there is a first data character set, which can
|
||||
then be retrieved using PCRE_INFO_FIRSTCHARACTER,
|
||||
2 if the first character is at the start of the data
|
||||
string or after a newline, and
|
||||
0 otherwise
|
||||
PCRE_INFO_RECURSIONLIMIT Recursion limit if set, otherwise PCRE_ERROR_UNSET
|
||||
PCRE_INFO_REQUIREDCHAR Literal last data unit required
|
||||
PCRE_INFO_REQUIREDCHARFLAGS Returns 1 if the last data character is set (which can then
|
||||
be retrieved using PCRE_INFO_REQUIREDCHAR); 0 otherwise
|
||||
</pre>
|
||||
The <i>where</i> argument must point to an integer variable, except for the
|
||||
following <i>what</i> values:
|
||||
<pre>
|
||||
PCRE_INFO_DEFAULT_TABLES const uint8_t *
|
||||
PCRE_INFO_FIRSTCHARACTER uint32_t
|
||||
PCRE_INFO_FIRSTTABLE const uint8_t *
|
||||
PCRE_INFO_JITSIZE size_t
|
||||
PCRE_INFO_MATCHLIMIT uint32_t
|
||||
PCRE_INFO_NAMETABLE PCRE_SPTR16 (16-bit library)
|
||||
PCRE_INFO_NAMETABLE PCRE_SPTR32 (32-bit library)
|
||||
PCRE_INFO_NAMETABLE const unsigned char * (8-bit library)
|
||||
PCRE_INFO_OPTIONS unsigned long int
|
||||
PCRE_INFO_SIZE size_t
|
||||
PCRE_INFO_STUDYSIZE size_t
|
||||
PCRE_INFO_RECURSIONLIMIT uint32_t
|
||||
PCRE_INFO_REQUIREDCHAR uint32_t
|
||||
</pre>
|
||||
The yield of the function is zero on success or:
|
||||
<pre>
|
||||
PCRE_ERROR_NULL the argument <i>code</i> was NULL
|
||||
the argument <i>where</i> was NULL
|
||||
PCRE_ERROR_BADMAGIC the "magic number" was not found
|
||||
PCRE_ERROR_BADOPTION the value of <i>what</i> was invalid
|
||||
PCRE_ERROR_UNSET the option was not set
|
||||
</PRE>
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,68 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_get_named_substring specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_get_named_substring man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre_get_named_substring(const pcre *<i>code</i>,</b>
|
||||
<b> const char *<i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, const char *<i>stringname</i>,</b>
|
||||
<b> const char **<i>stringptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_get_named_substring(const pcre16 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR16 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, PCRE_SPTR16 <i>stringname</i>,</b>
|
||||
<b> PCRE_SPTR16 *<i>stringptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_get_named_substring(const pcre32 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, PCRE_SPTR32 <i>stringname</i>,</b>
|
||||
<b> PCRE_SPTR32 *<i>stringptr</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This is a convenience function for extracting a captured substring by name. The
|
||||
arguments are:
|
||||
<pre>
|
||||
<i>code</i> Compiled pattern
|
||||
<i>subject</i> Subject that has been successfully matched
|
||||
<i>ovector</i> Offset vector that <b>pcre[16|32]_exec()</b> used
|
||||
<i>stringcount</i> Value returned by <b>pcre[16|32]_exec()</b>
|
||||
<i>stringname</i> Name of the required substring
|
||||
<i>stringptr</i> Where to put the string pointer
|
||||
</pre>
|
||||
The memory in which the substring is placed is obtained by calling
|
||||
<b>pcre[16|32]_malloc()</b>. The convenience function
|
||||
<b>pcre[16|32]_free_substring()</b> can be used to free it when it is no longer
|
||||
needed. The yield of the function is the length of the extracted substring,
|
||||
PCRE_ERROR_NOMEMORY if sufficient memory could not be obtained, or
|
||||
PCRE_ERROR_NOSUBSTRING if the string name is invalid.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,57 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_get_stringnumber specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_get_stringnumber man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>
|
||||
<b> const char *<i>name</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_get_stringnumber(const pcre16 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR16 <i>name</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_get_stringnumber(const pcre32 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>name</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This convenience function finds the number of a named substring capturing
|
||||
parenthesis in a compiled pattern. Its arguments are:
|
||||
<pre>
|
||||
<i>code</i> Compiled regular expression
|
||||
<i>name</i> Name whose number is required
|
||||
</pre>
|
||||
The yield of the function is the number of the parenthesis if the name is
|
||||
found, or PCRE_ERROR_NOSUBSTRING otherwise. When duplicate names are allowed
|
||||
(PCRE_DUPNAMES is set), it is not defined which of the numbers is returned by
|
||||
<b>pcre[16|32]_get_stringnumber()</b>. You can obtain the complete list by calling
|
||||
<b>pcre[16|32]_get_stringtable_entries()</b>.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,60 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_get_stringtable_entries specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_get_stringtable_entries man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>
|
||||
<b> const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_get_stringtable_entries(const pcre16 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR16 <i>name</i>, PCRE_UCHAR16 **<i>first</i>, PCRE_UCHAR16 **<i>last</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_get_stringtable_entries(const pcre32 *<i>code</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>name</i>, PCRE_UCHAR32 **<i>first</i>, PCRE_UCHAR32 **<i>last</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This convenience function finds, for a compiled pattern, the first and last
|
||||
entries for a given name in the table that translates capturing parenthesis
|
||||
names into numbers. When names are required to be unique (PCRE_DUPNAMES is
|
||||
<i>not</i> set), it is usually easier to use <b>pcre[16|32]_get_stringnumber()</b>
|
||||
instead.
|
||||
<pre>
|
||||
<i>code</i> Compiled regular expression
|
||||
<i>name</i> Name whose entries required
|
||||
<i>first</i> Where to return a pointer to the first entry
|
||||
<i>last</i> Where to return a pointer to the last entry
|
||||
</pre>
|
||||
The yield of the function is the length of each entry, or
|
||||
PCRE_ERROR_NOSUBSTRING if none are found.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API, including the format of
|
||||
the table entries, in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page, and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,64 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_get_substring specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_get_substring man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre_get_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, int <i>stringnumber</i>,</b>
|
||||
<b> const char **<i>stringptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_get_substring(PCRE_SPTR16 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, int <i>stringnumber</i>,</b>
|
||||
<b> PCRE_SPTR16 *<i>stringptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_get_substring(PCRE_SPTR32 <i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, int <i>stringnumber</i>,</b>
|
||||
<b> PCRE_SPTR32 *<i>stringptr</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This is a convenience function for extracting a captured substring. The
|
||||
arguments are:
|
||||
<pre>
|
||||
<i>subject</i> Subject that has been successfully matched
|
||||
<i>ovector</i> Offset vector that <b>pcre[16|32]_exec()</b> used
|
||||
<i>stringcount</i> Value returned by <b>pcre[16|32]_exec()</b>
|
||||
<i>stringnumber</i> Number of the required substring
|
||||
<i>stringptr</i> Where to put the string pointer
|
||||
</pre>
|
||||
The memory in which the substring is placed is obtained by calling
|
||||
<b>pcre[16|32]_malloc()</b>. The convenience function
|
||||
<b>pcre[16|32]_free_substring()</b> can be used to free it when it is no longer
|
||||
needed. The yield of the function is the length of the substring,
|
||||
PCRE_ERROR_NOMEMORY if sufficient memory could not be obtained, or
|
||||
PCRE_ERROR_NOSUBSTRING if the string number is invalid.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,61 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_get_substring_list specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_get_substring_list man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre_get_substring_list(const char *<i>subject</i>,</b>
|
||||
<b> int *<i>ovector</i>, int <i>stringcount</i>, const char ***<i>listptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_get_substring_list(PCRE_SPTR16 <i>subject</i>,</b>
|
||||
<b> int *<i>ovector</i>, int <i>stringcount</i>, PCRE_SPTR16 **<i>listptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_get_substring_list(PCRE_SPTR32 <i>subject</i>,</b>
|
||||
<b> int *<i>ovector</i>, int <i>stringcount</i>, PCRE_SPTR32 **<i>listptr</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This is a convenience function for extracting a list of all the captured
|
||||
substrings. The arguments are:
|
||||
<pre>
|
||||
<i>subject</i> Subject that has been successfully matched
|
||||
<i>ovector</i> Offset vector that <b>pcre[16|32]_exec</b> used
|
||||
<i>stringcount</i> Value returned by <b>pcre[16|32]_exec</b>
|
||||
<i>listptr</i> Where to put a pointer to the list
|
||||
</pre>
|
||||
The memory in which the substrings and the list are placed is obtained by
|
||||
calling <b>pcre[16|32]_malloc()</b>. The convenience function
|
||||
<b>pcre[16|32]_free_substring_list()</b> can be used to free it when it is no
|
||||
longer needed. A pointer to a list of pointers is put in the variable whose
|
||||
address is in <i>listptr</i>. The list is terminated by a NULL pointer. The
|
||||
yield of the function is zero on success or PCRE_ERROR_NOMEMORY if sufficient
|
||||
memory could not be obtained.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,108 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_jit_exec specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_jit_exec man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre_jit_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
|
||||
<b> const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
|
||||
<b> pcre_jit_stack *<i>jstack</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_jit_exec(const pcre16 *<i>code</i>, const pcre16_extra *<i>extra</i>,</b>
|
||||
<b> PCRE_SPTR16 <i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
|
||||
<b> pcre_jit_stack *<i>jstack</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_jit_exec(const pcre32 *<i>code</i>, const pcre32_extra *<i>extra</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
|
||||
<b> pcre_jit_stack *<i>jstack</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function matches a compiled regular expression that has been successfully
|
||||
studied with one of the JIT options against a given subject string, using a
|
||||
matching algorithm that is similar to Perl's. It is a "fast path" interface to
|
||||
JIT, and it bypasses some of the sanity checks that <b>pcre_exec()</b> applies.
|
||||
It returns offsets to captured substrings. Its arguments are:
|
||||
<pre>
|
||||
<i>code</i> Points to the compiled pattern
|
||||
<i>extra</i> Points to an associated <b>pcre[16|32]_extra</b> structure,
|
||||
or is NULL
|
||||
<i>subject</i> Points to the subject string
|
||||
<i>length</i> Length of the subject string, in bytes
|
||||
<i>startoffset</i> Offset in bytes in the subject at which to
|
||||
start matching
|
||||
<i>options</i> Option bits
|
||||
<i>ovector</i> Points to a vector of ints for result offsets
|
||||
<i>ovecsize</i> Number of elements in the vector (a multiple of 3)
|
||||
<i>jstack</i> Pointer to a JIT stack
|
||||
</pre>
|
||||
The allowed options are:
|
||||
<pre>
|
||||
PCRE_NOTBOL Subject string is not the beginning of a line
|
||||
PCRE_NOTEOL Subject string is not the end of a line
|
||||
PCRE_NOTEMPTY An empty string is not a valid match
|
||||
PCRE_NOTEMPTY_ATSTART An empty string at the start of the subject
|
||||
is not a valid match
|
||||
PCRE_NO_UTF16_CHECK Do not check the subject for UTF-16
|
||||
validity (only relevant if PCRE_UTF16
|
||||
was set at compile time)
|
||||
PCRE_NO_UTF32_CHECK Do not check the subject for UTF-32
|
||||
validity (only relevant if PCRE_UTF32
|
||||
was set at compile time)
|
||||
PCRE_NO_UTF8_CHECK Do not check the subject for UTF-8
|
||||
validity (only relevant if PCRE_UTF8
|
||||
was set at compile time)
|
||||
PCRE_PARTIAL ) Return PCRE_ERROR_PARTIAL for a partial
|
||||
PCRE_PARTIAL_SOFT ) match if no full matches are found
|
||||
PCRE_PARTIAL_HARD Return PCRE_ERROR_PARTIAL for a partial match
|
||||
if that is found before a full match
|
||||
</pre>
|
||||
However, the PCRE_NO_UTF[8|16|32]_CHECK options have no effect, as this check
|
||||
is never applied. For details of partial matching, see the
|
||||
<a href="pcrepartial.html"><b>pcrepartial</b></a>
|
||||
page. A <b>pcre_extra</b> structure contains the following fields:
|
||||
<pre>
|
||||
<i>flags</i> Bits indicating which fields are set
|
||||
<i>study_data</i> Opaque data from <b>pcre[16|32]_study()</b>
|
||||
<i>match_limit</i> Limit on internal resource use
|
||||
<i>match_limit_recursion</i> Limit on internal recursion depth
|
||||
<i>callout_data</i> Opaque data passed back to callouts
|
||||
<i>tables</i> Points to character tables or is NULL
|
||||
<i>mark</i> For passing back a *MARK pointer
|
||||
<i>executable_jit</i> Opaque data from JIT compilation
|
||||
</pre>
|
||||
The flag bits are PCRE_EXTRA_STUDY_DATA, PCRE_EXTRA_MATCH_LIMIT,
|
||||
PCRE_EXTRA_MATCH_LIMIT_RECURSION, PCRE_EXTRA_CALLOUT_DATA,
|
||||
PCRE_EXTRA_TABLES, PCRE_EXTRA_MARK and PCRE_EXTRA_EXECUTABLE_JIT.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the JIT API in the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,55 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_jit_stack_alloc specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_jit_stack_alloc man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>pcre_jit_stack *pcre_jit_stack_alloc(int <i>startsize</i>,</b>
|
||||
<b> int <i>maxsize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre16_jit_stack *pcre16_jit_stack_alloc(int <i>startsize</i>,</b>
|
||||
<b> int <i>maxsize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre32_jit_stack *pcre32_jit_stack_alloc(int <i>startsize</i>,</b>
|
||||
<b> int <i>maxsize</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function is used to create a stack for use by the code compiled by the JIT
|
||||
optimization of <b>pcre[16|32]_study()</b>. The arguments are a starting size for
|
||||
the stack, and a maximum size to which it is allowed to grow. The result can be
|
||||
passed to the JIT run-time code by <b>pcre[16|32]_assign_jit_stack()</b>, or that
|
||||
function can set up a callback for obtaining a stack. A maximum stack size of
|
||||
512K to 1M should be more than enough for any pattern. For more details, see
|
||||
the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
page.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,48 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_jit_stack_free specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_jit_stack_free man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>void pcre_jit_stack_free(pcre_jit_stack *<i>stack</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>void pcre16_jit_stack_free(pcre16_jit_stack *<i>stack</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>void pcre32_jit_stack_free(pcre32_jit_stack *<i>stack</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function is used to free a JIT stack that was created by
|
||||
<b>pcre[16|32]_jit_stack_alloc()</b> when it is no longer needed. For more details,
|
||||
see the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
page.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,48 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_maketables specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_maketables man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>const unsigned char *pcre_maketables(void);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>const unsigned char *pcre16_maketables(void);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>const unsigned char *pcre32_maketables(void);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function builds a set of character tables for character values less than
|
||||
256. These can be passed to <b>pcre[16|32]_compile()</b> to override PCRE's
|
||||
internal, built-in tables (which were made by <b>pcre[16|32]_maketables()</b> when
|
||||
PCRE was compiled). You might want to do this if you are using a non-standard
|
||||
locale. The function yields a pointer to the tables.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,58 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_pattern_to_host_byte_order specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_pattern_to_host_byte_order man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre_pattern_to_host_byte_order(pcre *<i>code</i>,</b>
|
||||
<b> pcre_extra *<i>extra</i>, const unsigned char *<i>tables</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre16_pattern_to_host_byte_order(pcre16 *<i>code</i>,</b>
|
||||
<b> pcre16_extra *<i>extra</i>, const unsigned char *<i>tables</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre32_pattern_to_host_byte_order(pcre32 *<i>code</i>,</b>
|
||||
<b> pcre32_extra *<i>extra</i>, const unsigned char *<i>tables</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function ensures that the bytes in 2-byte and 4-byte values in a compiled
|
||||
pattern are in the correct order for the current host. It is useful when a
|
||||
pattern that has been compiled on one host is transferred to another that might
|
||||
have different endianness. The arguments are:
|
||||
<pre>
|
||||
<i>code</i> A compiled regular expression
|
||||
<i>extra</i> Points to an associated <b>pcre[16|32]_extra</b> structure,
|
||||
or is NULL
|
||||
<i>tables</i> Pointer to character tables, or NULL to
|
||||
set the built-in default
|
||||
</pre>
|
||||
The result is 0 for success, a negative PCRE_ERROR_xxx value otherwise.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,51 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_refcount specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_refcount man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre_refcount(pcre *<i>code</i>, int <i>adjust</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre16_refcount(pcre16 *<i>code</i>, int <i>adjust</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre32_refcount(pcre32 *<i>code</i>, int <i>adjust</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function is used to maintain a reference count inside a data block that
|
||||
contains a compiled pattern. Its arguments are:
|
||||
<pre>
|
||||
<i>code</i> Compiled regular expression
|
||||
<i>adjust</i> Adjustment to reference value
|
||||
</pre>
|
||||
The yield of the function is the adjusted reference value, which is constrained
|
||||
to lie between 0 and 65535.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,68 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_study specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_study man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>pcre_extra *pcre_study(const pcre *<i>code</i>, int <i>options</i>,</b>
|
||||
<b> const char **<i>errptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre16_extra *pcre16_study(const pcre16 *<i>code</i>, int <i>options</i>,</b>
|
||||
<b> const char **<i>errptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre32_extra *pcre32_study(const pcre32 *<i>code</i>, int <i>options</i>,</b>
|
||||
<b> const char **<i>errptr</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function studies a compiled pattern, to see if additional information can
|
||||
be extracted that might speed up matching. Its arguments are:
|
||||
<pre>
|
||||
<i>code</i> A compiled regular expression
|
||||
<i>options</i> Options for <b>pcre[16|32]_study()</b>
|
||||
<i>errptr</i> Where to put an error message
|
||||
</pre>
|
||||
If the function succeeds, it returns a value that can be passed to
|
||||
<b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b> via their <i>extra</i>
|
||||
arguments.
|
||||
</P>
|
||||
<P>
|
||||
If the function returns NULL, either it could not find any additional
|
||||
information, or there was an error. You can tell the difference by looking at
|
||||
the error value. It is NULL in first case.
|
||||
</P>
|
||||
<P>
|
||||
The only option is PCRE_STUDY_JIT_COMPILE. It requests just-in-time compilation
|
||||
if possible. If PCRE has been compiled without JIT support, this option is
|
||||
ignored. See the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
page for further details.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,57 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_utf16_to_host_byte_order specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_utf16_to_host_byte_order man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre16_utf16_to_host_byte_order(PCRE_UCHAR16 *<i>output</i>,</b>
|
||||
<b> PCRE_SPTR16 <i>input</i>, int <i>length</i>, int *<i>host_byte_order</i>,</b>
|
||||
<b> int <i>keep_boms</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function, which exists only in the 16-bit library, converts a UTF-16
|
||||
string to the correct order for the current host, taking account of any byte
|
||||
order marks (BOMs) within the string. Its arguments are:
|
||||
<pre>
|
||||
<i>output</i> pointer to output buffer, may be the same as <i>input</i>
|
||||
<i>input</i> pointer to input buffer
|
||||
<i>length</i> number of 16-bit units in the input, or negative for
|
||||
a zero-terminated string
|
||||
<i>host_byte_order</i> a NULL value or a non-zero value pointed to means
|
||||
start in host byte order
|
||||
<i>keep_boms</i> if non-zero, BOMs are copied to the output string
|
||||
</pre>
|
||||
The result of the function is the number of 16-bit units placed into the output
|
||||
buffer, including the zero terminator if the string was zero-terminated.
|
||||
</P>
|
||||
<P>
|
||||
If <i>host_byte_order</i> is not NULL, it is set to indicate the byte order that
|
||||
is current at the end of the string.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,57 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_utf32_to_host_byte_order specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_utf32_to_host_byte_order man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int pcre32_utf32_to_host_byte_order(PCRE_UCHAR32 *<i>output</i>,</b>
|
||||
<b> PCRE_SPTR32 <i>input</i>, int <i>length</i>, int *<i>host_byte_order</i>,</b>
|
||||
<b> int <i>keep_boms</i>);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function, which exists only in the 32-bit library, converts a UTF-32
|
||||
string to the correct order for the current host, taking account of any byte
|
||||
order marks (BOMs) within the string. Its arguments are:
|
||||
<pre>
|
||||
<i>output</i> pointer to output buffer, may be the same as <i>input</i>
|
||||
<i>input</i> pointer to input buffer
|
||||
<i>length</i> number of 32-bit units in the input, or negative for
|
||||
a zero-terminated string
|
||||
<i>host_byte_order</i> a NULL value or a non-zero value pointed to means
|
||||
start in host byte order
|
||||
<i>keep_boms</i> if non-zero, BOMs are copied to the output string
|
||||
</pre>
|
||||
The result of the function is the number of 32-bit units placed into the output
|
||||
buffer, including the zero terminator if the string was zero-terminated.
|
||||
</P>
|
||||
<P>
|
||||
If <i>host_byte_order</i> is not NULL, it is set to indicate the byte order that
|
||||
is current at the end of the string.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,46 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcre_version specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcre_version man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SYNOPSIS
|
||||
</b><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>const char *pcre_version(void);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>const char *pcre16_version(void);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>const char *pcre32_version(void);</b>
|
||||
</P>
|
||||
<br><b>
|
||||
DESCRIPTION
|
||||
</b><br>
|
||||
<P>
|
||||
This function (even in the 16-bit and 32-bit libraries) returns a
|
||||
zero-terminated, 8-bit character string that gives the version number of the
|
||||
PCRE library and the date of its release.
|
||||
</P>
|
||||
<P>
|
||||
There is a complete description of the PCRE native API in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page and a description of the POSIX API in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
page.
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,2921 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcreapi specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcreapi man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">PCRE NATIVE API BASIC FUNCTIONS</a>
|
||||
<li><a name="TOC2" href="#SEC2">PCRE NATIVE API STRING EXTRACTION FUNCTIONS</a>
|
||||
<li><a name="TOC3" href="#SEC3">PCRE NATIVE API AUXILIARY FUNCTIONS</a>
|
||||
<li><a name="TOC4" href="#SEC4">PCRE NATIVE API INDIRECTED FUNCTIONS</a>
|
||||
<li><a name="TOC5" href="#SEC5">PCRE 8-BIT, 16-BIT, AND 32-BIT LIBRARIES</a>
|
||||
<li><a name="TOC6" href="#SEC6">PCRE API OVERVIEW</a>
|
||||
<li><a name="TOC7" href="#SEC7">NEWLINES</a>
|
||||
<li><a name="TOC8" href="#SEC8">MULTITHREADING</a>
|
||||
<li><a name="TOC9" href="#SEC9">SAVING PRECOMPILED PATTERNS FOR LATER USE</a>
|
||||
<li><a name="TOC10" href="#SEC10">CHECKING BUILD-TIME OPTIONS</a>
|
||||
<li><a name="TOC11" href="#SEC11">COMPILING A PATTERN</a>
|
||||
<li><a name="TOC12" href="#SEC12">COMPILATION ERROR CODES</a>
|
||||
<li><a name="TOC13" href="#SEC13">STUDYING A PATTERN</a>
|
||||
<li><a name="TOC14" href="#SEC14">LOCALE SUPPORT</a>
|
||||
<li><a name="TOC15" href="#SEC15">INFORMATION ABOUT A PATTERN</a>
|
||||
<li><a name="TOC16" href="#SEC16">REFERENCE COUNTS</a>
|
||||
<li><a name="TOC17" href="#SEC17">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a>
|
||||
<li><a name="TOC18" href="#SEC18">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a>
|
||||
<li><a name="TOC19" href="#SEC19">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a>
|
||||
<li><a name="TOC20" href="#SEC20">DUPLICATE SUBPATTERN NAMES</a>
|
||||
<li><a name="TOC21" href="#SEC21">FINDING ALL POSSIBLE MATCHES</a>
|
||||
<li><a name="TOC22" href="#SEC22">OBTAINING AN ESTIMATE OF STACK USAGE</a>
|
||||
<li><a name="TOC23" href="#SEC23">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a>
|
||||
<li><a name="TOC24" href="#SEC24">SEE ALSO</a>
|
||||
<li><a name="TOC25" href="#SEC25">AUTHOR</a>
|
||||
<li><a name="TOC26" href="#SEC26">REVISION</a>
|
||||
</ul>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<br><a name="SEC1" href="#TOC1">PCRE NATIVE API BASIC FUNCTIONS</a><br>
|
||||
<P>
|
||||
<b>pcre *pcre_compile(const char *<i>pattern</i>, int <i>options</i>,</b>
|
||||
<b> const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
|
||||
<b> const unsigned char *<i>tableptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre *pcre_compile2(const char *<i>pattern</i>, int <i>options</i>,</b>
|
||||
<b> int *<i>errorcodeptr</i>,</b>
|
||||
<b> const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
|
||||
<b> const unsigned char *<i>tableptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre_extra *pcre_study(const pcre *<i>code</i>, int <i>options</i>,</b>
|
||||
<b> const char **<i>errptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre_free_study(pcre_extra *<i>extra</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
|
||||
<b> const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_dfa_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
|
||||
<b> const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
|
||||
<b> int *<i>workspace</i>, int <i>wscount</i>);</b>
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">PCRE NATIVE API STRING EXTRACTION FUNCTIONS</a><br>
|
||||
<P>
|
||||
<b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b>
|
||||
<b> const char *<i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, const char *<i>stringname</i>,</b>
|
||||
<b> char *<i>buffer</i>, int <i>buffersize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_copy_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, int <i>stringnumber</i>, char *<i>buffer</i>,</b>
|
||||
<b> int <i>buffersize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_get_named_substring(const pcre *<i>code</i>,</b>
|
||||
<b> const char *<i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, const char *<i>stringname</i>,</b>
|
||||
<b> const char **<i>stringptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>
|
||||
<b> const char *<i>name</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>
|
||||
<b> const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_get_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, int <i>stringnumber</i>,</b>
|
||||
<b> const char **<i>stringptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_get_substring_list(const char *<i>subject</i>,</b>
|
||||
<b> int *<i>ovector</i>, int <i>stringcount</i>, const char ***<i>listptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre_free_substring(const char *<i>stringptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre_free_substring_list(const char **<i>stringptr</i>);</b>
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">PCRE NATIVE API AUXILIARY FUNCTIONS</a><br>
|
||||
<P>
|
||||
<b>int pcre_jit_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
|
||||
<b> const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
|
||||
<b> pcre_jit_stack *<i>jstack</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre_jit_stack *pcre_jit_stack_alloc(int <i>startsize</i>, int <i>maxsize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre_jit_stack_free(pcre_jit_stack *<i>stack</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void pcre_assign_jit_stack(pcre_extra *<i>extra</i>,</b>
|
||||
<b> pcre_jit_callback <i>callback</i>, void *<i>data</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>const unsigned char *pcre_maketables(void);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_fullinfo(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
|
||||
<b> int <i>what</i>, void *<i>where</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_refcount(pcre *<i>code</i>, int <i>adjust</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_config(int <i>what</i>, void *<i>where</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>const char *pcre_version(void);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_pattern_to_host_byte_order(pcre *<i>code</i>,</b>
|
||||
<b> pcre_extra *<i>extra</i>, const unsigned char *<i>tables</i>);</b>
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">PCRE NATIVE API INDIRECTED FUNCTIONS</a><br>
|
||||
<P>
|
||||
<b>void *(*pcre_malloc)(size_t);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void (*pcre_free)(void *);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void *(*pcre_stack_malloc)(size_t);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void (*pcre_stack_free)(void *);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int (*pcre_callout)(pcre_callout_block *);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int (*pcre_stack_guard)(void);</b>
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">PCRE 8-BIT, 16-BIT, AND 32-BIT LIBRARIES</a><br>
|
||||
<P>
|
||||
As well as support for 8-bit character strings, PCRE also supports 16-bit
|
||||
strings (from release 8.30) and 32-bit strings (from release 8.32), by means of
|
||||
two additional libraries. They can be built as well as, or instead of, the
|
||||
8-bit library. To avoid too much complication, this document describes the
|
||||
8-bit versions of the functions, with only occasional references to the 16-bit
|
||||
and 32-bit libraries.
|
||||
</P>
|
||||
<P>
|
||||
The 16-bit and 32-bit functions operate in the same way as their 8-bit
|
||||
counterparts; they just use different data types for their arguments and
|
||||
results, and their names start with <b>pcre16_</b> or <b>pcre32_</b> instead of
|
||||
<b>pcre_</b>. For every option that has UTF8 in its name (for example,
|
||||
PCRE_UTF8), there are corresponding 16-bit and 32-bit names with UTF8 replaced
|
||||
by UTF16 or UTF32, respectively. This facility is in fact just cosmetic; the
|
||||
16-bit and 32-bit option names define the same bit values.
|
||||
</P>
|
||||
<P>
|
||||
References to bytes and UTF-8 in this document should be read as references to
|
||||
16-bit data units and UTF-16 when using the 16-bit library, or 32-bit data
|
||||
units and UTF-32 when using the 32-bit library, unless specified otherwise.
|
||||
More details of the specific differences for the 16-bit and 32-bit libraries
|
||||
are given in the
|
||||
<a href="pcre16.html"><b>pcre16</b></a>
|
||||
and
|
||||
<a href="pcre32.html"><b>pcre32</b></a>
|
||||
pages.
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">PCRE API OVERVIEW</a><br>
|
||||
<P>
|
||||
PCRE has its own native API, which is described in this document. There are
|
||||
also some wrapper functions (for the 8-bit library only) that correspond to the
|
||||
POSIX regular expression API, but they do not give access to all the
|
||||
functionality. They are described in the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
documentation. Both of these APIs define a set of C function calls. A C++
|
||||
wrapper (again for the 8-bit library only) is also distributed with PCRE. It is
|
||||
documented in the
|
||||
<a href="pcrecpp.html"><b>pcrecpp</b></a>
|
||||
page.
|
||||
</P>
|
||||
<P>
|
||||
The native API C function prototypes are defined in the header file
|
||||
<b>pcre.h</b>, and on Unix-like systems the (8-bit) library itself is called
|
||||
<b>libpcre</b>. It can normally be accessed by adding <b>-lpcre</b> to the
|
||||
command for linking an application that uses PCRE. The header file defines the
|
||||
macros PCRE_MAJOR and PCRE_MINOR to contain the major and minor release numbers
|
||||
for the library. Applications can use these to include support for different
|
||||
releases of PCRE.
|
||||
</P>
|
||||
<P>
|
||||
In a Windows environment, if you want to statically link an application program
|
||||
against a non-dll <b>pcre.a</b> file, you must define PCRE_STATIC before
|
||||
including <b>pcre.h</b> or <b>pcrecpp.h</b>, because otherwise the
|
||||
<b>pcre_malloc()</b> and <b>pcre_free()</b> exported functions will be declared
|
||||
<b>__declspec(dllimport)</b>, with unwanted results.
|
||||
</P>
|
||||
<P>
|
||||
The functions <b>pcre_compile()</b>, <b>pcre_compile2()</b>, <b>pcre_study()</b>,
|
||||
and <b>pcre_exec()</b> are used for compiling and matching regular expressions
|
||||
in a Perl-compatible manner. A sample program that demonstrates the simplest
|
||||
way of using them is provided in the file called <i>pcredemo.c</i> in the PCRE
|
||||
source distribution. A listing of this program is given in the
|
||||
<a href="pcredemo.html"><b>pcredemo</b></a>
|
||||
documentation, and the
|
||||
<a href="pcresample.html"><b>pcresample</b></a>
|
||||
documentation describes how to compile and run it.
|
||||
</P>
|
||||
<P>
|
||||
Just-in-time compiler support is an optional feature of PCRE that can be built
|
||||
in appropriate hardware environments. It greatly speeds up the matching
|
||||
performance of many patterns. Simple programs can easily request that it be
|
||||
used if available, by setting an option that is ignored when it is not
|
||||
relevant. More complicated programs might need to make use of the functions
|
||||
<b>pcre_jit_stack_alloc()</b>, <b>pcre_jit_stack_free()</b>, and
|
||||
<b>pcre_assign_jit_stack()</b> in order to control the JIT code's memory usage.
|
||||
</P>
|
||||
<P>
|
||||
From release 8.32 there is also a direct interface for JIT execution, which
|
||||
gives improved performance. The JIT-specific functions are discussed in the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
A second matching function, <b>pcre_dfa_exec()</b>, which is not
|
||||
Perl-compatible, is also provided. This uses a different algorithm for the
|
||||
matching. The alternative algorithm finds all possible matches (at a given
|
||||
point in the subject), and scans the subject just once (unless there are
|
||||
lookbehind assertions). However, this algorithm does not return captured
|
||||
substrings. A description of the two matching algorithms and their advantages
|
||||
and disadvantages is given in the
|
||||
<a href="pcrematching.html"><b>pcrematching</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
In addition to the main compiling and matching functions, there are convenience
|
||||
functions for extracting captured substrings from a subject string that is
|
||||
matched by <b>pcre_exec()</b>. They are:
|
||||
<pre>
|
||||
<b>pcre_copy_substring()</b>
|
||||
<b>pcre_copy_named_substring()</b>
|
||||
<b>pcre_get_substring()</b>
|
||||
<b>pcre_get_named_substring()</b>
|
||||
<b>pcre_get_substring_list()</b>
|
||||
<b>pcre_get_stringnumber()</b>
|
||||
<b>pcre_get_stringtable_entries()</b>
|
||||
</pre>
|
||||
<b>pcre_free_substring()</b> and <b>pcre_free_substring_list()</b> are also
|
||||
provided, to free the memory used for extracted strings.
|
||||
</P>
|
||||
<P>
|
||||
The function <b>pcre_maketables()</b> is used to build a set of character tables
|
||||
in the current locale for passing to <b>pcre_compile()</b>, <b>pcre_exec()</b>,
|
||||
or <b>pcre_dfa_exec()</b>. This is an optional facility that is provided for
|
||||
specialist use. Most commonly, no special tables are passed, in which case
|
||||
internal tables that are generated when PCRE is built are used.
|
||||
</P>
|
||||
<P>
|
||||
The function <b>pcre_fullinfo()</b> is used to find out information about a
|
||||
compiled pattern. The function <b>pcre_version()</b> returns a pointer to a
|
||||
string containing the version of PCRE and its date of release.
|
||||
</P>
|
||||
<P>
|
||||
The function <b>pcre_refcount()</b> maintains a reference count in a data block
|
||||
containing a compiled pattern. This is provided for the benefit of
|
||||
object-oriented applications.
|
||||
</P>
|
||||
<P>
|
||||
The global variables <b>pcre_malloc</b> and <b>pcre_free</b> initially contain
|
||||
the entry points of the standard <b>malloc()</b> and <b>free()</b> functions,
|
||||
respectively. PCRE calls the memory management functions via these variables,
|
||||
so a calling program can replace them if it wishes to intercept the calls. This
|
||||
should be done before calling any PCRE functions.
|
||||
</P>
|
||||
<P>
|
||||
The global variables <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> are also
|
||||
indirections to memory management functions. These special functions are used
|
||||
only when PCRE is compiled to use the heap for remembering data, instead of
|
||||
recursive function calls, when running the <b>pcre_exec()</b> function. See the
|
||||
<a href="pcrebuild.html"><b>pcrebuild</b></a>
|
||||
documentation for details of how to do this. It is a non-standard way of
|
||||
building PCRE, for use in environments that have limited stacks. Because of the
|
||||
greater use of memory management, it runs more slowly. Separate functions are
|
||||
provided so that special-purpose external code can be used for this case. When
|
||||
used, these functions always allocate memory blocks of the same size. There is
|
||||
a discussion about PCRE's stack usage in the
|
||||
<a href="pcrestack.html"><b>pcrestack</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
The global variable <b>pcre_callout</b> initially contains NULL. It can be set
|
||||
by the caller to a "callout" function, which PCRE will then call at specified
|
||||
points during a matching operation. Details are given in the
|
||||
<a href="pcrecallout.html"><b>pcrecallout</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
The global variable <b>pcre_stack_guard</b> initially contains NULL. It can be
|
||||
set by the caller to a function that is called by PCRE whenever it starts
|
||||
to compile a parenthesized part of a pattern. When parentheses are nested, PCRE
|
||||
uses recursive function calls, which use up the system stack. This function is
|
||||
provided so that applications with restricted stacks can force a compilation
|
||||
error if the stack runs out. The function should return zero if all is well, or
|
||||
non-zero to force an error.
|
||||
<a name="newlines"></a></P>
|
||||
<br><a name="SEC7" href="#TOC1">NEWLINES</a><br>
|
||||
<P>
|
||||
PCRE supports five different conventions for indicating line breaks in
|
||||
strings: a single CR (carriage return) character, a single LF (linefeed)
|
||||
character, the two-character sequence CRLF, any of the three preceding, or any
|
||||
Unicode newline sequence. The Unicode newline sequences are the three just
|
||||
mentioned, plus the single characters VT (vertical tab, U+000B), FF (form feed,
|
||||
U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
|
||||
(paragraph separator, U+2029).
|
||||
</P>
|
||||
<P>
|
||||
Each of the first three conventions is used by at least one operating system as
|
||||
its standard newline sequence. When PCRE is built, a default can be specified.
|
||||
The default default is LF, which is the Unix standard. When PCRE is run, the
|
||||
default can be overridden, either when a pattern is compiled, or when it is
|
||||
matched.
|
||||
</P>
|
||||
<P>
|
||||
At compile time, the newline convention can be specified by the <i>options</i>
|
||||
argument of <b>pcre_compile()</b>, or it can be specified by special text at the
|
||||
start of the pattern itself; this overrides any other settings. See the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
page for details of the special character sequences.
|
||||
</P>
|
||||
<P>
|
||||
In the PCRE documentation the word "newline" is used to mean "the character or
|
||||
pair of characters that indicate a line break". The choice of newline
|
||||
convention affects the handling of the dot, circumflex, and dollar
|
||||
metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
|
||||
recognized line ending sequence, the match position advancement for a
|
||||
non-anchored pattern. There is more detail about this in the
|
||||
<a href="#execoptions">section on <b>pcre_exec()</b> options</a>
|
||||
below.
|
||||
</P>
|
||||
<P>
|
||||
The choice of newline convention does not affect the interpretation of
|
||||
the \n or \r escape sequences, nor does it affect what \R matches, which is
|
||||
controlled in a similar way, but by separate options.
|
||||
</P>
|
||||
<br><a name="SEC8" href="#TOC1">MULTITHREADING</a><br>
|
||||
<P>
|
||||
The PCRE functions can be used in multi-threading applications, with the
|
||||
proviso that the memory management functions pointed to by <b>pcre_malloc</b>,
|
||||
<b>pcre_free</b>, <b>pcre_stack_malloc</b>, and <b>pcre_stack_free</b>, and the
|
||||
callout and stack-checking functions pointed to by <b>pcre_callout</b> and
|
||||
<b>pcre_stack_guard</b>, are shared by all threads.
|
||||
</P>
|
||||
<P>
|
||||
The compiled form of a regular expression is not altered during matching, so
|
||||
the same compiled pattern can safely be used by several threads at once.
|
||||
</P>
|
||||
<P>
|
||||
If the just-in-time optimization feature is being used, it needs separate
|
||||
memory stack areas for each thread. See the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
documentation for more details.
|
||||
</P>
|
||||
<br><a name="SEC9" href="#TOC1">SAVING PRECOMPILED PATTERNS FOR LATER USE</a><br>
|
||||
<P>
|
||||
The compiled form of a regular expression can be saved and re-used at a later
|
||||
time, possibly by a different program, and even on a host other than the one on
|
||||
which it was compiled. Details are given in the
|
||||
<a href="pcreprecompile.html"><b>pcreprecompile</b></a>
|
||||
documentation, which includes a description of the
|
||||
<b>pcre_pattern_to_host_byte_order()</b> function. However, compiling a regular
|
||||
expression with one version of PCRE for use with a different version is not
|
||||
guaranteed to work and may cause crashes.
|
||||
</P>
|
||||
<br><a name="SEC10" href="#TOC1">CHECKING BUILD-TIME OPTIONS</a><br>
|
||||
<P>
|
||||
<b>int pcre_config(int <i>what</i>, void *<i>where</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
The function <b>pcre_config()</b> makes it possible for a PCRE client to
|
||||
discover which optional features have been compiled into the PCRE library. The
|
||||
<a href="pcrebuild.html"><b>pcrebuild</b></a>
|
||||
documentation has more details about these optional features.
|
||||
</P>
|
||||
<P>
|
||||
The first argument for <b>pcre_config()</b> is an integer, specifying which
|
||||
information is required; the second argument is a pointer to a variable into
|
||||
which the information is placed. The returned value is zero on success, or the
|
||||
negative error code PCRE_ERROR_BADOPTION if the value in the first argument is
|
||||
not recognized. The following information is available:
|
||||
<pre>
|
||||
PCRE_CONFIG_UTF8
|
||||
</pre>
|
||||
The output is an integer that is set to one if UTF-8 support is available;
|
||||
otherwise it is set to zero. This value should normally be given to the 8-bit
|
||||
version of this function, <b>pcre_config()</b>. If it is given to the 16-bit
|
||||
or 32-bit version of this function, the result is PCRE_ERROR_BADOPTION.
|
||||
<pre>
|
||||
PCRE_CONFIG_UTF16
|
||||
</pre>
|
||||
The output is an integer that is set to one if UTF-16 support is available;
|
||||
otherwise it is set to zero. This value should normally be given to the 16-bit
|
||||
version of this function, <b>pcre16_config()</b>. If it is given to the 8-bit
|
||||
or 32-bit version of this function, the result is PCRE_ERROR_BADOPTION.
|
||||
<pre>
|
||||
PCRE_CONFIG_UTF32
|
||||
</pre>
|
||||
The output is an integer that is set to one if UTF-32 support is available;
|
||||
otherwise it is set to zero. This value should normally be given to the 32-bit
|
||||
version of this function, <b>pcre32_config()</b>. If it is given to the 8-bit
|
||||
or 16-bit version of this function, the result is PCRE_ERROR_BADOPTION.
|
||||
<pre>
|
||||
PCRE_CONFIG_UNICODE_PROPERTIES
|
||||
</pre>
|
||||
The output is an integer that is set to one if support for Unicode character
|
||||
properties is available; otherwise it is set to zero.
|
||||
<pre>
|
||||
PCRE_CONFIG_JIT
|
||||
</pre>
|
||||
The output is an integer that is set to one if support for just-in-time
|
||||
compiling is available; otherwise it is set to zero.
|
||||
<pre>
|
||||
PCRE_CONFIG_JITTARGET
|
||||
</pre>
|
||||
The output is a pointer to a zero-terminated "const char *" string. If JIT
|
||||
support is available, the string contains the name of the architecture for
|
||||
which the JIT compiler is configured, for example "x86 32bit (little endian +
|
||||
unaligned)". If JIT support is not available, the result is NULL.
|
||||
<pre>
|
||||
PCRE_CONFIG_NEWLINE
|
||||
</pre>
|
||||
The output is an integer whose value specifies the default character sequence
|
||||
that is recognized as meaning "newline". The values that are supported in
|
||||
ASCII/Unicode environments are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for
|
||||
ANYCRLF, and -1 for ANY. In EBCDIC environments, CR, ANYCRLF, and ANY yield the
|
||||
same values. However, the value for LF is normally 21, though some EBCDIC
|
||||
environments use 37. The corresponding values for CRLF are 3349 and 3365. The
|
||||
default should normally correspond to the standard sequence for your operating
|
||||
system.
|
||||
<pre>
|
||||
PCRE_CONFIG_BSR
|
||||
</pre>
|
||||
The output is an integer whose value indicates what character sequences the \R
|
||||
escape sequence matches by default. A value of 0 means that \R matches any
|
||||
Unicode line ending sequence; a value of 1 means that \R matches only CR, LF,
|
||||
or CRLF. The default can be overridden when a pattern is compiled or matched.
|
||||
<pre>
|
||||
PCRE_CONFIG_LINK_SIZE
|
||||
</pre>
|
||||
The output is an integer that contains the number of bytes used for internal
|
||||
linkage in compiled regular expressions. For the 8-bit library, the value can
|
||||
be 2, 3, or 4. For the 16-bit library, the value is either 2 or 4 and is still
|
||||
a number of bytes. For the 32-bit library, the value is either 2 or 4 and is
|
||||
still a number of bytes. The default value of 2 is sufficient for all but the
|
||||
most massive patterns, since it allows the compiled pattern to be up to 64K in
|
||||
size. Larger values allow larger regular expressions to be compiled, at the
|
||||
expense of slower matching.
|
||||
<pre>
|
||||
PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
|
||||
</pre>
|
||||
The output is an integer that contains the threshold above which the POSIX
|
||||
interface uses <b>malloc()</b> for output vectors. Further details are given in
|
||||
the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
documentation.
|
||||
<pre>
|
||||
PCRE_CONFIG_PARENS_LIMIT
|
||||
</pre>
|
||||
The output is a long integer that gives the maximum depth of nesting of
|
||||
parentheses (of any kind) in a pattern. This limit is imposed to cap the amount
|
||||
of system stack used when a pattern is compiled. It is specified when PCRE is
|
||||
built; the default is 250. This limit does not take into account the stack that
|
||||
may already be used by the calling application. For finer control over
|
||||
compilation stack usage, you can set a pointer to an external checking function
|
||||
in <b>pcre_stack_guard</b>.
|
||||
<pre>
|
||||
PCRE_CONFIG_MATCH_LIMIT
|
||||
</pre>
|
||||
The output is a long integer that gives the default limit for the number of
|
||||
internal matching function calls in a <b>pcre_exec()</b> execution. Further
|
||||
details are given with <b>pcre_exec()</b> below.
|
||||
<pre>
|
||||
PCRE_CONFIG_MATCH_LIMIT_RECURSION
|
||||
</pre>
|
||||
The output is a long integer that gives the default limit for the depth of
|
||||
recursion when calling the internal matching function in a <b>pcre_exec()</b>
|
||||
execution. Further details are given with <b>pcre_exec()</b> below.
|
||||
<pre>
|
||||
PCRE_CONFIG_STACKRECURSE
|
||||
</pre>
|
||||
The output is an integer that is set to one if internal recursion when running
|
||||
<b>pcre_exec()</b> is implemented by recursive function calls that use the stack
|
||||
to remember their state. This is the usual way that PCRE is compiled. The
|
||||
output is zero if PCRE was compiled to use blocks of data on the heap instead
|
||||
of recursive function calls. In this case, <b>pcre_stack_malloc</b> and
|
||||
<b>pcre_stack_free</b> are called to manage memory blocks on the heap, thus
|
||||
avoiding the use of the stack.
|
||||
</P>
|
||||
<br><a name="SEC11" href="#TOC1">COMPILING A PATTERN</a><br>
|
||||
<P>
|
||||
<b>pcre *pcre_compile(const char *<i>pattern</i>, int <i>options</i>,</b>
|
||||
<b> const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
|
||||
<b> const unsigned char *<i>tableptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcre *pcre_compile2(const char *<i>pattern</i>, int <i>options</i>,</b>
|
||||
<b> int *<i>errorcodeptr</i>,</b>
|
||||
<b> const char **<i>errptr</i>, int *<i>erroffset</i>,</b>
|
||||
<b> const unsigned char *<i>tableptr</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
Either of the functions <b>pcre_compile()</b> or <b>pcre_compile2()</b> can be
|
||||
called to compile a pattern into an internal form. The only difference between
|
||||
the two interfaces is that <b>pcre_compile2()</b> has an additional argument,
|
||||
<i>errorcodeptr</i>, via which a numerical error code can be returned. To avoid
|
||||
too much repetition, we refer just to <b>pcre_compile()</b> below, but the
|
||||
information applies equally to <b>pcre_compile2()</b>.
|
||||
</P>
|
||||
<P>
|
||||
The pattern is a C string terminated by a binary zero, and is passed in the
|
||||
<i>pattern</i> argument. A pointer to a single block of memory that is obtained
|
||||
via <b>pcre_malloc</b> is returned. This contains the compiled code and related
|
||||
data. The <b>pcre</b> type is defined for the returned block; this is a typedef
|
||||
for a structure whose contents are not externally defined. It is up to the
|
||||
caller to free the memory (via <b>pcre_free</b>) when it is no longer required.
|
||||
</P>
|
||||
<P>
|
||||
Although the compiled code of a PCRE regex is relocatable, that is, it does not
|
||||
depend on memory location, the complete <b>pcre</b> data block is not
|
||||
fully relocatable, because it may contain a copy of the <i>tableptr</i>
|
||||
argument, which is an address (see below).
|
||||
</P>
|
||||
<P>
|
||||
The <i>options</i> argument contains various bit settings that affect the
|
||||
compilation. It should be zero if no options are required. The available
|
||||
options are described below. Some of them (in particular, those that are
|
||||
compatible with Perl, but some others as well) can also be set and unset from
|
||||
within the pattern (see the detailed description in the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
documentation). For those options that can be different in different parts of
|
||||
the pattern, the contents of the <i>options</i> argument specifies their
|
||||
settings at the start of compilation and execution. The PCRE_ANCHORED,
|
||||
PCRE_BSR_<i>xxx</i>, PCRE_NEWLINE_<i>xxx</i>, PCRE_NO_UTF8_CHECK, and
|
||||
PCRE_NO_START_OPTIMIZE options can be set at the time of matching as well as at
|
||||
compile time.
|
||||
</P>
|
||||
<P>
|
||||
If <i>errptr</i> is NULL, <b>pcre_compile()</b> returns NULL immediately.
|
||||
Otherwise, if compilation of a pattern fails, <b>pcre_compile()</b> returns
|
||||
NULL, and sets the variable pointed to by <i>errptr</i> to point to a textual
|
||||
error message. This is a static string that is part of the library. You must
|
||||
not try to free it. Normally, the offset from the start of the pattern to the
|
||||
data unit that was being processed when the error was discovered is placed in
|
||||
the variable pointed to by <i>erroffset</i>, which must not be NULL (if it is,
|
||||
an immediate error is given). However, for an invalid UTF-8 or UTF-16 string,
|
||||
the offset is that of the first data unit of the failing character.
|
||||
</P>
|
||||
<P>
|
||||
Some errors are not detected until the whole pattern has been scanned; in these
|
||||
cases, the offset passed back is the length of the pattern. Note that the
|
||||
offset is in data units, not characters, even in a UTF mode. It may sometimes
|
||||
point into the middle of a UTF-8 or UTF-16 character.
|
||||
</P>
|
||||
<P>
|
||||
If <b>pcre_compile2()</b> is used instead of <b>pcre_compile()</b>, and the
|
||||
<i>errorcodeptr</i> argument is not NULL, a non-zero error code number is
|
||||
returned via this argument in the event of an error. This is in addition to the
|
||||
textual error message. Error codes and messages are listed below.
|
||||
</P>
|
||||
<P>
|
||||
If the final argument, <i>tableptr</i>, is NULL, PCRE uses a default set of
|
||||
character tables that are built when PCRE is compiled, using the default C
|
||||
locale. Otherwise, <i>tableptr</i> must be an address that is the result of a
|
||||
call to <b>pcre_maketables()</b>. This value is stored with the compiled
|
||||
pattern, and used again by <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b> when the
|
||||
pattern is matched. For more discussion, see the section on locale support
|
||||
below.
|
||||
</P>
|
||||
<P>
|
||||
This code fragment shows a typical straightforward call to <b>pcre_compile()</b>:
|
||||
<pre>
|
||||
pcre *re;
|
||||
const char *error;
|
||||
int erroffset;
|
||||
re = pcre_compile(
|
||||
"^A.*Z", /* the pattern */
|
||||
0, /* default options */
|
||||
&error, /* for error message */
|
||||
&erroffset, /* for error offset */
|
||||
NULL); /* use default character tables */
|
||||
</pre>
|
||||
The following names for option bits are defined in the <b>pcre.h</b> header
|
||||
file:
|
||||
<pre>
|
||||
PCRE_ANCHORED
|
||||
</pre>
|
||||
If this bit is set, the pattern is forced to be "anchored", that is, it is
|
||||
constrained to match only at the first matching point in the string that is
|
||||
being searched (the "subject string"). This effect can also be achieved by
|
||||
appropriate constructs in the pattern itself, which is the only way to do it in
|
||||
Perl.
|
||||
<pre>
|
||||
PCRE_AUTO_CALLOUT
|
||||
</pre>
|
||||
If this bit is set, <b>pcre_compile()</b> automatically inserts callout items,
|
||||
all with number 255, before each pattern item. For discussion of the callout
|
||||
facility, see the
|
||||
<a href="pcrecallout.html"><b>pcrecallout</b></a>
|
||||
documentation.
|
||||
<pre>
|
||||
PCRE_BSR_ANYCRLF
|
||||
PCRE_BSR_UNICODE
|
||||
</pre>
|
||||
These options (which are mutually exclusive) control what the \R escape
|
||||
sequence matches. The choice is either to match only CR, LF, or CRLF, or to
|
||||
match any Unicode newline sequence. The default is specified when PCRE is
|
||||
built. It can be overridden from within the pattern, or by setting an option
|
||||
when a compiled pattern is matched.
|
||||
<pre>
|
||||
PCRE_CASELESS
|
||||
</pre>
|
||||
If this bit is set, letters in the pattern match both upper and lower case
|
||||
letters. It is equivalent to Perl's /i option, and it can be changed within a
|
||||
pattern by a (?i) option setting. In UTF-8 mode, PCRE always understands the
|
||||
concept of case for characters whose values are less than 128, so caseless
|
||||
matching is always possible. For characters with higher values, the concept of
|
||||
case is supported if PCRE is compiled with Unicode property support, but not
|
||||
otherwise. If you want to use caseless matching for characters 128 and above,
|
||||
you must ensure that PCRE is compiled with Unicode property support as well as
|
||||
with UTF-8 support.
|
||||
<pre>
|
||||
PCRE_DOLLAR_ENDONLY
|
||||
</pre>
|
||||
If this bit is set, a dollar metacharacter in the pattern matches only at the
|
||||
end of the subject string. Without this option, a dollar also matches
|
||||
immediately before a newline at the end of the string (but not before any other
|
||||
newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is set.
|
||||
There is no equivalent to this option in Perl, and no way to set it within a
|
||||
pattern.
|
||||
<pre>
|
||||
PCRE_DOTALL
|
||||
</pre>
|
||||
If this bit is set, a dot metacharacter in the pattern matches a character of
|
||||
any value, including one that indicates a newline. However, it only ever
|
||||
matches one character, even if newlines are coded as CRLF. Without this option,
|
||||
a dot does not match when the current position is at a newline. This option is
|
||||
equivalent to Perl's /s option, and it can be changed within a pattern by a
|
||||
(?s) option setting. A negative class such as [^a] always matches newline
|
||||
characters, independent of the setting of this option.
|
||||
<pre>
|
||||
PCRE_DUPNAMES
|
||||
</pre>
|
||||
If this bit is set, names used to identify capturing subpatterns need not be
|
||||
unique. This can be helpful for certain types of pattern when it is known that
|
||||
only one instance of the named subpattern can ever be matched. There are more
|
||||
details of named subpatterns below; see also the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
documentation.
|
||||
<pre>
|
||||
PCRE_EXTENDED
|
||||
</pre>
|
||||
If this bit is set, most white space characters in the pattern are totally
|
||||
ignored except when escaped or inside a character class. However, white space
|
||||
is not allowed within sequences such as (?> that introduce various
|
||||
parenthesized subpatterns, nor within a numerical quantifier such as {1,3}.
|
||||
However, ignorable white space is permitted between an item and a following
|
||||
quantifier and between a quantifier and a following + that indicates
|
||||
possessiveness.
|
||||
</P>
|
||||
<P>
|
||||
White space did not used to include the VT character (code 11), because Perl
|
||||
did not treat this character as white space. However, Perl changed at release
|
||||
5.18, so PCRE followed at release 8.34, and VT is now treated as white space.
|
||||
</P>
|
||||
<P>
|
||||
PCRE_EXTENDED also causes characters between an unescaped # outside a character
|
||||
class and the next newline, inclusive, to be ignored. PCRE_EXTENDED is
|
||||
equivalent to Perl's /x option, and it can be changed within a pattern by a
|
||||
(?x) option setting.
|
||||
</P>
|
||||
<P>
|
||||
Which characters are interpreted as newlines is controlled by the options
|
||||
passed to <b>pcre_compile()</b> or by a special sequence at the start of the
|
||||
pattern, as described in the section entitled
|
||||
<a href="pcrepattern.html#newlines">"Newline conventions"</a>
|
||||
in the <b>pcrepattern</b> documentation. Note that the end of this type of
|
||||
comment is a literal newline sequence in the pattern; escape sequences that
|
||||
happen to represent a newline do not count.
|
||||
</P>
|
||||
<P>
|
||||
This option makes it possible to include comments inside complicated patterns.
|
||||
Note, however, that this applies only to data characters. White space characters
|
||||
may never appear within special character sequences in a pattern, for example
|
||||
within the sequence (?( that introduces a conditional subpattern.
|
||||
<pre>
|
||||
PCRE_EXTRA
|
||||
</pre>
|
||||
This option was invented in order to turn on additional functionality of PCRE
|
||||
that is incompatible with Perl, but it is currently of very little use. When
|
||||
set, any backslash in a pattern that is followed by a letter that has no
|
||||
special meaning causes an error, thus reserving these combinations for future
|
||||
expansion. By default, as in Perl, a backslash followed by a letter with no
|
||||
special meaning is treated as a literal. (Perl can, however, be persuaded to
|
||||
give an error for this, by running it with the -w option.) There are at present
|
||||
no other features controlled by this option. It can also be set by a (?X)
|
||||
option setting within a pattern.
|
||||
<pre>
|
||||
PCRE_FIRSTLINE
|
||||
</pre>
|
||||
If this option is set, an unanchored pattern is required to match before or at
|
||||
the first newline in the subject string, though the matched text may continue
|
||||
over the newline.
|
||||
<pre>
|
||||
PCRE_JAVASCRIPT_COMPAT
|
||||
</pre>
|
||||
If this option is set, PCRE's behaviour is changed in some ways so that it is
|
||||
compatible with JavaScript rather than Perl. The changes are as follows:
|
||||
</P>
|
||||
<P>
|
||||
(1) A lone closing square bracket in a pattern causes a compile-time error,
|
||||
because this is illegal in JavaScript (by default it is treated as a data
|
||||
character). Thus, the pattern AB]CD becomes illegal when this option is set.
|
||||
</P>
|
||||
<P>
|
||||
(2) At run time, a back reference to an unset subpattern group matches an empty
|
||||
string (by default this causes the current matching alternative to fail). A
|
||||
pattern such as (\1)(a) succeeds when this option is set (assuming it can find
|
||||
an "a" in the subject), whereas it fails by default, for Perl compatibility.
|
||||
</P>
|
||||
<P>
|
||||
(3) \U matches an upper case "U" character; by default \U causes a compile
|
||||
time error (Perl uses \U to upper case subsequent characters).
|
||||
</P>
|
||||
<P>
|
||||
(4) \u matches a lower case "u" character unless it is followed by four
|
||||
hexadecimal digits, in which case the hexadecimal number defines the code point
|
||||
to match. By default, \u causes a compile time error (Perl uses it to upper
|
||||
case the following character).
|
||||
</P>
|
||||
<P>
|
||||
(5) \x matches a lower case "x" character unless it is followed by two
|
||||
hexadecimal digits, in which case the hexadecimal number defines the code point
|
||||
to match. By default, as in Perl, a hexadecimal number is always expected after
|
||||
\x, but it may have zero, one, or two digits (so, for example, \xz matches a
|
||||
binary zero character followed by z).
|
||||
<pre>
|
||||
PCRE_MULTILINE
|
||||
</pre>
|
||||
By default, for the purposes of matching "start of line" and "end of line",
|
||||
PCRE treats the subject string as consisting of a single line of characters,
|
||||
even if it actually contains newlines. The "start of line" metacharacter (^)
|
||||
matches only at the start of the string, and the "end of line" metacharacter
|
||||
($) matches only at the end of the string, or before a terminating newline
|
||||
(except when PCRE_DOLLAR_ENDONLY is set). Note, however, that unless
|
||||
PCRE_DOTALL is set, the "any character" metacharacter (.) does not match at a
|
||||
newline. This behaviour (for ^, $, and dot) is the same as Perl.
|
||||
</P>
|
||||
<P>
|
||||
When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs
|
||||
match immediately following or immediately before internal newlines in the
|
||||
subject string, respectively, as well as at the very start and end. This is
|
||||
equivalent to Perl's /m option, and it can be changed within a pattern by a
|
||||
(?m) option setting. If there are no newlines in a subject string, or no
|
||||
occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect.
|
||||
<pre>
|
||||
PCRE_NEVER_UTF
|
||||
</pre>
|
||||
This option locks out interpretation of the pattern as UTF-8 (or UTF-16 or
|
||||
UTF-32 in the 16-bit and 32-bit libraries). In particular, it prevents the
|
||||
creator of the pattern from switching to UTF interpretation by starting the
|
||||
pattern with (*UTF). This may be useful in applications that process patterns
|
||||
from external sources. The combination of PCRE_UTF8 and PCRE_NEVER_UTF also
|
||||
causes an error.
|
||||
<pre>
|
||||
PCRE_NEWLINE_CR
|
||||
PCRE_NEWLINE_LF
|
||||
PCRE_NEWLINE_CRLF
|
||||
PCRE_NEWLINE_ANYCRLF
|
||||
PCRE_NEWLINE_ANY
|
||||
</pre>
|
||||
These options override the default newline definition that was chosen when PCRE
|
||||
was built. Setting the first or the second specifies that a newline is
|
||||
indicated by a single character (CR or LF, respectively). Setting
|
||||
PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character
|
||||
CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three
|
||||
preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies
|
||||
that any Unicode newline sequence should be recognized.
|
||||
</P>
|
||||
<P>
|
||||
In an ASCII/Unicode environment, the Unicode newline sequences are the three
|
||||
just mentioned, plus the single characters VT (vertical tab, U+000B), FF (form
|
||||
feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS
|
||||
(paragraph separator, U+2029). For the 8-bit library, the last two are
|
||||
recognized only in UTF-8 mode.
|
||||
</P>
|
||||
<P>
|
||||
When PCRE is compiled to run in an EBCDIC (mainframe) environment, the code for
|
||||
CR is 0x0d, the same as ASCII. However, the character code for LF is normally
|
||||
0x15, though in some EBCDIC environments 0x25 is used. Whichever of these is
|
||||
not LF is made to correspond to Unicode's NEL character. EBCDIC codes are all
|
||||
less than 256. For more details, see the
|
||||
<a href="pcrebuild.html"><b>pcrebuild</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
The newline setting in the options word uses three bits that are treated
|
||||
as a number, giving eight possibilities. Currently only six are used (default
|
||||
plus the five values above). This means that if you set more than one newline
|
||||
option, the combination may or may not be sensible. For example,
|
||||
PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but
|
||||
other combinations may yield unused numbers and cause an error.
|
||||
</P>
|
||||
<P>
|
||||
The only time that a line break in a pattern is specially recognized when
|
||||
compiling is when PCRE_EXTENDED is set. CR and LF are white space characters,
|
||||
and so are ignored in this mode. Also, an unescaped # outside a character class
|
||||
indicates a comment that lasts until after the next line break sequence. In
|
||||
other circumstances, line break sequences in patterns are treated as literal
|
||||
data.
|
||||
</P>
|
||||
<P>
|
||||
The newline option that is set at compile time becomes the default that is used
|
||||
for <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, but it can be overridden.
|
||||
<pre>
|
||||
PCRE_NO_AUTO_CAPTURE
|
||||
</pre>
|
||||
If this option is set, it disables the use of numbered capturing parentheses in
|
||||
the pattern. Any opening parenthesis that is not followed by ? behaves as if it
|
||||
were followed by ?: but named parentheses can still be used for capturing (and
|
||||
they acquire numbers in the usual way). There is no equivalent of this option
|
||||
in Perl.
|
||||
<pre>
|
||||
PCRE_NO_AUTO_POSSESS
|
||||
</pre>
|
||||
If this option is set, it disables "auto-possessification". This is an
|
||||
optimization that, for example, turns a+b into a++b in order to avoid
|
||||
backtracks into a+ that can never be successful. However, if callouts are in
|
||||
use, auto-possessification means that some of them are never taken. You can set
|
||||
this option if you want the matching functions to do a full unoptimized search
|
||||
and run all the callouts, but it is mainly provided for testing purposes.
|
||||
<pre>
|
||||
PCRE_NO_START_OPTIMIZE
|
||||
</pre>
|
||||
This is an option that acts at matching time; that is, it is really an option
|
||||
for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>. If it is set at compile time,
|
||||
it is remembered with the compiled pattern and assumed at matching time. This
|
||||
is necessary if you want to use JIT execution, because the JIT compiler needs
|
||||
to know whether or not this option is set. For details see the discussion of
|
||||
PCRE_NO_START_OPTIMIZE
|
||||
<a href="#execoptions">below.</a>
|
||||
<pre>
|
||||
PCRE_UCP
|
||||
</pre>
|
||||
This option changes the way PCRE processes \B, \b, \D, \d, \S, \s, \W,
|
||||
\w, and some of the POSIX character classes. By default, only ASCII characters
|
||||
are recognized, but if PCRE_UCP is set, Unicode properties are used instead to
|
||||
classify characters. More details are given in the section on
|
||||
<a href="pcre.html#genericchartypes">generic character types</a>
|
||||
in the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
page. If you set PCRE_UCP, matching one of the items it affects takes much
|
||||
longer. The option is available only if PCRE has been compiled with Unicode
|
||||
property support.
|
||||
<pre>
|
||||
PCRE_UNGREEDY
|
||||
</pre>
|
||||
This option inverts the "greediness" of the quantifiers so that they are not
|
||||
greedy by default, but become greedy if followed by "?". It is not compatible
|
||||
with Perl. It can also be set by a (?U) option setting within the pattern.
|
||||
<pre>
|
||||
PCRE_UTF8
|
||||
</pre>
|
||||
This option causes PCRE to regard both the pattern and the subject as strings
|
||||
of UTF-8 characters instead of single-byte strings. However, it is available
|
||||
only when PCRE is built to include UTF support. If not, the use of this option
|
||||
provokes an error. Details of how this option changes the behaviour of PCRE are
|
||||
given in the
|
||||
<a href="pcreunicode.html"><b>pcreunicode</b></a>
|
||||
page.
|
||||
<pre>
|
||||
PCRE_NO_UTF8_CHECK
|
||||
</pre>
|
||||
When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
|
||||
automatically checked. There is a discussion about the
|
||||
<a href="pcreunicode.html#utf8strings">validity of UTF-8 strings</a>
|
||||
in the
|
||||
<a href="pcreunicode.html"><b>pcreunicode</b></a>
|
||||
page. If an invalid UTF-8 sequence is found, <b>pcre_compile()</b> returns an
|
||||
error. If you already know that your pattern is valid, and you want to skip
|
||||
this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK option.
|
||||
When it is set, the effect of passing an invalid UTF-8 string as a pattern is
|
||||
undefined. It may cause your program to crash or loop. Note that this option
|
||||
can also be passed to <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, to suppress
|
||||
the validity checking of subject strings only. If the same string is being
|
||||
matched many times, the option can be safely set for the second and subsequent
|
||||
matchings to improve performance.
|
||||
</P>
|
||||
<br><a name="SEC12" href="#TOC1">COMPILATION ERROR CODES</a><br>
|
||||
<P>
|
||||
The following table lists the error codes than may be returned by
|
||||
<b>pcre_compile2()</b>, along with the error messages that may be returned by
|
||||
both compiling functions. Note that error messages are always 8-bit ASCII
|
||||
strings, even in 16-bit or 32-bit mode. As PCRE has developed, some error codes
|
||||
have fallen out of use. To avoid confusion, they have not been re-used.
|
||||
<pre>
|
||||
0 no error
|
||||
1 \ at end of pattern
|
||||
2 \c at end of pattern
|
||||
3 unrecognized character follows \
|
||||
4 numbers out of order in {} quantifier
|
||||
5 number too big in {} quantifier
|
||||
6 missing terminating ] for character class
|
||||
7 invalid escape sequence in character class
|
||||
8 range out of order in character class
|
||||
9 nothing to repeat
|
||||
10 [this code is not in use]
|
||||
11 internal error: unexpected repeat
|
||||
12 unrecognized character after (? or (?-
|
||||
13 POSIX named classes are supported only within a class
|
||||
14 missing )
|
||||
15 reference to non-existent subpattern
|
||||
16 erroffset passed as NULL
|
||||
17 unknown option bit(s) set
|
||||
18 missing ) after comment
|
||||
19 [this code is not in use]
|
||||
20 regular expression is too large
|
||||
21 failed to get memory
|
||||
22 unmatched parentheses
|
||||
23 internal error: code overflow
|
||||
24 unrecognized character after (?<
|
||||
25 lookbehind assertion is not fixed length
|
||||
26 malformed number or name after (?(
|
||||
27 conditional group contains more than two branches
|
||||
28 assertion expected after (?(
|
||||
29 (?R or (?[+-]digits must be followed by )
|
||||
30 unknown POSIX class name
|
||||
31 POSIX collating elements are not supported
|
||||
32 this version of PCRE is compiled without UTF support
|
||||
33 [this code is not in use]
|
||||
34 character value in \x{} or \o{} is too large
|
||||
35 invalid condition (?(0)
|
||||
36 \C not allowed in lookbehind assertion
|
||||
37 PCRE does not support \L, \l, \N{name}, \U, or \u
|
||||
38 number after (?C is > 255
|
||||
39 closing ) for (?C expected
|
||||
40 recursive call could loop indefinitely
|
||||
41 unrecognized character after (?P
|
||||
42 syntax error in subpattern name (missing terminator)
|
||||
43 two named subpatterns have the same name
|
||||
44 invalid UTF-8 string (specifically UTF-8)
|
||||
45 support for \P, \p, and \X has not been compiled
|
||||
46 malformed \P or \p sequence
|
||||
47 unknown property name after \P or \p
|
||||
48 subpattern name is too long (maximum 32 characters)
|
||||
49 too many named subpatterns (maximum 10000)
|
||||
50 [this code is not in use]
|
||||
51 octal value is greater than \377 in 8-bit non-UTF-8 mode
|
||||
52 internal error: overran compiling workspace
|
||||
53 internal error: previously-checked referenced subpattern
|
||||
not found
|
||||
54 DEFINE group contains more than one branch
|
||||
55 repeating a DEFINE group is not allowed
|
||||
56 inconsistent NEWLINE options
|
||||
57 \g is not followed by a braced, angle-bracketed, or quoted
|
||||
name/number or by a plain number
|
||||
58 a numbered reference must not be zero
|
||||
59 an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)
|
||||
60 (*VERB) not recognized or malformed
|
||||
61 number is too big
|
||||
62 subpattern name expected
|
||||
63 digit expected after (?+
|
||||
64 ] is an invalid data character in JavaScript compatibility mode
|
||||
65 different names for subpatterns of the same number are
|
||||
not allowed
|
||||
66 (*MARK) must have an argument
|
||||
67 this version of PCRE is not compiled with Unicode property
|
||||
support
|
||||
68 \c must be followed by an ASCII character
|
||||
69 \k is not followed by a braced, angle-bracketed, or quoted name
|
||||
70 internal error: unknown opcode in find_fixedlength()
|
||||
71 \N is not supported in a class
|
||||
72 too many forward references
|
||||
73 disallowed Unicode code point (>= 0xd800 && <= 0xdfff)
|
||||
74 invalid UTF-16 string (specifically UTF-16)
|
||||
75 name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)
|
||||
76 character value in \u.... sequence is too large
|
||||
77 invalid UTF-32 string (specifically UTF-32)
|
||||
78 setting UTF is disabled by the application
|
||||
79 non-hex character in \x{} (closing brace missing?)
|
||||
80 non-octal character in \o{} (closing brace missing?)
|
||||
81 missing opening brace after \o
|
||||
82 parentheses are too deeply nested
|
||||
83 invalid range in character class
|
||||
84 group name must start with a non-digit
|
||||
85 parentheses are too deeply nested (stack check)
|
||||
</pre>
|
||||
The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may
|
||||
be used if the limits were changed when PCRE was built.
|
||||
<a name="studyingapattern"></a></P>
|
||||
<br><a name="SEC13" href="#TOC1">STUDYING A PATTERN</a><br>
|
||||
<P>
|
||||
<b>pcre_extra *pcre_study(const pcre *<i>code</i>, int <i>options</i>,</b>
|
||||
<b> const char **<i>errptr</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
If a compiled pattern is going to be used several times, it is worth spending
|
||||
more time analyzing it in order to speed up the time taken for matching. The
|
||||
function <b>pcre_study()</b> takes a pointer to a compiled pattern as its first
|
||||
argument. If studying the pattern produces additional information that will
|
||||
help speed up matching, <b>pcre_study()</b> returns a pointer to a
|
||||
<b>pcre_extra</b> block, in which the <i>study_data</i> field points to the
|
||||
results of the study.
|
||||
</P>
|
||||
<P>
|
||||
The returned value from <b>pcre_study()</b> can be passed directly to
|
||||
<b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>. However, a <b>pcre_extra</b> block
|
||||
also contains other fields that can be set by the caller before the block is
|
||||
passed; these are described
|
||||
<a href="#extradata">below</a>
|
||||
in the section on matching a pattern.
|
||||
</P>
|
||||
<P>
|
||||
If studying the pattern does not produce any useful information,
|
||||
<b>pcre_study()</b> returns NULL by default. In that circumstance, if the
|
||||
calling program wants to pass any of the other fields to <b>pcre_exec()</b> or
|
||||
<b>pcre_dfa_exec()</b>, it must set up its own <b>pcre_extra</b> block. However,
|
||||
if <b>pcre_study()</b> is called with the PCRE_STUDY_EXTRA_NEEDED option, it
|
||||
returns a <b>pcre_extra</b> block even if studying did not find any additional
|
||||
information. It may still return NULL, however, if an error occurs in
|
||||
<b>pcre_study()</b>.
|
||||
</P>
|
||||
<P>
|
||||
The second argument of <b>pcre_study()</b> contains option bits. There are three
|
||||
further options in addition to PCRE_STUDY_EXTRA_NEEDED:
|
||||
<pre>
|
||||
PCRE_STUDY_JIT_COMPILE
|
||||
PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
|
||||
PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
|
||||
</pre>
|
||||
If any of these are set, and the just-in-time compiler is available, the
|
||||
pattern is further compiled into machine code that executes much faster than
|
||||
the <b>pcre_exec()</b> interpretive matching function. If the just-in-time
|
||||
compiler is not available, these options are ignored. All undefined bits in the
|
||||
<i>options</i> argument must be zero.
|
||||
</P>
|
||||
<P>
|
||||
JIT compilation is a heavyweight optimization. It can take some time for
|
||||
patterns to be analyzed, and for one-off matches and simple patterns the
|
||||
benefit of faster execution might be offset by a much slower study time.
|
||||
Not all patterns can be optimized by the JIT compiler. For those that cannot be
|
||||
handled, matching automatically falls back to the <b>pcre_exec()</b>
|
||||
interpreter. For more details, see the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
The third argument for <b>pcre_study()</b> is a pointer for an error message. If
|
||||
studying succeeds (even if no data is returned), the variable it points to is
|
||||
set to NULL. Otherwise it is set to point to a textual error message. This is a
|
||||
static string that is part of the library. You must not try to free it. You
|
||||
should test the error pointer for NULL after calling <b>pcre_study()</b>, to be
|
||||
sure that it has run successfully.
|
||||
</P>
|
||||
<P>
|
||||
When you are finished with a pattern, you can free the memory used for the
|
||||
study data by calling <b>pcre_free_study()</b>. This function was added to the
|
||||
API for release 8.20. For earlier versions, the memory could be freed with
|
||||
<b>pcre_free()</b>, just like the pattern itself. This will still work in cases
|
||||
where JIT optimization is not used, but it is advisable to change to the new
|
||||
function when convenient.
|
||||
</P>
|
||||
<P>
|
||||
This is a typical way in which <b>pcre_study</b>() is used (except that in a
|
||||
real application there should be tests for errors):
|
||||
<pre>
|
||||
int rc;
|
||||
pcre *re;
|
||||
pcre_extra *sd;
|
||||
re = pcre_compile("pattern", 0, &error, &erroroffset, NULL);
|
||||
sd = pcre_study(
|
||||
re, /* result of pcre_compile() */
|
||||
0, /* no options */
|
||||
&error); /* set to NULL or points to a message */
|
||||
rc = pcre_exec( /* see below for details of pcre_exec() options */
|
||||
re, sd, "subject", 7, 0, 0, ovector, 30);
|
||||
...
|
||||
pcre_free_study(sd);
|
||||
pcre_free(re);
|
||||
</pre>
|
||||
Studying a pattern does two things: first, a lower bound for the length of
|
||||
subject string that is needed to match the pattern is computed. This does not
|
||||
mean that there are any strings of that length that match, but it does
|
||||
guarantee that no shorter strings match. The value is used to avoid wasting
|
||||
time by trying to match strings that are shorter than the lower bound. You can
|
||||
find out the value in a calling program via the <b>pcre_fullinfo()</b> function.
|
||||
</P>
|
||||
<P>
|
||||
Studying a pattern is also useful for non-anchored patterns that do not have a
|
||||
single fixed starting character. A bitmap of possible starting bytes is
|
||||
created. This speeds up finding a position in the subject at which to start
|
||||
matching. (In 16-bit mode, the bitmap is used for 16-bit values less than 256.
|
||||
In 32-bit mode, the bitmap is used for 32-bit values less than 256.)
|
||||
</P>
|
||||
<P>
|
||||
These two optimizations apply to both <b>pcre_exec()</b> and
|
||||
<b>pcre_dfa_exec()</b>, and the information is also used by the JIT compiler.
|
||||
The optimizations can be disabled by setting the PCRE_NO_START_OPTIMIZE option.
|
||||
You might want to do this if your pattern contains callouts or (*MARK) and you
|
||||
want to make use of these facilities in cases where matching fails.
|
||||
</P>
|
||||
<P>
|
||||
PCRE_NO_START_OPTIMIZE can be specified at either compile time or execution
|
||||
time. However, if PCRE_NO_START_OPTIMIZE is passed to <b>pcre_exec()</b>, (that
|
||||
is, after any JIT compilation has happened) JIT execution is disabled. For JIT
|
||||
execution to work with PCRE_NO_START_OPTIMIZE, the option must be set at
|
||||
compile time.
|
||||
</P>
|
||||
<P>
|
||||
There is a longer discussion of PCRE_NO_START_OPTIMIZE
|
||||
<a href="#execoptions">below.</a>
|
||||
<a name="localesupport"></a></P>
|
||||
<br><a name="SEC14" href="#TOC1">LOCALE SUPPORT</a><br>
|
||||
<P>
|
||||
PCRE handles caseless matching, and determines whether characters are letters,
|
||||
digits, or whatever, by reference to a set of tables, indexed by character
|
||||
code point. When running in UTF-8 mode, or in the 16- or 32-bit libraries, this
|
||||
applies only to characters with code points less than 256. By default,
|
||||
higher-valued code points never match escapes such as \w or \d. However, if
|
||||
PCRE is built with Unicode property support, all characters can be tested with
|
||||
\p and \P, or, alternatively, the PCRE_UCP option can be set when a pattern
|
||||
is compiled; this causes \w and friends to use Unicode property support
|
||||
instead of the built-in tables.
|
||||
</P>
|
||||
<P>
|
||||
The use of locales with Unicode is discouraged. If you are handling characters
|
||||
with code points greater than 128, you should either use Unicode support, or
|
||||
use locales, but not try to mix the two.
|
||||
</P>
|
||||
<P>
|
||||
PCRE contains an internal set of tables that are used when the final argument
|
||||
of <b>pcre_compile()</b> is NULL. These are sufficient for many applications.
|
||||
Normally, the internal tables recognize only ASCII characters. However, when
|
||||
PCRE is built, it is possible to cause the internal tables to be rebuilt in the
|
||||
default "C" locale of the local system, which may cause them to be different.
|
||||
</P>
|
||||
<P>
|
||||
The internal tables can always be overridden by tables supplied by the
|
||||
application that calls PCRE. These may be created in a different locale from
|
||||
the default. As more and more applications change to using Unicode, the need
|
||||
for this locale support is expected to die away.
|
||||
</P>
|
||||
<P>
|
||||
External tables are built by calling the <b>pcre_maketables()</b> function,
|
||||
which has no arguments, in the relevant locale. The result can then be passed
|
||||
to <b>pcre_compile()</b> as often as necessary. For example, to build and use
|
||||
tables that are appropriate for the French locale (where accented characters
|
||||
with values greater than 128 are treated as letters), the following code could
|
||||
be used:
|
||||
<pre>
|
||||
setlocale(LC_CTYPE, "fr_FR");
|
||||
tables = pcre_maketables();
|
||||
re = pcre_compile(..., tables);
|
||||
</pre>
|
||||
The locale name "fr_FR" is used on Linux and other Unix-like systems; if you
|
||||
are using Windows, the name for the French locale is "french".
|
||||
</P>
|
||||
<P>
|
||||
When <b>pcre_maketables()</b> runs, the tables are built in memory that is
|
||||
obtained via <b>pcre_malloc</b>. It is the caller's responsibility to ensure
|
||||
that the memory containing the tables remains available for as long as it is
|
||||
needed.
|
||||
</P>
|
||||
<P>
|
||||
The pointer that is passed to <b>pcre_compile()</b> is saved with the compiled
|
||||
pattern, and the same tables are used via this pointer by <b>pcre_study()</b>
|
||||
and also by <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>. Thus, for any single
|
||||
pattern, compilation, studying and matching all happen in the same locale, but
|
||||
different patterns can be processed in different locales.
|
||||
</P>
|
||||
<P>
|
||||
It is possible to pass a table pointer or NULL (indicating the use of the
|
||||
internal tables) to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> (see the
|
||||
discussion below in the section on matching a pattern). This facility is
|
||||
provided for use with pre-compiled patterns that have been saved and reloaded.
|
||||
Character tables are not saved with patterns, so if a non-standard table was
|
||||
used at compile time, it must be provided again when the reloaded pattern is
|
||||
matched. Attempting to use this facility to match a pattern in a different
|
||||
locale from the one in which it was compiled is likely to lead to anomalous
|
||||
(usually incorrect) results.
|
||||
<a name="infoaboutpattern"></a></P>
|
||||
<br><a name="SEC15" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br>
|
||||
<P>
|
||||
<b>int pcre_fullinfo(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
|
||||
<b> int <i>what</i>, void *<i>where</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
The <b>pcre_fullinfo()</b> function returns information about a compiled
|
||||
pattern. It replaces the <b>pcre_info()</b> function, which was removed from the
|
||||
library at version 8.30, after more than 10 years of obsolescence.
|
||||
</P>
|
||||
<P>
|
||||
The first argument for <b>pcre_fullinfo()</b> is a pointer to the compiled
|
||||
pattern. The second argument is the result of <b>pcre_study()</b>, or NULL if
|
||||
the pattern was not studied. The third argument specifies which piece of
|
||||
information is required, and the fourth argument is a pointer to a variable
|
||||
to receive the data. The yield of the function is zero for success, or one of
|
||||
the following negative numbers:
|
||||
<pre>
|
||||
PCRE_ERROR_NULL the argument <i>code</i> was NULL
|
||||
the argument <i>where</i> was NULL
|
||||
PCRE_ERROR_BADMAGIC the "magic number" was not found
|
||||
PCRE_ERROR_BADENDIANNESS the pattern was compiled with different
|
||||
endianness
|
||||
PCRE_ERROR_BADOPTION the value of <i>what</i> was invalid
|
||||
PCRE_ERROR_UNSET the requested field is not set
|
||||
</pre>
|
||||
The "magic number" is placed at the start of each compiled pattern as an simple
|
||||
check against passing an arbitrary memory pointer. The endianness error can
|
||||
occur if a compiled pattern is saved and reloaded on a different host. Here is
|
||||
a typical call of <b>pcre_fullinfo()</b>, to obtain the length of the compiled
|
||||
pattern:
|
||||
<pre>
|
||||
int rc;
|
||||
size_t length;
|
||||
rc = pcre_fullinfo(
|
||||
re, /* result of pcre_compile() */
|
||||
sd, /* result of pcre_study(), or NULL */
|
||||
PCRE_INFO_SIZE, /* what is required */
|
||||
&length); /* where to put the data */
|
||||
</pre>
|
||||
The possible values for the third argument are defined in <b>pcre.h</b>, and are
|
||||
as follows:
|
||||
<pre>
|
||||
PCRE_INFO_BACKREFMAX
|
||||
</pre>
|
||||
Return the number of the highest back reference in the pattern. The fourth
|
||||
argument should point to an <b>int</b> variable. Zero is returned if there are
|
||||
no back references.
|
||||
<pre>
|
||||
PCRE_INFO_CAPTURECOUNT
|
||||
</pre>
|
||||
Return the number of capturing subpatterns in the pattern. The fourth argument
|
||||
should point to an <b>int</b> variable.
|
||||
<pre>
|
||||
PCRE_INFO_DEFAULT_TABLES
|
||||
</pre>
|
||||
Return a pointer to the internal default character tables within PCRE. The
|
||||
fourth argument should point to an <b>unsigned char *</b> variable. This
|
||||
information call is provided for internal use by the <b>pcre_study()</b>
|
||||
function. External callers can cause PCRE to use its internal tables by passing
|
||||
a NULL table pointer.
|
||||
<pre>
|
||||
PCRE_INFO_FIRSTBYTE (deprecated)
|
||||
</pre>
|
||||
Return information about the first data unit of any matched string, for a
|
||||
non-anchored pattern. The name of this option refers to the 8-bit library,
|
||||
where data units are bytes. The fourth argument should point to an <b>int</b>
|
||||
variable. Negative values are used for special cases. However, this means that
|
||||
when the 32-bit library is in non-UTF-32 mode, the full 32-bit range of
|
||||
characters cannot be returned. For this reason, this value is deprecated; use
|
||||
PCRE_INFO_FIRSTCHARACTERFLAGS and PCRE_INFO_FIRSTCHARACTER instead.
|
||||
</P>
|
||||
<P>
|
||||
If there is a fixed first value, for example, the letter "c" from a pattern
|
||||
such as (cat|cow|coyote), its value is returned. In the 8-bit library, the
|
||||
value is always less than 256. In the 16-bit library the value can be up to
|
||||
0xffff. In the 32-bit library the value can be up to 0x10ffff.
|
||||
</P>
|
||||
<P>
|
||||
If there is no fixed first value, and if either
|
||||
<br>
|
||||
<br>
|
||||
(a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
|
||||
starts with "^", or
|
||||
<br>
|
||||
<br>
|
||||
(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
|
||||
(if it were set, the pattern would be anchored),
|
||||
<br>
|
||||
<br>
|
||||
-1 is returned, indicating that the pattern matches only at the start of a
|
||||
subject string or after any newline within the string. Otherwise -2 is
|
||||
returned. For anchored patterns, -2 is returned.
|
||||
<pre>
|
||||
PCRE_INFO_FIRSTCHARACTER
|
||||
</pre>
|
||||
Return the value of the first data unit (non-UTF character) of any matched
|
||||
string in the situation where PCRE_INFO_FIRSTCHARACTERFLAGS returns 1;
|
||||
otherwise return 0. The fourth argument should point to an <b>uint_t</b>
|
||||
variable.
|
||||
</P>
|
||||
<P>
|
||||
In the 8-bit library, the value is always less than 256. In the 16-bit library
|
||||
the value can be up to 0xffff. In the 32-bit library in UTF-32 mode the value
|
||||
can be up to 0x10ffff, and up to 0xffffffff when not using UTF-32 mode.
|
||||
<pre>
|
||||
PCRE_INFO_FIRSTCHARACTERFLAGS
|
||||
</pre>
|
||||
Return information about the first data unit of any matched string, for a
|
||||
non-anchored pattern. The fourth argument should point to an <b>int</b>
|
||||
variable.
|
||||
</P>
|
||||
<P>
|
||||
If there is a fixed first value, for example, the letter "c" from a pattern
|
||||
such as (cat|cow|coyote), 1 is returned, and the character value can be
|
||||
retrieved using PCRE_INFO_FIRSTCHARACTER. If there is no fixed first value, and
|
||||
if either
|
||||
<br>
|
||||
<br>
|
||||
(a) the pattern was compiled with the PCRE_MULTILINE option, and every branch
|
||||
starts with "^", or
|
||||
<br>
|
||||
<br>
|
||||
(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set
|
||||
(if it were set, the pattern would be anchored),
|
||||
<br>
|
||||
<br>
|
||||
2 is returned, indicating that the pattern matches only at the start of a
|
||||
subject string or after any newline within the string. Otherwise 0 is
|
||||
returned. For anchored patterns, 0 is returned.
|
||||
<pre>
|
||||
PCRE_INFO_FIRSTTABLE
|
||||
</pre>
|
||||
If the pattern was studied, and this resulted in the construction of a 256-bit
|
||||
table indicating a fixed set of values for the first data unit in any matching
|
||||
string, a pointer to the table is returned. Otherwise NULL is returned. The
|
||||
fourth argument should point to an <b>unsigned char *</b> variable.
|
||||
<pre>
|
||||
PCRE_INFO_HASCRORLF
|
||||
</pre>
|
||||
Return 1 if the pattern contains any explicit matches for CR or LF characters,
|
||||
otherwise 0. The fourth argument should point to an <b>int</b> variable. An
|
||||
explicit match is either a literal CR or LF character, or \r or \n.
|
||||
<pre>
|
||||
PCRE_INFO_JCHANGED
|
||||
</pre>
|
||||
Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
|
||||
0. The fourth argument should point to an <b>int</b> variable. (?J) and
|
||||
(?-J) set and unset the local PCRE_DUPNAMES option, respectively.
|
||||
<pre>
|
||||
PCRE_INFO_JIT
|
||||
</pre>
|
||||
Return 1 if the pattern was studied with one of the JIT options, and
|
||||
just-in-time compiling was successful. The fourth argument should point to an
|
||||
<b>int</b> variable. A return value of 0 means that JIT support is not available
|
||||
in this version of PCRE, or that the pattern was not studied with a JIT option,
|
||||
or that the JIT compiler could not handle this particular pattern. See the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
documentation for details of what can and cannot be handled.
|
||||
<pre>
|
||||
PCRE_INFO_JITSIZE
|
||||
</pre>
|
||||
If the pattern was successfully studied with a JIT option, return the size of
|
||||
the JIT compiled code, otherwise return zero. The fourth argument should point
|
||||
to a <b>size_t</b> variable.
|
||||
<pre>
|
||||
PCRE_INFO_LASTLITERAL
|
||||
</pre>
|
||||
Return the value of the rightmost literal data unit that must exist in any
|
||||
matched string, other than at its start, if such a value has been recorded. The
|
||||
fourth argument should point to an <b>int</b> variable. If there is no such
|
||||
value, -1 is returned. For anchored patterns, a last literal value is recorded
|
||||
only if it follows something of variable length. For example, for the pattern
|
||||
/^a\d+z\d+/ the returned value is "z", but for /^a\dz\d/ the returned value
|
||||
is -1.
|
||||
</P>
|
||||
<P>
|
||||
Since for the 32-bit library using the non-UTF-32 mode, this function is unable
|
||||
to return the full 32-bit range of characters, this value is deprecated;
|
||||
instead the PCRE_INFO_REQUIREDCHARFLAGS and PCRE_INFO_REQUIREDCHAR values should
|
||||
be used.
|
||||
<pre>
|
||||
PCRE_INFO_MATCH_EMPTY
|
||||
</pre>
|
||||
Return 1 if the pattern can match an empty string, otherwise 0. The fourth
|
||||
argument should point to an <b>int</b> variable.
|
||||
<pre>
|
||||
PCRE_INFO_MATCHLIMIT
|
||||
</pre>
|
||||
If the pattern set a match limit by including an item of the form
|
||||
(*LIMIT_MATCH=nnnn) at the start, the value is returned. The fourth argument
|
||||
should point to an unsigned 32-bit integer. If no such value has been set, the
|
||||
call to <b>pcre_fullinfo()</b> returns the error PCRE_ERROR_UNSET.
|
||||
<pre>
|
||||
PCRE_INFO_MAXLOOKBEHIND
|
||||
</pre>
|
||||
Return the number of characters (NB not data units) in the longest lookbehind
|
||||
assertion in the pattern. This information is useful when doing multi-segment
|
||||
matching using the partial matching facilities. Note that the simple assertions
|
||||
\b and \B require a one-character lookbehind. \A also registers a
|
||||
one-character lookbehind, though it does not actually inspect the previous
|
||||
character. This is to ensure that at least one character from the old segment
|
||||
is retained when a new segment is processed. Otherwise, if there are no
|
||||
lookbehinds in the pattern, \A might match incorrectly at the start of a new
|
||||
segment.
|
||||
<pre>
|
||||
PCRE_INFO_MINLENGTH
|
||||
</pre>
|
||||
If the pattern was studied and a minimum length for matching subject strings
|
||||
was computed, its value is returned. Otherwise the returned value is -1. The
|
||||
value is a number of characters, which in UTF mode may be different from the
|
||||
number of data units. The fourth argument should point to an <b>int</b>
|
||||
variable. A non-negative value is a lower bound to the length of any matching
|
||||
string. There may not be any strings of that length that do actually match, but
|
||||
every string that does match is at least that long.
|
||||
<pre>
|
||||
PCRE_INFO_NAMECOUNT
|
||||
PCRE_INFO_NAMEENTRYSIZE
|
||||
PCRE_INFO_NAMETABLE
|
||||
</pre>
|
||||
PCRE supports the use of named as well as numbered capturing parentheses. The
|
||||
names are just an additional way of identifying the parentheses, which still
|
||||
acquire numbers. Several convenience functions such as
|
||||
<b>pcre_get_named_substring()</b> are provided for extracting captured
|
||||
substrings by name. It is also possible to extract the data directly, by first
|
||||
converting the name to a number in order to access the correct pointers in the
|
||||
output vector (described with <b>pcre_exec()</b> below). To do the conversion,
|
||||
you need to use the name-to-number map, which is described by these three
|
||||
values.
|
||||
</P>
|
||||
<P>
|
||||
The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT gives
|
||||
the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size of each
|
||||
entry; both of these return an <b>int</b> value. The entry size depends on the
|
||||
length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first
|
||||
entry of the table. This is a pointer to <b>char</b> in the 8-bit library, where
|
||||
the first two bytes of each entry are the number of the capturing parenthesis,
|
||||
most significant byte first. In the 16-bit library, the pointer points to
|
||||
16-bit data units, the first of which contains the parenthesis number. In the
|
||||
32-bit library, the pointer points to 32-bit data units, the first of which
|
||||
contains the parenthesis number. The rest of the entry is the corresponding
|
||||
name, zero terminated.
|
||||
</P>
|
||||
<P>
|
||||
The names are in alphabetical order. If (?| is used to create multiple groups
|
||||
with the same number, as described in the
|
||||
<a href="pcrepattern.html#dupsubpatternnumber">section on duplicate subpattern numbers</a>
|
||||
in the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
page, the groups may be given the same name, but there is only one entry in the
|
||||
table. Different names for groups of the same number are not permitted.
|
||||
Duplicate names for subpatterns with different numbers are permitted,
|
||||
but only if PCRE_DUPNAMES is set. They appear in the table in the order in
|
||||
which they were found in the pattern. In the absence of (?| this is the order
|
||||
of increasing number; when (?| is used this is not necessarily the case because
|
||||
later subpatterns may have lower numbers.
|
||||
</P>
|
||||
<P>
|
||||
As a simple example of the name/number table, consider the following pattern
|
||||
after compilation by the 8-bit library (assume PCRE_EXTENDED is set, so white
|
||||
space - including newlines - is ignored):
|
||||
<pre>
|
||||
(?<date> (?<year>(\d\d)?\d\d) - (?<month>\d\d) - (?<day>\d\d) )
|
||||
</pre>
|
||||
There are four named subpatterns, so the table has four entries, and each entry
|
||||
in the table is eight bytes long. The table is as follows, with non-printing
|
||||
bytes shows in hexadecimal, and undefined bytes shown as ??:
|
||||
<pre>
|
||||
00 01 d a t e 00 ??
|
||||
00 05 d a y 00 ?? ??
|
||||
00 04 m o n t h 00
|
||||
00 02 y e a r 00 ??
|
||||
</pre>
|
||||
When writing code to extract data from named subpatterns using the
|
||||
name-to-number map, remember that the length of the entries is likely to be
|
||||
different for each compiled pattern.
|
||||
<pre>
|
||||
PCRE_INFO_OKPARTIAL
|
||||
</pre>
|
||||
Return 1 if the pattern can be used for partial matching with
|
||||
<b>pcre_exec()</b>, otherwise 0. The fourth argument should point to an
|
||||
<b>int</b> variable. From release 8.00, this always returns 1, because the
|
||||
restrictions that previously applied to partial matching have been lifted. The
|
||||
<a href="pcrepartial.html"><b>pcrepartial</b></a>
|
||||
documentation gives details of partial matching.
|
||||
<pre>
|
||||
PCRE_INFO_OPTIONS
|
||||
</pre>
|
||||
Return a copy of the options with which the pattern was compiled. The fourth
|
||||
argument should point to an <b>unsigned long int</b> variable. These option bits
|
||||
are those specified in the call to <b>pcre_compile()</b>, modified by any
|
||||
top-level option settings at the start of the pattern itself. In other words,
|
||||
they are the options that will be in force when matching starts. For example,
|
||||
if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
|
||||
result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
|
||||
</P>
|
||||
<P>
|
||||
A pattern is automatically anchored by PCRE if all of its top-level
|
||||
alternatives begin with one of the following:
|
||||
<pre>
|
||||
^ unless PCRE_MULTILINE is set
|
||||
\A always
|
||||
\G always
|
||||
.* if PCRE_DOTALL is set and there are no back references to the subpattern in which .* appears
|
||||
</pre>
|
||||
For such patterns, the PCRE_ANCHORED bit is set in the options returned by
|
||||
<b>pcre_fullinfo()</b>.
|
||||
<pre>
|
||||
PCRE_INFO_RECURSIONLIMIT
|
||||
</pre>
|
||||
If the pattern set a recursion limit by including an item of the form
|
||||
(*LIMIT_RECURSION=nnnn) at the start, the value is returned. The fourth
|
||||
argument should point to an unsigned 32-bit integer. If no such value has been
|
||||
set, the call to <b>pcre_fullinfo()</b> returns the error PCRE_ERROR_UNSET.
|
||||
<pre>
|
||||
PCRE_INFO_SIZE
|
||||
</pre>
|
||||
Return the size of the compiled pattern in bytes (for all three libraries). The
|
||||
fourth argument should point to a <b>size_t</b> variable. This value does not
|
||||
include the size of the <b>pcre</b> structure that is returned by
|
||||
<b>pcre_compile()</b>. The value that is passed as the argument to
|
||||
<b>pcre_malloc()</b> when <b>pcre_compile()</b> is getting memory in which to
|
||||
place the compiled data is the value returned by this option plus the size of
|
||||
the <b>pcre</b> structure. Studying a compiled pattern, with or without JIT,
|
||||
does not alter the value returned by this option.
|
||||
<pre>
|
||||
PCRE_INFO_STUDYSIZE
|
||||
</pre>
|
||||
Return the size in bytes (for all three libraries) of the data block pointed to
|
||||
by the <i>study_data</i> field in a <b>pcre_extra</b> block. If <b>pcre_extra</b>
|
||||
is NULL, or there is no study data, zero is returned. The fourth argument
|
||||
should point to a <b>size_t</b> variable. The <i>study_data</i> field is set by
|
||||
<b>pcre_study()</b> to record information that will speed up matching (see the
|
||||
section entitled
|
||||
<a href="#studyingapattern">"Studying a pattern"</a>
|
||||
above). The format of the <i>study_data</i> block is private, but its length
|
||||
is made available via this option so that it can be saved and restored (see the
|
||||
<a href="pcreprecompile.html"><b>pcreprecompile</b></a>
|
||||
documentation for details).
|
||||
<pre>
|
||||
PCRE_INFO_REQUIREDCHARFLAGS
|
||||
</pre>
|
||||
Returns 1 if there is a rightmost literal data unit that must exist in any
|
||||
matched string, other than at its start. The fourth argument should point to
|
||||
an <b>int</b> variable. If there is no such value, 0 is returned. If returning
|
||||
1, the character value itself can be retrieved using PCRE_INFO_REQUIREDCHAR.
|
||||
</P>
|
||||
<P>
|
||||
For anchored patterns, a last literal value is recorded only if it follows
|
||||
something of variable length. For example, for the pattern /^a\d+z\d+/ the
|
||||
returned value 1 (with "z" returned from PCRE_INFO_REQUIREDCHAR), but for
|
||||
/^a\dz\d/ the returned value is 0.
|
||||
<pre>
|
||||
PCRE_INFO_REQUIREDCHAR
|
||||
</pre>
|
||||
Return the value of the rightmost literal data unit that must exist in any
|
||||
matched string, other than at its start, if such a value has been recorded. The
|
||||
fourth argument should point to an <b>uint32_t</b> variable. If there is no such
|
||||
value, 0 is returned.
|
||||
</P>
|
||||
<br><a name="SEC16" href="#TOC1">REFERENCE COUNTS</a><br>
|
||||
<P>
|
||||
<b>int pcre_refcount(pcre *<i>code</i>, int <i>adjust</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
The <b>pcre_refcount()</b> function is used to maintain a reference count in the
|
||||
data block that contains a compiled pattern. It is provided for the benefit of
|
||||
applications that operate in an object-oriented manner, where different parts
|
||||
of the application may be using the same compiled pattern, but you want to free
|
||||
the block when they are all done.
|
||||
</P>
|
||||
<P>
|
||||
When a pattern is compiled, the reference count field is initialized to zero.
|
||||
It is changed only by calling this function, whose action is to add the
|
||||
<i>adjust</i> value (which may be positive or negative) to it. The yield of the
|
||||
function is the new value. However, the value of the count is constrained to
|
||||
lie between 0 and 65535, inclusive. If the new value is outside these limits,
|
||||
it is forced to the appropriate limit value.
|
||||
</P>
|
||||
<P>
|
||||
Except when it is zero, the reference count is not correctly preserved if a
|
||||
pattern is compiled on one host and then transferred to a host whose byte-order
|
||||
is different. (This seems a highly unlikely scenario.)
|
||||
</P>
|
||||
<br><a name="SEC17" href="#TOC1">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a><br>
|
||||
<P>
|
||||
<b>int pcre_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
|
||||
<b> const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
The function <b>pcre_exec()</b> is called to match a subject string against a
|
||||
compiled pattern, which is passed in the <i>code</i> argument. If the
|
||||
pattern was studied, the result of the study should be passed in the
|
||||
<i>extra</i> argument. You can call <b>pcre_exec()</b> with the same <i>code</i>
|
||||
and <i>extra</i> arguments as many times as you like, in order to match
|
||||
different subject strings with the same pattern.
|
||||
</P>
|
||||
<P>
|
||||
This function is the main matching facility of the library, and it operates in
|
||||
a Perl-like manner. For specialist use there is also an alternative matching
|
||||
function, which is described
|
||||
<a href="#dfamatch">below</a>
|
||||
in the section about the <b>pcre_dfa_exec()</b> function.
|
||||
</P>
|
||||
<P>
|
||||
In most applications, the pattern will have been compiled (and optionally
|
||||
studied) in the same process that calls <b>pcre_exec()</b>. However, it is
|
||||
possible to save compiled patterns and study data, and then use them later
|
||||
in different processes, possibly even on different hosts. For a discussion
|
||||
about this, see the
|
||||
<a href="pcreprecompile.html"><b>pcreprecompile</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
Here is an example of a simple call to <b>pcre_exec()</b>:
|
||||
<pre>
|
||||
int rc;
|
||||
int ovector[30];
|
||||
rc = pcre_exec(
|
||||
re, /* result of pcre_compile() */
|
||||
NULL, /* we didn't study the pattern */
|
||||
"some string", /* the subject string */
|
||||
11, /* the length of the subject string */
|
||||
0, /* start at offset 0 in the subject */
|
||||
0, /* default options */
|
||||
ovector, /* vector of integers for substring information */
|
||||
30); /* number of elements (NOT size in bytes) */
|
||||
<a name="extradata"></a></PRE>
|
||||
</P>
|
||||
<br><b>
|
||||
Extra data for <b>pcre_exec()</b>
|
||||
</b><br>
|
||||
<P>
|
||||
If the <i>extra</i> argument is not NULL, it must point to a <b>pcre_extra</b>
|
||||
data block. The <b>pcre_study()</b> function returns such a block (when it
|
||||
doesn't return NULL), but you can also create one for yourself, and pass
|
||||
additional information in it. The <b>pcre_extra</b> block contains the following
|
||||
fields (not necessarily in this order):
|
||||
<pre>
|
||||
unsigned long int <i>flags</i>;
|
||||
void *<i>study_data</i>;
|
||||
void *<i>executable_jit</i>;
|
||||
unsigned long int <i>match_limit</i>;
|
||||
unsigned long int <i>match_limit_recursion</i>;
|
||||
void *<i>callout_data</i>;
|
||||
const unsigned char *<i>tables</i>;
|
||||
unsigned char **<i>mark</i>;
|
||||
</pre>
|
||||
In the 16-bit version of this structure, the <i>mark</i> field has type
|
||||
"PCRE_UCHAR16 **".
|
||||
<br>
|
||||
<br>
|
||||
In the 32-bit version of this structure, the <i>mark</i> field has type
|
||||
"PCRE_UCHAR32 **".
|
||||
</P>
|
||||
<P>
|
||||
The <i>flags</i> field is used to specify which of the other fields are set. The
|
||||
flag bits are:
|
||||
<pre>
|
||||
PCRE_EXTRA_CALLOUT_DATA
|
||||
PCRE_EXTRA_EXECUTABLE_JIT
|
||||
PCRE_EXTRA_MARK
|
||||
PCRE_EXTRA_MATCH_LIMIT
|
||||
PCRE_EXTRA_MATCH_LIMIT_RECURSION
|
||||
PCRE_EXTRA_STUDY_DATA
|
||||
PCRE_EXTRA_TABLES
|
||||
</pre>
|
||||
Other flag bits should be set to zero. The <i>study_data</i> field and sometimes
|
||||
the <i>executable_jit</i> field are set in the <b>pcre_extra</b> block that is
|
||||
returned by <b>pcre_study()</b>, together with the appropriate flag bits. You
|
||||
should not set these yourself, but you may add to the block by setting other
|
||||
fields and their corresponding flag bits.
|
||||
</P>
|
||||
<P>
|
||||
The <i>match_limit</i> field provides a means of preventing PCRE from using up a
|
||||
vast amount of resources when running patterns that are not going to match,
|
||||
but which have a very large number of possibilities in their search trees. The
|
||||
classic example is a pattern that uses nested unlimited repeats.
|
||||
</P>
|
||||
<P>
|
||||
Internally, <b>pcre_exec()</b> uses a function called <b>match()</b>, which it
|
||||
calls repeatedly (sometimes recursively). The limit set by <i>match_limit</i> is
|
||||
imposed on the number of times this function is called during a match, which
|
||||
has the effect of limiting the amount of backtracking that can take place. For
|
||||
patterns that are not anchored, the count restarts from zero for each position
|
||||
in the subject string.
|
||||
</P>
|
||||
<P>
|
||||
When <b>pcre_exec()</b> is called with a pattern that was successfully studied
|
||||
with a JIT option, the way that the matching is executed is entirely different.
|
||||
However, there is still the possibility of runaway matching that goes on for a
|
||||
very long time, and so the <i>match_limit</i> value is also used in this case
|
||||
(but in a different way) to limit how long the matching can continue.
|
||||
</P>
|
||||
<P>
|
||||
The default value for the limit can be set when PCRE is built; the default
|
||||
default is 10 million, which handles all but the most extreme cases. You can
|
||||
override the default by suppling <b>pcre_exec()</b> with a <b>pcre_extra</b>
|
||||
block in which <i>match_limit</i> is set, and PCRE_EXTRA_MATCH_LIMIT is set in
|
||||
the <i>flags</i> field. If the limit is exceeded, <b>pcre_exec()</b> returns
|
||||
PCRE_ERROR_MATCHLIMIT.
|
||||
</P>
|
||||
<P>
|
||||
A value for the match limit may also be supplied by an item at the start of a
|
||||
pattern of the form
|
||||
<pre>
|
||||
(*LIMIT_MATCH=d)
|
||||
</pre>
|
||||
where d is a decimal number. However, such a setting is ignored unless d is
|
||||
less than the limit set by the caller of <b>pcre_exec()</b> or, if no such limit
|
||||
is set, less than the default.
|
||||
</P>
|
||||
<P>
|
||||
The <i>match_limit_recursion</i> field is similar to <i>match_limit</i>, but
|
||||
instead of limiting the total number of times that <b>match()</b> is called, it
|
||||
limits the depth of recursion. The recursion depth is a smaller number than the
|
||||
total number of calls, because not all calls to <b>match()</b> are recursive.
|
||||
This limit is of use only if it is set smaller than <i>match_limit</i>.
|
||||
</P>
|
||||
<P>
|
||||
Limiting the recursion depth limits the amount of machine stack that can be
|
||||
used, or, when PCRE has been compiled to use memory on the heap instead of the
|
||||
stack, the amount of heap memory that can be used. This limit is not relevant,
|
||||
and is ignored, when matching is done using JIT compiled code.
|
||||
</P>
|
||||
<P>
|
||||
The default value for <i>match_limit_recursion</i> can be set when PCRE is
|
||||
built; the default default is the same value as the default for
|
||||
<i>match_limit</i>. You can override the default by suppling <b>pcre_exec()</b>
|
||||
with a <b>pcre_extra</b> block in which <i>match_limit_recursion</i> is set, and
|
||||
PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the <i>flags</i> field. If the limit
|
||||
is exceeded, <b>pcre_exec()</b> returns PCRE_ERROR_RECURSIONLIMIT.
|
||||
</P>
|
||||
<P>
|
||||
A value for the recursion limit may also be supplied by an item at the start of
|
||||
a pattern of the form
|
||||
<pre>
|
||||
(*LIMIT_RECURSION=d)
|
||||
</pre>
|
||||
where d is a decimal number. However, such a setting is ignored unless d is
|
||||
less than the limit set by the caller of <b>pcre_exec()</b> or, if no such limit
|
||||
is set, less than the default.
|
||||
</P>
|
||||
<P>
|
||||
The <i>callout_data</i> field is used in conjunction with the "callout" feature,
|
||||
and is described in the
|
||||
<a href="pcrecallout.html"><b>pcrecallout</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
The <i>tables</i> field is provided for use with patterns that have been
|
||||
pre-compiled using custom character tables, saved to disc or elsewhere, and
|
||||
then reloaded, because the tables that were used to compile a pattern are not
|
||||
saved with it. See the
|
||||
<a href="pcreprecompile.html"><b>pcreprecompile</b></a>
|
||||
documentation for a discussion of saving compiled patterns for later use. If
|
||||
NULL is passed using this mechanism, it forces PCRE's internal tables to be
|
||||
used.
|
||||
</P>
|
||||
<P>
|
||||
<b>Warning:</b> The tables that <b>pcre_exec()</b> uses must be the same as those
|
||||
that were used when the pattern was compiled. If this is not the case, the
|
||||
behaviour of <b>pcre_exec()</b> is undefined. Therefore, when a pattern is
|
||||
compiled and matched in the same process, this field should never be set. In
|
||||
this (the most common) case, the correct table pointer is automatically passed
|
||||
with the compiled pattern from <b>pcre_compile()</b> to <b>pcre_exec()</b>.
|
||||
</P>
|
||||
<P>
|
||||
If PCRE_EXTRA_MARK is set in the <i>flags</i> field, the <i>mark</i> field must
|
||||
be set to point to a suitable variable. If the pattern contains any
|
||||
backtracking control verbs such as (*MARK:NAME), and the execution ends up with
|
||||
a name to pass back, a pointer to the name string (zero terminated) is placed
|
||||
in the variable pointed to by the <i>mark</i> field. The names are within the
|
||||
compiled pattern; if you wish to retain such a name you must copy it before
|
||||
freeing the memory of a compiled pattern. If there is no name to pass back, the
|
||||
variable pointed to by the <i>mark</i> field is set to NULL. For details of the
|
||||
backtracking control verbs, see the section entitled
|
||||
<a href="pcrepattern#backtrackcontrol">"Backtracking control"</a>
|
||||
in the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
documentation.
|
||||
<a name="execoptions"></a></P>
|
||||
<br><b>
|
||||
Option bits for <b>pcre_exec()</b>
|
||||
</b><br>
|
||||
<P>
|
||||
The unused bits of the <i>options</i> argument for <b>pcre_exec()</b> must be
|
||||
zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>,
|
||||
PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
|
||||
PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, and
|
||||
PCRE_PARTIAL_SOFT.
|
||||
</P>
|
||||
<P>
|
||||
If the pattern was successfully studied with one of the just-in-time (JIT)
|
||||
compile options, the only supported options for JIT execution are
|
||||
PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY,
|
||||
PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
|
||||
unsupported option is used, JIT execution is disabled and the normal
|
||||
interpretive code in <b>pcre_exec()</b> is run.
|
||||
<pre>
|
||||
PCRE_ANCHORED
|
||||
</pre>
|
||||
The PCRE_ANCHORED option limits <b>pcre_exec()</b> to matching at the first
|
||||
matching position. If a pattern was compiled with PCRE_ANCHORED, or turned out
|
||||
to be anchored by virtue of its contents, it cannot be made unachored at
|
||||
matching time.
|
||||
<pre>
|
||||
PCRE_BSR_ANYCRLF
|
||||
PCRE_BSR_UNICODE
|
||||
</pre>
|
||||
These options (which are mutually exclusive) control what the \R escape
|
||||
sequence matches. The choice is either to match only CR, LF, or CRLF, or to
|
||||
match any Unicode newline sequence. These options override the choice that was
|
||||
made or defaulted when the pattern was compiled.
|
||||
<pre>
|
||||
PCRE_NEWLINE_CR
|
||||
PCRE_NEWLINE_LF
|
||||
PCRE_NEWLINE_CRLF
|
||||
PCRE_NEWLINE_ANYCRLF
|
||||
PCRE_NEWLINE_ANY
|
||||
</pre>
|
||||
These options override the newline definition that was chosen or defaulted when
|
||||
the pattern was compiled. For details, see the description of
|
||||
<b>pcre_compile()</b> above. During matching, the newline choice affects the
|
||||
behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
|
||||
the way the match position is advanced after a match failure for an unanchored
|
||||
pattern.
|
||||
</P>
|
||||
<P>
|
||||
When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
|
||||
match attempt for an unanchored pattern fails when the current position is at a
|
||||
CRLF sequence, and the pattern contains no explicit matches for CR or LF
|
||||
characters, the match position is advanced by two characters instead of one, in
|
||||
other words, to after the CRLF.
|
||||
</P>
|
||||
<P>
|
||||
The above rule is a compromise that makes the most common cases work as
|
||||
expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
|
||||
set), it does not match the string "\r\nA" because, after failing at the
|
||||
start, it skips both the CR and the LF before retrying. However, the pattern
|
||||
[\r\n]A does match that string, because it contains an explicit CR or LF
|
||||
reference, and so advances only by one character after the first failure.
|
||||
</P>
|
||||
<P>
|
||||
An explicit match for CR of LF is either a literal appearance of one of those
|
||||
characters, or one of the \r or \n escape sequences. Implicit matches such as
|
||||
[^X] do not count, nor does \s (which includes CR and LF in the characters
|
||||
that it matches).
|
||||
</P>
|
||||
<P>
|
||||
Notwithstanding the above, anomalous effects may still occur when CRLF is a
|
||||
valid newline sequence and explicit \r or \n escapes appear in the pattern.
|
||||
<pre>
|
||||
PCRE_NOTBOL
|
||||
</pre>
|
||||
This option specifies that first character of the subject string is not the
|
||||
beginning of a line, so the circumflex metacharacter should not match before
|
||||
it. Setting this without PCRE_MULTILINE (at compile time) causes circumflex
|
||||
never to match. This option affects only the behaviour of the circumflex
|
||||
metacharacter. It does not affect \A.
|
||||
<pre>
|
||||
PCRE_NOTEOL
|
||||
</pre>
|
||||
This option specifies that the end of the subject string is not the end of a
|
||||
line, so the dollar metacharacter should not match it nor (except in multiline
|
||||
mode) a newline immediately before it. Setting this without PCRE_MULTILINE (at
|
||||
compile time) causes dollar never to match. This option affects only the
|
||||
behaviour of the dollar metacharacter. It does not affect \Z or \z.
|
||||
<pre>
|
||||
PCRE_NOTEMPTY
|
||||
</pre>
|
||||
An empty string is not considered to be a valid match if this option is set. If
|
||||
there are alternatives in the pattern, they are tried. If all the alternatives
|
||||
match the empty string, the entire match fails. For example, if the pattern
|
||||
<pre>
|
||||
a?b?
|
||||
</pre>
|
||||
is applied to a string not beginning with "a" or "b", it matches an empty
|
||||
string at the start of the subject. With PCRE_NOTEMPTY set, this match is not
|
||||
valid, so PCRE searches further into the string for occurrences of "a" or "b".
|
||||
<pre>
|
||||
PCRE_NOTEMPTY_ATSTART
|
||||
</pre>
|
||||
This is like PCRE_NOTEMPTY, except that an empty string match that is not at
|
||||
the start of the subject is permitted. If the pattern is anchored, such a match
|
||||
can occur only if the pattern contains \K.
|
||||
</P>
|
||||
<P>
|
||||
Perl has no direct equivalent of PCRE_NOTEMPTY or PCRE_NOTEMPTY_ATSTART, but it
|
||||
does make a special case of a pattern match of the empty string within its
|
||||
<b>split()</b> function, and when using the /g modifier. It is possible to
|
||||
emulate Perl's behaviour after matching a null string by first trying the match
|
||||
again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then
|
||||
if that fails, by advancing the starting offset (see below) and trying an
|
||||
ordinary match again. There is some code that demonstrates how to do this in
|
||||
the
|
||||
<a href="pcredemo.html"><b>pcredemo</b></a>
|
||||
sample program. In the most general case, you have to check to see if the
|
||||
newline convention recognizes CRLF as a newline, and if so, and the current
|
||||
character is CR followed by LF, advance the starting offset by two characters
|
||||
instead of one.
|
||||
<pre>
|
||||
PCRE_NO_START_OPTIMIZE
|
||||
</pre>
|
||||
There are a number of optimizations that <b>pcre_exec()</b> uses at the start of
|
||||
a match, in order to speed up the process. For example, if it is known that an
|
||||
unanchored match must start with a specific character, it searches the subject
|
||||
for that character, and fails immediately if it cannot find it, without
|
||||
actually running the main matching function. This means that a special item
|
||||
such as (*COMMIT) at the start of a pattern is not considered until after a
|
||||
suitable starting point for the match has been found. Also, when callouts or
|
||||
(*MARK) items are in use, these "start-up" optimizations can cause them to be
|
||||
skipped if the pattern is never actually used. The start-up optimizations are
|
||||
in effect a pre-scan of the subject that takes place before the pattern is run.
|
||||
</P>
|
||||
<P>
|
||||
The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly
|
||||
causing performance to suffer, but ensuring that in cases where the result is
|
||||
"no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK)
|
||||
are considered at every possible starting position in the subject string. If
|
||||
PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
|
||||
time. The use of PCRE_NO_START_OPTIMIZE at matching time (that is, passing it
|
||||
to <b>pcre_exec()</b>) disables JIT execution; in this situation, matching is
|
||||
always done using interpretively.
|
||||
</P>
|
||||
<P>
|
||||
Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
|
||||
Consider the pattern
|
||||
<pre>
|
||||
(*COMMIT)ABC
|
||||
</pre>
|
||||
When this is compiled, PCRE records the fact that a match must start with the
|
||||
character "A". Suppose the subject string is "DEFABC". The start-up
|
||||
optimization scans along the subject, finds "A" and runs the first match
|
||||
attempt from there. The (*COMMIT) item means that the pattern must match the
|
||||
current starting position, which in this case, it does. However, if the same
|
||||
match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the
|
||||
subject string does not happen. The first match attempt is run starting from
|
||||
"D" and when this fails, (*COMMIT) prevents any further matches being tried, so
|
||||
the overall result is "no match". If the pattern is studied, more start-up
|
||||
optimizations may be used. For example, a minimum length for the subject may be
|
||||
recorded. Consider the pattern
|
||||
<pre>
|
||||
(*MARK:A)(X|Y)
|
||||
</pre>
|
||||
The minimum length for a match is one character. If the subject is "ABC", there
|
||||
will be attempts to match "ABC", "BC", "C", and then finally an empty string.
|
||||
If the pattern is studied, the final attempt does not take place, because PCRE
|
||||
knows that the subject is too short, and so the (*MARK) is never encountered.
|
||||
In this case, studying the pattern does not affect the overall match result,
|
||||
which is still "no match", but it does affect the auxiliary information that is
|
||||
returned.
|
||||
<pre>
|
||||
PCRE_NO_UTF8_CHECK
|
||||
</pre>
|
||||
When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
|
||||
string is automatically checked when <b>pcre_exec()</b> is subsequently called.
|
||||
The entire string is checked before any other processing takes place. The value
|
||||
of <i>startoffset</i> is also checked to ensure that it points to the start of a
|
||||
UTF-8 character. There is a discussion about the
|
||||
<a href="pcreunicode.html#utf8strings">validity of UTF-8 strings</a>
|
||||
in the
|
||||
<a href="pcreunicode.html"><b>pcreunicode</b></a>
|
||||
page. If an invalid sequence of bytes is found, <b>pcre_exec()</b> returns the
|
||||
error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
|
||||
truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In both
|
||||
cases, information about the precise nature of the error may also be returned
|
||||
(see the descriptions of these errors in the section entitled \fIError return
|
||||
values from\fP <b>pcre_exec()</b>
|
||||
<a href="#errorlist">below).</a>
|
||||
If <i>startoffset</i> contains a value that does not point to the start of a
|
||||
UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is
|
||||
returned.
|
||||
</P>
|
||||
<P>
|
||||
If you already know that your subject is valid, and you want to skip these
|
||||
checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
|
||||
calling <b>pcre_exec()</b>. You might want to do this for the second and
|
||||
subsequent calls to <b>pcre_exec()</b> if you are making repeated calls to find
|
||||
all the matches in a single subject string. However, you should be sure that
|
||||
the value of <i>startoffset</i> points to the start of a character (or the end
|
||||
of the subject). When PCRE_NO_UTF8_CHECK is set, the effect of passing an
|
||||
invalid string as a subject or an invalid value of <i>startoffset</i> is
|
||||
undefined. Your program may crash or loop.
|
||||
<pre>
|
||||
PCRE_PARTIAL_HARD
|
||||
PCRE_PARTIAL_SOFT
|
||||
</pre>
|
||||
These options turn on the partial matching feature. For backwards
|
||||
compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match
|
||||
occurs if the end of the subject string is reached successfully, but there are
|
||||
not enough subject characters to complete the match. If this happens when
|
||||
PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by
|
||||
testing any remaining alternatives. Only if no complete match can be found is
|
||||
PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words,
|
||||
PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match,
|
||||
but only if no complete match can be found.
|
||||
</P>
|
||||
<P>
|
||||
If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a
|
||||
partial match is found, <b>pcre_exec()</b> immediately returns
|
||||
PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words,
|
||||
when PCRE_PARTIAL_HARD is set, a partial match is considered to be more
|
||||
important that an alternative complete match.
|
||||
</P>
|
||||
<P>
|
||||
In both cases, the portion of the string that was inspected when the partial
|
||||
match was found is set as the first matching string. There is a more detailed
|
||||
discussion of partial and multi-segment matching, with examples, in the
|
||||
<a href="pcrepartial.html"><b>pcrepartial</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<br><b>
|
||||
The string to be matched by <b>pcre_exec()</b>
|
||||
</b><br>
|
||||
<P>
|
||||
The subject string is passed to <b>pcre_exec()</b> as a pointer in
|
||||
<i>subject</i>, a length in <i>length</i>, and a starting offset in
|
||||
<i>startoffset</i>. The units for <i>length</i> and <i>startoffset</i> are bytes
|
||||
for the 8-bit library, 16-bit data items for the 16-bit library, and 32-bit
|
||||
data items for the 32-bit library.
|
||||
</P>
|
||||
<P>
|
||||
If <i>startoffset</i> is negative or greater than the length of the subject,
|
||||
<b>pcre_exec()</b> returns PCRE_ERROR_BADOFFSET. When the starting offset is
|
||||
zero, the search for a match starts at the beginning of the subject, and this
|
||||
is by far the most common case. In UTF-8 or UTF-16 mode, the offset must point
|
||||
to the start of a character, or the end of the subject (in UTF-32 mode, one
|
||||
data unit equals one character, so all offsets are valid). Unlike the pattern
|
||||
string, the subject may contain binary zeroes.
|
||||
</P>
|
||||
<P>
|
||||
A non-zero starting offset is useful when searching for another match in the
|
||||
same subject by calling <b>pcre_exec()</b> again after a previous success.
|
||||
Setting <i>startoffset</i> differs from just passing over a shortened string and
|
||||
setting PCRE_NOTBOL in the case of a pattern that begins with any kind of
|
||||
lookbehind. For example, consider the pattern
|
||||
<pre>
|
||||
\Biss\B
|
||||
</pre>
|
||||
which finds occurrences of "iss" in the middle of words. (\B matches only if
|
||||
the current position in the subject is not a word boundary.) When applied to
|
||||
the string "Mississipi" the first call to <b>pcre_exec()</b> finds the first
|
||||
occurrence. If <b>pcre_exec()</b> is called again with just the remainder of the
|
||||
subject, namely "issipi", it does not match, because \B is always false at the
|
||||
start of the subject, which is deemed to be a word boundary. However, if
|
||||
<b>pcre_exec()</b> is passed the entire string again, but with <i>startoffset</i>
|
||||
set to 4, it finds the second occurrence of "iss" because it is able to look
|
||||
behind the starting point to discover that it is preceded by a letter.
|
||||
</P>
|
||||
<P>
|
||||
Finding all the matches in a subject is tricky when the pattern can match an
|
||||
empty string. It is possible to emulate Perl's /g behaviour by first trying the
|
||||
match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and
|
||||
PCRE_ANCHORED options, and then if that fails, advancing the starting offset
|
||||
and trying an ordinary match again. There is some code that demonstrates how to
|
||||
do this in the
|
||||
<a href="pcredemo.html"><b>pcredemo</b></a>
|
||||
sample program. In the most general case, you have to check to see if the
|
||||
newline convention recognizes CRLF as a newline, and if so, and the current
|
||||
character is CR followed by LF, advance the starting offset by two characters
|
||||
instead of one.
|
||||
</P>
|
||||
<P>
|
||||
If a non-zero starting offset is passed when the pattern is anchored, one
|
||||
attempt to match at the given offset is made. This can only succeed if the
|
||||
pattern does not require the match to be at the start of the subject.
|
||||
</P>
|
||||
<br><b>
|
||||
How <b>pcre_exec()</b> returns captured substrings
|
||||
</b><br>
|
||||
<P>
|
||||
In general, a pattern matches a certain portion of the subject, and in
|
||||
addition, further substrings from the subject may be picked out by parts of the
|
||||
pattern. Following the usage in Jeffrey Friedl's book, this is called
|
||||
"capturing" in what follows, and the phrase "capturing subpattern" is used for
|
||||
a fragment of a pattern that picks out a substring. PCRE supports several other
|
||||
kinds of parenthesized subpattern that do not cause substrings to be captured.
|
||||
</P>
|
||||
<P>
|
||||
Captured substrings are returned to the caller via a vector of integers whose
|
||||
address is passed in <i>ovector</i>. The number of elements in the vector is
|
||||
passed in <i>ovecsize</i>, which must be a non-negative number. <b>Note</b>: this
|
||||
argument is NOT the size of <i>ovector</i> in bytes.
|
||||
</P>
|
||||
<P>
|
||||
The first two-thirds of the vector is used to pass back captured substrings,
|
||||
each substring using a pair of integers. The remaining third of the vector is
|
||||
used as workspace by <b>pcre_exec()</b> while matching capturing subpatterns,
|
||||
and is not available for passing back information. The number passed in
|
||||
<i>ovecsize</i> should always be a multiple of three. If it is not, it is
|
||||
rounded down.
|
||||
</P>
|
||||
<P>
|
||||
When a match is successful, information about captured substrings is returned
|
||||
in pairs of integers, starting at the beginning of <i>ovector</i>, and
|
||||
continuing up to two-thirds of its length at the most. The first element of
|
||||
each pair is set to the offset of the first character in a substring, and the
|
||||
second is set to the offset of the first character after the end of a
|
||||
substring. These values are always data unit offsets, even in UTF mode. They
|
||||
are byte offsets in the 8-bit library, 16-bit data item offsets in the 16-bit
|
||||
library, and 32-bit data item offsets in the 32-bit library. <b>Note</b>: they
|
||||
are not character counts.
|
||||
</P>
|
||||
<P>
|
||||
The first pair of integers, <i>ovector[0]</i> and <i>ovector[1]</i>, identify the
|
||||
portion of the subject string matched by the entire pattern. The next pair is
|
||||
used for the first capturing subpattern, and so on. The value returned by
|
||||
<b>pcre_exec()</b> is one more than the highest numbered pair that has been set.
|
||||
For example, if two substrings have been captured, the returned value is 3. If
|
||||
there are no capturing subpatterns, the return value from a successful match is
|
||||
1, indicating that just the first pair of offsets has been set.
|
||||
</P>
|
||||
<P>
|
||||
If a capturing subpattern is matched repeatedly, it is the last portion of the
|
||||
string that it matched that is returned.
|
||||
</P>
|
||||
<P>
|
||||
If the vector is too small to hold all the captured substring offsets, it is
|
||||
used as far as possible (up to two-thirds of its length), and the function
|
||||
returns a value of zero. If neither the actual string matched nor any captured
|
||||
substrings are of interest, <b>pcre_exec()</b> may be called with <i>ovector</i>
|
||||
passed as NULL and <i>ovecsize</i> as zero. However, if the pattern contains
|
||||
back references and the <i>ovector</i> is not big enough to remember the related
|
||||
substrings, PCRE has to get additional memory for use during matching. Thus it
|
||||
is usually advisable to supply an <i>ovector</i> of reasonable size.
|
||||
</P>
|
||||
<P>
|
||||
There are some cases where zero is returned (indicating vector overflow) when
|
||||
in fact the vector is exactly the right size for the final match. For example,
|
||||
consider the pattern
|
||||
<pre>
|
||||
(a)(?:(b)c|bd)
|
||||
</pre>
|
||||
If a vector of 6 elements (allowing for only 1 captured substring) is given
|
||||
with subject string "abd", <b>pcre_exec()</b> will try to set the second
|
||||
captured string, thereby recording a vector overflow, before failing to match
|
||||
"c" and backing up to try the second alternative. The zero return, however,
|
||||
does correctly indicate that the maximum number of slots (namely 2) have been
|
||||
filled. In similar cases where there is temporary overflow, but the final
|
||||
number of used slots is actually less than the maximum, a non-zero value is
|
||||
returned.
|
||||
</P>
|
||||
<P>
|
||||
The <b>pcre_fullinfo()</b> function can be used to find out how many capturing
|
||||
subpatterns there are in a compiled pattern. The smallest size for
|
||||
<i>ovector</i> that will allow for <i>n</i> captured substrings, in addition to
|
||||
the offsets of the substring matched by the whole pattern, is (<i>n</i>+1)*3.
|
||||
</P>
|
||||
<P>
|
||||
It is possible for capturing subpattern number <i>n+1</i> to match some part of
|
||||
the subject when subpattern <i>n</i> has not been used at all. For example, if
|
||||
the string "abc" is matched against the pattern (a|(z))(bc) the return from the
|
||||
function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this
|
||||
happens, both values in the offset pairs corresponding to unused subpatterns
|
||||
are set to -1.
|
||||
</P>
|
||||
<P>
|
||||
Offset values that correspond to unused subpatterns at the end of the
|
||||
expression are also set to -1. For example, if the string "abc" is matched
|
||||
against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The
|
||||
return from the function is 2, because the highest used capturing subpattern
|
||||
number is 1, and the offsets for for the second and third capturing subpatterns
|
||||
(assuming the vector is large enough, of course) are set to -1.
|
||||
</P>
|
||||
<P>
|
||||
<b>Note</b>: Elements in the first two-thirds of <i>ovector</i> that do not
|
||||
correspond to capturing parentheses in the pattern are never changed. That is,
|
||||
if a pattern contains <i>n</i> capturing parentheses, no more than
|
||||
<i>ovector[0]</i> to <i>ovector[2n+1]</i> are set by <b>pcre_exec()</b>. The other
|
||||
elements (in the first two-thirds) retain whatever values they previously had.
|
||||
</P>
|
||||
<P>
|
||||
Some convenience functions are provided for extracting the captured substrings
|
||||
as separate strings. These are described below.
|
||||
<a name="errorlist"></a></P>
|
||||
<br><b>
|
||||
Error return values from <b>pcre_exec()</b>
|
||||
</b><br>
|
||||
<P>
|
||||
If <b>pcre_exec()</b> fails, it returns a negative number. The following are
|
||||
defined in the header file:
|
||||
<pre>
|
||||
PCRE_ERROR_NOMATCH (-1)
|
||||
</pre>
|
||||
The subject string did not match the pattern.
|
||||
<pre>
|
||||
PCRE_ERROR_NULL (-2)
|
||||
</pre>
|
||||
Either <i>code</i> or <i>subject</i> was passed as NULL, or <i>ovector</i> was
|
||||
NULL and <i>ovecsize</i> was not zero.
|
||||
<pre>
|
||||
PCRE_ERROR_BADOPTION (-3)
|
||||
</pre>
|
||||
An unrecognized bit was set in the <i>options</i> argument.
|
||||
<pre>
|
||||
PCRE_ERROR_BADMAGIC (-4)
|
||||
</pre>
|
||||
PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch
|
||||
the case when it is passed a junk pointer and to detect when a pattern that was
|
||||
compiled in an environment of one endianness is run in an environment with the
|
||||
other endianness. This is the error that PCRE gives when the magic number is
|
||||
not present.
|
||||
<pre>
|
||||
PCRE_ERROR_UNKNOWN_OPCODE (-5)
|
||||
</pre>
|
||||
While running the pattern match, an unknown item was encountered in the
|
||||
compiled pattern. This error could be caused by a bug in PCRE or by overwriting
|
||||
of the compiled pattern.
|
||||
<pre>
|
||||
PCRE_ERROR_NOMEMORY (-6)
|
||||
</pre>
|
||||
If a pattern contains back references, but the <i>ovector</i> that is passed to
|
||||
<b>pcre_exec()</b> is not big enough to remember the referenced substrings, PCRE
|
||||
gets a block of memory at the start of matching to use for this purpose. If the
|
||||
call via <b>pcre_malloc()</b> fails, this error is given. The memory is
|
||||
automatically freed at the end of matching.
|
||||
</P>
|
||||
<P>
|
||||
This error is also given if <b>pcre_stack_malloc()</b> fails in
|
||||
<b>pcre_exec()</b>. This can happen only when PCRE has been compiled with
|
||||
<b>--disable-stack-for-recursion</b>.
|
||||
<pre>
|
||||
PCRE_ERROR_NOSUBSTRING (-7)
|
||||
</pre>
|
||||
This error is used by the <b>pcre_copy_substring()</b>,
|
||||
<b>pcre_get_substring()</b>, and <b>pcre_get_substring_list()</b> functions (see
|
||||
below). It is never returned by <b>pcre_exec()</b>.
|
||||
<pre>
|
||||
PCRE_ERROR_MATCHLIMIT (-8)
|
||||
</pre>
|
||||
The backtracking limit, as specified by the <i>match_limit</i> field in a
|
||||
<b>pcre_extra</b> structure (or defaulted) was reached. See the description
|
||||
above.
|
||||
<pre>
|
||||
PCRE_ERROR_CALLOUT (-9)
|
||||
</pre>
|
||||
This error is never generated by <b>pcre_exec()</b> itself. It is provided for
|
||||
use by callout functions that want to yield a distinctive error code. See the
|
||||
<a href="pcrecallout.html"><b>pcrecallout</b></a>
|
||||
documentation for details.
|
||||
<pre>
|
||||
PCRE_ERROR_BADUTF8 (-10)
|
||||
</pre>
|
||||
A string that contains an invalid UTF-8 byte sequence was passed as a subject,
|
||||
and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector
|
||||
(<i>ovecsize</i>) is at least 2, the byte offset to the start of the the invalid
|
||||
UTF-8 character is placed in the first element, and a reason code is placed in
|
||||
the second element. The reason codes are listed in the
|
||||
<a href="#badutf8reasons">following section.</a>
|
||||
For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a
|
||||
truncated UTF-8 character at the end of the subject (reason codes 1 to 5),
|
||||
PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
|
||||
<pre>
|
||||
PCRE_ERROR_BADUTF8_OFFSET (-11)
|
||||
</pre>
|
||||
The UTF-8 byte sequence that was passed as a subject was checked and found to
|
||||
be valid (the PCRE_NO_UTF8_CHECK option was not set), but the value of
|
||||
<i>startoffset</i> did not point to the beginning of a UTF-8 character or the
|
||||
end of the subject.
|
||||
<pre>
|
||||
PCRE_ERROR_PARTIAL (-12)
|
||||
</pre>
|
||||
The subject string did not match, but it did match partially. See the
|
||||
<a href="pcrepartial.html"><b>pcrepartial</b></a>
|
||||
documentation for details of partial matching.
|
||||
<pre>
|
||||
PCRE_ERROR_BADPARTIAL (-13)
|
||||
</pre>
|
||||
This code is no longer in use. It was formerly returned when the PCRE_PARTIAL
|
||||
option was used with a compiled pattern containing items that were not
|
||||
supported for partial matching. From release 8.00 onwards, there are no
|
||||
restrictions on partial matching.
|
||||
<pre>
|
||||
PCRE_ERROR_INTERNAL (-14)
|
||||
</pre>
|
||||
An unexpected internal error has occurred. This error could be caused by a bug
|
||||
in PCRE or by overwriting of the compiled pattern.
|
||||
<pre>
|
||||
PCRE_ERROR_BADCOUNT (-15)
|
||||
</pre>
|
||||
This error is given if the value of the <i>ovecsize</i> argument is negative.
|
||||
<pre>
|
||||
PCRE_ERROR_RECURSIONLIMIT (-21)
|
||||
</pre>
|
||||
The internal recursion limit, as specified by the <i>match_limit_recursion</i>
|
||||
field in a <b>pcre_extra</b> structure (or defaulted) was reached. See the
|
||||
description above.
|
||||
<pre>
|
||||
PCRE_ERROR_BADNEWLINE (-23)
|
||||
</pre>
|
||||
An invalid combination of PCRE_NEWLINE_<i>xxx</i> options was given.
|
||||
<pre>
|
||||
PCRE_ERROR_BADOFFSET (-24)
|
||||
</pre>
|
||||
The value of <i>startoffset</i> was negative or greater than the length of the
|
||||
subject, that is, the value in <i>length</i>.
|
||||
<pre>
|
||||
PCRE_ERROR_SHORTUTF8 (-25)
|
||||
</pre>
|
||||
This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string
|
||||
ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set.
|
||||
Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in
|
||||
fact sufficient to detect this case, but this special error code for
|
||||
PCRE_PARTIAL_HARD precedes the implementation of returned information; it is
|
||||
retained for backwards compatibility.
|
||||
<pre>
|
||||
PCRE_ERROR_RECURSELOOP (-26)
|
||||
</pre>
|
||||
This error is returned when <b>pcre_exec()</b> detects a recursion loop within
|
||||
the pattern. Specifically, it means that either the whole pattern or a
|
||||
subpattern has been called recursively for the second time at the same position
|
||||
in the subject string. Some simple patterns that might do this are detected and
|
||||
faulted at compile time, but more complicated cases, in particular mutual
|
||||
recursions between two different subpatterns, cannot be detected until run
|
||||
time.
|
||||
<pre>
|
||||
PCRE_ERROR_JIT_STACKLIMIT (-27)
|
||||
</pre>
|
||||
This error is returned when a pattern that was successfully studied using a
|
||||
JIT compile option is being matched, but the memory available for the
|
||||
just-in-time processing stack is not large enough. See the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
documentation for more details.
|
||||
<pre>
|
||||
PCRE_ERROR_BADMODE (-28)
|
||||
</pre>
|
||||
This error is given if a pattern that was compiled by the 8-bit library is
|
||||
passed to a 16-bit or 32-bit library function, or vice versa.
|
||||
<pre>
|
||||
PCRE_ERROR_BADENDIANNESS (-29)
|
||||
</pre>
|
||||
This error is given if a pattern that was compiled and saved is reloaded on a
|
||||
host with different endianness. The utility function
|
||||
<b>pcre_pattern_to_host_byte_order()</b> can be used to convert such a pattern
|
||||
so that it runs on the new host.
|
||||
<pre>
|
||||
PCRE_ERROR_JIT_BADOPTION
|
||||
</pre>
|
||||
This error is returned when a pattern that was successfully studied using a JIT
|
||||
compile option is being matched, but the matching mode (partial or complete
|
||||
match) does not correspond to any JIT compilation mode. When the JIT fast path
|
||||
function is used, this error may be also given for invalid options. See the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
documentation for more details.
|
||||
<pre>
|
||||
PCRE_ERROR_BADLENGTH (-32)
|
||||
</pre>
|
||||
This error is given if <b>pcre_exec()</b> is called with a negative value for
|
||||
the <i>length</i> argument.
|
||||
</P>
|
||||
<P>
|
||||
Error numbers -16 to -20, -22, and 30 are not used by <b>pcre_exec()</b>.
|
||||
<a name="badutf8reasons"></a></P>
|
||||
<br><b>
|
||||
Reason codes for invalid UTF-8 strings
|
||||
</b><br>
|
||||
<P>
|
||||
This section applies only to the 8-bit library. The corresponding information
|
||||
for the 16-bit and 32-bit libraries is given in the
|
||||
<a href="pcre16.html"><b>pcre16</b></a>
|
||||
and
|
||||
<a href="pcre32.html"><b>pcre32</b></a>
|
||||
pages.
|
||||
</P>
|
||||
<P>
|
||||
When <b>pcre_exec()</b> returns either PCRE_ERROR_BADUTF8 or
|
||||
PCRE_ERROR_SHORTUTF8, and the size of the output vector (<i>ovecsize</i>) is at
|
||||
least 2, the offset of the start of the invalid UTF-8 character is placed in
|
||||
the first output vector element (<i>ovector[0]</i>) and a reason code is placed
|
||||
in the second element (<i>ovector[1]</i>). The reason codes are given names in
|
||||
the <b>pcre.h</b> header file:
|
||||
<pre>
|
||||
PCRE_UTF8_ERR1
|
||||
PCRE_UTF8_ERR2
|
||||
PCRE_UTF8_ERR3
|
||||
PCRE_UTF8_ERR4
|
||||
PCRE_UTF8_ERR5
|
||||
</pre>
|
||||
The string ends with a truncated UTF-8 character; the code specifies how many
|
||||
bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be
|
||||
no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279)
|
||||
allows for up to 6 bytes, and this is checked first; hence the possibility of
|
||||
4 or 5 missing bytes.
|
||||
<pre>
|
||||
PCRE_UTF8_ERR6
|
||||
PCRE_UTF8_ERR7
|
||||
PCRE_UTF8_ERR8
|
||||
PCRE_UTF8_ERR9
|
||||
PCRE_UTF8_ERR10
|
||||
</pre>
|
||||
The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the
|
||||
character do not have the binary value 0b10 (that is, either the most
|
||||
significant bit is 0, or the next bit is 1).
|
||||
<pre>
|
||||
PCRE_UTF8_ERR11
|
||||
PCRE_UTF8_ERR12
|
||||
</pre>
|
||||
A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long;
|
||||
these code points are excluded by RFC 3629.
|
||||
<pre>
|
||||
PCRE_UTF8_ERR13
|
||||
</pre>
|
||||
A 4-byte character has a value greater than 0x10fff; these code points are
|
||||
excluded by RFC 3629.
|
||||
<pre>
|
||||
PCRE_UTF8_ERR14
|
||||
</pre>
|
||||
A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of
|
||||
code points are reserved by RFC 3629 for use with UTF-16, and so are excluded
|
||||
from UTF-8.
|
||||
<pre>
|
||||
PCRE_UTF8_ERR15
|
||||
PCRE_UTF8_ERR16
|
||||
PCRE_UTF8_ERR17
|
||||
PCRE_UTF8_ERR18
|
||||
PCRE_UTF8_ERR19
|
||||
</pre>
|
||||
A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a
|
||||
value that can be represented by fewer bytes, which is invalid. For example,
|
||||
the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just
|
||||
one byte.
|
||||
<pre>
|
||||
PCRE_UTF8_ERR20
|
||||
</pre>
|
||||
The two most significant bits of the first byte of a character have the binary
|
||||
value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a
|
||||
byte can only validly occur as the second or subsequent byte of a multi-byte
|
||||
character.
|
||||
<pre>
|
||||
PCRE_UTF8_ERR21
|
||||
</pre>
|
||||
The first byte of a character has the value 0xfe or 0xff. These values can
|
||||
never occur in a valid UTF-8 string.
|
||||
<pre>
|
||||
PCRE_UTF8_ERR22
|
||||
</pre>
|
||||
This error code was formerly used when the presence of a so-called
|
||||
"non-character" caused an error. Unicode corrigendum #9 makes it clear that
|
||||
such characters should not cause a string to be rejected, and so this code is
|
||||
no longer in use and is never returned.
|
||||
</P>
|
||||
<br><a name="SEC18" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br>
|
||||
<P>
|
||||
<b>int pcre_copy_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, int <i>stringnumber</i>, char *<i>buffer</i>,</b>
|
||||
<b> int <i>buffersize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_get_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, int <i>stringnumber</i>,</b>
|
||||
<b> const char **<i>stringptr</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_get_substring_list(const char *<i>subject</i>,</b>
|
||||
<b> int *<i>ovector</i>, int <i>stringcount</i>, const char ***<i>listptr</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
Captured substrings can be accessed directly by using the offsets returned by
|
||||
<b>pcre_exec()</b> in <i>ovector</i>. For convenience, the functions
|
||||
<b>pcre_copy_substring()</b>, <b>pcre_get_substring()</b>, and
|
||||
<b>pcre_get_substring_list()</b> are provided for extracting captured substrings
|
||||
as new, separate, zero-terminated strings. These functions identify substrings
|
||||
by number. The next section describes functions for extracting named
|
||||
substrings.
|
||||
</P>
|
||||
<P>
|
||||
A substring that contains a binary zero is correctly extracted and has a
|
||||
further zero added on the end, but the result is not, of course, a C string.
|
||||
However, you can process such a string by referring to the length that is
|
||||
returned by <b>pcre_copy_substring()</b> and <b>pcre_get_substring()</b>.
|
||||
Unfortunately, the interface to <b>pcre_get_substring_list()</b> is not adequate
|
||||
for handling strings containing binary zeros, because the end of the final
|
||||
string is not independently indicated.
|
||||
</P>
|
||||
<P>
|
||||
The first three arguments are the same for all three of these functions:
|
||||
<i>subject</i> is the subject string that has just been successfully matched,
|
||||
<i>ovector</i> is a pointer to the vector of integer offsets that was passed to
|
||||
<b>pcre_exec()</b>, and <i>stringcount</i> is the number of substrings that were
|
||||
captured by the match, including the substring that matched the entire regular
|
||||
expression. This is the value returned by <b>pcre_exec()</b> if it is greater
|
||||
than zero. If <b>pcre_exec()</b> returned zero, indicating that it ran out of
|
||||
space in <i>ovector</i>, the value passed as <i>stringcount</i> should be the
|
||||
number of elements in the vector divided by three.
|
||||
</P>
|
||||
<P>
|
||||
The functions <b>pcre_copy_substring()</b> and <b>pcre_get_substring()</b>
|
||||
extract a single substring, whose number is given as <i>stringnumber</i>. A
|
||||
value of zero extracts the substring that matched the entire pattern, whereas
|
||||
higher values extract the captured substrings. For <b>pcre_copy_substring()</b>,
|
||||
the string is placed in <i>buffer</i>, whose length is given by
|
||||
<i>buffersize</i>, while for <b>pcre_get_substring()</b> a new block of memory is
|
||||
obtained via <b>pcre_malloc</b>, and its address is returned via
|
||||
<i>stringptr</i>. The yield of the function is the length of the string, not
|
||||
including the terminating zero, or one of these error codes:
|
||||
<pre>
|
||||
PCRE_ERROR_NOMEMORY (-6)
|
||||
</pre>
|
||||
The buffer was too small for <b>pcre_copy_substring()</b>, or the attempt to get
|
||||
memory failed for <b>pcre_get_substring()</b>.
|
||||
<pre>
|
||||
PCRE_ERROR_NOSUBSTRING (-7)
|
||||
</pre>
|
||||
There is no substring whose number is <i>stringnumber</i>.
|
||||
</P>
|
||||
<P>
|
||||
The <b>pcre_get_substring_list()</b> function extracts all available substrings
|
||||
and builds a list of pointers to them. All this is done in a single block of
|
||||
memory that is obtained via <b>pcre_malloc</b>. The address of the memory block
|
||||
is returned via <i>listptr</i>, which is also the start of the list of string
|
||||
pointers. The end of the list is marked by a NULL pointer. The yield of the
|
||||
function is zero if all went well, or the error code
|
||||
<pre>
|
||||
PCRE_ERROR_NOMEMORY (-6)
|
||||
</pre>
|
||||
if the attempt to get the memory block failed.
|
||||
</P>
|
||||
<P>
|
||||
When any of these functions encounter a substring that is unset, which can
|
||||
happen when capturing subpattern number <i>n+1</i> matches some part of the
|
||||
subject, but subpattern <i>n</i> has not been used at all, they return an empty
|
||||
string. This can be distinguished from a genuine zero-length substring by
|
||||
inspecting the appropriate offset in <i>ovector</i>, which is negative for unset
|
||||
substrings.
|
||||
</P>
|
||||
<P>
|
||||
The two convenience functions <b>pcre_free_substring()</b> and
|
||||
<b>pcre_free_substring_list()</b> can be used to free the memory returned by
|
||||
a previous call of <b>pcre_get_substring()</b> or
|
||||
<b>pcre_get_substring_list()</b>, respectively. They do nothing more than call
|
||||
the function pointed to by <b>pcre_free</b>, which of course could be called
|
||||
directly from a C program. However, PCRE is used in some situations where it is
|
||||
linked via a special interface to another programming language that cannot use
|
||||
<b>pcre_free</b> directly; it is for these cases that the functions are
|
||||
provided.
|
||||
</P>
|
||||
<br><a name="SEC19" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a><br>
|
||||
<P>
|
||||
<b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b>
|
||||
<b> const char *<i>name</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b>
|
||||
<b> const char *<i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, const char *<i>stringname</i>,</b>
|
||||
<b> char *<i>buffer</i>, int <i>buffersize</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int pcre_get_named_substring(const pcre *<i>code</i>,</b>
|
||||
<b> const char *<i>subject</i>, int *<i>ovector</i>,</b>
|
||||
<b> int <i>stringcount</i>, const char *<i>stringname</i>,</b>
|
||||
<b> const char **<i>stringptr</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
To extract a substring by name, you first have to find associated number.
|
||||
For example, for this pattern
|
||||
<pre>
|
||||
(a+)b(?<xxx>\d+)...
|
||||
</pre>
|
||||
the number of the subpattern called "xxx" is 2. If the name is known to be
|
||||
unique (PCRE_DUPNAMES was not set), you can find the number from the name by
|
||||
calling <b>pcre_get_stringnumber()</b>. The first argument is the compiled
|
||||
pattern, and the second is the name. The yield of the function is the
|
||||
subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of
|
||||
that name.
|
||||
</P>
|
||||
<P>
|
||||
Given the number, you can extract the substring directly, or use one of the
|
||||
functions described in the previous section. For convenience, there are also
|
||||
two functions that do the whole job.
|
||||
</P>
|
||||
<P>
|
||||
Most of the arguments of <b>pcre_copy_named_substring()</b> and
|
||||
<b>pcre_get_named_substring()</b> are the same as those for the similarly named
|
||||
functions that extract by number. As these are described in the previous
|
||||
section, they are not re-described here. There are just two differences:
|
||||
</P>
|
||||
<P>
|
||||
First, instead of a substring number, a substring name is given. Second, there
|
||||
is an extra argument, given at the start, which is a pointer to the compiled
|
||||
pattern. This is needed in order to gain access to the name-to-number
|
||||
translation table.
|
||||
</P>
|
||||
<P>
|
||||
These functions call <b>pcre_get_stringnumber()</b>, and if it succeeds, they
|
||||
then call <b>pcre_copy_substring()</b> or <b>pcre_get_substring()</b>, as
|
||||
appropriate. <b>NOTE:</b> If PCRE_DUPNAMES is set and there are duplicate names,
|
||||
the behaviour may not be what you want (see the next section).
|
||||
</P>
|
||||
<P>
|
||||
<b>Warning:</b> If the pattern uses the (?| feature to set up multiple
|
||||
subpatterns with the same number, as described in the
|
||||
<a href="pcrepattern.html#dupsubpatternnumber">section on duplicate subpattern numbers</a>
|
||||
in the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
page, you cannot use names to distinguish the different subpatterns, because
|
||||
names are not included in the compiled code. The matching process uses only
|
||||
numbers. For this reason, the use of different names for subpatterns of the
|
||||
same number causes an error at compile time.
|
||||
</P>
|
||||
<br><a name="SEC20" href="#TOC1">DUPLICATE SUBPATTERN NAMES</a><br>
|
||||
<P>
|
||||
<b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b>
|
||||
<b> const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns
|
||||
are not required to be unique. (Duplicate names are always allowed for
|
||||
subpatterns with the same number, created by using the (?| feature. Indeed, if
|
||||
such subpatterns are named, they are required to use the same names.)
|
||||
</P>
|
||||
<P>
|
||||
Normally, patterns with duplicate names are such that in any one match, only
|
||||
one of the named subpatterns participates. An example is shown in the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
When duplicates are present, <b>pcre_copy_named_substring()</b> and
|
||||
<b>pcre_get_named_substring()</b> return the first substring corresponding to
|
||||
the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING (-7) is
|
||||
returned; no data is returned. The <b>pcre_get_stringnumber()</b> function
|
||||
returns one of the numbers that are associated with the name, but it is not
|
||||
defined which it is.
|
||||
</P>
|
||||
<P>
|
||||
If you want to get full details of all captured substrings for a given name,
|
||||
you must use the <b>pcre_get_stringtable_entries()</b> function. The first
|
||||
argument is the compiled pattern, and the second is the name. The third and
|
||||
fourth are pointers to variables which are updated by the function. After it
|
||||
has run, they point to the first and last entries in the name-to-number table
|
||||
for the given name. The function itself returns the length of each entry, or
|
||||
PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is
|
||||
described above in the section entitled <i>Information about a pattern</i>
|
||||
<a href="#infoaboutpattern">above.</a>
|
||||
Given all the relevant entries for the name, you can extract each of their
|
||||
numbers, and hence the captured data, if any.
|
||||
</P>
|
||||
<br><a name="SEC21" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br>
|
||||
<P>
|
||||
The traditional matching function uses a similar algorithm to Perl, which stops
|
||||
when it finds the first match, starting at a given point in the subject. If you
|
||||
want to find all possible matches, or the longest possible match, consider
|
||||
using the alternative matching function (see below) instead. If you cannot use
|
||||
the alternative function, but still need to find all possible matches, you
|
||||
can kludge it up by making use of the callout facility, which is described in
|
||||
the
|
||||
<a href="pcrecallout.html"><b>pcrecallout</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
What you have to do is to insert a callout right at the end of the pattern.
|
||||
When your callout function is called, extract and save the current matched
|
||||
substring. Then return 1, which forces <b>pcre_exec()</b> to backtrack and try
|
||||
other alternatives. Ultimately, when it runs out of matches, <b>pcre_exec()</b>
|
||||
will yield PCRE_ERROR_NOMATCH.
|
||||
</P>
|
||||
<br><a name="SEC22" href="#TOC1">OBTAINING AN ESTIMATE OF STACK USAGE</a><br>
|
||||
<P>
|
||||
Matching certain patterns using <b>pcre_exec()</b> can use a lot of process
|
||||
stack, which in certain environments can be rather limited in size. Some users
|
||||
find it helpful to have an estimate of the amount of stack that is used by
|
||||
<b>pcre_exec()</b>, to help them set recursion limits, as described in the
|
||||
<a href="pcrestack.html"><b>pcrestack</b></a>
|
||||
documentation. The estimate that is output by <b>pcretest</b> when called with
|
||||
the <b>-m</b> and <b>-C</b> options is obtained by calling <b>pcre_exec</b> with
|
||||
the values NULL, NULL, NULL, -999, and -999 for its first five arguments.
|
||||
</P>
|
||||
<P>
|
||||
Normally, if its first argument is NULL, <b>pcre_exec()</b> immediately returns
|
||||
the negative error code PCRE_ERROR_NULL, but with this special combination of
|
||||
arguments, it returns instead a negative number whose absolute value is the
|
||||
approximate stack frame size in bytes. (A negative number is used so that it is
|
||||
clear that no match has happened.) The value is approximate because in some
|
||||
cases, recursive calls to <b>pcre_exec()</b> occur when there are one or two
|
||||
additional variables on the stack.
|
||||
</P>
|
||||
<P>
|
||||
If PCRE has been compiled to use the heap instead of the stack for recursion,
|
||||
the value returned is the size of each block that is obtained from the heap.
|
||||
<a name="dfamatch"></a></P>
|
||||
<br><a name="SEC23" href="#TOC1">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a><br>
|
||||
<P>
|
||||
<b>int pcre_dfa_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b>
|
||||
<b> const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b>
|
||||
<b> int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b>
|
||||
<b> int *<i>workspace</i>, int <i>wscount</i>);</b>
|
||||
</P>
|
||||
<P>
|
||||
The function <b>pcre_dfa_exec()</b> is called to match a subject string against
|
||||
a compiled pattern, using a matching algorithm that scans the subject string
|
||||
just once, and does not backtrack. This has different characteristics to the
|
||||
normal algorithm, and is not compatible with Perl. Some of the features of PCRE
|
||||
patterns are not supported. Nevertheless, there are times when this kind of
|
||||
matching can be useful. For a discussion of the two matching algorithms, and a
|
||||
list of features that <b>pcre_dfa_exec()</b> does not support, see the
|
||||
<a href="pcrematching.html"><b>pcrematching</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
The arguments for the <b>pcre_dfa_exec()</b> function are the same as for
|
||||
<b>pcre_exec()</b>, plus two extras. The <i>ovector</i> argument is used in a
|
||||
different way, and this is described below. The other common arguments are used
|
||||
in the same way as for <b>pcre_exec()</b>, so their description is not repeated
|
||||
here.
|
||||
</P>
|
||||
<P>
|
||||
The two additional arguments provide workspace for the function. The workspace
|
||||
vector should contain at least 20 elements. It is used for keeping track of
|
||||
multiple paths through the pattern tree. More workspace will be needed for
|
||||
patterns and subjects where there are a lot of potential matches.
|
||||
</P>
|
||||
<P>
|
||||
Here is an example of a simple call to <b>pcre_dfa_exec()</b>:
|
||||
<pre>
|
||||
int rc;
|
||||
int ovector[10];
|
||||
int wspace[20];
|
||||
rc = pcre_dfa_exec(
|
||||
re, /* result of pcre_compile() */
|
||||
NULL, /* we didn't study the pattern */
|
||||
"some string", /* the subject string */
|
||||
11, /* the length of the subject string */
|
||||
0, /* start at offset 0 in the subject */
|
||||
0, /* default options */
|
||||
ovector, /* vector of integers for substring information */
|
||||
10, /* number of elements (NOT size in bytes) */
|
||||
wspace, /* working space vector */
|
||||
20); /* number of elements (NOT size in bytes) */
|
||||
</PRE>
|
||||
</P>
|
||||
<br><b>
|
||||
Option bits for <b>pcre_dfa_exec()</b>
|
||||
</b><br>
|
||||
<P>
|
||||
The unused bits of the <i>options</i> argument for <b>pcre_dfa_exec()</b> must be
|
||||
zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>,
|
||||
PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
|
||||
PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF, PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE,
|
||||
PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART.
|
||||
All but the last four of these are exactly the same as for <b>pcre_exec()</b>,
|
||||
so their description is not repeated here.
|
||||
<pre>
|
||||
PCRE_PARTIAL_HARD
|
||||
PCRE_PARTIAL_SOFT
|
||||
</pre>
|
||||
These have the same general effect as they do for <b>pcre_exec()</b>, but the
|
||||
details are slightly different. When PCRE_PARTIAL_HARD is set for
|
||||
<b>pcre_dfa_exec()</b>, it returns PCRE_ERROR_PARTIAL if the end of the subject
|
||||
is reached and there is still at least one matching possibility that requires
|
||||
additional characters. This happens even if some complete matches have also
|
||||
been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH
|
||||
is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached,
|
||||
there have been no complete matches, but there is still at least one matching
|
||||
possibility. The portion of the string that was inspected when the longest
|
||||
partial match was found is set as the first matching string in both cases.
|
||||
There is a more detailed discussion of partial and multi-segment matching, with
|
||||
examples, in the
|
||||
<a href="pcrepartial.html"><b>pcrepartial</b></a>
|
||||
documentation.
|
||||
<pre>
|
||||
PCRE_DFA_SHORTEST
|
||||
</pre>
|
||||
Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as
|
||||
soon as it has found one match. Because of the way the alternative algorithm
|
||||
works, this is necessarily the shortest possible match at the first possible
|
||||
matching point in the subject string.
|
||||
<pre>
|
||||
PCRE_DFA_RESTART
|
||||
</pre>
|
||||
When <b>pcre_dfa_exec()</b> returns a partial match, it is possible to call it
|
||||
again, with additional subject characters, and have it continue with the same
|
||||
match. The PCRE_DFA_RESTART option requests this action; when it is set, the
|
||||
<i>workspace</i> and <i>wscount</i> options must reference the same vector as
|
||||
before because data about the match so far is left in them after a partial
|
||||
match. There is more discussion of this facility in the
|
||||
<a href="pcrepartial.html"><b>pcrepartial</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<br><b>
|
||||
Successful returns from <b>pcre_dfa_exec()</b>
|
||||
</b><br>
|
||||
<P>
|
||||
When <b>pcre_dfa_exec()</b> succeeds, it may have matched more than one
|
||||
substring in the subject. Note, however, that all the matches from one run of
|
||||
the function start at the same point in the subject. The shorter matches are
|
||||
all initial substrings of the longer matches. For example, if the pattern
|
||||
<pre>
|
||||
<.*>
|
||||
</pre>
|
||||
is matched against the string
|
||||
<pre>
|
||||
This is <something> <something else> <something further> no more
|
||||
</pre>
|
||||
the three matched strings are
|
||||
<pre>
|
||||
<something>
|
||||
<something> <something else>
|
||||
<something> <something else> <something further>
|
||||
</pre>
|
||||
On success, the yield of the function is a number greater than zero, which is
|
||||
the number of matched substrings. The substrings themselves are returned in
|
||||
<i>ovector</i>. Each string uses two elements; the first is the offset to the
|
||||
start, and the second is the offset to the end. In fact, all the strings have
|
||||
the same start offset. (Space could have been saved by giving this only once,
|
||||
but it was decided to retain some compatibility with the way <b>pcre_exec()</b>
|
||||
returns data, even though the meaning of the strings is different.)
|
||||
</P>
|
||||
<P>
|
||||
The strings are returned in reverse order of length; that is, the longest
|
||||
matching string is given first. If there were too many matches to fit into
|
||||
<i>ovector</i>, the yield of the function is zero, and the vector is filled with
|
||||
the longest matches. Unlike <b>pcre_exec()</b>, <b>pcre_dfa_exec()</b> can use
|
||||
the entire <i>ovector</i> for returning matched strings.
|
||||
</P>
|
||||
<P>
|
||||
NOTE: PCRE's "auto-possessification" optimization usually applies to character
|
||||
repeats at the end of a pattern (as well as internally). For example, the
|
||||
pattern "a\d+" is compiled as if it were "a\d++" because there is no point
|
||||
even considering the possibility of backtracking into the repeated digits. For
|
||||
DFA matching, this means that only one possible match is found. If you really
|
||||
do want multiple matches in such cases, either use an ungreedy repeat
|
||||
("a\d+?") or set the PCRE_NO_AUTO_POSSESS option when compiling.
|
||||
</P>
|
||||
<br><b>
|
||||
Error returns from <b>pcre_dfa_exec()</b>
|
||||
</b><br>
|
||||
<P>
|
||||
The <b>pcre_dfa_exec()</b> function returns a negative number when it fails.
|
||||
Many of the errors are the same as for <b>pcre_exec()</b>, and these are
|
||||
described
|
||||
<a href="#errorlist">above.</a>
|
||||
There are in addition the following errors that are specific to
|
||||
<b>pcre_dfa_exec()</b>:
|
||||
<pre>
|
||||
PCRE_ERROR_DFA_UITEM (-16)
|
||||
</pre>
|
||||
This return is given if <b>pcre_dfa_exec()</b> encounters an item in the pattern
|
||||
that it does not support, for instance, the use of \C or a back reference.
|
||||
<pre>
|
||||
PCRE_ERROR_DFA_UCOND (-17)
|
||||
</pre>
|
||||
This return is given if <b>pcre_dfa_exec()</b> encounters a condition item that
|
||||
uses a back reference for the condition, or a test for recursion in a specific
|
||||
group. These are not supported.
|
||||
<pre>
|
||||
PCRE_ERROR_DFA_UMLIMIT (-18)
|
||||
</pre>
|
||||
This return is given if <b>pcre_dfa_exec()</b> is called with an <i>extra</i>
|
||||
block that contains a setting of the <i>match_limit</i> or
|
||||
<i>match_limit_recursion</i> fields. This is not supported (these fields are
|
||||
meaningless for DFA matching).
|
||||
<pre>
|
||||
PCRE_ERROR_DFA_WSSIZE (-19)
|
||||
</pre>
|
||||
This return is given if <b>pcre_dfa_exec()</b> runs out of space in the
|
||||
<i>workspace</i> vector.
|
||||
<pre>
|
||||
PCRE_ERROR_DFA_RECURSE (-20)
|
||||
</pre>
|
||||
When a recursive subpattern is processed, the matching function calls itself
|
||||
recursively, using private vectors for <i>ovector</i> and <i>workspace</i>. This
|
||||
error is given if the output vector is not large enough. This should be
|
||||
extremely rare, as a vector of size 1000 is used.
|
||||
<pre>
|
||||
PCRE_ERROR_DFA_BADRESTART (-30)
|
||||
</pre>
|
||||
When <b>pcre_dfa_exec()</b> is called with the <b>PCRE_DFA_RESTART</b> option,
|
||||
some plausibility checks are made on the contents of the workspace, which
|
||||
should contain data about the previous partial match. If any of these checks
|
||||
fail, this error is given.
|
||||
</P>
|
||||
<br><a name="SEC24" href="#TOC1">SEE ALSO</a><br>
|
||||
<P>
|
||||
<b>pcre16</b>(3), <b>pcre32</b>(3), <b>pcrebuild</b>(3), <b>pcrecallout</b>(3),
|
||||
<b>pcrecpp(3)</b>(3), <b>pcrematching</b>(3), <b>pcrepartial</b>(3),
|
||||
<b>pcreposix</b>(3), <b>pcreprecompile</b>(3), <b>pcresample</b>(3),
|
||||
<b>pcrestack</b>(3).
|
||||
</P>
|
||||
<br><a name="SEC25" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC26" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 18 December 2015
|
||||
<br>
|
||||
Copyright © 1997-2015 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,534 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcrebuild specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcrebuild man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">BUILDING PCRE</a>
|
||||
<li><a name="TOC2" href="#SEC2">PCRE BUILD-TIME OPTIONS</a>
|
||||
<li><a name="TOC3" href="#SEC3">BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES</a>
|
||||
<li><a name="TOC4" href="#SEC4">BUILDING SHARED AND STATIC LIBRARIES</a>
|
||||
<li><a name="TOC5" href="#SEC5">C++ SUPPORT</a>
|
||||
<li><a name="TOC6" href="#SEC6">UTF-8, UTF-16 AND UTF-32 SUPPORT</a>
|
||||
<li><a name="TOC7" href="#SEC7">UNICODE CHARACTER PROPERTY SUPPORT</a>
|
||||
<li><a name="TOC8" href="#SEC8">JUST-IN-TIME COMPILER SUPPORT</a>
|
||||
<li><a name="TOC9" href="#SEC9">CODE VALUE OF NEWLINE</a>
|
||||
<li><a name="TOC10" href="#SEC10">WHAT \R MATCHES</a>
|
||||
<li><a name="TOC11" href="#SEC11">POSIX MALLOC USAGE</a>
|
||||
<li><a name="TOC12" href="#SEC12">HANDLING VERY LARGE PATTERNS</a>
|
||||
<li><a name="TOC13" href="#SEC13">AVOIDING EXCESSIVE STACK USAGE</a>
|
||||
<li><a name="TOC14" href="#SEC14">LIMITING PCRE RESOURCE USAGE</a>
|
||||
<li><a name="TOC15" href="#SEC15">CREATING CHARACTER TABLES AT BUILD TIME</a>
|
||||
<li><a name="TOC16" href="#SEC16">USING EBCDIC CODE</a>
|
||||
<li><a name="TOC17" href="#SEC17">PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT</a>
|
||||
<li><a name="TOC18" href="#SEC18">PCREGREP BUFFER SIZE</a>
|
||||
<li><a name="TOC19" href="#SEC19">PCRETEST OPTION FOR LIBREADLINE SUPPORT</a>
|
||||
<li><a name="TOC20" href="#SEC20">DEBUGGING WITH VALGRIND SUPPORT</a>
|
||||
<li><a name="TOC21" href="#SEC21">CODE COVERAGE REPORTING</a>
|
||||
<li><a name="TOC22" href="#SEC22">SEE ALSO</a>
|
||||
<li><a name="TOC23" href="#SEC23">AUTHOR</a>
|
||||
<li><a name="TOC24" href="#SEC24">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">BUILDING PCRE</a><br>
|
||||
<P>
|
||||
PCRE is distributed with a <b>configure</b> script that can be used to build the
|
||||
library in Unix-like environments using the applications known as Autotools.
|
||||
Also in the distribution are files to support building using <b>CMake</b>
|
||||
instead of <b>configure</b>. The text file
|
||||
<a href="README.txt"><b>README</b></a>
|
||||
contains general information about building with Autotools (some of which is
|
||||
repeated below), and also has some comments about building on various operating
|
||||
systems. There is a lot more information about building PCRE without using
|
||||
Autotools (including information about using <b>CMake</b> and building "by
|
||||
hand") in the text file called
|
||||
<a href="NON-AUTOTOOLS-BUILD.txt"><b>NON-AUTOTOOLS-BUILD</b>.</a>
|
||||
You should consult this file as well as the
|
||||
<a href="README.txt"><b>README</b></a>
|
||||
file if you are building in a non-Unix-like environment.
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">PCRE BUILD-TIME OPTIONS</a><br>
|
||||
<P>
|
||||
The rest of this document describes the optional features of PCRE that can be
|
||||
selected when the library is compiled. It assumes use of the <b>configure</b>
|
||||
script, where the optional features are selected or deselected by providing
|
||||
options to <b>configure</b> before running the <b>make</b> command. However, the
|
||||
same options can be selected in both Unix-like and non-Unix-like environments
|
||||
using the GUI facility of <b>cmake-gui</b> if you are using <b>CMake</b> instead
|
||||
of <b>configure</b> to build PCRE.
|
||||
</P>
|
||||
<P>
|
||||
If you are not using Autotools or <b>CMake</b>, option selection can be done by
|
||||
editing the <b>config.h</b> file, or by passing parameter settings to the
|
||||
compiler, as described in
|
||||
<a href="NON-AUTOTOOLS-BUILD.txt"><b>NON-AUTOTOOLS-BUILD</b>.</a>
|
||||
</P>
|
||||
<P>
|
||||
The complete list of options for <b>configure</b> (which includes the standard
|
||||
ones such as the selection of the installation directory) can be obtained by
|
||||
running
|
||||
<pre>
|
||||
./configure --help
|
||||
</pre>
|
||||
The following sections include descriptions of options whose names begin with
|
||||
--enable or --disable. These settings specify changes to the defaults for the
|
||||
<b>configure</b> command. Because of the way that <b>configure</b> works,
|
||||
--enable and --disable always come in pairs, so the complementary option always
|
||||
exists as well, but as it specifies the default, it is not described.
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES</a><br>
|
||||
<P>
|
||||
By default, a library called <b>libpcre</b> is built, containing functions that
|
||||
take string arguments contained in vectors of bytes, either as single-byte
|
||||
characters, or interpreted as UTF-8 strings. You can also build a separate
|
||||
library, called <b>libpcre16</b>, in which strings are contained in vectors of
|
||||
16-bit data units and interpreted either as single-unit characters or UTF-16
|
||||
strings, by adding
|
||||
<pre>
|
||||
--enable-pcre16
|
||||
</pre>
|
||||
to the <b>configure</b> command. You can also build yet another separate
|
||||
library, called <b>libpcre32</b>, in which strings are contained in vectors of
|
||||
32-bit data units and interpreted either as single-unit characters or UTF-32
|
||||
strings, by adding
|
||||
<pre>
|
||||
--enable-pcre32
|
||||
</pre>
|
||||
to the <b>configure</b> command. If you do not want the 8-bit library, add
|
||||
<pre>
|
||||
--disable-pcre8
|
||||
</pre>
|
||||
as well. At least one of the three libraries must be built. Note that the C++
|
||||
and POSIX wrappers are for the 8-bit library only, and that <b>pcregrep</b> is
|
||||
an 8-bit program. None of these are built if you select only the 16-bit or
|
||||
32-bit libraries.
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">BUILDING SHARED AND STATIC LIBRARIES</a><br>
|
||||
<P>
|
||||
The Autotools PCRE building process uses <b>libtool</b> to build both shared and
|
||||
static libraries by default. You can suppress one of these by adding one of
|
||||
<pre>
|
||||
--disable-shared
|
||||
--disable-static
|
||||
</pre>
|
||||
to the <b>configure</b> command, as required.
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">C++ SUPPORT</a><br>
|
||||
<P>
|
||||
By default, if the 8-bit library is being built, the <b>configure</b> script
|
||||
will search for a C++ compiler and C++ header files. If it finds them, it
|
||||
automatically builds the C++ wrapper library (which supports only 8-bit
|
||||
strings). You can disable this by adding
|
||||
<pre>
|
||||
--disable-cpp
|
||||
</pre>
|
||||
to the <b>configure</b> command.
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">UTF-8, UTF-16 AND UTF-32 SUPPORT</a><br>
|
||||
<P>
|
||||
To build PCRE with support for UTF Unicode character strings, add
|
||||
<pre>
|
||||
--enable-utf
|
||||
</pre>
|
||||
to the <b>configure</b> command. This setting applies to all three libraries,
|
||||
adding support for UTF-8 to the 8-bit library, support for UTF-16 to the 16-bit
|
||||
library, and support for UTF-32 to the to the 32-bit library. There are no
|
||||
separate options for enabling UTF-8, UTF-16 and UTF-32 independently because
|
||||
that would allow ridiculous settings such as requesting UTF-16 support while
|
||||
building only the 8-bit library. It is not possible to build one library with
|
||||
UTF support and another without in the same configuration. (For backwards
|
||||
compatibility, --enable-utf8 is a synonym of --enable-utf.)
|
||||
</P>
|
||||
<P>
|
||||
Of itself, this setting does not make PCRE treat strings as UTF-8, UTF-16 or
|
||||
UTF-32. As well as compiling PCRE with this option, you also have have to set
|
||||
the PCRE_UTF8, PCRE_UTF16 or PCRE_UTF32 option (as appropriate) when you call
|
||||
one of the pattern compiling functions.
|
||||
</P>
|
||||
<P>
|
||||
If you set --enable-utf when compiling in an EBCDIC environment, PCRE expects
|
||||
its input to be either ASCII or UTF-8 (depending on the run-time option). It is
|
||||
not possible to support both EBCDIC and UTF-8 codes in the same version of the
|
||||
library. Consequently, --enable-utf and --enable-ebcdic are mutually
|
||||
exclusive.
|
||||
</P>
|
||||
<br><a name="SEC7" href="#TOC1">UNICODE CHARACTER PROPERTY SUPPORT</a><br>
|
||||
<P>
|
||||
UTF support allows the libraries to process character codepoints up to 0x10ffff
|
||||
in the strings that they handle. On its own, however, it does not provide any
|
||||
facilities for accessing the properties of such characters. If you want to be
|
||||
able to use the pattern escapes \P, \p, and \X, which refer to Unicode
|
||||
character properties, you must add
|
||||
<pre>
|
||||
--enable-unicode-properties
|
||||
</pre>
|
||||
to the <b>configure</b> command. This implies UTF support, even if you have
|
||||
not explicitly requested it.
|
||||
</P>
|
||||
<P>
|
||||
Including Unicode property support adds around 30K of tables to the PCRE
|
||||
library. Only the general category properties such as <i>Lu</i> and <i>Nd</i> are
|
||||
supported. Details are given in the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<br><a name="SEC8" href="#TOC1">JUST-IN-TIME COMPILER SUPPORT</a><br>
|
||||
<P>
|
||||
Just-in-time compiler support is included in the build by specifying
|
||||
<pre>
|
||||
--enable-jit
|
||||
</pre>
|
||||
This support is available only for certain hardware architectures. If this
|
||||
option is set for an unsupported architecture, a compile time error occurs.
|
||||
See the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
documentation for a discussion of JIT usage. When JIT support is enabled,
|
||||
pcregrep automatically makes use of it, unless you add
|
||||
<pre>
|
||||
--disable-pcregrep-jit
|
||||
</pre>
|
||||
to the "configure" command.
|
||||
</P>
|
||||
<br><a name="SEC9" href="#TOC1">CODE VALUE OF NEWLINE</a><br>
|
||||
<P>
|
||||
By default, PCRE interprets the linefeed (LF) character as indicating the end
|
||||
of a line. This is the normal newline character on Unix-like systems. You can
|
||||
compile PCRE to use carriage return (CR) instead, by adding
|
||||
<pre>
|
||||
--enable-newline-is-cr
|
||||
</pre>
|
||||
to the <b>configure</b> command. There is also a --enable-newline-is-lf option,
|
||||
which explicitly specifies linefeed as the newline character.
|
||||
<br>
|
||||
<br>
|
||||
Alternatively, you can specify that line endings are to be indicated by the two
|
||||
character sequence CRLF. If you want this, add
|
||||
<pre>
|
||||
--enable-newline-is-crlf
|
||||
</pre>
|
||||
to the <b>configure</b> command. There is a fourth option, specified by
|
||||
<pre>
|
||||
--enable-newline-is-anycrlf
|
||||
</pre>
|
||||
which causes PCRE to recognize any of the three sequences CR, LF, or CRLF as
|
||||
indicating a line ending. Finally, a fifth option, specified by
|
||||
<pre>
|
||||
--enable-newline-is-any
|
||||
</pre>
|
||||
causes PCRE to recognize any Unicode newline sequence.
|
||||
</P>
|
||||
<P>
|
||||
Whatever line ending convention is selected when PCRE is built can be
|
||||
overridden when the library functions are called. At build time it is
|
||||
conventional to use the standard for your operating system.
|
||||
</P>
|
||||
<br><a name="SEC10" href="#TOC1">WHAT \R MATCHES</a><br>
|
||||
<P>
|
||||
By default, the sequence \R in a pattern matches any Unicode newline sequence,
|
||||
whatever has been selected as the line ending sequence. If you specify
|
||||
<pre>
|
||||
--enable-bsr-anycrlf
|
||||
</pre>
|
||||
the default is changed so that \R matches only CR, LF, or CRLF. Whatever is
|
||||
selected when PCRE is built can be overridden when the library functions are
|
||||
called.
|
||||
</P>
|
||||
<br><a name="SEC11" href="#TOC1">POSIX MALLOC USAGE</a><br>
|
||||
<P>
|
||||
When the 8-bit library is called through the POSIX interface (see the
|
||||
<a href="pcreposix.html"><b>pcreposix</b></a>
|
||||
documentation), additional working storage is required for holding the pointers
|
||||
to capturing substrings, because PCRE requires three integers per substring,
|
||||
whereas the POSIX interface provides only two. If the number of expected
|
||||
substrings is small, the wrapper function uses space on the stack, because this
|
||||
is faster than using <b>malloc()</b> for each call. The default threshold above
|
||||
which the stack is no longer used is 10; it can be changed by adding a setting
|
||||
such as
|
||||
<pre>
|
||||
--with-posix-malloc-threshold=20
|
||||
</pre>
|
||||
to the <b>configure</b> command.
|
||||
</P>
|
||||
<br><a name="SEC12" href="#TOC1">HANDLING VERY LARGE PATTERNS</a><br>
|
||||
<P>
|
||||
Within a compiled pattern, offset values are used to point from one part to
|
||||
another (for example, from an opening parenthesis to an alternation
|
||||
metacharacter). By default, in the 8-bit and 16-bit libraries, two-byte values
|
||||
are used for these offsets, leading to a maximum size for a compiled pattern of
|
||||
around 64K. This is sufficient to handle all but the most gigantic patterns.
|
||||
Nevertheless, some people do want to process truly enormous patterns, so it is
|
||||
possible to compile PCRE to use three-byte or four-byte offsets by adding a
|
||||
setting such as
|
||||
<pre>
|
||||
--with-link-size=3
|
||||
</pre>
|
||||
to the <b>configure</b> command. The value given must be 2, 3, or 4. For the
|
||||
16-bit library, a value of 3 is rounded up to 4. In these libraries, using
|
||||
longer offsets slows down the operation of PCRE because it has to load
|
||||
additional data when handling them. For the 32-bit library the value is always
|
||||
4 and cannot be overridden; the value of --with-link-size is ignored.
|
||||
</P>
|
||||
<br><a name="SEC13" href="#TOC1">AVOIDING EXCESSIVE STACK USAGE</a><br>
|
||||
<P>
|
||||
When matching with the <b>pcre_exec()</b> function, PCRE implements backtracking
|
||||
by making recursive calls to an internal function called <b>match()</b>. In
|
||||
environments where the size of the stack is limited, this can severely limit
|
||||
PCRE's operation. (The Unix environment does not usually suffer from this
|
||||
problem, but it may sometimes be necessary to increase the maximum stack size.
|
||||
There is a discussion in the
|
||||
<a href="pcrestack.html"><b>pcrestack</b></a>
|
||||
documentation.) An alternative approach to recursion that uses memory from the
|
||||
heap to remember data, instead of using recursive function calls, has been
|
||||
implemented to work round the problem of limited stack size. If you want to
|
||||
build a version of PCRE that works this way, add
|
||||
<pre>
|
||||
--disable-stack-for-recursion
|
||||
</pre>
|
||||
to the <b>configure</b> command. With this configuration, PCRE will use the
|
||||
<b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> variables to call memory
|
||||
management functions. By default these point to <b>malloc()</b> and
|
||||
<b>free()</b>, but you can replace the pointers so that your own functions are
|
||||
used instead.
|
||||
</P>
|
||||
<P>
|
||||
Separate functions are provided rather than using <b>pcre_malloc</b> and
|
||||
<b>pcre_free</b> because the usage is very predictable: the block sizes
|
||||
requested are always the same, and the blocks are always freed in reverse
|
||||
order. A calling program might be able to implement optimized functions that
|
||||
perform better than <b>malloc()</b> and <b>free()</b>. PCRE runs noticeably more
|
||||
slowly when built in this way. This option affects only the <b>pcre_exec()</b>
|
||||
function; it is not relevant for <b>pcre_dfa_exec()</b>.
|
||||
</P>
|
||||
<br><a name="SEC14" href="#TOC1">LIMITING PCRE RESOURCE USAGE</a><br>
|
||||
<P>
|
||||
Internally, PCRE has a function called <b>match()</b>, which it calls repeatedly
|
||||
(sometimes recursively) when matching a pattern with the <b>pcre_exec()</b>
|
||||
function. By controlling the maximum number of times this function may be
|
||||
called during a single matching operation, a limit can be placed on the
|
||||
resources used by a single call to <b>pcre_exec()</b>. The limit can be changed
|
||||
at run time, as described in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
documentation. The default is 10 million, but this can be changed by adding a
|
||||
setting such as
|
||||
<pre>
|
||||
--with-match-limit=500000
|
||||
</pre>
|
||||
to the <b>configure</b> command. This setting has no effect on the
|
||||
<b>pcre_dfa_exec()</b> matching function.
|
||||
</P>
|
||||
<P>
|
||||
In some environments it is desirable to limit the depth of recursive calls of
|
||||
<b>match()</b> more strictly than the total number of calls, in order to
|
||||
restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion
|
||||
is specified) that is used. A second limit controls this; it defaults to the
|
||||
value that is set for --with-match-limit, which imposes no additional
|
||||
constraints. However, you can set a lower limit by adding, for example,
|
||||
<pre>
|
||||
--with-match-limit-recursion=10000
|
||||
</pre>
|
||||
to the <b>configure</b> command. This value can also be overridden at run time.
|
||||
</P>
|
||||
<br><a name="SEC15" href="#TOC1">CREATING CHARACTER TABLES AT BUILD TIME</a><br>
|
||||
<P>
|
||||
PCRE uses fixed tables for processing characters whose code values are less
|
||||
than 256. By default, PCRE is built with a set of tables that are distributed
|
||||
in the file <i>pcre_chartables.c.dist</i>. These tables are for ASCII codes
|
||||
only. If you add
|
||||
<pre>
|
||||
--enable-rebuild-chartables
|
||||
</pre>
|
||||
to the <b>configure</b> command, the distributed tables are no longer used.
|
||||
Instead, a program called <b>dftables</b> is compiled and run. This outputs the
|
||||
source for new set of tables, created in the default locale of your C run-time
|
||||
system. (This method of replacing the tables does not work if you are cross
|
||||
compiling, because <b>dftables</b> is run on the local host. If you need to
|
||||
create alternative tables when cross compiling, you will have to do so "by
|
||||
hand".)
|
||||
</P>
|
||||
<br><a name="SEC16" href="#TOC1">USING EBCDIC CODE</a><br>
|
||||
<P>
|
||||
PCRE assumes by default that it will run in an environment where the character
|
||||
code is ASCII (or Unicode, which is a superset of ASCII). This is the case for
|
||||
most computer operating systems. PCRE can, however, be compiled to run in an
|
||||
EBCDIC environment by adding
|
||||
<pre>
|
||||
--enable-ebcdic
|
||||
</pre>
|
||||
to the <b>configure</b> command. This setting implies
|
||||
--enable-rebuild-chartables. You should only use it if you know that you are in
|
||||
an EBCDIC environment (for example, an IBM mainframe operating system). The
|
||||
--enable-ebcdic option is incompatible with --enable-utf.
|
||||
</P>
|
||||
<P>
|
||||
The EBCDIC character that corresponds to an ASCII LF is assumed to have the
|
||||
value 0x15 by default. However, in some EBCDIC environments, 0x25 is used. In
|
||||
such an environment you should use
|
||||
<pre>
|
||||
--enable-ebcdic-nl25
|
||||
</pre>
|
||||
as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR has the
|
||||
same value as in ASCII, namely, 0x0d. Whichever of 0x15 and 0x25 is <i>not</i>
|
||||
chosen as LF is made to correspond to the Unicode NEL character (which, in
|
||||
Unicode, is 0x85).
|
||||
</P>
|
||||
<P>
|
||||
The options that select newline behaviour, such as --enable-newline-is-cr,
|
||||
and equivalent run-time options, refer to these character values in an EBCDIC
|
||||
environment.
|
||||
</P>
|
||||
<br><a name="SEC17" href="#TOC1">PCREGREP OPTIONS FOR COMPRESSED FILE SUPPORT</a><br>
|
||||
<P>
|
||||
By default, <b>pcregrep</b> reads all files as plain text. You can build it so
|
||||
that it recognizes files whose names end in <b>.gz</b> or <b>.bz2</b>, and reads
|
||||
them with <b>libz</b> or <b>libbz2</b>, respectively, by adding one or both of
|
||||
<pre>
|
||||
--enable-pcregrep-libz
|
||||
--enable-pcregrep-libbz2
|
||||
</pre>
|
||||
to the <b>configure</b> command. These options naturally require that the
|
||||
relevant libraries are installed on your system. Configuration will fail if
|
||||
they are not.
|
||||
</P>
|
||||
<br><a name="SEC18" href="#TOC1">PCREGREP BUFFER SIZE</a><br>
|
||||
<P>
|
||||
<b>pcregrep</b> uses an internal buffer to hold a "window" on the file it is
|
||||
scanning, in order to be able to output "before" and "after" lines when it
|
||||
finds a match. The size of the buffer is controlled by a parameter whose
|
||||
default value is 20K. The buffer itself is three times this size, but because
|
||||
of the way it is used for holding "before" lines, the longest line that is
|
||||
guaranteed to be processable is the parameter size. You can change the default
|
||||
parameter value by adding, for example,
|
||||
<pre>
|
||||
--with-pcregrep-bufsize=50K
|
||||
</pre>
|
||||
to the <b>configure</b> command. The caller of \fPpcregrep\fP can, however,
|
||||
override this value by specifying a run-time option.
|
||||
</P>
|
||||
<br><a name="SEC19" href="#TOC1">PCRETEST OPTION FOR LIBREADLINE SUPPORT</a><br>
|
||||
<P>
|
||||
If you add
|
||||
<pre>
|
||||
--enable-pcretest-libreadline
|
||||
</pre>
|
||||
to the <b>configure</b> command, <b>pcretest</b> is linked with the
|
||||
<b>libreadline</b> library, and when its input is from a terminal, it reads it
|
||||
using the <b>readline()</b> function. This provides line-editing and history
|
||||
facilities. Note that <b>libreadline</b> is GPL-licensed, so if you distribute a
|
||||
binary of <b>pcretest</b> linked in this way, there may be licensing issues.
|
||||
</P>
|
||||
<P>
|
||||
Setting this option causes the <b>-lreadline</b> option to be added to the
|
||||
<b>pcretest</b> build. In many operating environments with a sytem-installed
|
||||
<b>libreadline</b> this is sufficient. However, in some environments (e.g.
|
||||
if an unmodified distribution version of readline is in use), some extra
|
||||
configuration may be necessary. The INSTALL file for <b>libreadline</b> says
|
||||
this:
|
||||
<pre>
|
||||
"Readline uses the termcap functions, but does not link with the
|
||||
termcap or curses library itself, allowing applications which link
|
||||
with readline the to choose an appropriate library."
|
||||
</pre>
|
||||
If your environment has not been set up so that an appropriate library is
|
||||
automatically included, you may need to add something like
|
||||
<pre>
|
||||
LIBS="-ncurses"
|
||||
</pre>
|
||||
immediately before the <b>configure</b> command.
|
||||
</P>
|
||||
<br><a name="SEC20" href="#TOC1">DEBUGGING WITH VALGRIND SUPPORT</a><br>
|
||||
<P>
|
||||
By adding the
|
||||
<pre>
|
||||
--enable-valgrind
|
||||
</pre>
|
||||
option to to the <b>configure</b> command, PCRE will use valgrind annotations
|
||||
to mark certain memory regions as unaddressable. This allows it to detect
|
||||
invalid memory accesses, and is mostly useful for debugging PCRE itself.
|
||||
</P>
|
||||
<br><a name="SEC21" href="#TOC1">CODE COVERAGE REPORTING</a><br>
|
||||
<P>
|
||||
If your C compiler is gcc, you can build a version of PCRE that can generate a
|
||||
code coverage report for its test suite. To enable this, you must install
|
||||
<b>lcov</b> version 1.6 or above. Then specify
|
||||
<pre>
|
||||
--enable-coverage
|
||||
</pre>
|
||||
to the <b>configure</b> command and build PCRE in the usual way.
|
||||
</P>
|
||||
<P>
|
||||
Note that using <b>ccache</b> (a caching C compiler) is incompatible with code
|
||||
coverage reporting. If you have configured <b>ccache</b> to run automatically
|
||||
on your system, you must set the environment variable
|
||||
<pre>
|
||||
CCACHE_DISABLE=1
|
||||
</pre>
|
||||
before running <b>make</b> to build PCRE, so that <b>ccache</b> is not used.
|
||||
</P>
|
||||
<P>
|
||||
When --enable-coverage is used, the following addition targets are added to the
|
||||
<i>Makefile</i>:
|
||||
<pre>
|
||||
make coverage
|
||||
</pre>
|
||||
This creates a fresh coverage report for the PCRE test suite. It is equivalent
|
||||
to running "make coverage-reset", "make coverage-baseline", "make check", and
|
||||
then "make coverage-report".
|
||||
<pre>
|
||||
make coverage-reset
|
||||
</pre>
|
||||
This zeroes the coverage counters, but does nothing else.
|
||||
<pre>
|
||||
make coverage-baseline
|
||||
</pre>
|
||||
This captures baseline coverage information.
|
||||
<pre>
|
||||
make coverage-report
|
||||
</pre>
|
||||
This creates the coverage report.
|
||||
<pre>
|
||||
make coverage-clean-report
|
||||
</pre>
|
||||
This removes the generated coverage report without cleaning the coverage data
|
||||
itself.
|
||||
<pre>
|
||||
make coverage-clean-data
|
||||
</pre>
|
||||
This removes the captured coverage data without removing the coverage files
|
||||
created at compile time (*.gcno).
|
||||
<pre>
|
||||
make coverage-clean
|
||||
</pre>
|
||||
This cleans all coverage data including the generated coverage report. For more
|
||||
information about code coverage, see the <b>gcov</b> and <b>lcov</b>
|
||||
documentation.
|
||||
</P>
|
||||
<br><a name="SEC22" href="#TOC1">SEE ALSO</a><br>
|
||||
<P>
|
||||
<b>pcreapi</b>(3), <b>pcre16</b>, <b>pcre32</b>, <b>pcre_config</b>(3).
|
||||
</P>
|
||||
<br><a name="SEC23" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC24" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 12 May 2013
|
||||
<br>
|
||||
Copyright © 1997-2013 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,286 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcrecallout specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcrecallout man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
|
||||
<li><a name="TOC2" href="#SEC2">DESCRIPTION</a>
|
||||
<li><a name="TOC3" href="#SEC3">MISSING CALLOUTS</a>
|
||||
<li><a name="TOC4" href="#SEC4">THE CALLOUT INTERFACE</a>
|
||||
<li><a name="TOC5" href="#SEC5">RETURN VALUES</a>
|
||||
<li><a name="TOC6" href="#SEC6">AUTHOR</a>
|
||||
<li><a name="TOC7" href="#SEC7">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
|
||||
<P>
|
||||
<b>#include <pcre.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int (*pcre_callout)(pcre_callout_block *);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int (*pcre16_callout)(pcre16_callout_block *);</b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int (*pcre32_callout)(pcre32_callout_block *);</b>
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">DESCRIPTION</a><br>
|
||||
<P>
|
||||
PCRE provides a feature called "callout", which is a means of temporarily
|
||||
passing control to the caller of PCRE in the middle of pattern matching. The
|
||||
caller of PCRE provides an external function by putting its entry point in the
|
||||
global variable <i>pcre_callout</i> (<i>pcre16_callout</i> for the 16-bit
|
||||
library, <i>pcre32_callout</i> for the 32-bit library). By default, this
|
||||
variable contains NULL, which disables all calling out.
|
||||
</P>
|
||||
<P>
|
||||
Within a regular expression, (?C) indicates the points at which the external
|
||||
function is to be called. Different callout points can be identified by putting
|
||||
a number less than 256 after the letter C. The default value is zero.
|
||||
For example, this pattern has two callout points:
|
||||
<pre>
|
||||
(?C1)abc(?C2)def
|
||||
</pre>
|
||||
If the PCRE_AUTO_CALLOUT option bit is set when a pattern is compiled, PCRE
|
||||
automatically inserts callouts, all with number 255, before each item in the
|
||||
pattern. For example, if PCRE_AUTO_CALLOUT is used with the pattern
|
||||
<pre>
|
||||
A(\d{2}|--)
|
||||
</pre>
|
||||
it is processed as if it were
|
||||
<br>
|
||||
<br>
|
||||
(?C255)A(?C255)((?C255)\d{2}(?C255)|(?C255)-(?C255)-(?C255))(?C255)
|
||||
<br>
|
||||
<br>
|
||||
Notice that there is a callout before and after each parenthesis and
|
||||
alternation bar. If the pattern contains a conditional group whose condition is
|
||||
an assertion, an automatic callout is inserted immediately before the
|
||||
condition. Such a callout may also be inserted explicitly, for example:
|
||||
<pre>
|
||||
(?(?C9)(?=a)ab|de)
|
||||
</pre>
|
||||
This applies only to assertion conditions (because they are themselves
|
||||
independent groups).
|
||||
</P>
|
||||
<P>
|
||||
Automatic callouts can be used for tracking the progress of pattern matching.
|
||||
The
|
||||
<a href="pcretest.html"><b>pcretest</b></a>
|
||||
program has a pattern qualifier (/C) that sets automatic callouts; when it is
|
||||
used, the output indicates how the pattern is being matched. This is useful
|
||||
information when you are trying to optimize the performance of a particular
|
||||
pattern.
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">MISSING CALLOUTS</a><br>
|
||||
<P>
|
||||
You should be aware that, because of optimizations in the way PCRE compiles and
|
||||
matches patterns, callouts sometimes do not happen exactly as you might expect.
|
||||
</P>
|
||||
<P>
|
||||
At compile time, PCRE "auto-possessifies" repeated items when it knows that
|
||||
what follows cannot be part of the repeat. For example, a+[bc] is compiled as
|
||||
if it were a++[bc]. The <b>pcretest</b> output when this pattern is anchored and
|
||||
then applied with automatic callouts to the string "aaaa" is:
|
||||
<pre>
|
||||
--->aaaa
|
||||
+0 ^ ^
|
||||
+1 ^ a+
|
||||
+3 ^ ^ [bc]
|
||||
No match
|
||||
</pre>
|
||||
This indicates that when matching [bc] fails, there is no backtracking into a+
|
||||
and therefore the callouts that would be taken for the backtracks do not occur.
|
||||
You can disable the auto-possessify feature by passing PCRE_NO_AUTO_POSSESS
|
||||
to <b>pcre_compile()</b>, or starting the pattern with (*NO_AUTO_POSSESS). If
|
||||
this is done in <b>pcretest</b> (using the /O qualifier), the output changes to
|
||||
this:
|
||||
<pre>
|
||||
--->aaaa
|
||||
+0 ^ ^
|
||||
+1 ^ a+
|
||||
+3 ^ ^ [bc]
|
||||
+3 ^ ^ [bc]
|
||||
+3 ^ ^ [bc]
|
||||
+3 ^^ [bc]
|
||||
No match
|
||||
</pre>
|
||||
This time, when matching [bc] fails, the matcher backtracks into a+ and tries
|
||||
again, repeatedly, until a+ itself fails.
|
||||
</P>
|
||||
<P>
|
||||
Other optimizations that provide fast "no match" results also affect callouts.
|
||||
For example, if the pattern is
|
||||
<pre>
|
||||
ab(?C4)cd
|
||||
</pre>
|
||||
PCRE knows that any matching string must contain the letter "d". If the subject
|
||||
string is "abyz", the lack of "d" means that matching doesn't ever start, and
|
||||
the callout is never reached. However, with "abyd", though the result is still
|
||||
no match, the callout is obeyed.
|
||||
</P>
|
||||
<P>
|
||||
If the pattern is studied, PCRE knows the minimum length of a matching string,
|
||||
and will immediately give a "no match" return without actually running a match
|
||||
if the subject is not long enough, or, for unanchored patterns, if it has
|
||||
been scanned far enough.
|
||||
</P>
|
||||
<P>
|
||||
You can disable these optimizations by passing the PCRE_NO_START_OPTIMIZE
|
||||
option to the matching function, or by starting the pattern with
|
||||
(*NO_START_OPT). This slows down the matching process, but does ensure that
|
||||
callouts such as the example above are obeyed.
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">THE CALLOUT INTERFACE</a><br>
|
||||
<P>
|
||||
During matching, when PCRE reaches a callout point, the external function
|
||||
defined by <i>pcre_callout</i> or <i>pcre[16|32]_callout</i> is called (if it is
|
||||
set). This applies to both normal and DFA matching. The only argument to the
|
||||
callout function is a pointer to a <b>pcre_callout</b> or
|
||||
<b>pcre[16|32]_callout</b> block. These structures contains the following
|
||||
fields:
|
||||
<pre>
|
||||
int <i>version</i>;
|
||||
int <i>callout_number</i>;
|
||||
int *<i>offset_vector</i>;
|
||||
const char *<i>subject</i>; (8-bit version)
|
||||
PCRE_SPTR16 <i>subject</i>; (16-bit version)
|
||||
PCRE_SPTR32 <i>subject</i>; (32-bit version)
|
||||
int <i>subject_length</i>;
|
||||
int <i>start_match</i>;
|
||||
int <i>current_position</i>;
|
||||
int <i>capture_top</i>;
|
||||
int <i>capture_last</i>;
|
||||
void *<i>callout_data</i>;
|
||||
int <i>pattern_position</i>;
|
||||
int <i>next_item_length</i>;
|
||||
const unsigned char *<i>mark</i>; (8-bit version)
|
||||
const PCRE_UCHAR16 *<i>mark</i>; (16-bit version)
|
||||
const PCRE_UCHAR32 *<i>mark</i>; (32-bit version)
|
||||
</pre>
|
||||
The <i>version</i> field is an integer containing the version number of the
|
||||
block format. The initial version was 0; the current version is 2. The version
|
||||
number will change again in future if additional fields are added, but the
|
||||
intention is never to remove any of the existing fields.
|
||||
</P>
|
||||
<P>
|
||||
The <i>callout_number</i> field contains the number of the callout, as compiled
|
||||
into the pattern (that is, the number after ?C for manual callouts, and 255 for
|
||||
automatically generated callouts).
|
||||
</P>
|
||||
<P>
|
||||
The <i>offset_vector</i> field is a pointer to the vector of offsets that was
|
||||
passed by the caller to the matching function. When <b>pcre_exec()</b> or
|
||||
<b>pcre[16|32]_exec()</b> is used, the contents can be inspected, in order to
|
||||
extract substrings that have been matched so far, in the same way as for
|
||||
extracting substrings after a match has completed. For the DFA matching
|
||||
functions, this field is not useful.
|
||||
</P>
|
||||
<P>
|
||||
The <i>subject</i> and <i>subject_length</i> fields contain copies of the values
|
||||
that were passed to the matching function.
|
||||
</P>
|
||||
<P>
|
||||
The <i>start_match</i> field normally contains the offset within the subject at
|
||||
which the current match attempt started. However, if the escape sequence \K
|
||||
has been encountered, this value is changed to reflect the modified starting
|
||||
point. If the pattern is not anchored, the callout function may be called
|
||||
several times from the same point in the pattern for different starting points
|
||||
in the subject.
|
||||
</P>
|
||||
<P>
|
||||
The <i>current_position</i> field contains the offset within the subject of the
|
||||
current match pointer.
|
||||
</P>
|
||||
<P>
|
||||
When the <b>pcre_exec()</b> or <b>pcre[16|32]_exec()</b> is used, the
|
||||
<i>capture_top</i> field contains one more than the number of the highest
|
||||
numbered captured substring so far. If no substrings have been captured, the
|
||||
value of <i>capture_top</i> is one. This is always the case when the DFA
|
||||
functions are used, because they do not support captured substrings.
|
||||
</P>
|
||||
<P>
|
||||
The <i>capture_last</i> field contains the number of the most recently captured
|
||||
substring. However, when a recursion exits, the value reverts to what it was
|
||||
outside the recursion, as do the values of all captured substrings. If no
|
||||
substrings have been captured, the value of <i>capture_last</i> is -1. This is
|
||||
always the case for the DFA matching functions.
|
||||
</P>
|
||||
<P>
|
||||
The <i>callout_data</i> field contains a value that is passed to a matching
|
||||
function specifically so that it can be passed back in callouts. It is passed
|
||||
in the <i>callout_data</i> field of a <b>pcre_extra</b> or <b>pcre[16|32]_extra</b>
|
||||
data structure. If no such data was passed, the value of <i>callout_data</i> in
|
||||
a callout block is NULL. There is a description of the <b>pcre_extra</b>
|
||||
structure in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
The <i>pattern_position</i> field is present from version 1 of the callout
|
||||
structure. It contains the offset to the next item to be matched in the pattern
|
||||
string.
|
||||
</P>
|
||||
<P>
|
||||
The <i>next_item_length</i> field is present from version 1 of the callout
|
||||
structure. It contains the length of the next item to be matched in the pattern
|
||||
string. When the callout immediately precedes an alternation bar, a closing
|
||||
parenthesis, or the end of the pattern, the length is zero. When the callout
|
||||
precedes an opening parenthesis, the length is that of the entire subpattern.
|
||||
</P>
|
||||
<P>
|
||||
The <i>pattern_position</i> and <i>next_item_length</i> fields are intended to
|
||||
help in distinguishing between different automatic callouts, which all have the
|
||||
same callout number. However, they are set for all callouts.
|
||||
</P>
|
||||
<P>
|
||||
The <i>mark</i> field is present from version 2 of the callout structure. In
|
||||
callouts from <b>pcre_exec()</b> or <b>pcre[16|32]_exec()</b> it contains a
|
||||
pointer to the zero-terminated name of the most recently passed (*MARK),
|
||||
(*PRUNE), or (*THEN) item in the match, or NULL if no such items have been
|
||||
passed. Instances of (*PRUNE) or (*THEN) without a name do not obliterate a
|
||||
previous (*MARK). In callouts from the DFA matching functions this field always
|
||||
contains NULL.
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">RETURN VALUES</a><br>
|
||||
<P>
|
||||
The external callout function returns an integer to PCRE. If the value is zero,
|
||||
matching proceeds as normal. If the value is greater than zero, matching fails
|
||||
at the current point, but the testing of other matching possibilities goes
|
||||
ahead, just as if a lookahead assertion had failed. If the value is less than
|
||||
zero, the match is abandoned, the matching function returns the negative value.
|
||||
</P>
|
||||
<P>
|
||||
Negative values should normally be chosen from the set of PCRE_ERROR_xxx
|
||||
values. In particular, PCRE_ERROR_NOMATCH forces a standard "no match" failure.
|
||||
The error number PCRE_ERROR_CALLOUT is reserved for use by callout functions;
|
||||
it will never be used by PCRE itself.
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC7" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 12 November 2013
|
||||
<br>
|
||||
Copyright © 1997-2013 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,235 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcrecompat specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcrecompat man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
DIFFERENCES BETWEEN PCRE AND PERL
|
||||
</b><br>
|
||||
<P>
|
||||
This document describes the differences in the ways that PCRE and Perl handle
|
||||
regular expressions. The differences described here are with respect to Perl
|
||||
versions 5.10 and above.
|
||||
</P>
|
||||
<P>
|
||||
1. PCRE has only a subset of Perl's Unicode support. Details of what it does
|
||||
have are given in the
|
||||
<a href="pcreunicode.html"><b>pcreunicode</b></a>
|
||||
page.
|
||||
</P>
|
||||
<P>
|
||||
2. PCRE allows repeat quantifiers only on parenthesized assertions, but they do
|
||||
not mean what you might think. For example, (?!a){3} does not assert that the
|
||||
next three characters are not "a". It just asserts that the next character is
|
||||
not "a" three times (in principle: PCRE optimizes this to run the assertion
|
||||
just once). Perl allows repeat quantifiers on other assertions such as \b, but
|
||||
these do not seem to have any use.
|
||||
</P>
|
||||
<P>
|
||||
3. Capturing subpatterns that occur inside negative lookahead assertions are
|
||||
counted, but their entries in the offsets vector are never set. Perl sometimes
|
||||
(but not always) sets its numerical variables from inside negative assertions.
|
||||
</P>
|
||||
<P>
|
||||
4. Though binary zero characters are supported in the subject string, they are
|
||||
not allowed in a pattern string because it is passed as a normal C string,
|
||||
terminated by zero. The escape sequence \0 can be used in the pattern to
|
||||
represent a binary zero.
|
||||
</P>
|
||||
<P>
|
||||
5. The following Perl escape sequences are not supported: \l, \u, \L,
|
||||
\U, and \N when followed by a character name or Unicode value. (\N on its
|
||||
own, matching a non-newline character, is supported.) In fact these are
|
||||
implemented by Perl's general string-handling and are not part of its pattern
|
||||
matching engine. If any of these are encountered by PCRE, an error is
|
||||
generated by default. However, if the PCRE_JAVASCRIPT_COMPAT option is set,
|
||||
\U and \u are interpreted as JavaScript interprets them.
|
||||
</P>
|
||||
<P>
|
||||
6. The Perl escape sequences \p, \P, and \X are supported only if PCRE is
|
||||
built with Unicode character property support. The properties that can be
|
||||
tested with \p and \P are limited to the general category properties such as
|
||||
Lu and Nd, script names such as Greek or Han, and the derived properties Any
|
||||
and L&. PCRE does support the Cs (surrogate) property, which Perl does not; the
|
||||
Perl documentation says "Because Perl hides the need for the user to understand
|
||||
the internal representation of Unicode characters, there is no need to
|
||||
implement the somewhat messy concept of surrogates."
|
||||
</P>
|
||||
<P>
|
||||
7. PCRE does support the \Q...\E escape for quoting substrings. Characters in
|
||||
between are treated as literals. This is slightly different from Perl in that $
|
||||
and @ are also handled as literals inside the quotes. In Perl, they cause
|
||||
variable interpolation (but of course PCRE does not have variables). Note the
|
||||
following examples:
|
||||
<pre>
|
||||
Pattern PCRE matches Perl matches
|
||||
|
||||
\Qabc$xyz\E abc$xyz abc followed by the contents of $xyz
|
||||
\Qabc\$xyz\E abc\$xyz abc\$xyz
|
||||
\Qabc\E\$\Qxyz\E abc$xyz abc$xyz
|
||||
</pre>
|
||||
The \Q...\E sequence is recognized both inside and outside character classes.
|
||||
</P>
|
||||
<P>
|
||||
8. Fairly obviously, PCRE does not support the (?{code}) and (??{code})
|
||||
constructions. However, there is support for recursive patterns. This is not
|
||||
available in Perl 5.8, but it is in Perl 5.10. Also, the PCRE "callout"
|
||||
feature allows an external function to be called during pattern matching. See
|
||||
the
|
||||
<a href="pcrecallout.html"><b>pcrecallout</b></a>
|
||||
documentation for details.
|
||||
</P>
|
||||
<P>
|
||||
9. Subpatterns that are called as subroutines (whether or not recursively) are
|
||||
always treated as atomic groups in PCRE. This is like Python, but unlike Perl.
|
||||
Captured values that are set outside a subroutine call can be reference from
|
||||
inside in PCRE, but not in Perl. There is a discussion that explains these
|
||||
differences in more detail in the
|
||||
<a href="pcrepattern.html#recursiondifference">section on recursion differences from Perl</a>
|
||||
in the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
page.
|
||||
</P>
|
||||
<P>
|
||||
10. If any of the backtracking control verbs are used in a subpattern that is
|
||||
called as a subroutine (whether or not recursively), their effect is confined
|
||||
to that subpattern; it does not extend to the surrounding pattern. This is not
|
||||
always the case in Perl. In particular, if (*THEN) is present in a group that
|
||||
is called as a subroutine, its action is limited to that group, even if the
|
||||
group does not contain any | characters. Note that such subpatterns are
|
||||
processed as anchored at the point where they are tested.
|
||||
</P>
|
||||
<P>
|
||||
11. If a pattern contains more than one backtracking control verb, the first
|
||||
one that is backtracked onto acts. For example, in the pattern
|
||||
A(*COMMIT)B(*PRUNE)C a failure in B triggers (*COMMIT), but a failure in C
|
||||
triggers (*PRUNE). Perl's behaviour is more complex; in many cases it is the
|
||||
same as PCRE, but there are examples where it differs.
|
||||
</P>
|
||||
<P>
|
||||
12. Most backtracking verbs in assertions have their normal actions. They are
|
||||
not confined to the assertion.
|
||||
</P>
|
||||
<P>
|
||||
13. There are some differences that are concerned with the settings of captured
|
||||
strings when part of a pattern is repeated. For example, matching "aba" against
|
||||
the pattern /^(a(b)?)+$/ in Perl leaves $2 unset, but in PCRE it is set to "b".
|
||||
</P>
|
||||
<P>
|
||||
14. PCRE's handling of duplicate subpattern numbers and duplicate subpattern
|
||||
names is not as general as Perl's. This is a consequence of the fact the PCRE
|
||||
works internally just with numbers, using an external table to translate
|
||||
between numbers and names. In particular, a pattern such as (?|(?<a>A)|(?<b>B),
|
||||
where the two capturing parentheses have the same number but different names,
|
||||
is not supported, and causes an error at compile time. If it were allowed, it
|
||||
would not be possible to distinguish which parentheses matched, because both
|
||||
names map to capturing subpattern number 1. To avoid this confusing situation,
|
||||
an error is given at compile time.
|
||||
</P>
|
||||
<P>
|
||||
15. Perl recognizes comments in some places that PCRE does not, for example,
|
||||
between the ( and ? at the start of a subpattern. If the /x modifier is set,
|
||||
Perl allows white space between ( and ? (though current Perls warn that this is
|
||||
deprecated) but PCRE never does, even if the PCRE_EXTENDED option is set.
|
||||
</P>
|
||||
<P>
|
||||
16. Perl, when in warning mode, gives warnings for character classes such as
|
||||
[A-\d] or [a-[:digit:]]. It then treats the hyphens as literals. PCRE has no
|
||||
warning features, so it gives an error in these cases because they are almost
|
||||
certainly user mistakes.
|
||||
</P>
|
||||
<P>
|
||||
17. In PCRE, the upper/lower case character properties Lu and Ll are not
|
||||
affected when case-independent matching is specified. For example, \p{Lu}
|
||||
always matches an upper case letter. I think Perl has changed in this respect;
|
||||
in the release at the time of writing (5.16), \p{Lu} and \p{Ll} match all
|
||||
letters, regardless of case, when case independence is specified.
|
||||
</P>
|
||||
<P>
|
||||
18. PCRE provides some extensions to the Perl regular expression facilities.
|
||||
Perl 5.10 includes new features that are not in earlier versions of Perl, some
|
||||
of which (such as named parentheses) have been in PCRE for some time. This list
|
||||
is with respect to Perl 5.10:
|
||||
<br>
|
||||
<br>
|
||||
(a) Although lookbehind assertions in PCRE must match fixed length strings,
|
||||
each alternative branch of a lookbehind assertion can match a different length
|
||||
of string. Perl requires them all to have the same length.
|
||||
<br>
|
||||
<br>
|
||||
(b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the $
|
||||
meta-character matches only at the very end of the string.
|
||||
<br>
|
||||
<br>
|
||||
(c) If PCRE_EXTRA is set, a backslash followed by a letter with no special
|
||||
meaning is faulted. Otherwise, like Perl, the backslash is quietly ignored.
|
||||
(Perl can be made to issue a warning.)
|
||||
<br>
|
||||
<br>
|
||||
(d) If PCRE_UNGREEDY is set, the greediness of the repetition quantifiers is
|
||||
inverted, that is, by default they are not greedy, but if followed by a
|
||||
question mark they are.
|
||||
<br>
|
||||
<br>
|
||||
(e) PCRE_ANCHORED can be used at matching time to force a pattern to be tried
|
||||
only at the first matching position in the subject string.
|
||||
<br>
|
||||
<br>
|
||||
(f) The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART, and
|
||||
PCRE_NO_AUTO_CAPTURE options for <b>pcre_exec()</b> have no Perl equivalents.
|
||||
<br>
|
||||
<br>
|
||||
(g) The \R escape sequence can be restricted to match only CR, LF, or CRLF
|
||||
by the PCRE_BSR_ANYCRLF option.
|
||||
<br>
|
||||
<br>
|
||||
(h) The callout facility is PCRE-specific.
|
||||
<br>
|
||||
<br>
|
||||
(i) The partial matching facility is PCRE-specific.
|
||||
<br>
|
||||
<br>
|
||||
(j) Patterns compiled by PCRE can be saved and re-used at a later time, even on
|
||||
different hosts that have the other endianness. However, this does not apply to
|
||||
optimized data created by the just-in-time compiler.
|
||||
<br>
|
||||
<br>
|
||||
(k) The alternative matching functions (<b>pcre_dfa_exec()</b>,
|
||||
<b>pcre16_dfa_exec()</b> and <b>pcre32_dfa_exec()</b>,) match in a different way
|
||||
and are not Perl-compatible.
|
||||
<br>
|
||||
<br>
|
||||
(l) PCRE recognizes some special sequences such as (*CR) at the start of
|
||||
a pattern that set overall options that cannot be changed within the pattern.
|
||||
</P>
|
||||
<br><b>
|
||||
AUTHOR
|
||||
</b><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><b>
|
||||
REVISION
|
||||
</b><br>
|
||||
<P>
|
||||
Last updated: 10 November 2013
|
||||
<br>
|
||||
Copyright © 1997-2013 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,368 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcrecpp specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcrecpp man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">SYNOPSIS OF C++ WRAPPER</a>
|
||||
<li><a name="TOC2" href="#SEC2">DESCRIPTION</a>
|
||||
<li><a name="TOC3" href="#SEC3">MATCHING INTERFACE</a>
|
||||
<li><a name="TOC4" href="#SEC4">QUOTING METACHARACTERS</a>
|
||||
<li><a name="TOC5" href="#SEC5">PARTIAL MATCHES</a>
|
||||
<li><a name="TOC6" href="#SEC6">UTF-8 AND THE MATCHING INTERFACE</a>
|
||||
<li><a name="TOC7" href="#SEC7">PASSING MODIFIERS TO THE REGULAR EXPRESSION ENGINE</a>
|
||||
<li><a name="TOC8" href="#SEC8">SCANNING TEXT INCREMENTALLY</a>
|
||||
<li><a name="TOC9" href="#SEC9">PARSING HEX/OCTAL/C-RADIX NUMBERS</a>
|
||||
<li><a name="TOC10" href="#SEC10">REPLACING PARTS OF STRINGS</a>
|
||||
<li><a name="TOC11" href="#SEC11">AUTHOR</a>
|
||||
<li><a name="TOC12" href="#SEC12">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">SYNOPSIS OF C++ WRAPPER</a><br>
|
||||
<P>
|
||||
<b>#include <pcrecpp.h></b>
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">DESCRIPTION</a><br>
|
||||
<P>
|
||||
The C++ wrapper for PCRE was provided by Google Inc. Some additional
|
||||
functionality was added by Giuseppe Maxia. This brief man page was constructed
|
||||
from the notes in the <i>pcrecpp.h</i> file, which should be consulted for
|
||||
further details. Note that the C++ wrapper supports only the original 8-bit
|
||||
PCRE library. There is no 16-bit or 32-bit support at present.
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">MATCHING INTERFACE</a><br>
|
||||
<P>
|
||||
The "FullMatch" operation checks that supplied text matches a supplied pattern
|
||||
exactly. If pointer arguments are supplied, it copies matched sub-strings that
|
||||
match sub-patterns into them.
|
||||
<pre>
|
||||
Example: successful match
|
||||
pcrecpp::RE re("h.*o");
|
||||
re.FullMatch("hello");
|
||||
|
||||
Example: unsuccessful match (requires full match):
|
||||
pcrecpp::RE re("e");
|
||||
!re.FullMatch("hello");
|
||||
|
||||
Example: creating a temporary RE object:
|
||||
pcrecpp::RE("h.*o").FullMatch("hello");
|
||||
</pre>
|
||||
You can pass in a "const char*" or a "string" for "text". The examples below
|
||||
tend to use a const char*. You can, as in the different examples above, store
|
||||
the RE object explicitly in a variable or use a temporary RE object. The
|
||||
examples below use one mode or the other arbitrarily. Either could correctly be
|
||||
used for any of these examples.
|
||||
</P>
|
||||
<P>
|
||||
You must supply extra pointer arguments to extract matched subpieces.
|
||||
<pre>
|
||||
Example: extracts "ruby" into "s" and 1234 into "i"
|
||||
int i;
|
||||
string s;
|
||||
pcrecpp::RE re("(\\w+):(\\d+)");
|
||||
re.FullMatch("ruby:1234", &s, &i);
|
||||
|
||||
Example: does not try to extract any extra sub-patterns
|
||||
re.FullMatch("ruby:1234", &s);
|
||||
|
||||
Example: does not try to extract into NULL
|
||||
re.FullMatch("ruby:1234", NULL, &i);
|
||||
|
||||
Example: integer overflow causes failure
|
||||
!re.FullMatch("ruby:1234567891234", NULL, &i);
|
||||
|
||||
Example: fails because there aren't enough sub-patterns:
|
||||
!pcrecpp::RE("\\w+:\\d+").FullMatch("ruby:1234", &s);
|
||||
|
||||
Example: fails because string cannot be stored in integer
|
||||
!pcrecpp::RE("(.*)").FullMatch("ruby", &i);
|
||||
</pre>
|
||||
The provided pointer arguments can be pointers to any scalar numeric
|
||||
type, or one of:
|
||||
<pre>
|
||||
string (matched piece is copied to string)
|
||||
StringPiece (StringPiece is mutated to point to matched piece)
|
||||
T (where "bool T::ParseFrom(const char*, int)" exists)
|
||||
NULL (the corresponding matched sub-pattern is not copied)
|
||||
</pre>
|
||||
The function returns true iff all of the following conditions are satisfied:
|
||||
<pre>
|
||||
a. "text" matches "pattern" exactly;
|
||||
|
||||
b. The number of matched sub-patterns is >= number of supplied
|
||||
pointers;
|
||||
|
||||
c. The "i"th argument has a suitable type for holding the
|
||||
string captured as the "i"th sub-pattern. If you pass in
|
||||
void * NULL for the "i"th argument, or a non-void * NULL
|
||||
of the correct type, or pass fewer arguments than the
|
||||
number of sub-patterns, "i"th captured sub-pattern is
|
||||
ignored.
|
||||
</pre>
|
||||
CAVEAT: An optional sub-pattern that does not exist in the matched
|
||||
string is assigned the empty string. Therefore, the following will
|
||||
return false (because the empty string is not a valid number):
|
||||
<pre>
|
||||
int number;
|
||||
pcrecpp::RE::FullMatch("abc", "[a-z]+(\\d+)?", &number);
|
||||
</pre>
|
||||
The matching interface supports at most 16 arguments per call.
|
||||
If you need more, consider using the more general interface
|
||||
<b>pcrecpp::RE::DoMatch</b>. See <b>pcrecpp.h</b> for the signature for
|
||||
<b>DoMatch</b>.
|
||||
</P>
|
||||
<P>
|
||||
NOTE: Do not use <b>no_arg</b>, which is used internally to mark the end of a
|
||||
list of optional arguments, as a placeholder for missing arguments, as this can
|
||||
lead to segfaults.
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">QUOTING METACHARACTERS</a><br>
|
||||
<P>
|
||||
You can use the "QuoteMeta" operation to insert backslashes before all
|
||||
potentially meaningful characters in a string. The returned string, used as a
|
||||
regular expression, will exactly match the original string.
|
||||
<pre>
|
||||
Example:
|
||||
string quoted = RE::QuoteMeta(unquoted);
|
||||
</pre>
|
||||
Note that it's legal to escape a character even if it has no special meaning in
|
||||
a regular expression -- so this function does that. (This also makes it
|
||||
identical to the perl function of the same name; see "perldoc -f quotemeta".)
|
||||
For example, "1.5-2.0?" becomes "1\.5\-2\.0\?".
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">PARTIAL MATCHES</a><br>
|
||||
<P>
|
||||
You can use the "PartialMatch" operation when you want the pattern
|
||||
to match any substring of the text.
|
||||
<pre>
|
||||
Example: simple search for a string:
|
||||
pcrecpp::RE("ell").PartialMatch("hello");
|
||||
|
||||
Example: find first number in a string:
|
||||
int number;
|
||||
pcrecpp::RE re("(\\d+)");
|
||||
re.PartialMatch("x*100 + 20", &number);
|
||||
assert(number == 100);
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">UTF-8 AND THE MATCHING INTERFACE</a><br>
|
||||
<P>
|
||||
By default, pattern and text are plain text, one byte per character. The UTF8
|
||||
flag, passed to the constructor, causes both pattern and string to be treated
|
||||
as UTF-8 text, still a byte stream but potentially multiple bytes per
|
||||
character. In practice, the text is likelier to be UTF-8 than the pattern, but
|
||||
the match returned may depend on the UTF8 flag, so always use it when matching
|
||||
UTF8 text. For example, "." will match one byte normally but with UTF8 set may
|
||||
match up to three bytes of a multi-byte character.
|
||||
<pre>
|
||||
Example:
|
||||
pcrecpp::RE_Options options;
|
||||
options.set_utf8();
|
||||
pcrecpp::RE re(utf8_pattern, options);
|
||||
re.FullMatch(utf8_string);
|
||||
|
||||
Example: using the convenience function UTF8():
|
||||
pcrecpp::RE re(utf8_pattern, pcrecpp::UTF8());
|
||||
re.FullMatch(utf8_string);
|
||||
</pre>
|
||||
NOTE: The UTF8 flag is ignored if pcre was not configured with the
|
||||
<pre>
|
||||
--enable-utf8 flag.
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC7" href="#TOC1">PASSING MODIFIERS TO THE REGULAR EXPRESSION ENGINE</a><br>
|
||||
<P>
|
||||
PCRE defines some modifiers to change the behavior of the regular expression
|
||||
engine. The C++ wrapper defines an auxiliary class, RE_Options, as a vehicle to
|
||||
pass such modifiers to a RE class. Currently, the following modifiers are
|
||||
supported:
|
||||
<pre>
|
||||
modifier description Perl corresponding
|
||||
|
||||
PCRE_CASELESS case insensitive match /i
|
||||
PCRE_MULTILINE multiple lines match /m
|
||||
PCRE_DOTALL dot matches newlines /s
|
||||
PCRE_DOLLAR_ENDONLY $ matches only at end N/A
|
||||
PCRE_EXTRA strict escape parsing N/A
|
||||
PCRE_EXTENDED ignore white spaces /x
|
||||
PCRE_UTF8 handles UTF8 chars built-in
|
||||
PCRE_UNGREEDY reverses * and *? N/A
|
||||
PCRE_NO_AUTO_CAPTURE disables capturing parens N/A (*)
|
||||
</pre>
|
||||
(*) Both Perl and PCRE allow non capturing parentheses by means of the
|
||||
"?:" modifier within the pattern itself. e.g. (?:ab|cd) does not
|
||||
capture, while (ab|cd) does.
|
||||
</P>
|
||||
<P>
|
||||
For a full account on how each modifier works, please check the
|
||||
PCRE API reference page.
|
||||
</P>
|
||||
<P>
|
||||
For each modifier, there are two member functions whose name is made
|
||||
out of the modifier in lowercase, without the "PCRE_" prefix. For
|
||||
instance, PCRE_CASELESS is handled by
|
||||
<pre>
|
||||
bool caseless()
|
||||
</pre>
|
||||
which returns true if the modifier is set, and
|
||||
<pre>
|
||||
RE_Options & set_caseless(bool)
|
||||
</pre>
|
||||
which sets or unsets the modifier. Moreover, PCRE_EXTRA_MATCH_LIMIT can be
|
||||
accessed through the <b>set_match_limit()</b> and <b>match_limit()</b> member
|
||||
functions. Setting <i>match_limit</i> to a non-zero value will limit the
|
||||
execution of pcre to keep it from doing bad things like blowing the stack or
|
||||
taking an eternity to return a result. A value of 5000 is good enough to stop
|
||||
stack blowup in a 2MB thread stack. Setting <i>match_limit</i> to zero disables
|
||||
match limiting. Alternatively, you can call <b>match_limit_recursion()</b>
|
||||
which uses PCRE_EXTRA_MATCH_LIMIT_RECURSION to limit how much PCRE
|
||||
recurses. <b>match_limit()</b> limits the number of matches PCRE does;
|
||||
<b>match_limit_recursion()</b> limits the depth of internal recursion, and
|
||||
therefore the amount of stack that is used.
|
||||
</P>
|
||||
<P>
|
||||
Normally, to pass one or more modifiers to a RE class, you declare
|
||||
a <i>RE_Options</i> object, set the appropriate options, and pass this
|
||||
object to a RE constructor. Example:
|
||||
<pre>
|
||||
RE_Options opt;
|
||||
opt.set_caseless(true);
|
||||
if (RE("HELLO", opt).PartialMatch("hello world")) ...
|
||||
</pre>
|
||||
RE_options has two constructors. The default constructor takes no arguments and
|
||||
creates a set of flags that are off by default. The optional parameter
|
||||
<i>option_flags</i> is to facilitate transfer of legacy code from C programs.
|
||||
This lets you do
|
||||
<pre>
|
||||
RE(pattern,
|
||||
RE_Options(PCRE_CASELESS|PCRE_MULTILINE)).PartialMatch(str);
|
||||
</pre>
|
||||
However, new code is better off doing
|
||||
<pre>
|
||||
RE(pattern,
|
||||
RE_Options().set_caseless(true).set_multiline(true))
|
||||
.PartialMatch(str);
|
||||
</pre>
|
||||
If you are going to pass one of the most used modifiers, there are some
|
||||
convenience functions that return a RE_Options class with the
|
||||
appropriate modifier already set: <b>CASELESS()</b>, <b>UTF8()</b>,
|
||||
<b>MULTILINE()</b>, <b>DOTALL</b>(), and <b>EXTENDED()</b>.
|
||||
</P>
|
||||
<P>
|
||||
If you need to set several options at once, and you don't want to go through
|
||||
the pains of declaring a RE_Options object and setting several options, there
|
||||
is a parallel method that give you such ability on the fly. You can concatenate
|
||||
several <b>set_xxxxx()</b> member functions, since each of them returns a
|
||||
reference to its class object. For example, to pass PCRE_CASELESS,
|
||||
PCRE_EXTENDED, and PCRE_MULTILINE to a RE with one statement, you may write:
|
||||
<pre>
|
||||
RE(" ^ xyz \\s+ .* blah$",
|
||||
RE_Options()
|
||||
.set_caseless(true)
|
||||
.set_extended(true)
|
||||
.set_multiline(true)).PartialMatch(sometext);
|
||||
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC8" href="#TOC1">SCANNING TEXT INCREMENTALLY</a><br>
|
||||
<P>
|
||||
The "Consume" operation may be useful if you want to repeatedly
|
||||
match regular expressions at the front of a string and skip over
|
||||
them as they match. This requires use of the "StringPiece" type,
|
||||
which represents a sub-range of a real string. Like RE, StringPiece
|
||||
is defined in the pcrecpp namespace.
|
||||
<pre>
|
||||
Example: read lines of the form "var = value" from a string.
|
||||
string contents = ...; // Fill string somehow
|
||||
pcrecpp::StringPiece input(contents); // Wrap in a StringPiece
|
||||
|
||||
string var;
|
||||
int value;
|
||||
pcrecpp::RE re("(\\w+) = (\\d+)\n");
|
||||
while (re.Consume(&input, &var, &value)) {
|
||||
...;
|
||||
}
|
||||
</pre>
|
||||
Each successful call to "Consume" will set "var/value", and also
|
||||
advance "input" so it points past the matched text.
|
||||
</P>
|
||||
<P>
|
||||
The "FindAndConsume" operation is similar to "Consume" but does not
|
||||
anchor your match at the beginning of the string. For example, you
|
||||
could extract all words from a string by repeatedly calling
|
||||
<pre>
|
||||
pcrecpp::RE("(\\w+)").FindAndConsume(&input, &word)
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC9" href="#TOC1">PARSING HEX/OCTAL/C-RADIX NUMBERS</a><br>
|
||||
<P>
|
||||
By default, if you pass a pointer to a numeric value, the
|
||||
corresponding text is interpreted as a base-10 number. You can
|
||||
instead wrap the pointer with a call to one of the operators Hex(),
|
||||
Octal(), or CRadix() to interpret the text in another base. The
|
||||
CRadix operator interprets C-style "0" (base-8) and "0x" (base-16)
|
||||
prefixes, but defaults to base-10.
|
||||
<pre>
|
||||
Example:
|
||||
int a, b, c, d;
|
||||
pcrecpp::RE re("(.*) (.*) (.*) (.*)");
|
||||
re.FullMatch("100 40 0100 0x40",
|
||||
pcrecpp::Octal(&a), pcrecpp::Hex(&b),
|
||||
pcrecpp::CRadix(&c), pcrecpp::CRadix(&d));
|
||||
</pre>
|
||||
will leave 64 in a, b, c, and d.
|
||||
</P>
|
||||
<br><a name="SEC10" href="#TOC1">REPLACING PARTS OF STRINGS</a><br>
|
||||
<P>
|
||||
You can replace the first match of "pattern" in "str" with "rewrite".
|
||||
Within "rewrite", backslash-escaped digits (\1 to \9) can be
|
||||
used to insert text matching corresponding parenthesized group
|
||||
from the pattern. \0 in "rewrite" refers to the entire matching
|
||||
text. For example:
|
||||
<pre>
|
||||
string s = "yabba dabba doo";
|
||||
pcrecpp::RE("b+").Replace("d", &s);
|
||||
</pre>
|
||||
will leave "s" containing "yada dabba doo". The result is true if the pattern
|
||||
matches and a replacement occurs, false otherwise.
|
||||
</P>
|
||||
<P>
|
||||
<b>GlobalReplace</b> is like <b>Replace</b> except that it replaces all
|
||||
occurrences of the pattern in the string with the rewrite. Replacements are
|
||||
not subject to re-matching. For example:
|
||||
<pre>
|
||||
string s = "yabba dabba doo";
|
||||
pcrecpp::RE("b+").GlobalReplace("d", &s);
|
||||
</pre>
|
||||
will leave "s" containing "yada dada doo". It returns the number of
|
||||
replacements made.
|
||||
</P>
|
||||
<P>
|
||||
<b>Extract</b> is like <b>Replace</b>, except that if the pattern matches,
|
||||
"rewrite" is copied into "out" (an additional argument) with substitutions.
|
||||
The non-matching portions of "text" are ignored. Returns true iff a match
|
||||
occurred and the extraction happened successfully; if no match occurs, the
|
||||
string is left unaffected.
|
||||
</P>
|
||||
<br><a name="SEC11" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
The C++ wrapper was contributed by Google Inc.
|
||||
<br>
|
||||
Copyright © 2007 Google Inc.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC12" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 08 January 2012
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,426 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcredemo specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcredemo man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
</ul>
|
||||
<PRE>
|
||||
/*************************************************
|
||||
* PCRE DEMONSTRATION PROGRAM *
|
||||
*************************************************/
|
||||
|
||||
/* This is a demonstration program to illustrate the most straightforward ways
|
||||
of calling the PCRE regular expression library from a C program. See the
|
||||
pcresample documentation for a short discussion ("man pcresample" if you have
|
||||
the PCRE man pages installed).
|
||||
|
||||
In Unix-like environments, if PCRE is installed in your standard system
|
||||
libraries, you should be able to compile this program using this command:
|
||||
|
||||
gcc -Wall pcredemo.c -lpcre -o pcredemo
|
||||
|
||||
If PCRE is not installed in a standard place, it is likely to be installed with
|
||||
support for the pkg-config mechanism. If you have pkg-config, you can compile
|
||||
this program using this command:
|
||||
|
||||
gcc -Wall pcredemo.c `pkg-config --cflags --libs libpcre` -o pcredemo
|
||||
|
||||
If you do not have pkg-config, you may have to use this:
|
||||
|
||||
gcc -Wall pcredemo.c -I/usr/local/include -L/usr/local/lib \
|
||||
-R/usr/local/lib -lpcre -o pcredemo
|
||||
|
||||
Replace "/usr/local/include" and "/usr/local/lib" with wherever the include and
|
||||
library files for PCRE are installed on your system. Only some operating
|
||||
systems (e.g. Solaris) use the -R option.
|
||||
|
||||
Building under Windows:
|
||||
|
||||
If you want to statically link this program against a non-dll .a file, you must
|
||||
define PCRE_STATIC before including pcre.h, otherwise the pcre_malloc() and
|
||||
pcre_free() exported functions will be declared __declspec(dllimport), with
|
||||
unwanted results. So in this environment, uncomment the following line. */
|
||||
|
||||
/* #define PCRE_STATIC */
|
||||
|
||||
#include <stdio.h>
|
||||
#include <string.h>
|
||||
#include <pcre.h>
|
||||
|
||||
#define OVECCOUNT 30 /* should be a multiple of 3 */
|
||||
|
||||
|
||||
int main(int argc, char **argv)
|
||||
{
|
||||
pcre *re;
|
||||
const char *error;
|
||||
char *pattern;
|
||||
char *subject;
|
||||
unsigned char *name_table;
|
||||
unsigned int option_bits;
|
||||
int erroffset;
|
||||
int find_all;
|
||||
int crlf_is_newline;
|
||||
int namecount;
|
||||
int name_entry_size;
|
||||
int ovector[OVECCOUNT];
|
||||
int subject_length;
|
||||
int rc, i;
|
||||
int utf8;
|
||||
|
||||
|
||||
/**************************************************************************
|
||||
* First, sort out the command line. There is only one possible option at *
|
||||
* the moment, "-g" to request repeated matching to find all occurrences, *
|
||||
* like Perl's /g option. We set the variable find_all to a non-zero value *
|
||||
* if the -g option is present. Apart from that, there must be exactly two *
|
||||
* arguments. *
|
||||
**************************************************************************/
|
||||
|
||||
find_all = 0;
|
||||
for (i = 1; i < argc; i++)
|
||||
{
|
||||
if (strcmp(argv[i], "-g") == 0) find_all = 1;
|
||||
else break;
|
||||
}
|
||||
|
||||
/* After the options, we require exactly two arguments, which are the pattern,
|
||||
and the subject string. */
|
||||
|
||||
if (argc - i != 2)
|
||||
{
|
||||
printf("Two arguments required: a regex and a subject string\n");
|
||||
return 1;
|
||||
}
|
||||
|
||||
pattern = argv[i];
|
||||
subject = argv[i+1];
|
||||
subject_length = (int)strlen(subject);
|
||||
|
||||
|
||||
/*************************************************************************
|
||||
* Now we are going to compile the regular expression pattern, and handle *
|
||||
* and errors that are detected. *
|
||||
*************************************************************************/
|
||||
|
||||
re = pcre_compile(
|
||||
pattern, /* the pattern */
|
||||
0, /* default options */
|
||||
&error, /* for error message */
|
||||
&erroffset, /* for error offset */
|
||||
NULL); /* use default character tables */
|
||||
|
||||
/* Compilation failed: print the error message and exit */
|
||||
|
||||
if (re == NULL)
|
||||
{
|
||||
printf("PCRE compilation failed at offset %d: %s\n", erroffset, error);
|
||||
return 1;
|
||||
}
|
||||
|
||||
|
||||
/*************************************************************************
|
||||
* If the compilation succeeded, we call PCRE again, in order to do a *
|
||||
* pattern match against the subject string. This does just ONE match. If *
|
||||
* further matching is needed, it will be done below. *
|
||||
*************************************************************************/
|
||||
|
||||
rc = pcre_exec(
|
||||
re, /* the compiled pattern */
|
||||
NULL, /* no extra data - we didn't study the pattern */
|
||||
subject, /* the subject string */
|
||||
subject_length, /* the length of the subject */
|
||||
0, /* start at offset 0 in the subject */
|
||||
0, /* default options */
|
||||
ovector, /* output vector for substring information */
|
||||
OVECCOUNT); /* number of elements in the output vector */
|
||||
|
||||
/* Matching failed: handle error cases */
|
||||
|
||||
if (rc < 0)
|
||||
{
|
||||
switch(rc)
|
||||
{
|
||||
case PCRE_ERROR_NOMATCH: printf("No match\n"); break;
|
||||
/*
|
||||
Handle other special cases if you like
|
||||
*/
|
||||
default: printf("Matching error %d\n", rc); break;
|
||||
}
|
||||
pcre_free(re); /* Release memory used for the compiled pattern */
|
||||
return 1;
|
||||
}
|
||||
|
||||
/* Match succeded */
|
||||
|
||||
printf("\nMatch succeeded at offset %d\n", ovector[0]);
|
||||
|
||||
|
||||
/*************************************************************************
|
||||
* We have found the first match within the subject string. If the output *
|
||||
* vector wasn't big enough, say so. Then output any substrings that were *
|
||||
* captured. *
|
||||
*************************************************************************/
|
||||
|
||||
/* The output vector wasn't big enough */
|
||||
|
||||
if (rc == 0)
|
||||
{
|
||||
rc = OVECCOUNT/3;
|
||||
printf("ovector only has room for %d captured substrings\n", rc - 1);
|
||||
}
|
||||
|
||||
/* Show substrings stored in the output vector by number. Obviously, in a real
|
||||
application you might want to do things other than print them. */
|
||||
|
||||
for (i = 0; i < rc; i++)
|
||||
{
|
||||
char *substring_start = subject + ovector[2*i];
|
||||
int substring_length = ovector[2*i+1] - ovector[2*i];
|
||||
printf("%2d: %.*s\n", i, substring_length, substring_start);
|
||||
}
|
||||
|
||||
|
||||
/**************************************************************************
|
||||
* That concludes the basic part of this demonstration program. We have *
|
||||
* compiled a pattern, and performed a single match. The code that follows *
|
||||
* shows first how to access named substrings, and then how to code for *
|
||||
* repeated matches on the same subject. *
|
||||
**************************************************************************/
|
||||
|
||||
/* See if there are any named substrings, and if so, show them by name. First
|
||||
we have to extract the count of named parentheses from the pattern. */
|
||||
|
||||
(void)pcre_fullinfo(
|
||||
re, /* the compiled pattern */
|
||||
NULL, /* no extra data - we didn't study the pattern */
|
||||
PCRE_INFO_NAMECOUNT, /* number of named substrings */
|
||||
&namecount); /* where to put the answer */
|
||||
|
||||
if (namecount <= 0) printf("No named substrings\n"); else
|
||||
{
|
||||
unsigned char *tabptr;
|
||||
printf("Named substrings\n");
|
||||
|
||||
/* Before we can access the substrings, we must extract the table for
|
||||
translating names to numbers, and the size of each entry in the table. */
|
||||
|
||||
(void)pcre_fullinfo(
|
||||
re, /* the compiled pattern */
|
||||
NULL, /* no extra data - we didn't study the pattern */
|
||||
PCRE_INFO_NAMETABLE, /* address of the table */
|
||||
&name_table); /* where to put the answer */
|
||||
|
||||
(void)pcre_fullinfo(
|
||||
re, /* the compiled pattern */
|
||||
NULL, /* no extra data - we didn't study the pattern */
|
||||
PCRE_INFO_NAMEENTRYSIZE, /* size of each entry in the table */
|
||||
&name_entry_size); /* where to put the answer */
|
||||
|
||||
/* Now we can scan the table and, for each entry, print the number, the name,
|
||||
and the substring itself. */
|
||||
|
||||
tabptr = name_table;
|
||||
for (i = 0; i < namecount; i++)
|
||||
{
|
||||
int n = (tabptr[0] << 8) | tabptr[1];
|
||||
printf("(%d) %*s: %.*s\n", n, name_entry_size - 3, tabptr + 2,
|
||||
ovector[2*n+1] - ovector[2*n], subject + ovector[2*n]);
|
||||
tabptr += name_entry_size;
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
/*************************************************************************
|
||||
* If the "-g" option was given on the command line, we want to continue *
|
||||
* to search for additional matches in the subject string, in a similar *
|
||||
* way to the /g option in Perl. This turns out to be trickier than you *
|
||||
* might think because of the possibility of matching an empty string. *
|
||||
* What happens is as follows: *
|
||||
* *
|
||||
* If the previous match was NOT for an empty string, we can just start *
|
||||
* the next match at the end of the previous one. *
|
||||
* *
|
||||
* If the previous match WAS for an empty string, we can't do that, as it *
|
||||
* would lead to an infinite loop. Instead, a special call of pcre_exec() *
|
||||
* is made with the PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED flags set. *
|
||||
* The first of these tells PCRE that an empty string at the start of the *
|
||||
* subject is not a valid match; other possibilities must be tried. The *
|
||||
* second flag restricts PCRE to one match attempt at the initial string *
|
||||
* position. If this match succeeds, an alternative to the empty string *
|
||||
* match has been found, and we can print it and proceed round the loop, *
|
||||
* advancing by the length of whatever was found. If this match does not *
|
||||
* succeed, we still stay in the loop, advancing by just one character. *
|
||||
* In UTF-8 mode, which can be set by (*UTF8) in the pattern, this may be *
|
||||
* more than one byte. *
|
||||
* *
|
||||
* However, there is a complication concerned with newlines. When the *
|
||||
* newline convention is such that CRLF is a valid newline, we must *
|
||||
* advance by two characters rather than one. The newline convention can *
|
||||
* be set in the regex by (*CR), etc.; if not, we must find the default. *
|
||||
*************************************************************************/
|
||||
|
||||
if (!find_all) /* Check for -g */
|
||||
{
|
||||
pcre_free(re); /* Release the memory used for the compiled pattern */
|
||||
return 0; /* Finish unless -g was given */
|
||||
}
|
||||
|
||||
/* Before running the loop, check for UTF-8 and whether CRLF is a valid newline
|
||||
sequence. First, find the options with which the regex was compiled; extract
|
||||
the UTF-8 state, and mask off all but the newline options. */
|
||||
|
||||
(void)pcre_fullinfo(re, NULL, PCRE_INFO_OPTIONS, &option_bits);
|
||||
utf8 = option_bits & PCRE_UTF8;
|
||||
option_bits &= PCRE_NEWLINE_CR|PCRE_NEWLINE_LF|PCRE_NEWLINE_CRLF|
|
||||
PCRE_NEWLINE_ANY|PCRE_NEWLINE_ANYCRLF;
|
||||
|
||||
/* If no newline options were set, find the default newline convention from the
|
||||
build configuration. */
|
||||
|
||||
if (option_bits == 0)
|
||||
{
|
||||
int d;
|
||||
(void)pcre_config(PCRE_CONFIG_NEWLINE, &d);
|
||||
/* Note that these values are always the ASCII ones, even in
|
||||
EBCDIC environments. CR = 13, NL = 10. */
|
||||
option_bits = (d == 13)? PCRE_NEWLINE_CR :
|
||||
(d == 10)? PCRE_NEWLINE_LF :
|
||||
(d == (13<<8 | 10))? PCRE_NEWLINE_CRLF :
|
||||
(d == -2)? PCRE_NEWLINE_ANYCRLF :
|
||||
(d == -1)? PCRE_NEWLINE_ANY : 0;
|
||||
}
|
||||
|
||||
/* See if CRLF is a valid newline sequence. */
|
||||
|
||||
crlf_is_newline =
|
||||
option_bits == PCRE_NEWLINE_ANY ||
|
||||
option_bits == PCRE_NEWLINE_CRLF ||
|
||||
option_bits == PCRE_NEWLINE_ANYCRLF;
|
||||
|
||||
/* Loop for second and subsequent matches */
|
||||
|
||||
for (;;)
|
||||
{
|
||||
int options = 0; /* Normally no options */
|
||||
int start_offset = ovector[1]; /* Start at end of previous match */
|
||||
|
||||
/* If the previous match was for an empty string, we are finished if we are
|
||||
at the end of the subject. Otherwise, arrange to run another match at the
|
||||
same point to see if a non-empty match can be found. */
|
||||
|
||||
if (ovector[0] == ovector[1])
|
||||
{
|
||||
if (ovector[0] == subject_length) break;
|
||||
options = PCRE_NOTEMPTY_ATSTART | PCRE_ANCHORED;
|
||||
}
|
||||
|
||||
/* Run the next matching operation */
|
||||
|
||||
rc = pcre_exec(
|
||||
re, /* the compiled pattern */
|
||||
NULL, /* no extra data - we didn't study the pattern */
|
||||
subject, /* the subject string */
|
||||
subject_length, /* the length of the subject */
|
||||
start_offset, /* starting offset in the subject */
|
||||
options, /* options */
|
||||
ovector, /* output vector for substring information */
|
||||
OVECCOUNT); /* number of elements in the output vector */
|
||||
|
||||
/* This time, a result of NOMATCH isn't an error. If the value in "options"
|
||||
is zero, it just means we have found all possible matches, so the loop ends.
|
||||
Otherwise, it means we have failed to find a non-empty-string match at a
|
||||
point where there was a previous empty-string match. In this case, we do what
|
||||
Perl does: advance the matching position by one character, and continue. We
|
||||
do this by setting the "end of previous match" offset, because that is picked
|
||||
up at the top of the loop as the point at which to start again.
|
||||
|
||||
There are two complications: (a) When CRLF is a valid newline sequence, and
|
||||
the current position is just before it, advance by an extra byte. (b)
|
||||
Otherwise we must ensure that we skip an entire UTF-8 character if we are in
|
||||
UTF-8 mode. */
|
||||
|
||||
if (rc == PCRE_ERROR_NOMATCH)
|
||||
{
|
||||
if (options == 0) break; /* All matches found */
|
||||
ovector[1] = start_offset + 1; /* Advance one byte */
|
||||
if (crlf_is_newline && /* If CRLF is newline & */
|
||||
start_offset < subject_length - 1 && /* we are at CRLF, */
|
||||
subject[start_offset] == '\r' &&
|
||||
subject[start_offset + 1] == '\n')
|
||||
ovector[1] += 1; /* Advance by one more. */
|
||||
else if (utf8) /* Otherwise, ensure we */
|
||||
{ /* advance a whole UTF-8 */
|
||||
while (ovector[1] < subject_length) /* character. */
|
||||
{
|
||||
if ((subject[ovector[1]] & 0xc0) != 0x80) break;
|
||||
ovector[1] += 1;
|
||||
}
|
||||
}
|
||||
continue; /* Go round the loop again */
|
||||
}
|
||||
|
||||
/* Other matching errors are not recoverable. */
|
||||
|
||||
if (rc < 0)
|
||||
{
|
||||
printf("Matching error %d\n", rc);
|
||||
pcre_free(re); /* Release memory used for the compiled pattern */
|
||||
return 1;
|
||||
}
|
||||
|
||||
/* Match succeded */
|
||||
|
||||
printf("\nMatch succeeded again at offset %d\n", ovector[0]);
|
||||
|
||||
/* The match succeeded, but the output vector wasn't big enough. */
|
||||
|
||||
if (rc == 0)
|
||||
{
|
||||
rc = OVECCOUNT/3;
|
||||
printf("ovector only has room for %d captured substrings\n", rc - 1);
|
||||
}
|
||||
|
||||
/* As before, show substrings stored in the output vector by number, and then
|
||||
also any named substrings. */
|
||||
|
||||
for (i = 0; i < rc; i++)
|
||||
{
|
||||
char *substring_start = subject + ovector[2*i];
|
||||
int substring_length = ovector[2*i+1] - ovector[2*i];
|
||||
printf("%2d: %.*s\n", i, substring_length, substring_start);
|
||||
}
|
||||
|
||||
if (namecount <= 0) printf("No named substrings\n"); else
|
||||
{
|
||||
unsigned char *tabptr = name_table;
|
||||
printf("Named substrings\n");
|
||||
for (i = 0; i < namecount; i++)
|
||||
{
|
||||
int n = (tabptr[0] << 8) | tabptr[1];
|
||||
printf("(%d) %*s: %.*s\n", n, name_entry_size - 3, tabptr + 2,
|
||||
ovector[2*n+1] - ovector[2*n], subject + ovector[2*n]);
|
||||
tabptr += name_entry_size;
|
||||
}
|
||||
}
|
||||
} /* End of loop to find second and subsequent matches */
|
||||
|
||||
printf("\n");
|
||||
pcre_free(re); /* Release memory used for the compiled pattern */
|
||||
return 0;
|
||||
}
|
||||
|
||||
/* End of pcredemo.c */
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,759 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcregrep specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcregrep man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
|
||||
<li><a name="TOC2" href="#SEC2">DESCRIPTION</a>
|
||||
<li><a name="TOC3" href="#SEC3">SUPPORT FOR COMPRESSED FILES</a>
|
||||
<li><a name="TOC4" href="#SEC4">BINARY FILES</a>
|
||||
<li><a name="TOC5" href="#SEC5">OPTIONS</a>
|
||||
<li><a name="TOC6" href="#SEC6">ENVIRONMENT VARIABLES</a>
|
||||
<li><a name="TOC7" href="#SEC7">NEWLINES</a>
|
||||
<li><a name="TOC8" href="#SEC8">OPTIONS COMPATIBILITY</a>
|
||||
<li><a name="TOC9" href="#SEC9">OPTIONS WITH DATA</a>
|
||||
<li><a name="TOC10" href="#SEC10">MATCHING ERRORS</a>
|
||||
<li><a name="TOC11" href="#SEC11">DIAGNOSTICS</a>
|
||||
<li><a name="TOC12" href="#SEC12">SEE ALSO</a>
|
||||
<li><a name="TOC13" href="#SEC13">AUTHOR</a>
|
||||
<li><a name="TOC14" href="#SEC14">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
|
||||
<P>
|
||||
<b>pcregrep [options] [long options] [pattern] [path1 path2 ...]</b>
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">DESCRIPTION</a><br>
|
||||
<P>
|
||||
<b>pcregrep</b> searches files for character patterns, in the same way as other
|
||||
grep commands do, but it uses the PCRE regular expression library to support
|
||||
patterns that are compatible with the regular expressions of Perl 5. See
|
||||
<a href="pcresyntax.html"><b>pcresyntax</b>(3)</a>
|
||||
for a quick-reference summary of pattern syntax, or
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b>(3)</a>
|
||||
for a full description of the syntax and semantics of the regular expressions
|
||||
that PCRE supports.
|
||||
</P>
|
||||
<P>
|
||||
Patterns, whether supplied on the command line or in a separate file, are given
|
||||
without delimiters. For example:
|
||||
<pre>
|
||||
pcregrep Thursday /etc/motd
|
||||
</pre>
|
||||
If you attempt to use delimiters (for example, by surrounding a pattern with
|
||||
slashes, as is common in Perl scripts), they are interpreted as part of the
|
||||
pattern. Quotes can of course be used to delimit patterns on the command line
|
||||
because they are interpreted by the shell, and indeed quotes are required if a
|
||||
pattern contains white space or shell metacharacters.
|
||||
</P>
|
||||
<P>
|
||||
The first argument that follows any option settings is treated as the single
|
||||
pattern to be matched when neither <b>-e</b> nor <b>-f</b> is present.
|
||||
Conversely, when one or both of these options are used to specify patterns, all
|
||||
arguments are treated as path names. At least one of <b>-e</b>, <b>-f</b>, or an
|
||||
argument pattern must be provided.
|
||||
</P>
|
||||
<P>
|
||||
If no files are specified, <b>pcregrep</b> reads the standard input. The
|
||||
standard input can also be referenced by a name consisting of a single hyphen.
|
||||
For example:
|
||||
<pre>
|
||||
pcregrep some-pattern /file1 - /file3
|
||||
</pre>
|
||||
By default, each line that matches a pattern is copied to the standard
|
||||
output, and if there is more than one file, the file name is output at the
|
||||
start of each line, followed by a colon. However, there are options that can
|
||||
change how <b>pcregrep</b> behaves. In particular, the <b>-M</b> option makes it
|
||||
possible to search for patterns that span line boundaries. What defines a line
|
||||
boundary is controlled by the <b>-N</b> (<b>--newline</b>) option.
|
||||
</P>
|
||||
<P>
|
||||
The amount of memory used for buffering files that are being scanned is
|
||||
controlled by a parameter that can be set by the <b>--buffer-size</b> option.
|
||||
The default value for this parameter is specified when <b>pcregrep</b> is built,
|
||||
with the default default being 20K. A block of memory three times this size is
|
||||
used (to allow for buffering "before" and "after" lines). An error occurs if a
|
||||
line overflows the buffer.
|
||||
</P>
|
||||
<P>
|
||||
Patterns can be no longer than 8K or BUFSIZ bytes, whichever is the greater.
|
||||
BUFSIZ is defined in <b><stdio.h></b>. When there is more than one pattern
|
||||
(specified by the use of <b>-e</b> and/or <b>-f</b>), each pattern is applied to
|
||||
each line in the order in which they are defined, except that all the <b>-e</b>
|
||||
patterns are tried before the <b>-f</b> patterns.
|
||||
</P>
|
||||
<P>
|
||||
By default, as soon as one pattern matches a line, no further patterns are
|
||||
considered. However, if <b>--colour</b> (or <b>--color</b>) is used to colour the
|
||||
matching substrings, or if <b>--only-matching</b>, <b>--file-offsets</b>, or
|
||||
<b>--line-offsets</b> is used to output only the part of the line that matched
|
||||
(either shown literally, or as an offset), scanning resumes immediately
|
||||
following the match, so that further matches on the same line can be found. If
|
||||
there are multiple patterns, they are all tried on the remainder of the line,
|
||||
but patterns that follow the one that matched are not tried on the earlier part
|
||||
of the line.
|
||||
</P>
|
||||
<P>
|
||||
This behaviour means that the order in which multiple patterns are specified
|
||||
can affect the output when one of the above options is used. This is no longer
|
||||
the same behaviour as GNU grep, which now manages to display earlier matches
|
||||
for later patterns (as long as there is no overlap).
|
||||
</P>
|
||||
<P>
|
||||
Patterns that can match an empty string are accepted, but empty string
|
||||
matches are never recognized. An example is the pattern "(super)?(man)?", in
|
||||
which all components are optional. This pattern finds all occurrences of both
|
||||
"super" and "man"; the output differs from matching with "super|man" when only
|
||||
the matching substrings are being shown.
|
||||
</P>
|
||||
<P>
|
||||
If the <b>LC_ALL</b> or <b>LC_CTYPE</b> environment variable is set,
|
||||
<b>pcregrep</b> uses the value to set a locale when calling the PCRE library.
|
||||
The <b>--locale</b> option can be used to override this.
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">SUPPORT FOR COMPRESSED FILES</a><br>
|
||||
<P>
|
||||
It is possible to compile <b>pcregrep</b> so that it uses <b>libz</b> or
|
||||
<b>libbz2</b> to read files whose names end in <b>.gz</b> or <b>.bz2</b>,
|
||||
respectively. You can find out whether your binary has support for one or both
|
||||
of these file types by running it with the <b>--help</b> option. If the
|
||||
appropriate support is not present, files are treated as plain text. The
|
||||
standard input is always so treated.
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">BINARY FILES</a><br>
|
||||
<P>
|
||||
By default, a file that contains a binary zero byte within the first 1024 bytes
|
||||
is identified as a binary file, and is processed specially. (GNU grep also
|
||||
identifies binary files in this manner.) See the <b>--binary-files</b> option
|
||||
for a means of changing the way binary files are handled.
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">OPTIONS</a><br>
|
||||
<P>
|
||||
The order in which some of the options appear can affect the output. For
|
||||
example, both the <b>-h</b> and <b>-l</b> options affect the printing of file
|
||||
names. Whichever comes later in the command line will be the one that takes
|
||||
effect. Similarly, except where noted below, if an option is given twice, the
|
||||
later setting is used. Numerical values for options may be followed by K or M,
|
||||
to signify multiplication by 1024 or 1024*1024 respectively.
|
||||
</P>
|
||||
<P>
|
||||
<b>--</b>
|
||||
This terminates the list of options. It is useful if the next item on the
|
||||
command line starts with a hyphen but is not an option. This allows for the
|
||||
processing of patterns and filenames that start with hyphens.
|
||||
</P>
|
||||
<P>
|
||||
<b>-A</b> <i>number</i>, <b>--after-context=</b><i>number</i>
|
||||
Output <i>number</i> lines of context after each matching line. If filenames
|
||||
and/or line numbers are being output, a hyphen separator is used instead of a
|
||||
colon for the context lines. A line containing "--" is output between each
|
||||
group of lines, unless they are in fact contiguous in the input file. The value
|
||||
of <i>number</i> is expected to be relatively small. However, <b>pcregrep</b>
|
||||
guarantees to have up to 8K of following text available for context output.
|
||||
</P>
|
||||
<P>
|
||||
<b>-a</b>, <b>--text</b>
|
||||
Treat binary files as text. This is equivalent to
|
||||
<b>--binary-files</b>=<i>text</i>.
|
||||
</P>
|
||||
<P>
|
||||
<b>-B</b> <i>number</i>, <b>--before-context=</b><i>number</i>
|
||||
Output <i>number</i> lines of context before each matching line. If filenames
|
||||
and/or line numbers are being output, a hyphen separator is used instead of a
|
||||
colon for the context lines. A line containing "--" is output between each
|
||||
group of lines, unless they are in fact contiguous in the input file. The value
|
||||
of <i>number</i> is expected to be relatively small. However, <b>pcregrep</b>
|
||||
guarantees to have up to 8K of preceding text available for context output.
|
||||
</P>
|
||||
<P>
|
||||
<b>--binary-files=</b><i>word</i>
|
||||
Specify how binary files are to be processed. If the word is "binary" (the
|
||||
default), pattern matching is performed on binary files, but the only output is
|
||||
"Binary file <name> matches" when a match succeeds. If the word is "text",
|
||||
which is equivalent to the <b>-a</b> or <b>--text</b> option, binary files are
|
||||
processed in the same way as any other file. In this case, when a match
|
||||
succeeds, the output may be binary garbage, which can have nasty effects if
|
||||
sent to a terminal. If the word is "without-match", which is equivalent to the
|
||||
<b>-I</b> option, binary files are not processed at all; they are assumed not to
|
||||
be of interest.
|
||||
</P>
|
||||
<P>
|
||||
<b>--buffer-size=</b><i>number</i>
|
||||
Set the parameter that controls how much memory is used for buffering files
|
||||
that are being scanned.
|
||||
</P>
|
||||
<P>
|
||||
<b>-C</b> <i>number</i>, <b>--context=</b><i>number</i>
|
||||
Output <i>number</i> lines of context both before and after each matching line.
|
||||
This is equivalent to setting both <b>-A</b> and <b>-B</b> to the same value.
|
||||
</P>
|
||||
<P>
|
||||
<b>-c</b>, <b>--count</b>
|
||||
Do not output individual lines from the files that are being scanned; instead
|
||||
output the number of lines that would otherwise have been shown. If no lines
|
||||
are selected, the number zero is output. If several files are are being
|
||||
scanned, a count is output for each of them. However, if the
|
||||
<b>--files-with-matches</b> option is also used, only those files whose counts
|
||||
are greater than zero are listed. When <b>-c</b> is used, the <b>-A</b>,
|
||||
<b>-B</b>, and <b>-C</b> options are ignored.
|
||||
</P>
|
||||
<P>
|
||||
<b>--colour</b>, <b>--color</b>
|
||||
If this option is given without any data, it is equivalent to "--colour=auto".
|
||||
If data is required, it must be given in the same shell item, separated by an
|
||||
equals sign.
|
||||
</P>
|
||||
<P>
|
||||
<b>--colour=</b><i>value</i>, <b>--color=</b><i>value</i>
|
||||
This option specifies under what circumstances the parts of a line that matched
|
||||
a pattern should be coloured in the output. By default, the output is not
|
||||
coloured. The value (which is optional, see above) may be "never", "always", or
|
||||
"auto". In the latter case, colouring happens only if the standard output is
|
||||
connected to a terminal. More resources are used when colouring is enabled,
|
||||
because <b>pcregrep</b> has to search for all possible matches in a line, not
|
||||
just one, in order to colour them all.
|
||||
<br>
|
||||
<br>
|
||||
The colour that is used can be specified by setting the environment variable
|
||||
PCREGREP_COLOUR or PCREGREP_COLOR. The value of this variable should be a
|
||||
string of two numbers, separated by a semicolon. They are copied directly into
|
||||
the control string for setting colour on a terminal, so it is your
|
||||
responsibility to ensure that they make sense. If neither of the environment
|
||||
variables is set, the default is "1;31", which gives red.
|
||||
</P>
|
||||
<P>
|
||||
<b>-D</b> <i>action</i>, <b>--devices=</b><i>action</i>
|
||||
If an input path is not a regular file or a directory, "action" specifies how
|
||||
it is to be processed. Valid values are "read" (the default) or "skip"
|
||||
(silently skip the path).
|
||||
</P>
|
||||
<P>
|
||||
<b>-d</b> <i>action</i>, <b>--directories=</b><i>action</i>
|
||||
If an input path is a directory, "action" specifies how it is to be processed.
|
||||
Valid values are "read" (the default in non-Windows environments, for
|
||||
compatibility with GNU grep), "recurse" (equivalent to the <b>-r</b> option), or
|
||||
"skip" (silently skip the path, the default in Windows environments). In the
|
||||
"read" case, directories are read as if they were ordinary files. In some
|
||||
operating systems the effect of reading a directory like this is an immediate
|
||||
end-of-file; in others it may provoke an error.
|
||||
</P>
|
||||
<P>
|
||||
<b>-e</b> <i>pattern</i>, <b>--regex=</b><i>pattern</i>, <b>--regexp=</b><i>pattern</i>
|
||||
Specify a pattern to be matched. This option can be used multiple times in
|
||||
order to specify several patterns. It can also be used as a way of specifying a
|
||||
single pattern that starts with a hyphen. When <b>-e</b> is used, no argument
|
||||
pattern is taken from the command line; all arguments are treated as file
|
||||
names. There is no limit to the number of patterns. They are applied to each
|
||||
line in the order in which they are defined until one matches.
|
||||
<br>
|
||||
<br>
|
||||
If <b>-f</b> is used with <b>-e</b>, the command line patterns are matched first,
|
||||
followed by the patterns from the file(s), independent of the order in which
|
||||
these options are specified. Note that multiple use of <b>-e</b> is not the same
|
||||
as a single pattern with alternatives. For example, X|Y finds the first
|
||||
character in a line that is X or Y, whereas if the two patterns are given
|
||||
separately, with X first, <b>pcregrep</b> finds X if it is present, even if it
|
||||
follows Y in the line. It finds Y only if there is no X in the line. This
|
||||
matters only if you are using <b>-o</b> or <b>--colo(u)r</b> to show the part(s)
|
||||
of the line that matched.
|
||||
</P>
|
||||
<P>
|
||||
<b>--exclude</b>=<i>pattern</i>
|
||||
Files (but not directories) whose names match the pattern are skipped without
|
||||
being processed. This applies to all files, whether listed on the command line,
|
||||
obtained from <b>--file-list</b>, or by scanning a directory. The pattern is a
|
||||
PCRE regular expression, and is matched against the final component of the file
|
||||
name, not the entire path. The <b>-F</b>, <b>-w</b>, and <b>-x</b> options do not
|
||||
apply to this pattern. The option may be given any number of times in order to
|
||||
specify multiple patterns. If a file name matches both an <b>--include</b>
|
||||
and an <b>--exclude</b> pattern, it is excluded. There is no short form for this
|
||||
option.
|
||||
</P>
|
||||
<P>
|
||||
<b>--exclude-from=</b><i>filename</i>
|
||||
Treat each non-empty line of the file as the data for an <b>--exclude</b>
|
||||
option. What constitutes a newline when reading the file is the operating
|
||||
system's default. The <b>--newline</b> option has no effect on this option. This
|
||||
option may be given more than once in order to specify a number of files to
|
||||
read.
|
||||
</P>
|
||||
<P>
|
||||
<b>--exclude-dir</b>=<i>pattern</i>
|
||||
Directories whose names match the pattern are skipped without being processed,
|
||||
whatever the setting of the <b>--recursive</b> option. This applies to all
|
||||
directories, whether listed on the command line, obtained from
|
||||
<b>--file-list</b>, or by scanning a parent directory. The pattern is a PCRE
|
||||
regular expression, and is matched against the final component of the directory
|
||||
name, not the entire path. The <b>-F</b>, <b>-w</b>, and <b>-x</b> options do not
|
||||
apply to this pattern. The option may be given any number of times in order to
|
||||
specify more than one pattern. If a directory matches both <b>--include-dir</b>
|
||||
and <b>--exclude-dir</b>, it is excluded. There is no short form for this
|
||||
option.
|
||||
</P>
|
||||
<P>
|
||||
<b>-F</b>, <b>--fixed-strings</b>
|
||||
Interpret each data-matching pattern as a list of fixed strings, separated by
|
||||
newlines, instead of as a regular expression. What constitutes a newline for
|
||||
this purpose is controlled by the <b>--newline</b> option. The <b>-w</b> (match
|
||||
as a word) and <b>-x</b> (match whole line) options can be used with <b>-F</b>.
|
||||
They apply to each of the fixed strings. A line is selected if any of the fixed
|
||||
strings are found in it (subject to <b>-w</b> or <b>-x</b>, if present). This
|
||||
option applies only to the patterns that are matched against the contents of
|
||||
files; it does not apply to patterns specified by any of the <b>--include</b> or
|
||||
<b>--exclude</b> options.
|
||||
</P>
|
||||
<P>
|
||||
<b>-f</b> <i>filename</i>, <b>--file=</b><i>filename</i>
|
||||
Read patterns from the file, one per line, and match them against
|
||||
each line of input. What constitutes a newline when reading the file is the
|
||||
operating system's default. The <b>--newline</b> option has no effect on this
|
||||
option. Trailing white space is removed from each line, and blank lines are
|
||||
ignored. An empty file contains no patterns and therefore matches nothing. See
|
||||
also the comments about multiple patterns versus a single pattern with
|
||||
alternatives in the description of <b>-e</b> above.
|
||||
<br>
|
||||
<br>
|
||||
If this option is given more than once, all the specified files are
|
||||
read. A data line is output if any of the patterns match it. A filename can
|
||||
be given as "-" to refer to the standard input. When <b>-f</b> is used, patterns
|
||||
specified on the command line using <b>-e</b> may also be present; they are
|
||||
tested before the file's patterns. However, no other pattern is taken from the
|
||||
command line; all arguments are treated as the names of paths to be searched.
|
||||
</P>
|
||||
<P>
|
||||
<b>--file-list</b>=<i>filename</i>
|
||||
Read a list of files and/or directories that are to be scanned from the given
|
||||
file, one per line. Trailing white space is removed from each line, and blank
|
||||
lines are ignored. These paths are processed before any that are listed on the
|
||||
command line. The filename can be given as "-" to refer to the standard input.
|
||||
If <b>--file</b> and <b>--file-list</b> are both specified as "-", patterns are
|
||||
read first. This is useful only when the standard input is a terminal, from
|
||||
which further lines (the list of files) can be read after an end-of-file
|
||||
indication. If this option is given more than once, all the specified files are
|
||||
read.
|
||||
</P>
|
||||
<P>
|
||||
<b>--file-offsets</b>
|
||||
Instead of showing lines or parts of lines that match, show each match as an
|
||||
offset from the start of the file and a length, separated by a comma. In this
|
||||
mode, no context is shown. That is, the <b>-A</b>, <b>-B</b>, and <b>-C</b>
|
||||
options are ignored. If there is more than one match in a line, each of them is
|
||||
shown separately. This option is mutually exclusive with <b>--line-offsets</b>
|
||||
and <b>--only-matching</b>.
|
||||
</P>
|
||||
<P>
|
||||
<b>-H</b>, <b>--with-filename</b>
|
||||
Force the inclusion of the filename at the start of output lines when searching
|
||||
a single file. By default, the filename is not shown in this case. For matching
|
||||
lines, the filename is followed by a colon; for context lines, a hyphen
|
||||
separator is used. If a line number is also being output, it follows the file
|
||||
name.
|
||||
</P>
|
||||
<P>
|
||||
<b>-h</b>, <b>--no-filename</b>
|
||||
Suppress the output filenames when searching multiple files. By default,
|
||||
filenames are shown when multiple files are searched. For matching lines, the
|
||||
filename is followed by a colon; for context lines, a hyphen separator is used.
|
||||
If a line number is also being output, it follows the file name.
|
||||
</P>
|
||||
<P>
|
||||
<b>--help</b>
|
||||
Output a help message, giving brief details of the command options and file
|
||||
type support, and then exit. Anything else on the command line is
|
||||
ignored.
|
||||
</P>
|
||||
<P>
|
||||
<b>-I</b>
|
||||
Treat binary files as never matching. This is equivalent to
|
||||
<b>--binary-files</b>=<i>without-match</i>.
|
||||
</P>
|
||||
<P>
|
||||
<b>-i</b>, <b>--ignore-case</b>
|
||||
Ignore upper/lower case distinctions during comparisons.
|
||||
</P>
|
||||
<P>
|
||||
<b>--include</b>=<i>pattern</i>
|
||||
If any <b>--include</b> patterns are specified, the only files that are
|
||||
processed are those that match one of the patterns (and do not match an
|
||||
<b>--exclude</b> pattern). This option does not affect directories, but it
|
||||
applies to all files, whether listed on the command line, obtained from
|
||||
<b>--file-list</b>, or by scanning a directory. The pattern is a PCRE regular
|
||||
expression, and is matched against the final component of the file name, not
|
||||
the entire path. The <b>-F</b>, <b>-w</b>, and <b>-x</b> options do not apply to
|
||||
this pattern. The option may be given any number of times. If a file name
|
||||
matches both an <b>--include</b> and an <b>--exclude</b> pattern, it is excluded.
|
||||
There is no short form for this option.
|
||||
</P>
|
||||
<P>
|
||||
<b>--include-from=</b><i>filename</i>
|
||||
Treat each non-empty line of the file as the data for an <b>--include</b>
|
||||
option. What constitutes a newline for this purpose is the operating system's
|
||||
default. The <b>--newline</b> option has no effect on this option. This option
|
||||
may be given any number of times; all the files are read.
|
||||
</P>
|
||||
<P>
|
||||
<b>--include-dir</b>=<i>pattern</i>
|
||||
If any <b>--include-dir</b> patterns are specified, the only directories that
|
||||
are processed are those that match one of the patterns (and do not match an
|
||||
<b>--exclude-dir</b> pattern). This applies to all directories, whether listed
|
||||
on the command line, obtained from <b>--file-list</b>, or by scanning a parent
|
||||
directory. The pattern is a PCRE regular expression, and is matched against the
|
||||
final component of the directory name, not the entire path. The <b>-F</b>,
|
||||
<b>-w</b>, and <b>-x</b> options do not apply to this pattern. The option may be
|
||||
given any number of times. If a directory matches both <b>--include-dir</b> and
|
||||
<b>--exclude-dir</b>, it is excluded. There is no short form for this option.
|
||||
</P>
|
||||
<P>
|
||||
<b>-L</b>, <b>--files-without-match</b>
|
||||
Instead of outputting lines from the files, just output the names of the files
|
||||
that do not contain any lines that would have been output. Each file name is
|
||||
output once, on a separate line.
|
||||
</P>
|
||||
<P>
|
||||
<b>-l</b>, <b>--files-with-matches</b>
|
||||
Instead of outputting lines from the files, just output the names of the files
|
||||
containing lines that would have been output. Each file name is output
|
||||
once, on a separate line. Searching normally stops as soon as a matching line
|
||||
is found in a file. However, if the <b>-c</b> (count) option is also used,
|
||||
matching continues in order to obtain the correct count, and those files that
|
||||
have at least one match are listed along with their counts. Using this option
|
||||
with <b>-c</b> is a way of suppressing the listing of files with no matches.
|
||||
</P>
|
||||
<P>
|
||||
<b>--label</b>=<i>name</i>
|
||||
This option supplies a name to be used for the standard input when file names
|
||||
are being output. If not supplied, "(standard input)" is used. There is no
|
||||
short form for this option.
|
||||
</P>
|
||||
<P>
|
||||
<b>--line-buffered</b>
|
||||
When this option is given, input is read and processed line by line, and the
|
||||
output is flushed after each write. By default, input is read in large chunks,
|
||||
unless <b>pcregrep</b> can determine that it is reading from a terminal (which
|
||||
is currently possible only in Unix-like environments). Output to terminal is
|
||||
normally automatically flushed by the operating system. This option can be
|
||||
useful when the input or output is attached to a pipe and you do not want
|
||||
<b>pcregrep</b> to buffer up large amounts of data. However, its use will affect
|
||||
performance, and the <b>-M</b> (multiline) option ceases to work.
|
||||
</P>
|
||||
<P>
|
||||
<b>--line-offsets</b>
|
||||
Instead of showing lines or parts of lines that match, show each match as a
|
||||
line number, the offset from the start of the line, and a length. The line
|
||||
number is terminated by a colon (as usual; see the <b>-n</b> option), and the
|
||||
offset and length are separated by a comma. In this mode, no context is shown.
|
||||
That is, the <b>-A</b>, <b>-B</b>, and <b>-C</b> options are ignored. If there is
|
||||
more than one match in a line, each of them is shown separately. This option is
|
||||
mutually exclusive with <b>--file-offsets</b> and <b>--only-matching</b>.
|
||||
</P>
|
||||
<P>
|
||||
<b>--locale</b>=<i>locale-name</i>
|
||||
This option specifies a locale to be used for pattern matching. It overrides
|
||||
the value in the <b>LC_ALL</b> or <b>LC_CTYPE</b> environment variables. If no
|
||||
locale is specified, the PCRE library's default (usually the "C" locale) is
|
||||
used. There is no short form for this option.
|
||||
</P>
|
||||
<P>
|
||||
<b>--match-limit</b>=<i>number</i>
|
||||
Processing some regular expression patterns can require a very large amount of
|
||||
memory, leading in some cases to a program crash if not enough is available.
|
||||
Other patterns may take a very long time to search for all possible matching
|
||||
strings. The <b>pcre_exec()</b> function that is called by <b>pcregrep</b> to do
|
||||
the matching has two parameters that can limit the resources that it uses.
|
||||
<br>
|
||||
<br>
|
||||
The <b>--match-limit</b> option provides a means of limiting resource usage
|
||||
when processing patterns that are not going to match, but which have a very
|
||||
large number of possibilities in their search trees. The classic example is a
|
||||
pattern that uses nested unlimited repeats. Internally, PCRE uses a function
|
||||
called <b>match()</b> which it calls repeatedly (sometimes recursively). The
|
||||
limit set by <b>--match-limit</b> is imposed on the number of times this
|
||||
function is called during a match, which has the effect of limiting the amount
|
||||
of backtracking that can take place.
|
||||
<br>
|
||||
<br>
|
||||
The <b>--recursion-limit</b> option is similar to <b>--match-limit</b>, but
|
||||
instead of limiting the total number of times that <b>match()</b> is called, it
|
||||
limits the depth of recursive calls, which in turn limits the amount of memory
|
||||
that can be used. The recursion depth is a smaller number than the total number
|
||||
of calls, because not all calls to <b>match()</b> are recursive. This limit is
|
||||
of use only if it is set smaller than <b>--match-limit</b>.
|
||||
<br>
|
||||
<br>
|
||||
There are no short forms for these options. The default settings are specified
|
||||
when the PCRE library is compiled, with the default default being 10 million.
|
||||
</P>
|
||||
<P>
|
||||
<b>-M</b>, <b>--multiline</b>
|
||||
Allow patterns to match more than one line. When this option is given, patterns
|
||||
may usefully contain literal newline characters and internal occurrences of ^
|
||||
and $ characters. The output for a successful match may consist of more than
|
||||
one line, the last of which is the one in which the match ended. If the matched
|
||||
string ends with a newline sequence the output ends at the end of that line.
|
||||
<br>
|
||||
<br>
|
||||
When this option is set, the PCRE library is called in "multiline" mode.
|
||||
There is a limit to the number of lines that can be matched, imposed by the way
|
||||
that <b>pcregrep</b> buffers the input file as it scans it. However,
|
||||
<b>pcregrep</b> ensures that at least 8K characters or the rest of the document
|
||||
(whichever is the shorter) are available for forward matching, and similarly
|
||||
the previous 8K characters (or all the previous characters, if fewer than 8K)
|
||||
are guaranteed to be available for lookbehind assertions. This option does not
|
||||
work when input is read line by line (see \fP--line-buffered\fP.)
|
||||
</P>
|
||||
<P>
|
||||
<b>-N</b> <i>newline-type</i>, <b>--newline</b>=<i>newline-type</i>
|
||||
The PCRE library supports five different conventions for indicating
|
||||
the ends of lines. They are the single-character sequences CR (carriage return)
|
||||
and LF (linefeed), the two-character sequence CRLF, an "anycrlf" convention,
|
||||
which recognizes any of the preceding three types, and an "any" convention, in
|
||||
which any Unicode line ending sequence is assumed to end a line. The Unicode
|
||||
sequences are the three just mentioned, plus VT (vertical tab, U+000B), FF
|
||||
(form feed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and
|
||||
PS (paragraph separator, U+2029).
|
||||
<br>
|
||||
<br>
|
||||
When the PCRE library is built, a default line-ending sequence is specified.
|
||||
This is normally the standard sequence for the operating system. Unless
|
||||
otherwise specified by this option, <b>pcregrep</b> uses the library's default.
|
||||
The possible values for this option are CR, LF, CRLF, ANYCRLF, or ANY. This
|
||||
makes it possible to use <b>pcregrep</b> to scan files that have come from other
|
||||
environments without having to modify their line endings. If the data that is
|
||||
being scanned does not agree with the convention set by this option,
|
||||
<b>pcregrep</b> may behave in strange ways. Note that this option does not
|
||||
apply to files specified by the <b>-f</b>, <b>--exclude-from</b>, or
|
||||
<b>--include-from</b> options, which are expected to use the operating system's
|
||||
standard newline sequence.
|
||||
</P>
|
||||
<P>
|
||||
<b>-n</b>, <b>--line-number</b>
|
||||
Precede each output line by its line number in the file, followed by a colon
|
||||
for matching lines or a hyphen for context lines. If the filename is also being
|
||||
output, it precedes the line number. This option is forced if
|
||||
<b>--line-offsets</b> is used.
|
||||
</P>
|
||||
<P>
|
||||
<b>--no-jit</b>
|
||||
If the PCRE library is built with support for just-in-time compiling (which
|
||||
speeds up matching), <b>pcregrep</b> automatically makes use of this, unless it
|
||||
was explicitly disabled at build time. This option can be used to disable the
|
||||
use of JIT at run time. It is provided for testing and working round problems.
|
||||
It should never be needed in normal use.
|
||||
</P>
|
||||
<P>
|
||||
<b>-o</b>, <b>--only-matching</b>
|
||||
Show only the part of the line that matched a pattern instead of the whole
|
||||
line. In this mode, no context is shown. That is, the <b>-A</b>, <b>-B</b>, and
|
||||
<b>-C</b> options are ignored. If there is more than one match in a line, each
|
||||
of them is shown separately. If <b>-o</b> is combined with <b>-v</b> (invert the
|
||||
sense of the match to find non-matching lines), no output is generated, but the
|
||||
return code is set appropriately. If the matched portion of the line is empty,
|
||||
nothing is output unless the file name or line number are being printed, in
|
||||
which case they are shown on an otherwise empty line. This option is mutually
|
||||
exclusive with <b>--file-offsets</b> and <b>--line-offsets</b>.
|
||||
</P>
|
||||
<P>
|
||||
<b>-o</b><i>number</i>, <b>--only-matching</b>=<i>number</i>
|
||||
Show only the part of the line that matched the capturing parentheses of the
|
||||
given number. Up to 32 capturing parentheses are supported, and -o0 is
|
||||
equivalent to <b>-o</b> without a number. Because these options can be given
|
||||
without an argument (see above), if an argument is present, it must be given in
|
||||
the same shell item, for example, -o3 or --only-matching=2. The comments given
|
||||
for the non-argument case above also apply to this case. If the specified
|
||||
capturing parentheses do not exist in the pattern, or were not set in the
|
||||
match, nothing is output unless the file name or line number are being printed.
|
||||
<br>
|
||||
<br>
|
||||
If this option is given multiple times, multiple substrings are output, in the
|
||||
order the options are given. For example, -o3 -o1 -o3 causes the substrings
|
||||
matched by capturing parentheses 3 and 1 and then 3 again to be output. By
|
||||
default, there is no separator (but see the next option).
|
||||
</P>
|
||||
<P>
|
||||
<b>--om-separator</b>=<i>text</i>
|
||||
Specify a separating string for multiple occurrences of <b>-o</b>. The default
|
||||
is an empty string. Separating strings are never coloured.
|
||||
</P>
|
||||
<P>
|
||||
<b>-q</b>, <b>--quiet</b>
|
||||
Work quietly, that is, display nothing except error messages. The exit
|
||||
status indicates whether or not any matches were found.
|
||||
</P>
|
||||
<P>
|
||||
<b>-r</b>, <b>--recursive</b>
|
||||
If any given path is a directory, recursively scan the files it contains,
|
||||
taking note of any <b>--include</b> and <b>--exclude</b> settings. By default, a
|
||||
directory is read as a normal file; in some operating systems this gives an
|
||||
immediate end-of-file. This option is a shorthand for setting the <b>-d</b>
|
||||
option to "recurse".
|
||||
</P>
|
||||
<P>
|
||||
<b>--recursion-limit</b>=<i>number</i>
|
||||
See <b>--match-limit</b> above.
|
||||
</P>
|
||||
<P>
|
||||
<b>-s</b>, <b>--no-messages</b>
|
||||
Suppress error messages about non-existent or unreadable files. Such files are
|
||||
quietly skipped. However, the return code is still 2, even if matches were
|
||||
found in other files.
|
||||
</P>
|
||||
<P>
|
||||
<b>-u</b>, <b>--utf-8</b>
|
||||
Operate in UTF-8 mode. This option is available only if PCRE has been compiled
|
||||
with UTF-8 support. All patterns (including those for any <b>--exclude</b> and
|
||||
<b>--include</b> options) and all subject lines that are scanned must be valid
|
||||
strings of UTF-8 characters.
|
||||
</P>
|
||||
<P>
|
||||
<b>-V</b>, <b>--version</b>
|
||||
Write the version numbers of <b>pcregrep</b> and the PCRE library to the
|
||||
standard output and then exit. Anything else on the command line is
|
||||
ignored.
|
||||
</P>
|
||||
<P>
|
||||
<b>-v</b>, <b>--invert-match</b>
|
||||
Invert the sense of the match, so that lines which do <i>not</i> match any of
|
||||
the patterns are the ones that are found.
|
||||
</P>
|
||||
<P>
|
||||
<b>-w</b>, <b>--word-regex</b>, <b>--word-regexp</b>
|
||||
Force the patterns to match only whole words. This is equivalent to having \b
|
||||
at the start and end of the pattern. This option applies only to the patterns
|
||||
that are matched against the contents of files; it does not apply to patterns
|
||||
specified by any of the <b>--include</b> or <b>--exclude</b> options.
|
||||
</P>
|
||||
<P>
|
||||
<b>-x</b>, <b>--line-regex</b>, <b>--line-regexp</b>
|
||||
Force the patterns to be anchored (each must start matching at the beginning of
|
||||
a line) and in addition, require them to match entire lines. This is equivalent
|
||||
to having ^ and $ characters at the start and end of each alternative branch in
|
||||
every pattern. This option applies only to the patterns that are matched
|
||||
against the contents of files; it does not apply to patterns specified by any
|
||||
of the <b>--include</b> or <b>--exclude</b> options.
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">ENVIRONMENT VARIABLES</a><br>
|
||||
<P>
|
||||
The environment variables <b>LC_ALL</b> and <b>LC_CTYPE</b> are examined, in that
|
||||
order, for a locale. The first one that is set is used. This can be overridden
|
||||
by the <b>--locale</b> option. If no locale is set, the PCRE library's default
|
||||
(usually the "C" locale) is used.
|
||||
</P>
|
||||
<br><a name="SEC7" href="#TOC1">NEWLINES</a><br>
|
||||
<P>
|
||||
The <b>-N</b> (<b>--newline</b>) option allows <b>pcregrep</b> to scan files with
|
||||
different newline conventions from the default. Any parts of the input files
|
||||
that are written to the standard output are copied identically, with whatever
|
||||
newline sequences they have in the input. However, the setting of this option
|
||||
does not affect the interpretation of files specified by the <b>-f</b>,
|
||||
<b>--exclude-from</b>, or <b>--include-from</b> options, which are assumed to use
|
||||
the operating system's standard newline sequence, nor does it affect the way in
|
||||
which <b>pcregrep</b> writes informational messages to the standard error and
|
||||
output streams. For these it uses the string "\n" to indicate newlines,
|
||||
relying on the C I/O library to convert this to an appropriate sequence.
|
||||
</P>
|
||||
<br><a name="SEC8" href="#TOC1">OPTIONS COMPATIBILITY</a><br>
|
||||
<P>
|
||||
Many of the short and long forms of <b>pcregrep</b>'s options are the same
|
||||
as in the GNU <b>grep</b> program. Any long option of the form
|
||||
<b>--xxx-regexp</b> (GNU terminology) is also available as <b>--xxx-regex</b>
|
||||
(PCRE terminology). However, the <b>--file-list</b>, <b>--file-offsets</b>,
|
||||
<b>--include-dir</b>, <b>--line-offsets</b>, <b>--locale</b>, <b>--match-limit</b>,
|
||||
<b>-M</b>, <b>--multiline</b>, <b>-N</b>, <b>--newline</b>, <b>--om-separator</b>,
|
||||
<b>--recursion-limit</b>, <b>-u</b>, and <b>--utf-8</b> options are specific to
|
||||
<b>pcregrep</b>, as is the use of the <b>--only-matching</b> option with a
|
||||
capturing parentheses number.
|
||||
</P>
|
||||
<P>
|
||||
Although most of the common options work the same way, a few are different in
|
||||
<b>pcregrep</b>. For example, the <b>--include</b> option's argument is a glob
|
||||
for GNU <b>grep</b>, but a regular expression for <b>pcregrep</b>. If both the
|
||||
<b>-c</b> and <b>-l</b> options are given, GNU grep lists only file names,
|
||||
without counts, but <b>pcregrep</b> gives the counts.
|
||||
</P>
|
||||
<br><a name="SEC9" href="#TOC1">OPTIONS WITH DATA</a><br>
|
||||
<P>
|
||||
There are four different ways in which an option with data can be specified.
|
||||
If a short form option is used, the data may follow immediately, or (with one
|
||||
exception) in the next command line item. For example:
|
||||
<pre>
|
||||
-f/some/file
|
||||
-f /some/file
|
||||
</pre>
|
||||
The exception is the <b>-o</b> option, which may appear with or without data.
|
||||
Because of this, if data is present, it must follow immediately in the same
|
||||
item, for example -o3.
|
||||
</P>
|
||||
<P>
|
||||
If a long form option is used, the data may appear in the same command line
|
||||
item, separated by an equals character, or (with two exceptions) it may appear
|
||||
in the next command line item. For example:
|
||||
<pre>
|
||||
--file=/some/file
|
||||
--file /some/file
|
||||
</pre>
|
||||
Note, however, that if you want to supply a file name beginning with ~ as data
|
||||
in a shell command, and have the shell expand ~ to a home directory, you must
|
||||
separate the file name from the option, because the shell does not treat ~
|
||||
specially unless it is at the start of an item.
|
||||
</P>
|
||||
<P>
|
||||
The exceptions to the above are the <b>--colour</b> (or <b>--color</b>) and
|
||||
<b>--only-matching</b> options, for which the data is optional. If one of these
|
||||
options does have data, it must be given in the first form, using an equals
|
||||
character. Otherwise <b>pcregrep</b> will assume that it has no data.
|
||||
</P>
|
||||
<br><a name="SEC10" href="#TOC1">MATCHING ERRORS</a><br>
|
||||
<P>
|
||||
It is possible to supply a regular expression that takes a very long time to
|
||||
fail to match certain lines. Such patterns normally involve nested indefinite
|
||||
repeats, for example: (a+)*\d when matched against a line of a's with no final
|
||||
digit. The PCRE matching function has a resource limit that causes it to abort
|
||||
in these circumstances. If this happens, <b>pcregrep</b> outputs an error
|
||||
message and the line that caused the problem to the standard error stream. If
|
||||
there are more than 20 such errors, <b>pcregrep</b> gives up.
|
||||
</P>
|
||||
<P>
|
||||
The <b>--match-limit</b> option of <b>pcregrep</b> can be used to set the overall
|
||||
resource limit; there is a second option called <b>--recursion-limit</b> that
|
||||
sets a limit on the amount of memory (usually stack) that is used (see the
|
||||
discussion of these options above).
|
||||
</P>
|
||||
<br><a name="SEC11" href="#TOC1">DIAGNOSTICS</a><br>
|
||||
<P>
|
||||
Exit status is 0 if any matches were found, 1 if no matches were found, and 2
|
||||
for syntax errors, overlong lines, non-existent or inaccessible files (even if
|
||||
matches were found in other files) or too many matching errors. Using the
|
||||
<b>-s</b> option to suppress error messages about inaccessible files does not
|
||||
affect the return code.
|
||||
</P>
|
||||
<br><a name="SEC12" href="#TOC1">SEE ALSO</a><br>
|
||||
<P>
|
||||
<b>pcrepattern</b>(3), <b>pcresyntax</b>(3), <b>pcretest</b>(1).
|
||||
</P>
|
||||
<br><a name="SEC13" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC14" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 03 April 2014
|
||||
<br>
|
||||
Copyright © 1997-2014 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,499 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcrejit specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcrejit man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">PCRE JUST-IN-TIME COMPILER SUPPORT</a>
|
||||
<li><a name="TOC2" href="#SEC2">8-BIT, 16-BIT AND 32-BIT SUPPORT</a>
|
||||
<li><a name="TOC3" href="#SEC3">AVAILABILITY OF JIT SUPPORT</a>
|
||||
<li><a name="TOC4" href="#SEC4">SIMPLE USE OF JIT</a>
|
||||
<li><a name="TOC5" href="#SEC5">UNSUPPORTED OPTIONS AND PATTERN ITEMS</a>
|
||||
<li><a name="TOC6" href="#SEC6">RETURN VALUES FROM JIT EXECUTION</a>
|
||||
<li><a name="TOC7" href="#SEC7">SAVING AND RESTORING COMPILED PATTERNS</a>
|
||||
<li><a name="TOC8" href="#SEC8">CONTROLLING THE JIT STACK</a>
|
||||
<li><a name="TOC9" href="#SEC9">JIT STACK FAQ</a>
|
||||
<li><a name="TOC10" href="#SEC10">EXAMPLE CODE</a>
|
||||
<li><a name="TOC11" href="#SEC11">JIT FAST PATH API</a>
|
||||
<li><a name="TOC12" href="#SEC12">SEE ALSO</a>
|
||||
<li><a name="TOC13" href="#SEC13">AUTHOR</a>
|
||||
<li><a name="TOC14" href="#SEC14">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">PCRE JUST-IN-TIME COMPILER SUPPORT</a><br>
|
||||
<P>
|
||||
Just-in-time compiling is a heavyweight optimization that can greatly speed up
|
||||
pattern matching. However, it comes at the cost of extra processing before the
|
||||
match is performed. Therefore, it is of most benefit when the same pattern is
|
||||
going to be matched many times. This does not necessarily mean many calls of a
|
||||
matching function; if the pattern is not anchored, matching attempts may take
|
||||
place many times at various positions in the subject, even for a single call.
|
||||
Therefore, if the subject string is very long, it may still pay to use JIT for
|
||||
one-off matches.
|
||||
</P>
|
||||
<P>
|
||||
JIT support applies only to the traditional Perl-compatible matching function.
|
||||
It does not apply when the DFA matching function is being used. The code for
|
||||
this support was written by Zoltan Herczeg.
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">8-BIT, 16-BIT AND 32-BIT SUPPORT</a><br>
|
||||
<P>
|
||||
JIT support is available for all of the 8-bit, 16-bit and 32-bit PCRE
|
||||
libraries. To keep this documentation simple, only the 8-bit interface is
|
||||
described in what follows. If you are using the 16-bit library, substitute the
|
||||
16-bit functions and 16-bit structures (for example, <i>pcre16_jit_stack</i>
|
||||
instead of <i>pcre_jit_stack</i>). If you are using the 32-bit library,
|
||||
substitute the 32-bit functions and 32-bit structures (for example,
|
||||
<i>pcre32_jit_stack</i> instead of <i>pcre_jit_stack</i>).
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">AVAILABILITY OF JIT SUPPORT</a><br>
|
||||
<P>
|
||||
JIT support is an optional feature of PCRE. The "configure" option --enable-jit
|
||||
(or equivalent CMake option) must be set when PCRE is built if you want to use
|
||||
JIT. The support is limited to the following hardware platforms:
|
||||
<pre>
|
||||
ARM v5, v7, and Thumb2
|
||||
Intel x86 32-bit and 64-bit
|
||||
MIPS 32-bit
|
||||
Power PC 32-bit and 64-bit
|
||||
SPARC 32-bit (experimental)
|
||||
</pre>
|
||||
If --enable-jit is set on an unsupported platform, compilation fails.
|
||||
</P>
|
||||
<P>
|
||||
A program that is linked with PCRE 8.20 or later can tell if JIT support is
|
||||
available by calling <b>pcre_config()</b> with the PCRE_CONFIG_JIT option. The
|
||||
result is 1 when JIT is available, and 0 otherwise. However, a simple program
|
||||
does not need to check this in order to use JIT. The normal API is implemented
|
||||
in a way that falls back to the interpretive code if JIT is not available. For
|
||||
programs that need the best possible performance, there is also a "fast path"
|
||||
API that is JIT-specific.
|
||||
</P>
|
||||
<P>
|
||||
If your program may sometimes be linked with versions of PCRE that are older
|
||||
than 8.20, but you want to use JIT when it is available, you can test the
|
||||
values of PCRE_MAJOR and PCRE_MINOR, or the existence of a JIT macro such as
|
||||
PCRE_CONFIG_JIT, for compile-time control of your code. Also beware that the
|
||||
<b>pcre_jit_exec()</b> function was not available at all before 8.32,
|
||||
and may not be available at all if PCRE isn't compiled with
|
||||
--enable-jit. See the "JIT FAST PATH API" section below for details.
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">SIMPLE USE OF JIT</a><br>
|
||||
<P>
|
||||
You have to do two things to make use of the JIT support in the simplest way:
|
||||
<pre>
|
||||
(1) Call <b>pcre_study()</b> with the PCRE_STUDY_JIT_COMPILE option for
|
||||
each compiled pattern, and pass the resulting <b>pcre_extra</b> block to
|
||||
<b>pcre_exec()</b>.
|
||||
|
||||
(2) Use <b>pcre_free_study()</b> to free the <b>pcre_extra</b> block when it is
|
||||
no longer needed, instead of just freeing it yourself. This ensures that
|
||||
any JIT data is also freed.
|
||||
</pre>
|
||||
For a program that may be linked with pre-8.20 versions of PCRE, you can insert
|
||||
<pre>
|
||||
#ifndef PCRE_STUDY_JIT_COMPILE
|
||||
#define PCRE_STUDY_JIT_COMPILE 0
|
||||
#endif
|
||||
</pre>
|
||||
so that no option is passed to <b>pcre_study()</b>, and then use something like
|
||||
this to free the study data:
|
||||
<pre>
|
||||
#ifdef PCRE_CONFIG_JIT
|
||||
pcre_free_study(study_ptr);
|
||||
#else
|
||||
pcre_free(study_ptr);
|
||||
#endif
|
||||
</pre>
|
||||
PCRE_STUDY_JIT_COMPILE requests the JIT compiler to generate code for complete
|
||||
matches. If you want to run partial matches using the PCRE_PARTIAL_HARD or
|
||||
PCRE_PARTIAL_SOFT options of <b>pcre_exec()</b>, you should set one or both of
|
||||
the following options in addition to, or instead of, PCRE_STUDY_JIT_COMPILE
|
||||
when you call <b>pcre_study()</b>:
|
||||
<pre>
|
||||
PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
|
||||
PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
|
||||
</pre>
|
||||
If using <b>pcre_jit_exec()</b> and supporting a pre-8.32 version of
|
||||
PCRE, you can insert:
|
||||
<pre>
|
||||
#if PCRE_MAJOR >= 8 && PCRE_MINOR >= 32
|
||||
pcre_jit_exec(...);
|
||||
#else
|
||||
pcre_exec(...)
|
||||
#endif
|
||||
</pre>
|
||||
but as described in the "JIT FAST PATH API" section below this assumes
|
||||
version 8.32 and later are compiled with --enable-jit, which may
|
||||
break.
|
||||
<br>
|
||||
<br>
|
||||
The JIT compiler generates different optimized code for each of the three
|
||||
modes (normal, soft partial, hard partial). When <b>pcre_exec()</b> is called,
|
||||
the appropriate code is run if it is available. Otherwise, the pattern is
|
||||
matched using interpretive code.
|
||||
</P>
|
||||
<P>
|
||||
In some circumstances you may need to call additional functions. These are
|
||||
described in the section entitled
|
||||
<a href="#stackcontrol">"Controlling the JIT stack"</a>
|
||||
below.
|
||||
</P>
|
||||
<P>
|
||||
If JIT support is not available, PCRE_STUDY_JIT_COMPILE etc. are ignored, and
|
||||
no JIT data is created. Otherwise, the compiled pattern is passed to the JIT
|
||||
compiler, which turns it into machine code that executes much faster than the
|
||||
normal interpretive code. When <b>pcre_exec()</b> is passed a <b>pcre_extra</b>
|
||||
block containing a pointer to JIT code of the appropriate mode (normal or
|
||||
hard/soft partial), it obeys that code instead of running the interpreter. The
|
||||
result is identical, but the compiled JIT code runs much faster.
|
||||
</P>
|
||||
<P>
|
||||
There are some <b>pcre_exec()</b> options that are not supported for JIT
|
||||
execution. There are also some pattern items that JIT cannot handle. Details
|
||||
are given below. In both cases, execution automatically falls back to the
|
||||
interpretive code. If you want to know whether JIT was actually used for a
|
||||
particular match, you should arrange for a JIT callback function to be set up
|
||||
as described in the section entitled
|
||||
<a href="#stackcontrol">"Controlling the JIT stack"</a>
|
||||
below, even if you do not need to supply a non-default JIT stack. Such a
|
||||
callback function is called whenever JIT code is about to be obeyed. If the
|
||||
execution options are not right for JIT execution, the callback function is not
|
||||
obeyed.
|
||||
</P>
|
||||
<P>
|
||||
If the JIT compiler finds an unsupported item, no JIT data is generated. You
|
||||
can find out if JIT execution is available after studying a pattern by calling
|
||||
<b>pcre_fullinfo()</b> with the PCRE_INFO_JIT option. A result of 1 means that
|
||||
JIT compilation was successful. A result of 0 means that JIT support is not
|
||||
available, or the pattern was not studied with PCRE_STUDY_JIT_COMPILE etc., or
|
||||
the JIT compiler was not able to handle the pattern.
|
||||
</P>
|
||||
<P>
|
||||
Once a pattern has been studied, with or without JIT, it can be used as many
|
||||
times as you like for matching different subject strings.
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">UNSUPPORTED OPTIONS AND PATTERN ITEMS</a><br>
|
||||
<P>
|
||||
The only <b>pcre_exec()</b> options that are supported for JIT execution are
|
||||
PCRE_NO_UTF8_CHECK, PCRE_NO_UTF16_CHECK, PCRE_NO_UTF32_CHECK, PCRE_NOTBOL,
|
||||
PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and
|
||||
PCRE_PARTIAL_SOFT.
|
||||
</P>
|
||||
<P>
|
||||
The only unsupported pattern items are \C (match a single data unit) when
|
||||
running in a UTF mode, and a callout immediately before an assertion condition
|
||||
in a conditional group.
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">RETURN VALUES FROM JIT EXECUTION</a><br>
|
||||
<P>
|
||||
When a pattern is matched using JIT execution, the return values are the same
|
||||
as those given by the interpretive <b>pcre_exec()</b> code, with the addition of
|
||||
one new error code: PCRE_ERROR_JIT_STACKLIMIT. This means that the memory used
|
||||
for the JIT stack was insufficient. See
|
||||
<a href="#stackcontrol">"Controlling the JIT stack"</a>
|
||||
below for a discussion of JIT stack usage. For compatibility with the
|
||||
interpretive <b>pcre_exec()</b> code, no more than two-thirds of the
|
||||
<i>ovector</i> argument is used for passing back captured substrings.
|
||||
</P>
|
||||
<P>
|
||||
The error code PCRE_ERROR_MATCHLIMIT is returned by the JIT code if searching a
|
||||
very large pattern tree goes on for too long, as it is in the same circumstance
|
||||
when JIT is not used, but the details of exactly what is counted are not the
|
||||
same. The PCRE_ERROR_RECURSIONLIMIT error code is never returned by JIT
|
||||
execution.
|
||||
</P>
|
||||
<br><a name="SEC7" href="#TOC1">SAVING AND RESTORING COMPILED PATTERNS</a><br>
|
||||
<P>
|
||||
The code that is generated by the JIT compiler is architecture-specific, and is
|
||||
also position dependent. For those reasons it cannot be saved (in a file or
|
||||
database) and restored later like the bytecode and other data of a compiled
|
||||
pattern. Saving and restoring compiled patterns is not something many people
|
||||
do. More detail about this facility is given in the
|
||||
<a href="pcreprecompile.html"><b>pcreprecompile</b></a>
|
||||
documentation. It should be possible to run <b>pcre_study()</b> on a saved and
|
||||
restored pattern, and thereby recreate the JIT data, but because JIT
|
||||
compilation uses significant resources, it is probably not worth doing this;
|
||||
you might as well recompile the original pattern.
|
||||
<a name="stackcontrol"></a></P>
|
||||
<br><a name="SEC8" href="#TOC1">CONTROLLING THE JIT STACK</a><br>
|
||||
<P>
|
||||
When the compiled JIT code runs, it needs a block of memory to use as a stack.
|
||||
By default, it uses 32K on the machine stack. However, some large or
|
||||
complicated patterns need more than this. The error PCRE_ERROR_JIT_STACKLIMIT
|
||||
is given when there is not enough stack. Three functions are provided for
|
||||
managing blocks of memory for use as JIT stacks. There is further discussion
|
||||
about the use of JIT stacks in the section entitled
|
||||
<a href="#stackcontrol">"JIT stack FAQ"</a>
|
||||
below.
|
||||
</P>
|
||||
<P>
|
||||
The <b>pcre_jit_stack_alloc()</b> function creates a JIT stack. Its arguments
|
||||
are a starting size and a maximum size, and it returns a pointer to an opaque
|
||||
structure of type <b>pcre_jit_stack</b>, or NULL if there is an error. The
|
||||
<b>pcre_jit_stack_free()</b> function can be used to free a stack that is no
|
||||
longer needed. (For the technically minded: the address space is allocated by
|
||||
mmap or VirtualAlloc.)
|
||||
</P>
|
||||
<P>
|
||||
JIT uses far less memory for recursion than the interpretive code,
|
||||
and a maximum stack size of 512K to 1M should be more than enough for any
|
||||
pattern.
|
||||
</P>
|
||||
<P>
|
||||
The <b>pcre_assign_jit_stack()</b> function specifies which stack JIT code
|
||||
should use. Its arguments are as follows:
|
||||
<pre>
|
||||
pcre_extra *extra
|
||||
pcre_jit_callback callback
|
||||
void *data
|
||||
</pre>
|
||||
The <i>extra</i> argument must be the result of studying a pattern with
|
||||
PCRE_STUDY_JIT_COMPILE etc. There are three cases for the values of the other
|
||||
two options:
|
||||
<pre>
|
||||
(1) If <i>callback</i> is NULL and <i>data</i> is NULL, an internal 32K block
|
||||
on the machine stack is used.
|
||||
|
||||
(2) If <i>callback</i> is NULL and <i>data</i> is not NULL, <i>data</i> must be
|
||||
a valid JIT stack, the result of calling <b>pcre_jit_stack_alloc()</b>.
|
||||
|
||||
(3) If <i>callback</i> is not NULL, it must point to a function that is
|
||||
called with <i>data</i> as an argument at the start of matching, in
|
||||
order to set up a JIT stack. If the return from the callback
|
||||
function is NULL, the internal 32K stack is used; otherwise the
|
||||
return value must be a valid JIT stack, the result of calling
|
||||
<b>pcre_jit_stack_alloc()</b>.
|
||||
</pre>
|
||||
A callback function is obeyed whenever JIT code is about to be run; it is not
|
||||
obeyed when <b>pcre_exec()</b> is called with options that are incompatible for
|
||||
JIT execution. A callback function can therefore be used to determine whether a
|
||||
match operation was executed by JIT or by the interpreter.
|
||||
</P>
|
||||
<P>
|
||||
You may safely use the same JIT stack for more than one pattern (either by
|
||||
assigning directly or by callback), as long as the patterns are all matched
|
||||
sequentially in the same thread. In a multithread application, if you do not
|
||||
specify a JIT stack, or if you assign or pass back NULL from a callback, that
|
||||
is thread-safe, because each thread has its own machine stack. However, if you
|
||||
assign or pass back a non-NULL JIT stack, this must be a different stack for
|
||||
each thread so that the application is thread-safe.
|
||||
</P>
|
||||
<P>
|
||||
Strictly speaking, even more is allowed. You can assign the same non-NULL stack
|
||||
to any number of patterns as long as they are not used for matching by multiple
|
||||
threads at the same time. For example, you can assign the same stack to all
|
||||
compiled patterns, and use a global mutex in the callback to wait until the
|
||||
stack is available for use. However, this is an inefficient solution, and not
|
||||
recommended.
|
||||
</P>
|
||||
<P>
|
||||
This is a suggestion for how a multithreaded program that needs to set up
|
||||
non-default JIT stacks might operate:
|
||||
<pre>
|
||||
During thread initalization
|
||||
thread_local_var = pcre_jit_stack_alloc(...)
|
||||
|
||||
During thread exit
|
||||
pcre_jit_stack_free(thread_local_var)
|
||||
|
||||
Use a one-line callback function
|
||||
return thread_local_var
|
||||
</pre>
|
||||
All the functions described in this section do nothing if JIT is not available,
|
||||
and <b>pcre_assign_jit_stack()</b> does nothing unless the <b>extra</b> argument
|
||||
is non-NULL and points to a <b>pcre_extra</b> block that is the result of a
|
||||
successful study with PCRE_STUDY_JIT_COMPILE etc.
|
||||
<a name="stackfaq"></a></P>
|
||||
<br><a name="SEC9" href="#TOC1">JIT STACK FAQ</a><br>
|
||||
<P>
|
||||
(1) Why do we need JIT stacks?
|
||||
<br>
|
||||
<br>
|
||||
PCRE (and JIT) is a recursive, depth-first engine, so it needs a stack where
|
||||
the local data of the current node is pushed before checking its child nodes.
|
||||
Allocating real machine stack on some platforms is difficult. For example, the
|
||||
stack chain needs to be updated every time if we extend the stack on PowerPC.
|
||||
Although it is possible, its updating time overhead decreases performance. So
|
||||
we do the recursion in memory.
|
||||
</P>
|
||||
<P>
|
||||
(2) Why don't we simply allocate blocks of memory with <b>malloc()</b>?
|
||||
<br>
|
||||
<br>
|
||||
Modern operating systems have a nice feature: they can reserve an address space
|
||||
instead of allocating memory. We can safely allocate memory pages inside this
|
||||
address space, so the stack could grow without moving memory data (this is
|
||||
important because of pointers). Thus we can allocate 1M address space, and use
|
||||
only a single memory page (usually 4K) if that is enough. However, we can still
|
||||
grow up to 1M anytime if needed.
|
||||
</P>
|
||||
<P>
|
||||
(3) Who "owns" a JIT stack?
|
||||
<br>
|
||||
<br>
|
||||
The owner of the stack is the user program, not the JIT studied pattern or
|
||||
anything else. The user program must ensure that if a stack is used by
|
||||
<b>pcre_exec()</b>, (that is, it is assigned to the pattern currently running),
|
||||
that stack must not be used by any other threads (to avoid overwriting the same
|
||||
memory area). The best practice for multithreaded programs is to allocate a
|
||||
stack for each thread, and return this stack through the JIT callback function.
|
||||
</P>
|
||||
<P>
|
||||
(4) When should a JIT stack be freed?
|
||||
<br>
|
||||
<br>
|
||||
You can free a JIT stack at any time, as long as it will not be used by
|
||||
<b>pcre_exec()</b> again. When you assign the stack to a pattern, only a pointer
|
||||
is set. There is no reference counting or any other magic. You can free the
|
||||
patterns and stacks in any order, anytime. Just <i>do not</i> call
|
||||
<b>pcre_exec()</b> with a pattern pointing to an already freed stack, as that
|
||||
will cause SEGFAULT. (Also, do not free a stack currently used by
|
||||
<b>pcre_exec()</b> in another thread). You can also replace the stack for a
|
||||
pattern at any time. You can even free the previous stack before assigning a
|
||||
replacement.
|
||||
</P>
|
||||
<P>
|
||||
(5) Should I allocate/free a stack every time before/after calling
|
||||
<b>pcre_exec()</b>?
|
||||
<br>
|
||||
<br>
|
||||
No, because this is too costly in terms of resources. However, you could
|
||||
implement some clever idea which release the stack if it is not used in let's
|
||||
say two minutes. The JIT callback can help to achieve this without keeping a
|
||||
list of the currently JIT studied patterns.
|
||||
</P>
|
||||
<P>
|
||||
(6) OK, the stack is for long term memory allocation. But what happens if a
|
||||
pattern causes stack overflow with a stack of 1M? Is that 1M kept until the
|
||||
stack is freed?
|
||||
<br>
|
||||
<br>
|
||||
Especially on embedded sytems, it might be a good idea to release memory
|
||||
sometimes without freeing the stack. There is no API for this at the moment.
|
||||
Probably a function call which returns with the currently allocated memory for
|
||||
any stack and another which allows releasing memory (shrinking the stack) would
|
||||
be a good idea if someone needs this.
|
||||
</P>
|
||||
<P>
|
||||
(7) This is too much of a headache. Isn't there any better solution for JIT
|
||||
stack handling?
|
||||
<br>
|
||||
<br>
|
||||
No, thanks to Windows. If POSIX threads were used everywhere, we could throw
|
||||
out this complicated API.
|
||||
</P>
|
||||
<br><a name="SEC10" href="#TOC1">EXAMPLE CODE</a><br>
|
||||
<P>
|
||||
This is a single-threaded example that specifies a JIT stack without using a
|
||||
callback.
|
||||
<pre>
|
||||
int rc;
|
||||
int ovector[30];
|
||||
pcre *re;
|
||||
pcre_extra *extra;
|
||||
pcre_jit_stack *jit_stack;
|
||||
|
||||
re = pcre_compile(pattern, 0, &error, &erroffset, NULL);
|
||||
/* Check for errors */
|
||||
extra = pcre_study(re, PCRE_STUDY_JIT_COMPILE, &error);
|
||||
jit_stack = pcre_jit_stack_alloc(32*1024, 512*1024);
|
||||
/* Check for error (NULL) */
|
||||
pcre_assign_jit_stack(extra, NULL, jit_stack);
|
||||
rc = pcre_exec(re, extra, subject, length, 0, 0, ovector, 30);
|
||||
/* Check results */
|
||||
pcre_free(re);
|
||||
pcre_free_study(extra);
|
||||
pcre_jit_stack_free(jit_stack);
|
||||
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC11" href="#TOC1">JIT FAST PATH API</a><br>
|
||||
<P>
|
||||
Because the API described above falls back to interpreted execution when JIT is
|
||||
not available, it is convenient for programs that are written for general use
|
||||
in many environments. However, calling JIT via <b>pcre_exec()</b> does have a
|
||||
performance impact. Programs that are written for use where JIT is known to be
|
||||
available, and which need the best possible performance, can instead use a
|
||||
"fast path" API to call JIT execution directly instead of calling
|
||||
<b>pcre_exec()</b> (obviously only for patterns that have been successfully
|
||||
studied by JIT).
|
||||
</P>
|
||||
<P>
|
||||
The fast path function is called <b>pcre_jit_exec()</b>, and it takes exactly
|
||||
the same arguments as <b>pcre_exec()</b>, plus one additional argument that
|
||||
must point to a JIT stack. The JIT stack arrangements described above do not
|
||||
apply. The return values are the same as for <b>pcre_exec()</b>.
|
||||
</P>
|
||||
<P>
|
||||
When you call <b>pcre_exec()</b>, as well as testing for invalid options, a
|
||||
number of other sanity checks are performed on the arguments. For example, if
|
||||
the subject pointer is NULL, or its length is negative, an immediate error is
|
||||
given. Also, unless PCRE_NO_UTF[8|16|32] is set, a UTF subject string is tested
|
||||
for validity. In the interests of speed, these checks do not happen on the JIT
|
||||
fast path, and if invalid data is passed, the result is undefined.
|
||||
</P>
|
||||
<P>
|
||||
Bypassing the sanity checks and the <b>pcre_exec()</b> wrapping can give
|
||||
speedups of more than 10%.
|
||||
</P>
|
||||
<P>
|
||||
Note that the <b>pcre_jit_exec()</b> function is not available in versions of
|
||||
PCRE before 8.32 (released in November 2012). If you need to support versions
|
||||
that old you must either use the slower <b>pcre_exec()</b>, or switch between
|
||||
the two codepaths by checking the values of PCRE_MAJOR and PCRE_MINOR.
|
||||
</P>
|
||||
<P>
|
||||
Due to an unfortunate implementation oversight, even in versions 8.32
|
||||
and later there will be no <b>pcre_jit_exec()</b> stub function defined
|
||||
when PCRE is compiled with --disable-jit, which is the default, and
|
||||
there's no way to detect whether PCRE was compiled with --enable-jit
|
||||
via a macro.
|
||||
</P>
|
||||
<P>
|
||||
If you need to support versions older than 8.32, or versions that may
|
||||
not build with --enable-jit, you must either use the slower
|
||||
<b>pcre_exec()</b>, or switch between the two codepaths by checking the
|
||||
values of PCRE_MAJOR and PCRE_MINOR.
|
||||
</P>
|
||||
<P>
|
||||
Switching between the two by checking the version assumes that all the
|
||||
versions being targeted are built with --enable-jit. To also support
|
||||
builds that may use --disable-jit either <b>pcre_exec()</b> must be
|
||||
used, or a compile-time check for JIT via <b>pcre_config()</b> (which
|
||||
assumes the runtime environment will be the same), or as the Git
|
||||
project decided to do, simply assume that <b>pcre_jit_exec()</b> is
|
||||
present in 8.32 or later unless a compile-time flag is provided, see
|
||||
the "grep: un-break building with PCRE >= 8.32 without --enable-jit"
|
||||
commit in git.git for an example of that.
|
||||
</P>
|
||||
<br><a name="SEC12" href="#TOC1">SEE ALSO</a><br>
|
||||
<P>
|
||||
<b>pcreapi</b>(3)
|
||||
</P>
|
||||
<br><a name="SEC13" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel (FAQ by Zoltan Herczeg)
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC14" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 05 July 2017
|
||||
<br>
|
||||
Copyright © 1997-2017 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,90 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcrelimits specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcrelimits man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
SIZE AND OTHER LIMITATIONS
|
||||
</b><br>
|
||||
<P>
|
||||
There are some size limitations in PCRE but it is hoped that they will never in
|
||||
practice be relevant.
|
||||
</P>
|
||||
<P>
|
||||
The maximum length of a compiled pattern is approximately 64K data units (bytes
|
||||
for the 8-bit library, 16-bit units for the 16-bit library, and 32-bit units for
|
||||
the 32-bit library) if PCRE is compiled with the default internal linkage size,
|
||||
which is 2 bytes for the 8-bit and 16-bit libraries, and 4 bytes for the 32-bit
|
||||
library. If you want to process regular expressions that are truly enormous,
|
||||
you can compile PCRE with an internal linkage size of 3 or 4 (when building the
|
||||
16-bit or 32-bit library, 3 is rounded up to 4). See the <b>README</b> file in
|
||||
the source distribution and the
|
||||
<a href="pcrebuild.html"><b>pcrebuild</b></a>
|
||||
documentation for details. In these cases the limit is substantially larger.
|
||||
However, the speed of execution is slower.
|
||||
</P>
|
||||
<P>
|
||||
All values in repeating quantifiers must be less than 65536.
|
||||
</P>
|
||||
<P>
|
||||
There is no limit to the number of parenthesized subpatterns, but there can be
|
||||
no more than 65535 capturing subpatterns. There is, however, a limit to the
|
||||
depth of nesting of parenthesized subpatterns of all kinds. This is imposed in
|
||||
order to limit the amount of system stack used at compile time. The limit can
|
||||
be specified when PCRE is built; the default is 250.
|
||||
</P>
|
||||
<P>
|
||||
There is a limit to the number of forward references to subsequent subpatterns
|
||||
of around 200,000. Repeated forward references with fixed upper limits, for
|
||||
example, (?2){0,100} when subpattern number 2 is to the right, are included in
|
||||
the count. There is no limit to the number of backward references.
|
||||
</P>
|
||||
<P>
|
||||
The maximum length of name for a named subpattern is 32 characters, and the
|
||||
maximum number of named subpatterns is 10000.
|
||||
</P>
|
||||
<P>
|
||||
The maximum length of a name in a (*MARK), (*PRUNE), (*SKIP), or (*THEN) verb
|
||||
is 255 for the 8-bit library and 65535 for the 16-bit and 32-bit libraries.
|
||||
</P>
|
||||
<P>
|
||||
The maximum length of a subject string is the largest positive number that an
|
||||
integer variable can hold. However, when using the traditional matching
|
||||
function, PCRE uses recursion to handle subpatterns and indefinite repetition.
|
||||
This means that the available stack space may limit the size of a subject
|
||||
string that can be processed by certain patterns. For a discussion of stack
|
||||
issues, see the
|
||||
<a href="pcrestack.html"><b>pcrestack</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<br><b>
|
||||
AUTHOR
|
||||
</b><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><b>
|
||||
REVISION
|
||||
</b><br>
|
||||
<P>
|
||||
Last updated: 05 November 2013
|
||||
<br>
|
||||
Copyright © 1997-2013 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,242 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcrematching specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcrematching man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">PCRE MATCHING ALGORITHMS</a>
|
||||
<li><a name="TOC2" href="#SEC2">REGULAR EXPRESSIONS AS TREES</a>
|
||||
<li><a name="TOC3" href="#SEC3">THE STANDARD MATCHING ALGORITHM</a>
|
||||
<li><a name="TOC4" href="#SEC4">THE ALTERNATIVE MATCHING ALGORITHM</a>
|
||||
<li><a name="TOC5" href="#SEC5">ADVANTAGES OF THE ALTERNATIVE ALGORITHM</a>
|
||||
<li><a name="TOC6" href="#SEC6">DISADVANTAGES OF THE ALTERNATIVE ALGORITHM</a>
|
||||
<li><a name="TOC7" href="#SEC7">AUTHOR</a>
|
||||
<li><a name="TOC8" href="#SEC8">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">PCRE MATCHING ALGORITHMS</a><br>
|
||||
<P>
|
||||
This document describes the two different algorithms that are available in PCRE
|
||||
for matching a compiled regular expression against a given subject string. The
|
||||
"standard" algorithm is the one provided by the <b>pcre_exec()</b>,
|
||||
<b>pcre16_exec()</b> and <b>pcre32_exec()</b> functions. These work in the same
|
||||
as as Perl's matching function, and provide a Perl-compatible matching operation.
|
||||
The just-in-time (JIT) optimization that is described in the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
documentation is compatible with these functions.
|
||||
</P>
|
||||
<P>
|
||||
An alternative algorithm is provided by the <b>pcre_dfa_exec()</b>,
|
||||
<b>pcre16_dfa_exec()</b> and <b>pcre32_dfa_exec()</b> functions; they operate in
|
||||
a different way, and are not Perl-compatible. This alternative has advantages
|
||||
and disadvantages compared with the standard algorithm, and these are described
|
||||
below.
|
||||
</P>
|
||||
<P>
|
||||
When there is only one possible way in which a given subject string can match a
|
||||
pattern, the two algorithms give the same answer. A difference arises, however,
|
||||
when there are multiple possibilities. For example, if the pattern
|
||||
<pre>
|
||||
^<.*>
|
||||
</pre>
|
||||
is matched against the string
|
||||
<pre>
|
||||
<something> <something else> <something further>
|
||||
</pre>
|
||||
there are three possible answers. The standard algorithm finds only one of
|
||||
them, whereas the alternative algorithm finds all three.
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">REGULAR EXPRESSIONS AS TREES</a><br>
|
||||
<P>
|
||||
The set of strings that are matched by a regular expression can be represented
|
||||
as a tree structure. An unlimited repetition in the pattern makes the tree of
|
||||
infinite size, but it is still a tree. Matching the pattern to a given subject
|
||||
string (from a given starting point) can be thought of as a search of the tree.
|
||||
There are two ways to search a tree: depth-first and breadth-first, and these
|
||||
correspond to the two matching algorithms provided by PCRE.
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">THE STANDARD MATCHING ALGORITHM</a><br>
|
||||
<P>
|
||||
In the terminology of Jeffrey Friedl's book "Mastering Regular
|
||||
Expressions", the standard algorithm is an "NFA algorithm". It conducts a
|
||||
depth-first search of the pattern tree. That is, it proceeds along a single
|
||||
path through the tree, checking that the subject matches what is required. When
|
||||
there is a mismatch, the algorithm tries any alternatives at the current point,
|
||||
and if they all fail, it backs up to the previous branch point in the tree, and
|
||||
tries the next alternative branch at that level. This often involves backing up
|
||||
(moving to the left) in the subject string as well. The order in which
|
||||
repetition branches are tried is controlled by the greedy or ungreedy nature of
|
||||
the quantifier.
|
||||
</P>
|
||||
<P>
|
||||
If a leaf node is reached, a matching string has been found, and at that point
|
||||
the algorithm stops. Thus, if there is more than one possible match, this
|
||||
algorithm returns the first one that it finds. Whether this is the shortest,
|
||||
the longest, or some intermediate length depends on the way the greedy and
|
||||
ungreedy repetition quantifiers are specified in the pattern.
|
||||
</P>
|
||||
<P>
|
||||
Because it ends up with a single path through the tree, it is relatively
|
||||
straightforward for this algorithm to keep track of the substrings that are
|
||||
matched by portions of the pattern in parentheses. This provides support for
|
||||
capturing parentheses and back references.
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">THE ALTERNATIVE MATCHING ALGORITHM</a><br>
|
||||
<P>
|
||||
This algorithm conducts a breadth-first search of the tree. Starting from the
|
||||
first matching point in the subject, it scans the subject string from left to
|
||||
right, once, character by character, and as it does this, it remembers all the
|
||||
paths through the tree that represent valid matches. In Friedl's terminology,
|
||||
this is a kind of "DFA algorithm", though it is not implemented as a
|
||||
traditional finite state machine (it keeps multiple states active
|
||||
simultaneously).
|
||||
</P>
|
||||
<P>
|
||||
Although the general principle of this matching algorithm is that it scans the
|
||||
subject string only once, without backtracking, there is one exception: when a
|
||||
lookaround assertion is encountered, the characters following or preceding the
|
||||
current point have to be independently inspected.
|
||||
</P>
|
||||
<P>
|
||||
The scan continues until either the end of the subject is reached, or there are
|
||||
no more unterminated paths. At this point, terminated paths represent the
|
||||
different matching possibilities (if there are none, the match has failed).
|
||||
Thus, if there is more than one possible match, this algorithm finds all of
|
||||
them, and in particular, it finds the longest. The matches are returned in
|
||||
decreasing order of length. There is an option to stop the algorithm after the
|
||||
first match (which is necessarily the shortest) is found.
|
||||
</P>
|
||||
<P>
|
||||
Note that all the matches that are found start at the same point in the
|
||||
subject. If the pattern
|
||||
<pre>
|
||||
cat(er(pillar)?)?
|
||||
</pre>
|
||||
is matched against the string "the caterpillar catchment", the result will be
|
||||
the three strings "caterpillar", "cater", and "cat" that start at the fifth
|
||||
character of the subject. The algorithm does not automatically move on to find
|
||||
matches that start at later positions.
|
||||
</P>
|
||||
<P>
|
||||
PCRE's "auto-possessification" optimization usually applies to character
|
||||
repeats at the end of a pattern (as well as internally). For example, the
|
||||
pattern "a\d+" is compiled as if it were "a\d++" because there is no point
|
||||
even considering the possibility of backtracking into the repeated digits. For
|
||||
DFA matching, this means that only one possible match is found. If you really
|
||||
do want multiple matches in such cases, either use an ungreedy repeat
|
||||
("a\d+?") or set the PCRE_NO_AUTO_POSSESS option when compiling.
|
||||
</P>
|
||||
<P>
|
||||
There are a number of features of PCRE regular expressions that are not
|
||||
supported by the alternative matching algorithm. They are as follows:
|
||||
</P>
|
||||
<P>
|
||||
1. Because the algorithm finds all possible matches, the greedy or ungreedy
|
||||
nature of repetition quantifiers is not relevant. Greedy and ungreedy
|
||||
quantifiers are treated in exactly the same way. However, possessive
|
||||
quantifiers can make a difference when what follows could also match what is
|
||||
quantified, for example in a pattern like this:
|
||||
<pre>
|
||||
^a++\w!
|
||||
</pre>
|
||||
This pattern matches "aaab!" but not "aaa!", which would be matched by a
|
||||
non-possessive quantifier. Similarly, if an atomic group is present, it is
|
||||
matched as if it were a standalone pattern at the current point, and the
|
||||
longest match is then "locked in" for the rest of the overall pattern.
|
||||
</P>
|
||||
<P>
|
||||
2. When dealing with multiple paths through the tree simultaneously, it is not
|
||||
straightforward to keep track of captured substrings for the different matching
|
||||
possibilities, and PCRE's implementation of this algorithm does not attempt to
|
||||
do this. This means that no captured substrings are available.
|
||||
</P>
|
||||
<P>
|
||||
3. Because no substrings are captured, back references within the pattern are
|
||||
not supported, and cause errors if encountered.
|
||||
</P>
|
||||
<P>
|
||||
4. For the same reason, conditional expressions that use a backreference as the
|
||||
condition or test for a specific group recursion are not supported.
|
||||
</P>
|
||||
<P>
|
||||
5. Because many paths through the tree may be active, the \K escape sequence,
|
||||
which resets the start of the match when encountered (but may be on some paths
|
||||
and not on others), is not supported. It causes an error if encountered.
|
||||
</P>
|
||||
<P>
|
||||
6. Callouts are supported, but the value of the <i>capture_top</i> field is
|
||||
always 1, and the value of the <i>capture_last</i> field is always -1.
|
||||
</P>
|
||||
<P>
|
||||
7. The \C escape sequence, which (in the standard algorithm) always matches a
|
||||
single data unit, even in UTF-8, UTF-16 or UTF-32 modes, is not supported in
|
||||
these modes, because the alternative algorithm moves through the subject string
|
||||
one character (not data unit) at a time, for all active paths through the tree.
|
||||
</P>
|
||||
<P>
|
||||
8. Except for (*FAIL), the backtracking control verbs such as (*PRUNE) are not
|
||||
supported. (*FAIL) is supported, and behaves like a failing negative assertion.
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">ADVANTAGES OF THE ALTERNATIVE ALGORITHM</a><br>
|
||||
<P>
|
||||
Using the alternative matching algorithm provides the following advantages:
|
||||
</P>
|
||||
<P>
|
||||
1. All possible matches (at a single point in the subject) are automatically
|
||||
found, and in particular, the longest match is found. To find more than one
|
||||
match using the standard algorithm, you have to do kludgy things with
|
||||
callouts.
|
||||
</P>
|
||||
<P>
|
||||
2. Because the alternative algorithm scans the subject string just once, and
|
||||
never needs to backtrack (except for lookbehinds), it is possible to pass very
|
||||
long subject strings to the matching function in several pieces, checking for
|
||||
partial matching each time. Although it is possible to do multi-segment
|
||||
matching using the standard algorithm by retaining partially matched
|
||||
substrings, it is more complicated. The
|
||||
<a href="pcrepartial.html"><b>pcrepartial</b></a>
|
||||
documentation gives details of partial matching and discusses multi-segment
|
||||
matching.
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">DISADVANTAGES OF THE ALTERNATIVE ALGORITHM</a><br>
|
||||
<P>
|
||||
The alternative algorithm suffers from a number of disadvantages:
|
||||
</P>
|
||||
<P>
|
||||
1. It is substantially slower than the standard algorithm. This is partly
|
||||
because it has to search for all possible matches, but is also because it is
|
||||
less susceptible to optimization.
|
||||
</P>
|
||||
<P>
|
||||
2. Capturing parentheses and back references are not supported.
|
||||
</P>
|
||||
<P>
|
||||
3. Although atomic groups are supported, their use does not provide the
|
||||
performance advantage that it does for the standard algorithm.
|
||||
</P>
|
||||
<br><a name="SEC7" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC8" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 12 November 2013
|
||||
<br>
|
||||
Copyright © 1997-2012 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,509 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcrepartial specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcrepartial man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">PARTIAL MATCHING IN PCRE</a>
|
||||
<li><a name="TOC2" href="#SEC2">PARTIAL MATCHING USING pcre_exec() OR pcre[16|32]_exec()</a>
|
||||
<li><a name="TOC3" href="#SEC3">PARTIAL MATCHING USING pcre_dfa_exec() OR pcre[16|32]_dfa_exec()</a>
|
||||
<li><a name="TOC4" href="#SEC4">PARTIAL MATCHING AND WORD BOUNDARIES</a>
|
||||
<li><a name="TOC5" href="#SEC5">FORMERLY RESTRICTED PATTERNS</a>
|
||||
<li><a name="TOC6" href="#SEC6">EXAMPLE OF PARTIAL MATCHING USING PCRETEST</a>
|
||||
<li><a name="TOC7" href="#SEC7">MULTI-SEGMENT MATCHING WITH pcre_dfa_exec() OR pcre[16|32]_dfa_exec()</a>
|
||||
<li><a name="TOC8" href="#SEC8">MULTI-SEGMENT MATCHING WITH pcre_exec() OR pcre[16|32]_exec()</a>
|
||||
<li><a name="TOC9" href="#SEC9">ISSUES WITH MULTI-SEGMENT MATCHING</a>
|
||||
<li><a name="TOC10" href="#SEC10">AUTHOR</a>
|
||||
<li><a name="TOC11" href="#SEC11">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">PARTIAL MATCHING IN PCRE</a><br>
|
||||
<P>
|
||||
In normal use of PCRE, if the subject string that is passed to a matching
|
||||
function matches as far as it goes, but is too short to match the entire
|
||||
pattern, PCRE_ERROR_NOMATCH is returned. There are circumstances where it might
|
||||
be helpful to distinguish this case from other cases in which there is no
|
||||
match.
|
||||
</P>
|
||||
<P>
|
||||
Consider, for example, an application where a human is required to type in data
|
||||
for a field with specific formatting requirements. An example might be a date
|
||||
in the form <i>ddmmmyy</i>, defined by this pattern:
|
||||
<pre>
|
||||
^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$
|
||||
</pre>
|
||||
If the application sees the user's keystrokes one by one, and can check that
|
||||
what has been typed so far is potentially valid, it is able to raise an error
|
||||
as soon as a mistake is made, by beeping and not reflecting the character that
|
||||
has been typed, for example. This immediate feedback is likely to be a better
|
||||
user interface than a check that is delayed until the entire string has been
|
||||
entered. Partial matching can also be useful when the subject string is very
|
||||
long and is not all available at once.
|
||||
</P>
|
||||
<P>
|
||||
PCRE supports partial matching by means of the PCRE_PARTIAL_SOFT and
|
||||
PCRE_PARTIAL_HARD options, which can be set when calling any of the matching
|
||||
functions. For backwards compatibility, PCRE_PARTIAL is a synonym for
|
||||
PCRE_PARTIAL_SOFT. The essential difference between the two options is whether
|
||||
or not a partial match is preferred to an alternative complete match, though
|
||||
the details differ between the two types of matching function. If both options
|
||||
are set, PCRE_PARTIAL_HARD takes precedence.
|
||||
</P>
|
||||
<P>
|
||||
If you want to use partial matching with just-in-time optimized code, you must
|
||||
call <b>pcre_study()</b>, <b>pcre16_study()</b> or <b>pcre32_study()</b> with one
|
||||
or both of these options:
|
||||
<pre>
|
||||
PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
|
||||
PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
|
||||
</pre>
|
||||
PCRE_STUDY_JIT_COMPILE should also be set if you are going to run non-partial
|
||||
matches on the same pattern. If the appropriate JIT study mode has not been set
|
||||
for a match, the interpretive matching code is used.
|
||||
</P>
|
||||
<P>
|
||||
Setting a partial matching option disables two of PCRE's standard
|
||||
optimizations. PCRE remembers the last literal data unit in a pattern, and
|
||||
abandons matching immediately if it is not present in the subject string. This
|
||||
optimization cannot be used for a subject string that might match only
|
||||
partially. If the pattern was studied, PCRE knows the minimum length of a
|
||||
matching string, and does not bother to run the matching function on shorter
|
||||
strings. This optimization is also disabled for partial matching.
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">PARTIAL MATCHING USING pcre_exec() OR pcre[16|32]_exec()</a><br>
|
||||
<P>
|
||||
A partial match occurs during a call to <b>pcre_exec()</b> or
|
||||
<b>pcre[16|32]_exec()</b> when the end of the subject string is reached
|
||||
successfully, but matching cannot continue because more characters are needed.
|
||||
However, at least one character in the subject must have been inspected. This
|
||||
character need not form part of the final matched string; lookbehind assertions
|
||||
and the \K escape sequence provide ways of inspecting characters before the
|
||||
start of a matched substring. The requirement for inspecting at least one
|
||||
character exists because an empty string can always be matched; without such a
|
||||
restriction there would always be a partial match of an empty string at the end
|
||||
of the subject.
|
||||
</P>
|
||||
<P>
|
||||
If there are at least two slots in the offsets vector when a partial match is
|
||||
returned, the first slot is set to the offset of the earliest character that
|
||||
was inspected. For convenience, the second offset points to the end of the
|
||||
subject so that a substring can easily be identified. If there are at least
|
||||
three slots in the offsets vector, the third slot is set to the offset of the
|
||||
character where matching started.
|
||||
</P>
|
||||
<P>
|
||||
For the majority of patterns, the contents of the first and third slots will be
|
||||
the same. However, for patterns that contain lookbehind assertions, or begin
|
||||
with \b or \B, characters before the one where matching started may have been
|
||||
inspected while carrying out the match. For example, consider this pattern:
|
||||
<pre>
|
||||
/(?<=abc)123/
|
||||
</pre>
|
||||
This pattern matches "123", but only if it is preceded by "abc". If the subject
|
||||
string is "xyzabc12", the first two offsets after a partial match are for the
|
||||
substring "abc12", because all these characters were inspected. However, the
|
||||
third offset is set to 6, because that is the offset where matching began.
|
||||
</P>
|
||||
<P>
|
||||
What happens when a partial match is identified depends on which of the two
|
||||
partial matching options are set.
|
||||
</P>
|
||||
<br><b>
|
||||
PCRE_PARTIAL_SOFT WITH pcre_exec() OR pcre[16|32]_exec()
|
||||
</b><br>
|
||||
<P>
|
||||
If PCRE_PARTIAL_SOFT is set when <b>pcre_exec()</b> or <b>pcre[16|32]_exec()</b>
|
||||
identifies a partial match, the partial match is remembered, but matching
|
||||
continues as normal, and other alternatives in the pattern are tried. If no
|
||||
complete match can be found, PCRE_ERROR_PARTIAL is returned instead of
|
||||
PCRE_ERROR_NOMATCH.
|
||||
</P>
|
||||
<P>
|
||||
This option is "soft" because it prefers a complete match over a partial match.
|
||||
All the various matching items in a pattern behave as if the subject string is
|
||||
potentially complete. For example, \z, \Z, and $ match at the end of the
|
||||
subject, as normal, and for \b and \B the end of the subject is treated as a
|
||||
non-alphanumeric.
|
||||
</P>
|
||||
<P>
|
||||
If there is more than one partial match, the first one that was found provides
|
||||
the data that is returned. Consider this pattern:
|
||||
<pre>
|
||||
/123\w+X|dogY/
|
||||
</pre>
|
||||
If this is matched against the subject string "abc123dog", both
|
||||
alternatives fail to match, but the end of the subject is reached during
|
||||
matching, so PCRE_ERROR_PARTIAL is returned. The offsets are set to 3 and 9,
|
||||
identifying "123dog" as the first partial match that was found. (In this
|
||||
example, there are two partial matches, because "dog" on its own partially
|
||||
matches the second alternative.)
|
||||
</P>
|
||||
<br><b>
|
||||
PCRE_PARTIAL_HARD WITH pcre_exec() OR pcre[16|32]_exec()
|
||||
</b><br>
|
||||
<P>
|
||||
If PCRE_PARTIAL_HARD is set for <b>pcre_exec()</b> or <b>pcre[16|32]_exec()</b>,
|
||||
PCRE_ERROR_PARTIAL is returned as soon as a partial match is found, without
|
||||
continuing to search for possible complete matches. This option is "hard"
|
||||
because it prefers an earlier partial match over a later complete match. For
|
||||
this reason, the assumption is made that the end of the supplied subject string
|
||||
may not be the true end of the available data, and so, if \z, \Z, \b, \B,
|
||||
or $ are encountered at the end of the subject, the result is
|
||||
PCRE_ERROR_PARTIAL, provided that at least one character in the subject has
|
||||
been inspected.
|
||||
</P>
|
||||
<P>
|
||||
Setting PCRE_PARTIAL_HARD also affects the way UTF-8 and UTF-16
|
||||
subject strings are checked for validity. Normally, an invalid sequence
|
||||
causes the error PCRE_ERROR_BADUTF8 or PCRE_ERROR_BADUTF16. However, in the
|
||||
special case of a truncated character at the end of the subject,
|
||||
PCRE_ERROR_SHORTUTF8 or PCRE_ERROR_SHORTUTF16 is returned when
|
||||
PCRE_PARTIAL_HARD is set.
|
||||
</P>
|
||||
<br><b>
|
||||
Comparing hard and soft partial matching
|
||||
</b><br>
|
||||
<P>
|
||||
The difference between the two partial matching options can be illustrated by a
|
||||
pattern such as:
|
||||
<pre>
|
||||
/dog(sbody)?/
|
||||
</pre>
|
||||
This matches either "dog" or "dogsbody", greedily (that is, it prefers the
|
||||
longer string if possible). If it is matched against the string "dog" with
|
||||
PCRE_PARTIAL_SOFT, it yields a complete match for "dog". However, if
|
||||
PCRE_PARTIAL_HARD is set, the result is PCRE_ERROR_PARTIAL. On the other hand,
|
||||
if the pattern is made ungreedy the result is different:
|
||||
<pre>
|
||||
/dog(sbody)??/
|
||||
</pre>
|
||||
In this case the result is always a complete match because that is found first,
|
||||
and matching never continues after finding a complete match. It might be easier
|
||||
to follow this explanation by thinking of the two patterns like this:
|
||||
<pre>
|
||||
/dog(sbody)?/ is the same as /dogsbody|dog/
|
||||
/dog(sbody)??/ is the same as /dog|dogsbody/
|
||||
</pre>
|
||||
The second pattern will never match "dogsbody", because it will always find the
|
||||
shorter match first.
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">PARTIAL MATCHING USING pcre_dfa_exec() OR pcre[16|32]_dfa_exec()</a><br>
|
||||
<P>
|
||||
The DFA functions move along the subject string character by character, without
|
||||
backtracking, searching for all possible matches simultaneously. If the end of
|
||||
the subject is reached before the end of the pattern, there is the possibility
|
||||
of a partial match, again provided that at least one character has been
|
||||
inspected.
|
||||
</P>
|
||||
<P>
|
||||
When PCRE_PARTIAL_SOFT is set, PCRE_ERROR_PARTIAL is returned only if there
|
||||
have been no complete matches. Otherwise, the complete matches are returned.
|
||||
However, if PCRE_PARTIAL_HARD is set, a partial match takes precedence over any
|
||||
complete matches. The portion of the string that was inspected when the longest
|
||||
partial match was found is set as the first matching string, provided there are
|
||||
at least two slots in the offsets vector.
|
||||
</P>
|
||||
<P>
|
||||
Because the DFA functions always search for all possible matches, and there is
|
||||
no difference between greedy and ungreedy repetition, their behaviour is
|
||||
different from the standard functions when PCRE_PARTIAL_HARD is set. Consider
|
||||
the string "dog" matched against the ungreedy pattern shown above:
|
||||
<pre>
|
||||
/dog(sbody)??/
|
||||
</pre>
|
||||
Whereas the standard functions stop as soon as they find the complete match for
|
||||
"dog", the DFA functions also find the partial match for "dogsbody", and so
|
||||
return that when PCRE_PARTIAL_HARD is set.
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">PARTIAL MATCHING AND WORD BOUNDARIES</a><br>
|
||||
<P>
|
||||
If a pattern ends with one of sequences \b or \B, which test for word
|
||||
boundaries, partial matching with PCRE_PARTIAL_SOFT can give counter-intuitive
|
||||
results. Consider this pattern:
|
||||
<pre>
|
||||
/\bcat\b/
|
||||
</pre>
|
||||
This matches "cat", provided there is a word boundary at either end. If the
|
||||
subject string is "the cat", the comparison of the final "t" with a following
|
||||
character cannot take place, so a partial match is found. However, normal
|
||||
matching carries on, and \b matches at the end of the subject when the last
|
||||
character is a letter, so a complete match is found. The result, therefore, is
|
||||
<i>not</i> PCRE_ERROR_PARTIAL. Using PCRE_PARTIAL_HARD in this case does yield
|
||||
PCRE_ERROR_PARTIAL, because then the partial match takes precedence.
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">FORMERLY RESTRICTED PATTERNS</a><br>
|
||||
<P>
|
||||
For releases of PCRE prior to 8.00, because of the way certain internal
|
||||
optimizations were implemented in the <b>pcre_exec()</b> function, the
|
||||
PCRE_PARTIAL option (predecessor of PCRE_PARTIAL_SOFT) could not be used with
|
||||
all patterns. From release 8.00 onwards, the restrictions no longer apply, and
|
||||
partial matching with can be requested for any pattern.
|
||||
</P>
|
||||
<P>
|
||||
Items that were formerly restricted were repeated single characters and
|
||||
repeated metasequences. If PCRE_PARTIAL was set for a pattern that did not
|
||||
conform to the restrictions, <b>pcre_exec()</b> returned the error code
|
||||
PCRE_ERROR_BADPARTIAL (-13). This error code is no longer in use. The
|
||||
PCRE_INFO_OKPARTIAL call to <b>pcre_fullinfo()</b> to find out if a compiled
|
||||
pattern can be used for partial matching now always returns 1.
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">EXAMPLE OF PARTIAL MATCHING USING PCRETEST</a><br>
|
||||
<P>
|
||||
If the escape sequence \P is present in a <b>pcretest</b> data line, the
|
||||
PCRE_PARTIAL_SOFT option is used for the match. Here is a run of <b>pcretest</b>
|
||||
that uses the date example quoted above:
|
||||
<pre>
|
||||
re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
|
||||
data> 25jun04\P
|
||||
0: 25jun04
|
||||
1: jun
|
||||
data> 25dec3\P
|
||||
Partial match: 23dec3
|
||||
data> 3ju\P
|
||||
Partial match: 3ju
|
||||
data> 3juj\P
|
||||
No match
|
||||
data> j\P
|
||||
No match
|
||||
</pre>
|
||||
The first data string is matched completely, so <b>pcretest</b> shows the
|
||||
matched substrings. The remaining four strings do not match the complete
|
||||
pattern, but the first two are partial matches. Similar output is obtained
|
||||
if DFA matching is used.
|
||||
</P>
|
||||
<P>
|
||||
If the escape sequence \P is present more than once in a <b>pcretest</b> data
|
||||
line, the PCRE_PARTIAL_HARD option is set for the match.
|
||||
</P>
|
||||
<br><a name="SEC7" href="#TOC1">MULTI-SEGMENT MATCHING WITH pcre_dfa_exec() OR pcre[16|32]_dfa_exec()</a><br>
|
||||
<P>
|
||||
When a partial match has been found using a DFA matching function, it is
|
||||
possible to continue the match by providing additional subject data and calling
|
||||
the function again with the same compiled regular expression, this time setting
|
||||
the PCRE_DFA_RESTART option. You must pass the same working space as before,
|
||||
because this is where details of the previous partial match are stored. Here is
|
||||
an example using <b>pcretest</b>, using the \R escape sequence to set the
|
||||
PCRE_DFA_RESTART option (\D specifies the use of the DFA matching function):
|
||||
<pre>
|
||||
re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
|
||||
data> 23ja\P\D
|
||||
Partial match: 23ja
|
||||
data> n05\R\D
|
||||
0: n05
|
||||
</pre>
|
||||
The first call has "23ja" as the subject, and requests partial matching; the
|
||||
second call has "n05" as the subject for the continued (restarted) match.
|
||||
Notice that when the match is complete, only the last part is shown; PCRE does
|
||||
not retain the previously partially-matched string. It is up to the calling
|
||||
program to do that if it needs to.
|
||||
</P>
|
||||
<P>
|
||||
That means that, for an unanchored pattern, if a continued match fails, it is
|
||||
not possible to try again at a new starting point. All this facility is capable
|
||||
of doing is continuing with the previous match attempt. In the previous
|
||||
example, if the second set of data is "ug23" the result is no match, even
|
||||
though there would be a match for "aug23" if the entire string were given at
|
||||
once. Depending on the application, this may or may not be what you want.
|
||||
The only way to allow for starting again at the next character is to retain the
|
||||
matched part of the subject and try a new complete match.
|
||||
</P>
|
||||
<P>
|
||||
You can set the PCRE_PARTIAL_SOFT or PCRE_PARTIAL_HARD options with
|
||||
PCRE_DFA_RESTART to continue partial matching over multiple segments. This
|
||||
facility can be used to pass very long subject strings to the DFA matching
|
||||
functions.
|
||||
</P>
|
||||
<br><a name="SEC8" href="#TOC1">MULTI-SEGMENT MATCHING WITH pcre_exec() OR pcre[16|32]_exec()</a><br>
|
||||
<P>
|
||||
From release 8.00, the standard matching functions can also be used to do
|
||||
multi-segment matching. Unlike the DFA functions, it is not possible to
|
||||
restart the previous match with a new segment of data. Instead, new data must
|
||||
be added to the previous subject string, and the entire match re-run, starting
|
||||
from the point where the partial match occurred. Earlier data can be discarded.
|
||||
</P>
|
||||
<P>
|
||||
It is best to use PCRE_PARTIAL_HARD in this situation, because it does not
|
||||
treat the end of a segment as the end of the subject when matching \z, \Z,
|
||||
\b, \B, and $. Consider an unanchored pattern that matches dates:
|
||||
<pre>
|
||||
re> /\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d/
|
||||
data> The date is 23ja\P\P
|
||||
Partial match: 23ja
|
||||
</pre>
|
||||
At this stage, an application could discard the text preceding "23ja", add on
|
||||
text from the next segment, and call the matching function again. Unlike the
|
||||
DFA matching functions, the entire matching string must always be available,
|
||||
and the complete matching process occurs for each call, so more memory and more
|
||||
processing time is needed.
|
||||
</P>
|
||||
<P>
|
||||
<b>Note:</b> If the pattern contains lookbehind assertions, or \K, or starts
|
||||
with \b or \B, the string that is returned for a partial match includes
|
||||
characters that precede the start of what would be returned for a complete
|
||||
match, because it contains all the characters that were inspected during the
|
||||
partial match.
|
||||
</P>
|
||||
<br><a name="SEC9" href="#TOC1">ISSUES WITH MULTI-SEGMENT MATCHING</a><br>
|
||||
<P>
|
||||
Certain types of pattern may give problems with multi-segment matching,
|
||||
whichever matching function is used.
|
||||
</P>
|
||||
<P>
|
||||
1. If the pattern contains a test for the beginning of a line, you need to pass
|
||||
the PCRE_NOTBOL option when the subject string for any call does start at the
|
||||
beginning of a line. There is also a PCRE_NOTEOL option, but in practice when
|
||||
doing multi-segment matching you should be using PCRE_PARTIAL_HARD, which
|
||||
includes the effect of PCRE_NOTEOL.
|
||||
</P>
|
||||
<P>
|
||||
2. Lookbehind assertions that have already been obeyed are catered for in the
|
||||
offsets that are returned for a partial match. However a lookbehind assertion
|
||||
later in the pattern could require even earlier characters to be inspected. You
|
||||
can handle this case by using the PCRE_INFO_MAXLOOKBEHIND option of the
|
||||
<b>pcre_fullinfo()</b> or <b>pcre[16|32]_fullinfo()</b> functions to obtain the
|
||||
length of the longest lookbehind in the pattern. This length is given in
|
||||
characters, not bytes. If you always retain at least that many characters
|
||||
before the partially matched string, all should be well. (Of course, near the
|
||||
start of the subject, fewer characters may be present; in that case all
|
||||
characters should be retained.)
|
||||
</P>
|
||||
<P>
|
||||
From release 8.33, there is a more accurate way of deciding which characters to
|
||||
retain. Instead of subtracting the length of the longest lookbehind from the
|
||||
earliest inspected character (<i>offsets[0]</i>), the match start position
|
||||
(<i>offsets[2]</i>) should be used, and the next match attempt started at the
|
||||
<i>offsets[2]</i> character by setting the <i>startoffset</i> argument of
|
||||
<b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>.
|
||||
</P>
|
||||
<P>
|
||||
For example, if the pattern "(?<=123)abc" is partially
|
||||
matched against the string "xx123a", the three offset values returned are 2, 6,
|
||||
and 5. This indicates that the matching process that gave a partial match
|
||||
started at offset 5, but the characters "123a" were all inspected. The maximum
|
||||
lookbehind for that pattern is 3, so taking that away from 5 shows that we need
|
||||
only keep "123a", and the next match attempt can be started at offset 3 (that
|
||||
is, at "a") when further characters have been added. When the match start is
|
||||
not the earliest inspected character, <b>pcretest</b> shows it explicitly:
|
||||
<pre>
|
||||
re> "(?<=123)abc"
|
||||
data> xx123a\P\P
|
||||
Partial match at offset 5: 123a
|
||||
</PRE>
|
||||
</P>
|
||||
<P>
|
||||
3. Because a partial match must always contain at least one character, what
|
||||
might be considered a partial match of an empty string actually gives a "no
|
||||
match" result. For example:
|
||||
<pre>
|
||||
re> /c(?<=abc)x/
|
||||
data> ab\P
|
||||
No match
|
||||
</pre>
|
||||
If the next segment begins "cx", a match should be found, but this will only
|
||||
happen if characters from the previous segment are retained. For this reason, a
|
||||
"no match" result should be interpreted as "partial match of an empty string"
|
||||
when the pattern contains lookbehinds.
|
||||
</P>
|
||||
<P>
|
||||
4. Matching a subject string that is split into multiple segments may not
|
||||
always produce exactly the same result as matching over one single long string,
|
||||
especially when PCRE_PARTIAL_SOFT is used. The section "Partial Matching and
|
||||
Word Boundaries" above describes an issue that arises if the pattern ends with
|
||||
\b or \B. Another kind of difference may occur when there are multiple
|
||||
matching possibilities, because (for PCRE_PARTIAL_SOFT) a partial match result
|
||||
is given only when there are no completed matches. This means that as soon as
|
||||
the shortest match has been found, continuation to a new subject segment is no
|
||||
longer possible. Consider again this <b>pcretest</b> example:
|
||||
<pre>
|
||||
re> /dog(sbody)?/
|
||||
data> dogsb\P
|
||||
0: dog
|
||||
data> do\P\D
|
||||
Partial match: do
|
||||
data> gsb\R\P\D
|
||||
0: g
|
||||
data> dogsbody\D
|
||||
0: dogsbody
|
||||
1: dog
|
||||
</pre>
|
||||
The first data line passes the string "dogsb" to a standard matching function,
|
||||
setting the PCRE_PARTIAL_SOFT option. Although the string is a partial match
|
||||
for "dogsbody", the result is not PCRE_ERROR_PARTIAL, because the shorter
|
||||
string "dog" is a complete match. Similarly, when the subject is presented to
|
||||
a DFA matching function in several parts ("do" and "gsb" being the first two)
|
||||
the match stops when "dog" has been found, and it is not possible to continue.
|
||||
On the other hand, if "dogsbody" is presented as a single string, a DFA
|
||||
matching function finds both matches.
|
||||
</P>
|
||||
<P>
|
||||
Because of these problems, it is best to use PCRE_PARTIAL_HARD when matching
|
||||
multi-segment data. The example above then behaves differently:
|
||||
<pre>
|
||||
re> /dog(sbody)?/
|
||||
data> dogsb\P\P
|
||||
Partial match: dogsb
|
||||
data> do\P\D
|
||||
Partial match: do
|
||||
data> gsb\R\P\P\D
|
||||
Partial match: gsb
|
||||
</pre>
|
||||
5. Patterns that contain alternatives at the top level which do not all start
|
||||
with the same pattern item may not work as expected when PCRE_DFA_RESTART is
|
||||
used. For example, consider this pattern:
|
||||
<pre>
|
||||
1234|3789
|
||||
</pre>
|
||||
If the first part of the subject is "ABC123", a partial match of the first
|
||||
alternative is found at offset 3. There is no partial match for the second
|
||||
alternative, because such a match does not start at the same point in the
|
||||
subject string. Attempting to continue with the string "7890" does not yield a
|
||||
match because only those alternatives that match at one point in the subject
|
||||
are remembered. The problem arises because the start of the second alternative
|
||||
matches within the first alternative. There is no problem with anchored
|
||||
patterns or patterns such as:
|
||||
<pre>
|
||||
1234|ABCD
|
||||
</pre>
|
||||
where no string can be a partial match for both alternatives. This is not a
|
||||
problem if a standard matching function is used, because the entire match has
|
||||
to be rerun each time:
|
||||
<pre>
|
||||
re> /1234|3789/
|
||||
data> ABC123\P\P
|
||||
Partial match: 123
|
||||
data> 1237890
|
||||
0: 3789
|
||||
</pre>
|
||||
Of course, instead of using PCRE_DFA_RESTART, the same technique of re-running
|
||||
the entire match can also be used with the DFA matching functions. Another
|
||||
possibility is to work with two buffers. If a partial match at offset <i>n</i>
|
||||
in the first buffer is followed by "no match" when PCRE_DFA_RESTART is used on
|
||||
the second buffer, you can then try a new match starting at offset <i>n+1</i> in
|
||||
the first buffer.
|
||||
</P>
|
||||
<br><a name="SEC10" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC11" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 02 July 2013
|
||||
<br>
|
||||
Copyright © 1997-2013 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,3276 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcrepattern specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcrepattern man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">PCRE REGULAR EXPRESSION DETAILS</a>
|
||||
<li><a name="TOC2" href="#SEC2">SPECIAL START-OF-PATTERN ITEMS</a>
|
||||
<li><a name="TOC3" href="#SEC3">EBCDIC CHARACTER CODES</a>
|
||||
<li><a name="TOC4" href="#SEC4">CHARACTERS AND METACHARACTERS</a>
|
||||
<li><a name="TOC5" href="#SEC5">BACKSLASH</a>
|
||||
<li><a name="TOC6" href="#SEC6">CIRCUMFLEX AND DOLLAR</a>
|
||||
<li><a name="TOC7" href="#SEC7">FULL STOP (PERIOD, DOT) AND \N</a>
|
||||
<li><a name="TOC8" href="#SEC8">MATCHING A SINGLE DATA UNIT</a>
|
||||
<li><a name="TOC9" href="#SEC9">SQUARE BRACKETS AND CHARACTER CLASSES</a>
|
||||
<li><a name="TOC10" href="#SEC10">POSIX CHARACTER CLASSES</a>
|
||||
<li><a name="TOC11" href="#SEC11">COMPATIBILITY FEATURE FOR WORD BOUNDARIES</a>
|
||||
<li><a name="TOC12" href="#SEC12">VERTICAL BAR</a>
|
||||
<li><a name="TOC13" href="#SEC13">INTERNAL OPTION SETTING</a>
|
||||
<li><a name="TOC14" href="#SEC14">SUBPATTERNS</a>
|
||||
<li><a name="TOC15" href="#SEC15">DUPLICATE SUBPATTERN NUMBERS</a>
|
||||
<li><a name="TOC16" href="#SEC16">NAMED SUBPATTERNS</a>
|
||||
<li><a name="TOC17" href="#SEC17">REPETITION</a>
|
||||
<li><a name="TOC18" href="#SEC18">ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS</a>
|
||||
<li><a name="TOC19" href="#SEC19">BACK REFERENCES</a>
|
||||
<li><a name="TOC20" href="#SEC20">ASSERTIONS</a>
|
||||
<li><a name="TOC21" href="#SEC21">CONDITIONAL SUBPATTERNS</a>
|
||||
<li><a name="TOC22" href="#SEC22">COMMENTS</a>
|
||||
<li><a name="TOC23" href="#SEC23">RECURSIVE PATTERNS</a>
|
||||
<li><a name="TOC24" href="#SEC24">SUBPATTERNS AS SUBROUTINES</a>
|
||||
<li><a name="TOC25" href="#SEC25">ONIGURUMA SUBROUTINE SYNTAX</a>
|
||||
<li><a name="TOC26" href="#SEC26">CALLOUTS</a>
|
||||
<li><a name="TOC27" href="#SEC27">BACKTRACKING CONTROL</a>
|
||||
<li><a name="TOC28" href="#SEC28">SEE ALSO</a>
|
||||
<li><a name="TOC29" href="#SEC29">AUTHOR</a>
|
||||
<li><a name="TOC30" href="#SEC30">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">PCRE REGULAR EXPRESSION DETAILS</a><br>
|
||||
<P>
|
||||
The syntax and semantics of the regular expressions that are supported by PCRE
|
||||
are described in detail below. There is a quick-reference syntax summary in the
|
||||
<a href="pcresyntax.html"><b>pcresyntax</b></a>
|
||||
page. PCRE tries to match Perl syntax and semantics as closely as it can. PCRE
|
||||
also supports some alternative regular expression syntax (which does not
|
||||
conflict with the Perl syntax) in order to provide some compatibility with
|
||||
regular expressions in Python, .NET, and Oniguruma.
|
||||
</P>
|
||||
<P>
|
||||
Perl's regular expressions are described in its own documentation, and
|
||||
regular expressions in general are covered in a number of books, some of which
|
||||
have copious examples. Jeffrey Friedl's "Mastering Regular Expressions",
|
||||
published by O'Reilly, covers regular expressions in great detail. This
|
||||
description of PCRE's regular expressions is intended as reference material.
|
||||
</P>
|
||||
<P>
|
||||
This document discusses the patterns that are supported by PCRE when one its
|
||||
main matching functions, <b>pcre_exec()</b> (8-bit) or <b>pcre[16|32]_exec()</b>
|
||||
(16- or 32-bit), is used. PCRE also has alternative matching functions,
|
||||
<b>pcre_dfa_exec()</b> and <b>pcre[16|32_dfa_exec()</b>, which match using a
|
||||
different algorithm that is not Perl-compatible. Some of the features discussed
|
||||
below are not available when DFA matching is used. The advantages and
|
||||
disadvantages of the alternative functions, and how they differ from the normal
|
||||
functions, are discussed in the
|
||||
<a href="pcrematching.html"><b>pcrematching</b></a>
|
||||
page.
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">SPECIAL START-OF-PATTERN ITEMS</a><br>
|
||||
<P>
|
||||
A number of options that can be passed to <b>pcre_compile()</b> can also be set
|
||||
by special items at the start of a pattern. These are not Perl-compatible, but
|
||||
are provided to make these options accessible to pattern writers who are not
|
||||
able to change the program that processes the pattern. Any number of these
|
||||
items may appear, but they must all be together right at the start of the
|
||||
pattern string, and the letters must be in upper case.
|
||||
</P>
|
||||
<br><b>
|
||||
UTF support
|
||||
</b><br>
|
||||
<P>
|
||||
The original operation of PCRE was on strings of one-byte characters. However,
|
||||
there is now also support for UTF-8 strings in the original library, an
|
||||
extra library that supports 16-bit and UTF-16 character strings, and a
|
||||
third library that supports 32-bit and UTF-32 character strings. To use these
|
||||
features, PCRE must be built to include appropriate support. When using UTF
|
||||
strings you must either call the compiling function with the PCRE_UTF8,
|
||||
PCRE_UTF16, or PCRE_UTF32 option, or the pattern must start with one of
|
||||
these special sequences:
|
||||
<pre>
|
||||
(*UTF8)
|
||||
(*UTF16)
|
||||
(*UTF32)
|
||||
(*UTF)
|
||||
</pre>
|
||||
(*UTF) is a generic sequence that can be used with any of the libraries.
|
||||
Starting a pattern with such a sequence is equivalent to setting the relevant
|
||||
option. How setting a UTF mode affects pattern matching is mentioned in several
|
||||
places below. There is also a summary of features in the
|
||||
<a href="pcreunicode.html"><b>pcreunicode</b></a>
|
||||
page.
|
||||
</P>
|
||||
<P>
|
||||
Some applications that allow their users to supply patterns may wish to
|
||||
restrict them to non-UTF data for security reasons. If the PCRE_NEVER_UTF
|
||||
option is set at compile time, (*UTF) etc. are not allowed, and their
|
||||
appearance causes an error.
|
||||
</P>
|
||||
<br><b>
|
||||
Unicode property support
|
||||
</b><br>
|
||||
<P>
|
||||
Another special sequence that may appear at the start of a pattern is (*UCP).
|
||||
This has the same effect as setting the PCRE_UCP option: it causes sequences
|
||||
such as \d and \w to use Unicode properties to determine character types,
|
||||
instead of recognizing only characters with codes less than 128 via a lookup
|
||||
table.
|
||||
</P>
|
||||
<br><b>
|
||||
Disabling auto-possessification
|
||||
</b><br>
|
||||
<P>
|
||||
If a pattern starts with (*NO_AUTO_POSSESS), it has the same effect as setting
|
||||
the PCRE_NO_AUTO_POSSESS option at compile time. This stops PCRE from making
|
||||
quantifiers possessive when what follows cannot match the repeated item. For
|
||||
example, by default a+b is treated as a++b. For more details, see the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<br><b>
|
||||
Disabling start-up optimizations
|
||||
</b><br>
|
||||
<P>
|
||||
If a pattern starts with (*NO_START_OPT), it has the same effect as setting the
|
||||
PCRE_NO_START_OPTIMIZE option either at compile or matching time. This disables
|
||||
several optimizations for quickly reaching "no match" results. For more
|
||||
details, see the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
documentation.
|
||||
<a name="newlines"></a></P>
|
||||
<br><b>
|
||||
Newline conventions
|
||||
</b><br>
|
||||
<P>
|
||||
PCRE supports five different conventions for indicating line breaks in
|
||||
strings: a single CR (carriage return) character, a single LF (linefeed)
|
||||
character, the two-character sequence CRLF, any of the three preceding, or any
|
||||
Unicode newline sequence. The
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page has
|
||||
<a href="pcreapi.html#newlines">further discussion</a>
|
||||
about newlines, and shows how to set the newline convention in the
|
||||
<i>options</i> arguments for the compiling and matching functions.
|
||||
</P>
|
||||
<P>
|
||||
It is also possible to specify a newline convention by starting a pattern
|
||||
string with one of the following five sequences:
|
||||
<pre>
|
||||
(*CR) carriage return
|
||||
(*LF) linefeed
|
||||
(*CRLF) carriage return, followed by linefeed
|
||||
(*ANYCRLF) any of the three above
|
||||
(*ANY) all Unicode newline sequences
|
||||
</pre>
|
||||
These override the default and the options given to the compiling function. For
|
||||
example, on a Unix system where LF is the default newline sequence, the pattern
|
||||
<pre>
|
||||
(*CR)a.b
|
||||
</pre>
|
||||
changes the convention to CR. That pattern matches "a\nb" because LF is no
|
||||
longer a newline. If more than one of these settings is present, the last one
|
||||
is used.
|
||||
</P>
|
||||
<P>
|
||||
The newline convention affects where the circumflex and dollar assertions are
|
||||
true. It also affects the interpretation of the dot metacharacter when
|
||||
PCRE_DOTALL is not set, and the behaviour of \N. However, it does not affect
|
||||
what the \R escape sequence matches. By default, this is any Unicode newline
|
||||
sequence, for Perl compatibility. However, this can be changed; see the
|
||||
description of \R in the section entitled
|
||||
<a href="#newlineseq">"Newline sequences"</a>
|
||||
below. A change of \R setting can be combined with a change of newline
|
||||
convention.
|
||||
</P>
|
||||
<br><b>
|
||||
Setting match and recursion limits
|
||||
</b><br>
|
||||
<P>
|
||||
The caller of <b>pcre_exec()</b> can set a limit on the number of times the
|
||||
internal <b>match()</b> function is called and on the maximum depth of
|
||||
recursive calls. These facilities are provided to catch runaway matches that
|
||||
are provoked by patterns with huge matching trees (a typical example is a
|
||||
pattern with nested unlimited repeats) and to avoid running out of system stack
|
||||
by too much recursion. When one of these limits is reached, <b>pcre_exec()</b>
|
||||
gives an error return. The limits can also be set by items at the start of the
|
||||
pattern of the form
|
||||
<pre>
|
||||
(*LIMIT_MATCH=d)
|
||||
(*LIMIT_RECURSION=d)
|
||||
</pre>
|
||||
where d is any number of decimal digits. However, the value of the setting must
|
||||
be less than the value set (or defaulted) by the caller of <b>pcre_exec()</b>
|
||||
for it to have any effect. In other words, the pattern writer can lower the
|
||||
limits set by the programmer, but not raise them. If there is more than one
|
||||
setting of one of these limits, the lower value is used.
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">EBCDIC CHARACTER CODES</a><br>
|
||||
<P>
|
||||
PCRE can be compiled to run in an environment that uses EBCDIC as its character
|
||||
code rather than ASCII or Unicode (typically a mainframe system). In the
|
||||
sections below, character code values are ASCII or Unicode; in an EBCDIC
|
||||
environment these characters may have different code values, and there are no
|
||||
code points greater than 255.
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">CHARACTERS AND METACHARACTERS</a><br>
|
||||
<P>
|
||||
A regular expression is a pattern that is matched against a subject string from
|
||||
left to right. Most characters stand for themselves in a pattern, and match the
|
||||
corresponding characters in the subject. As a trivial example, the pattern
|
||||
<pre>
|
||||
The quick brown fox
|
||||
</pre>
|
||||
matches a portion of a subject string that is identical to itself. When
|
||||
caseless matching is specified (the PCRE_CASELESS option), letters are matched
|
||||
independently of case. In a UTF mode, PCRE always understands the concept of
|
||||
case for characters whose values are less than 128, so caseless matching is
|
||||
always possible. For characters with higher values, the concept of case is
|
||||
supported if PCRE is compiled with Unicode property support, but not otherwise.
|
||||
If you want to use caseless matching for characters 128 and above, you must
|
||||
ensure that PCRE is compiled with Unicode property support as well as with
|
||||
UTF support.
|
||||
</P>
|
||||
<P>
|
||||
The power of regular expressions comes from the ability to include alternatives
|
||||
and repetitions in the pattern. These are encoded in the pattern by the use of
|
||||
<i>metacharacters</i>, which do not stand for themselves but instead are
|
||||
interpreted in some special way.
|
||||
</P>
|
||||
<P>
|
||||
There are two different sets of metacharacters: those that are recognized
|
||||
anywhere in the pattern except within square brackets, and those that are
|
||||
recognized within square brackets. Outside square brackets, the metacharacters
|
||||
are as follows:
|
||||
<pre>
|
||||
\ general escape character with several uses
|
||||
^ assert start of string (or line, in multiline mode)
|
||||
$ assert end of string (or line, in multiline mode)
|
||||
. match any character except newline (by default)
|
||||
[ start character class definition
|
||||
| start of alternative branch
|
||||
( start subpattern
|
||||
) end subpattern
|
||||
? extends the meaning of (
|
||||
also 0 or 1 quantifier
|
||||
also quantifier minimizer
|
||||
* 0 or more quantifier
|
||||
+ 1 or more quantifier
|
||||
also "possessive quantifier"
|
||||
{ start min/max quantifier
|
||||
</pre>
|
||||
Part of a pattern that is in square brackets is called a "character class". In
|
||||
a character class the only metacharacters are:
|
||||
<pre>
|
||||
\ general escape character
|
||||
^ negate the class, but only if the first character
|
||||
- indicates character range
|
||||
[ POSIX character class (only if followed by POSIX syntax)
|
||||
] terminates the character class
|
||||
</pre>
|
||||
The following sections describe the use of each of the metacharacters.
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">BACKSLASH</a><br>
|
||||
<P>
|
||||
The backslash character has several uses. Firstly, if it is followed by a
|
||||
character that is not a number or a letter, it takes away any special meaning
|
||||
that character may have. This use of backslash as an escape character applies
|
||||
both inside and outside character classes.
|
||||
</P>
|
||||
<P>
|
||||
For example, if you want to match a * character, you write \* in the pattern.
|
||||
This escaping action applies whether or not the following character would
|
||||
otherwise be interpreted as a metacharacter, so it is always safe to precede a
|
||||
non-alphanumeric with backslash to specify that it stands for itself. In
|
||||
particular, if you want to match a backslash, you write \\.
|
||||
</P>
|
||||
<P>
|
||||
In a UTF mode, only ASCII numbers and letters have any special meaning after a
|
||||
backslash. All other characters (in particular, those whose codepoints are
|
||||
greater than 127) are treated as literals.
|
||||
</P>
|
||||
<P>
|
||||
If a pattern is compiled with the PCRE_EXTENDED option, most white space in the
|
||||
pattern (other than in a character class), and characters between a # outside a
|
||||
character class and the next newline, inclusive, are ignored. An escaping
|
||||
backslash can be used to include a white space or # character as part of the
|
||||
pattern.
|
||||
</P>
|
||||
<P>
|
||||
If you want to remove the special meaning from a sequence of characters, you
|
||||
can do so by putting them between \Q and \E. This is different from Perl in
|
||||
that $ and @ are handled as literals in \Q...\E sequences in PCRE, whereas in
|
||||
Perl, $ and @ cause variable interpolation. Note the following examples:
|
||||
<pre>
|
||||
Pattern PCRE matches Perl matches
|
||||
|
||||
\Qabc$xyz\E abc$xyz abc followed by the contents of $xyz
|
||||
\Qabc\$xyz\E abc\$xyz abc\$xyz
|
||||
\Qabc\E\$\Qxyz\E abc$xyz abc$xyz
|
||||
</pre>
|
||||
The \Q...\E sequence is recognized both inside and outside character classes.
|
||||
An isolated \E that is not preceded by \Q is ignored. If \Q is not followed
|
||||
by \E later in the pattern, the literal interpretation continues to the end of
|
||||
the pattern (that is, \E is assumed at the end). If the isolated \Q is inside
|
||||
a character class, this causes an error, because the character class is not
|
||||
terminated.
|
||||
<a name="digitsafterbackslash"></a></P>
|
||||
<br><b>
|
||||
Non-printing characters
|
||||
</b><br>
|
||||
<P>
|
||||
A second use of backslash provides a way of encoding non-printing characters
|
||||
in patterns in a visible manner. There is no restriction on the appearance of
|
||||
non-printing characters, apart from the binary zero that terminates a pattern,
|
||||
but when a pattern is being prepared by text editing, it is often easier to use
|
||||
one of the following escape sequences than the binary character it represents.
|
||||
In an ASCII or Unicode environment, these escapes are as follows:
|
||||
<pre>
|
||||
\a alarm, that is, the BEL character (hex 07)
|
||||
\cx "control-x", where x is any ASCII character
|
||||
\e escape (hex 1B)
|
||||
\f form feed (hex 0C)
|
||||
\n linefeed (hex 0A)
|
||||
\r carriage return (hex 0D)
|
||||
\t tab (hex 09)
|
||||
\0dd character with octal code 0dd
|
||||
\ddd character with octal code ddd, or back reference
|
||||
\o{ddd..} character with octal code ddd..
|
||||
\xhh character with hex code hh
|
||||
\x{hhh..} character with hex code hhh.. (non-JavaScript mode)
|
||||
\uhhhh character with hex code hhhh (JavaScript mode only)
|
||||
</pre>
|
||||
The precise effect of \cx on ASCII characters is as follows: if x is a lower
|
||||
case letter, it is converted to upper case. Then bit 6 of the character (hex
|
||||
40) is inverted. Thus \cA to \cZ become hex 01 to hex 1A (A is 41, Z is 5A),
|
||||
but \c{ becomes hex 3B ({ is 7B), and \c; becomes hex 7B (; is 3B). If the
|
||||
data item (byte or 16-bit value) following \c has a value greater than 127, a
|
||||
compile-time error occurs. This locks out non-ASCII characters in all modes.
|
||||
</P>
|
||||
<P>
|
||||
When PCRE is compiled in EBCDIC mode, \a, \e, \f, \n, \r, and \t
|
||||
generate the appropriate EBCDIC code values. The \c escape is processed
|
||||
as specified for Perl in the <b>perlebcdic</b> document. The only characters
|
||||
that are allowed after \c are A-Z, a-z, or one of @, [, \, ], ^, _, or ?. Any
|
||||
other character provokes a compile-time error. The sequence \c@ encodes
|
||||
character code 0; after \c the letters (in either case) encode characters 1-26
|
||||
(hex 01 to hex 1A); [, \, ], ^, and _ encode characters 27-31 (hex 1B to hex
|
||||
1F), and \c? becomes either 255 (hex FF) or 95 (hex 5F).
|
||||
</P>
|
||||
<P>
|
||||
Thus, apart from \c?, these escapes generate the same character code values as
|
||||
they do in an ASCII environment, though the meanings of the values mostly
|
||||
differ. For example, \cG always generates code value 7, which is BEL in ASCII
|
||||
but DEL in EBCDIC.
|
||||
</P>
|
||||
<P>
|
||||
The sequence \c? generates DEL (127, hex 7F) in an ASCII environment, but
|
||||
because 127 is not a control character in EBCDIC, Perl makes it generate the
|
||||
APC character. Unfortunately, there are several variants of EBCDIC. In most of
|
||||
them the APC character has the value 255 (hex FF), but in the one Perl calls
|
||||
POSIX-BC its value is 95 (hex 5F). If certain other characters have POSIX-BC
|
||||
values, PCRE makes \c? generate 95; otherwise it generates 255.
|
||||
</P>
|
||||
<P>
|
||||
After \0 up to two further octal digits are read. If there are fewer than two
|
||||
digits, just those that are present are used. Thus the sequence \0\x\015
|
||||
specifies two binary zeros followed by a CR character (code value 13). Make
|
||||
sure you supply two digits after the initial zero if the pattern character that
|
||||
follows is itself an octal digit.
|
||||
</P>
|
||||
<P>
|
||||
The escape \o must be followed by a sequence of octal digits, enclosed in
|
||||
braces. An error occurs if this is not the case. This escape is a recent
|
||||
addition to Perl; it provides way of specifying character code points as octal
|
||||
numbers greater than 0777, and it also allows octal numbers and back references
|
||||
to be unambiguously specified.
|
||||
</P>
|
||||
<P>
|
||||
For greater clarity and unambiguity, it is best to avoid following \ by a
|
||||
digit greater than zero. Instead, use \o{} or \x{} to specify character
|
||||
numbers, and \g{} to specify back references. The following paragraphs
|
||||
describe the old, ambiguous syntax.
|
||||
</P>
|
||||
<P>
|
||||
The handling of a backslash followed by a digit other than 0 is complicated,
|
||||
and Perl has changed in recent releases, causing PCRE also to change. Outside a
|
||||
character class, PCRE reads the digit and any following digits as a decimal
|
||||
number. If the number is less than 8, or if there have been at least that many
|
||||
previous capturing left parentheses in the expression, the entire sequence is
|
||||
taken as a <i>back reference</i>. A description of how this works is given
|
||||
<a href="#backreferences">later,</a>
|
||||
following the discussion of
|
||||
<a href="#subpattern">parenthesized subpatterns.</a>
|
||||
</P>
|
||||
<P>
|
||||
Inside a character class, or if the decimal number following \ is greater than
|
||||
7 and there have not been that many capturing subpatterns, PCRE handles \8 and
|
||||
\9 as the literal characters "8" and "9", and otherwise re-reads up to three
|
||||
octal digits following the backslash, using them to generate a data character.
|
||||
Any subsequent digits stand for themselves. For example:
|
||||
<pre>
|
||||
\040 is another way of writing an ASCII space
|
||||
\40 is the same, provided there are fewer than 40 previous capturing subpatterns
|
||||
\7 is always a back reference
|
||||
\11 might be a back reference, or another way of writing a tab
|
||||
\011 is always a tab
|
||||
\0113 is a tab followed by the character "3"
|
||||
\113 might be a back reference, otherwise the character with octal code 113
|
||||
\377 might be a back reference, otherwise the value 255 (decimal)
|
||||
\81 is either a back reference, or the two characters "8" and "1"
|
||||
</pre>
|
||||
Note that octal values of 100 or greater that are specified using this syntax
|
||||
must not be introduced by a leading zero, because no more than three octal
|
||||
digits are ever read.
|
||||
</P>
|
||||
<P>
|
||||
By default, after \x that is not followed by {, from zero to two hexadecimal
|
||||
digits are read (letters can be in upper or lower case). Any number of
|
||||
hexadecimal digits may appear between \x{ and }. If a character other than
|
||||
a hexadecimal digit appears between \x{ and }, or if there is no terminating
|
||||
}, an error occurs.
|
||||
</P>
|
||||
<P>
|
||||
If the PCRE_JAVASCRIPT_COMPAT option is set, the interpretation of \x is
|
||||
as just described only when it is followed by two hexadecimal digits.
|
||||
Otherwise, it matches a literal "x" character. In JavaScript mode, support for
|
||||
code points greater than 256 is provided by \u, which must be followed by
|
||||
four hexadecimal digits; otherwise it matches a literal "u" character.
|
||||
</P>
|
||||
<P>
|
||||
Characters whose value is less than 256 can be defined by either of the two
|
||||
syntaxes for \x (or by \u in JavaScript mode). There is no difference in the
|
||||
way they are handled. For example, \xdc is exactly the same as \x{dc} (or
|
||||
\u00dc in JavaScript mode).
|
||||
</P>
|
||||
<br><b>
|
||||
Constraints on character values
|
||||
</b><br>
|
||||
<P>
|
||||
Characters that are specified using octal or hexadecimal numbers are
|
||||
limited to certain values, as follows:
|
||||
<pre>
|
||||
8-bit non-UTF mode less than 0x100
|
||||
8-bit UTF-8 mode less than 0x10ffff and a valid codepoint
|
||||
16-bit non-UTF mode less than 0x10000
|
||||
16-bit UTF-16 mode less than 0x10ffff and a valid codepoint
|
||||
32-bit non-UTF mode less than 0x100000000
|
||||
32-bit UTF-32 mode less than 0x10ffff and a valid codepoint
|
||||
</pre>
|
||||
Invalid Unicode codepoints are the range 0xd800 to 0xdfff (the so-called
|
||||
"surrogate" codepoints), and 0xffef.
|
||||
</P>
|
||||
<br><b>
|
||||
Escape sequences in character classes
|
||||
</b><br>
|
||||
<P>
|
||||
All the sequences that define a single character value can be used both inside
|
||||
and outside character classes. In addition, inside a character class, \b is
|
||||
interpreted as the backspace character (hex 08).
|
||||
</P>
|
||||
<P>
|
||||
\N is not allowed in a character class. \B, \R, and \X are not special
|
||||
inside a character class. Like other unrecognized escape sequences, they are
|
||||
treated as the literal characters "B", "R", and "X" by default, but cause an
|
||||
error if the PCRE_EXTRA option is set. Outside a character class, these
|
||||
sequences have different meanings.
|
||||
</P>
|
||||
<br><b>
|
||||
Unsupported escape sequences
|
||||
</b><br>
|
||||
<P>
|
||||
In Perl, the sequences \l, \L, \u, and \U are recognized by its string
|
||||
handler and used to modify the case of following characters. By default, PCRE
|
||||
does not support these escape sequences. However, if the PCRE_JAVASCRIPT_COMPAT
|
||||
option is set, \U matches a "U" character, and \u can be used to define a
|
||||
character by code point, as described in the previous section.
|
||||
</P>
|
||||
<br><b>
|
||||
Absolute and relative back references
|
||||
</b><br>
|
||||
<P>
|
||||
The sequence \g followed by an unsigned or a negative number, optionally
|
||||
enclosed in braces, is an absolute or relative back reference. A named back
|
||||
reference can be coded as \g{name}. Back references are discussed
|
||||
<a href="#backreferences">later,</a>
|
||||
following the discussion of
|
||||
<a href="#subpattern">parenthesized subpatterns.</a>
|
||||
</P>
|
||||
<br><b>
|
||||
Absolute and relative subroutine calls
|
||||
</b><br>
|
||||
<P>
|
||||
For compatibility with Oniguruma, the non-Perl syntax \g followed by a name or
|
||||
a number enclosed either in angle brackets or single quotes, is an alternative
|
||||
syntax for referencing a subpattern as a "subroutine". Details are discussed
|
||||
<a href="#onigurumasubroutines">later.</a>
|
||||
Note that \g{...} (Perl syntax) and \g<...> (Oniguruma syntax) are <i>not</i>
|
||||
synonymous. The former is a back reference; the latter is a
|
||||
<a href="#subpatternsassubroutines">subroutine</a>
|
||||
call.
|
||||
<a name="genericchartypes"></a></P>
|
||||
<br><b>
|
||||
Generic character types
|
||||
</b><br>
|
||||
<P>
|
||||
Another use of backslash is for specifying generic character types:
|
||||
<pre>
|
||||
\d any decimal digit
|
||||
\D any character that is not a decimal digit
|
||||
\h any horizontal white space character
|
||||
\H any character that is not a horizontal white space character
|
||||
\s any white space character
|
||||
\S any character that is not a white space character
|
||||
\v any vertical white space character
|
||||
\V any character that is not a vertical white space character
|
||||
\w any "word" character
|
||||
\W any "non-word" character
|
||||
</pre>
|
||||
There is also the single sequence \N, which matches a non-newline character.
|
||||
This is the same as
|
||||
<a href="#fullstopdot">the "." metacharacter</a>
|
||||
when PCRE_DOTALL is not set. Perl also uses \N to match characters by name;
|
||||
PCRE does not support this.
|
||||
</P>
|
||||
<P>
|
||||
Each pair of lower and upper case escape sequences partitions the complete set
|
||||
of characters into two disjoint sets. Any given character matches one, and only
|
||||
one, of each pair. The sequences can appear both inside and outside character
|
||||
classes. They each match one character of the appropriate type. If the current
|
||||
matching point is at the end of the subject string, all of them fail, because
|
||||
there is no character to match.
|
||||
</P>
|
||||
<P>
|
||||
For compatibility with Perl, \s did not used to match the VT character (code
|
||||
11), which made it different from the the POSIX "space" class. However, Perl
|
||||
added VT at release 5.18, and PCRE followed suit at release 8.34. The default
|
||||
\s characters are now HT (9), LF (10), VT (11), FF (12), CR (13), and space
|
||||
(32), which are defined as white space in the "C" locale. This list may vary if
|
||||
locale-specific matching is taking place. For example, in some locales the
|
||||
"non-breaking space" character (\xA0) is recognized as white space, and in
|
||||
others the VT character is not.
|
||||
</P>
|
||||
<P>
|
||||
A "word" character is an underscore or any character that is a letter or digit.
|
||||
By default, the definition of letters and digits is controlled by PCRE's
|
||||
low-valued character tables, and may vary if locale-specific matching is taking
|
||||
place (see
|
||||
<a href="pcreapi.html#localesupport">"Locale support"</a>
|
||||
in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page). For example, in a French locale such as "fr_FR" in Unix-like systems,
|
||||
or "french" in Windows, some character codes greater than 127 are used for
|
||||
accented letters, and these are then matched by \w. The use of locales with
|
||||
Unicode is discouraged.
|
||||
</P>
|
||||
<P>
|
||||
By default, characters whose code points are greater than 127 never match \d,
|
||||
\s, or \w, and always match \D, \S, and \W, although this may vary for
|
||||
characters in the range 128-255 when locale-specific matching is happening.
|
||||
These escape sequences retain their original meanings from before Unicode
|
||||
support was available, mainly for efficiency reasons. If PCRE is compiled with
|
||||
Unicode property support, and the PCRE_UCP option is set, the behaviour is
|
||||
changed so that Unicode properties are used to determine character types, as
|
||||
follows:
|
||||
<pre>
|
||||
\d any character that matches \p{Nd} (decimal digit)
|
||||
\s any character that matches \p{Z} or \h or \v
|
||||
\w any character that matches \p{L} or \p{N}, plus underscore
|
||||
</pre>
|
||||
The upper case escapes match the inverse sets of characters. Note that \d
|
||||
matches only decimal digits, whereas \w matches any Unicode digit, as well as
|
||||
any Unicode letter, and underscore. Note also that PCRE_UCP affects \b, and
|
||||
\B because they are defined in terms of \w and \W. Matching these sequences
|
||||
is noticeably slower when PCRE_UCP is set.
|
||||
</P>
|
||||
<P>
|
||||
The sequences \h, \H, \v, and \V are features that were added to Perl at
|
||||
release 5.10. In contrast to the other sequences, which match only ASCII
|
||||
characters by default, these always match certain high-valued code points,
|
||||
whether or not PCRE_UCP is set. The horizontal space characters are:
|
||||
<pre>
|
||||
U+0009 Horizontal tab (HT)
|
||||
U+0020 Space
|
||||
U+00A0 Non-break space
|
||||
U+1680 Ogham space mark
|
||||
U+180E Mongolian vowel separator
|
||||
U+2000 En quad
|
||||
U+2001 Em quad
|
||||
U+2002 En space
|
||||
U+2003 Em space
|
||||
U+2004 Three-per-em space
|
||||
U+2005 Four-per-em space
|
||||
U+2006 Six-per-em space
|
||||
U+2007 Figure space
|
||||
U+2008 Punctuation space
|
||||
U+2009 Thin space
|
||||
U+200A Hair space
|
||||
U+202F Narrow no-break space
|
||||
U+205F Medium mathematical space
|
||||
U+3000 Ideographic space
|
||||
</pre>
|
||||
The vertical space characters are:
|
||||
<pre>
|
||||
U+000A Linefeed (LF)
|
||||
U+000B Vertical tab (VT)
|
||||
U+000C Form feed (FF)
|
||||
U+000D Carriage return (CR)
|
||||
U+0085 Next line (NEL)
|
||||
U+2028 Line separator
|
||||
U+2029 Paragraph separator
|
||||
</pre>
|
||||
In 8-bit, non-UTF-8 mode, only the characters with codepoints less than 256 are
|
||||
relevant.
|
||||
<a name="newlineseq"></a></P>
|
||||
<br><b>
|
||||
Newline sequences
|
||||
</b><br>
|
||||
<P>
|
||||
Outside a character class, by default, the escape sequence \R matches any
|
||||
Unicode newline sequence. In 8-bit non-UTF-8 mode \R is equivalent to the
|
||||
following:
|
||||
<pre>
|
||||
(?>\r\n|\n|\x0b|\f|\r|\x85)
|
||||
</pre>
|
||||
This is an example of an "atomic group", details of which are given
|
||||
<a href="#atomicgroup">below.</a>
|
||||
This particular group matches either the two-character sequence CR followed by
|
||||
LF, or one of the single characters LF (linefeed, U+000A), VT (vertical tab,
|
||||
U+000B), FF (form feed, U+000C), CR (carriage return, U+000D), or NEL (next
|
||||
line, U+0085). The two-character sequence is treated as a single unit that
|
||||
cannot be split.
|
||||
</P>
|
||||
<P>
|
||||
In other modes, two additional characters whose codepoints are greater than 255
|
||||
are added: LS (line separator, U+2028) and PS (paragraph separator, U+2029).
|
||||
Unicode character property support is not needed for these characters to be
|
||||
recognized.
|
||||
</P>
|
||||
<P>
|
||||
It is possible to restrict \R to match only CR, LF, or CRLF (instead of the
|
||||
complete set of Unicode line endings) by setting the option PCRE_BSR_ANYCRLF
|
||||
either at compile time or when the pattern is matched. (BSR is an abbrevation
|
||||
for "backslash R".) This can be made the default when PCRE is built; if this is
|
||||
the case, the other behaviour can be requested via the PCRE_BSR_UNICODE option.
|
||||
It is also possible to specify these settings by starting a pattern string with
|
||||
one of the following sequences:
|
||||
<pre>
|
||||
(*BSR_ANYCRLF) CR, LF, or CRLF only
|
||||
(*BSR_UNICODE) any Unicode newline sequence
|
||||
</pre>
|
||||
These override the default and the options given to the compiling function, but
|
||||
they can themselves be overridden by options given to a matching function. Note
|
||||
that these special settings, which are not Perl-compatible, are recognized only
|
||||
at the very start of a pattern, and that they must be in upper case. If more
|
||||
than one of them is present, the last one is used. They can be combined with a
|
||||
change of newline convention; for example, a pattern can start with:
|
||||
<pre>
|
||||
(*ANY)(*BSR_ANYCRLF)
|
||||
</pre>
|
||||
They can also be combined with the (*UTF8), (*UTF16), (*UTF32), (*UTF) or
|
||||
(*UCP) special sequences. Inside a character class, \R is treated as an
|
||||
unrecognized escape sequence, and so matches the letter "R" by default, but
|
||||
causes an error if PCRE_EXTRA is set.
|
||||
<a name="uniextseq"></a></P>
|
||||
<br><b>
|
||||
Unicode character properties
|
||||
</b><br>
|
||||
<P>
|
||||
When PCRE is built with Unicode character property support, three additional
|
||||
escape sequences that match characters with specific properties are available.
|
||||
When in 8-bit non-UTF-8 mode, these sequences are of course limited to testing
|
||||
characters whose codepoints are less than 256, but they do work in this mode.
|
||||
The extra escape sequences are:
|
||||
<pre>
|
||||
\p{<i>xx</i>} a character with the <i>xx</i> property
|
||||
\P{<i>xx</i>} a character without the <i>xx</i> property
|
||||
\X a Unicode extended grapheme cluster
|
||||
</pre>
|
||||
The property names represented by <i>xx</i> above are limited to the Unicode
|
||||
script names, the general category properties, "Any", which matches any
|
||||
character (including newline), and some special PCRE properties (described
|
||||
in the
|
||||
<a href="#extraprops">next section).</a>
|
||||
Other Perl properties such as "InMusicalSymbols" are not currently supported by
|
||||
PCRE. Note that \P{Any} does not match any characters, so always causes a
|
||||
match failure.
|
||||
</P>
|
||||
<P>
|
||||
Sets of Unicode characters are defined as belonging to certain scripts. A
|
||||
character from one of these sets can be matched using a script name. For
|
||||
example:
|
||||
<pre>
|
||||
\p{Greek}
|
||||
\P{Han}
|
||||
</pre>
|
||||
Those that are not part of an identified script are lumped together as
|
||||
"Common". The current list of scripts is:
|
||||
</P>
|
||||
<P>
|
||||
Arabic,
|
||||
Armenian,
|
||||
Avestan,
|
||||
Balinese,
|
||||
Bamum,
|
||||
Bassa_Vah,
|
||||
Batak,
|
||||
Bengali,
|
||||
Bopomofo,
|
||||
Brahmi,
|
||||
Braille,
|
||||
Buginese,
|
||||
Buhid,
|
||||
Canadian_Aboriginal,
|
||||
Carian,
|
||||
Caucasian_Albanian,
|
||||
Chakma,
|
||||
Cham,
|
||||
Cherokee,
|
||||
Common,
|
||||
Coptic,
|
||||
Cuneiform,
|
||||
Cypriot,
|
||||
Cyrillic,
|
||||
Deseret,
|
||||
Devanagari,
|
||||
Duployan,
|
||||
Egyptian_Hieroglyphs,
|
||||
Elbasan,
|
||||
Ethiopic,
|
||||
Georgian,
|
||||
Glagolitic,
|
||||
Gothic,
|
||||
Grantha,
|
||||
Greek,
|
||||
Gujarati,
|
||||
Gurmukhi,
|
||||
Han,
|
||||
Hangul,
|
||||
Hanunoo,
|
||||
Hebrew,
|
||||
Hiragana,
|
||||
Imperial_Aramaic,
|
||||
Inherited,
|
||||
Inscriptional_Pahlavi,
|
||||
Inscriptional_Parthian,
|
||||
Javanese,
|
||||
Kaithi,
|
||||
Kannada,
|
||||
Katakana,
|
||||
Kayah_Li,
|
||||
Kharoshthi,
|
||||
Khmer,
|
||||
Khojki,
|
||||
Khudawadi,
|
||||
Lao,
|
||||
Latin,
|
||||
Lepcha,
|
||||
Limbu,
|
||||
Linear_A,
|
||||
Linear_B,
|
||||
Lisu,
|
||||
Lycian,
|
||||
Lydian,
|
||||
Mahajani,
|
||||
Malayalam,
|
||||
Mandaic,
|
||||
Manichaean,
|
||||
Meetei_Mayek,
|
||||
Mende_Kikakui,
|
||||
Meroitic_Cursive,
|
||||
Meroitic_Hieroglyphs,
|
||||
Miao,
|
||||
Modi,
|
||||
Mongolian,
|
||||
Mro,
|
||||
Myanmar,
|
||||
Nabataean,
|
||||
New_Tai_Lue,
|
||||
Nko,
|
||||
Ogham,
|
||||
Ol_Chiki,
|
||||
Old_Italic,
|
||||
Old_North_Arabian,
|
||||
Old_Permic,
|
||||
Old_Persian,
|
||||
Old_South_Arabian,
|
||||
Old_Turkic,
|
||||
Oriya,
|
||||
Osmanya,
|
||||
Pahawh_Hmong,
|
||||
Palmyrene,
|
||||
Pau_Cin_Hau,
|
||||
Phags_Pa,
|
||||
Phoenician,
|
||||
Psalter_Pahlavi,
|
||||
Rejang,
|
||||
Runic,
|
||||
Samaritan,
|
||||
Saurashtra,
|
||||
Sharada,
|
||||
Shavian,
|
||||
Siddham,
|
||||
Sinhala,
|
||||
Sora_Sompeng,
|
||||
Sundanese,
|
||||
Syloti_Nagri,
|
||||
Syriac,
|
||||
Tagalog,
|
||||
Tagbanwa,
|
||||
Tai_Le,
|
||||
Tai_Tham,
|
||||
Tai_Viet,
|
||||
Takri,
|
||||
Tamil,
|
||||
Telugu,
|
||||
Thaana,
|
||||
Thai,
|
||||
Tibetan,
|
||||
Tifinagh,
|
||||
Tirhuta,
|
||||
Ugaritic,
|
||||
Vai,
|
||||
Warang_Citi,
|
||||
Yi.
|
||||
</P>
|
||||
<P>
|
||||
Each character has exactly one Unicode general category property, specified by
|
||||
a two-letter abbreviation. For compatibility with Perl, negation can be
|
||||
specified by including a circumflex between the opening brace and the property
|
||||
name. For example, \p{^Lu} is the same as \P{Lu}.
|
||||
</P>
|
||||
<P>
|
||||
If only one letter is specified with \p or \P, it includes all the general
|
||||
category properties that start with that letter. In this case, in the absence
|
||||
of negation, the curly brackets in the escape sequence are optional; these two
|
||||
examples have the same effect:
|
||||
<pre>
|
||||
\p{L}
|
||||
\pL
|
||||
</pre>
|
||||
The following general category property codes are supported:
|
||||
<pre>
|
||||
C Other
|
||||
Cc Control
|
||||
Cf Format
|
||||
Cn Unassigned
|
||||
Co Private use
|
||||
Cs Surrogate
|
||||
|
||||
L Letter
|
||||
Ll Lower case letter
|
||||
Lm Modifier letter
|
||||
Lo Other letter
|
||||
Lt Title case letter
|
||||
Lu Upper case letter
|
||||
|
||||
M Mark
|
||||
Mc Spacing mark
|
||||
Me Enclosing mark
|
||||
Mn Non-spacing mark
|
||||
|
||||
N Number
|
||||
Nd Decimal number
|
||||
Nl Letter number
|
||||
No Other number
|
||||
|
||||
P Punctuation
|
||||
Pc Connector punctuation
|
||||
Pd Dash punctuation
|
||||
Pe Close punctuation
|
||||
Pf Final punctuation
|
||||
Pi Initial punctuation
|
||||
Po Other punctuation
|
||||
Ps Open punctuation
|
||||
|
||||
S Symbol
|
||||
Sc Currency symbol
|
||||
Sk Modifier symbol
|
||||
Sm Mathematical symbol
|
||||
So Other symbol
|
||||
|
||||
Z Separator
|
||||
Zl Line separator
|
||||
Zp Paragraph separator
|
||||
Zs Space separator
|
||||
</pre>
|
||||
The special property L& is also supported: it matches a character that has
|
||||
the Lu, Ll, or Lt property, in other words, a letter that is not classified as
|
||||
a modifier or "other".
|
||||
</P>
|
||||
<P>
|
||||
The Cs (Surrogate) property applies only to characters in the range U+D800 to
|
||||
U+DFFF. Such characters are not valid in Unicode strings and so
|
||||
cannot be tested by PCRE, unless UTF validity checking has been turned off
|
||||
(see the discussion of PCRE_NO_UTF8_CHECK, PCRE_NO_UTF16_CHECK and
|
||||
PCRE_NO_UTF32_CHECK in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
page). Perl does not support the Cs property.
|
||||
</P>
|
||||
<P>
|
||||
The long synonyms for property names that Perl supports (such as \p{Letter})
|
||||
are not supported by PCRE, nor is it permitted to prefix any of these
|
||||
properties with "Is".
|
||||
</P>
|
||||
<P>
|
||||
No character that is in the Unicode table has the Cn (unassigned) property.
|
||||
Instead, this property is assumed for any code point that is not in the
|
||||
Unicode table.
|
||||
</P>
|
||||
<P>
|
||||
Specifying caseless matching does not affect these escape sequences. For
|
||||
example, \p{Lu} always matches only upper case letters. This is different from
|
||||
the behaviour of current versions of Perl.
|
||||
</P>
|
||||
<P>
|
||||
Matching characters by Unicode property is not fast, because PCRE has to do a
|
||||
multistage table lookup in order to find a character's property. That is why
|
||||
the traditional escape sequences such as \d and \w do not use Unicode
|
||||
properties in PCRE by default, though you can make them do so by setting the
|
||||
PCRE_UCP option or by starting the pattern with (*UCP).
|
||||
</P>
|
||||
<br><b>
|
||||
Extended grapheme clusters
|
||||
</b><br>
|
||||
<P>
|
||||
The \X escape matches any number of Unicode characters that form an "extended
|
||||
grapheme cluster", and treats the sequence as an atomic group
|
||||
<a href="#atomicgroup">(see below).</a>
|
||||
Up to and including release 8.31, PCRE matched an earlier, simpler definition
|
||||
that was equivalent to
|
||||
<pre>
|
||||
(?>\PM\pM*)
|
||||
</pre>
|
||||
That is, it matched a character without the "mark" property, followed by zero
|
||||
or more characters with the "mark" property. Characters with the "mark"
|
||||
property are typically non-spacing accents that affect the preceding character.
|
||||
</P>
|
||||
<P>
|
||||
This simple definition was extended in Unicode to include more complicated
|
||||
kinds of composite character by giving each character a grapheme breaking
|
||||
property, and creating rules that use these properties to define the boundaries
|
||||
of extended grapheme clusters. In releases of PCRE later than 8.31, \X matches
|
||||
one of these clusters.
|
||||
</P>
|
||||
<P>
|
||||
\X always matches at least one character. Then it decides whether to add
|
||||
additional characters according to the following rules for ending a cluster:
|
||||
</P>
|
||||
<P>
|
||||
1. End at the end of the subject string.
|
||||
</P>
|
||||
<P>
|
||||
2. Do not end between CR and LF; otherwise end after any control character.
|
||||
</P>
|
||||
<P>
|
||||
3. Do not break Hangul (a Korean script) syllable sequences. Hangul characters
|
||||
are of five types: L, V, T, LV, and LVT. An L character may be followed by an
|
||||
L, V, LV, or LVT character; an LV or V character may be followed by a V or T
|
||||
character; an LVT or T character may be follwed only by a T character.
|
||||
</P>
|
||||
<P>
|
||||
4. Do not end before extending characters or spacing marks. Characters with
|
||||
the "mark" property always have the "extend" grapheme breaking property.
|
||||
</P>
|
||||
<P>
|
||||
5. Do not end after prepend characters.
|
||||
</P>
|
||||
<P>
|
||||
6. Otherwise, end the cluster.
|
||||
<a name="extraprops"></a></P>
|
||||
<br><b>
|
||||
PCRE's additional properties
|
||||
</b><br>
|
||||
<P>
|
||||
As well as the standard Unicode properties described above, PCRE supports four
|
||||
more that make it possible to convert traditional escape sequences such as \w
|
||||
and \s to use Unicode properties. PCRE uses these non-standard, non-Perl
|
||||
properties internally when PCRE_UCP is set. However, they may also be used
|
||||
explicitly. These properties are:
|
||||
<pre>
|
||||
Xan Any alphanumeric character
|
||||
Xps Any POSIX space character
|
||||
Xsp Any Perl space character
|
||||
Xwd Any Perl "word" character
|
||||
</pre>
|
||||
Xan matches characters that have either the L (letter) or the N (number)
|
||||
property. Xps matches the characters tab, linefeed, vertical tab, form feed, or
|
||||
carriage return, and any other character that has the Z (separator) property.
|
||||
Xsp is the same as Xps; it used to exclude vertical tab, for Perl
|
||||
compatibility, but Perl changed, and so PCRE followed at release 8.34. Xwd
|
||||
matches the same characters as Xan, plus underscore.
|
||||
</P>
|
||||
<P>
|
||||
There is another non-standard property, Xuc, which matches any character that
|
||||
can be represented by a Universal Character Name in C++ and other programming
|
||||
languages. These are the characters $, @, ` (grave accent), and all characters
|
||||
with Unicode code points greater than or equal to U+00A0, except for the
|
||||
surrogates U+D800 to U+DFFF. Note that most base (ASCII) characters are
|
||||
excluded. (Universal Character Names are of the form \uHHHH or \UHHHHHHHH
|
||||
where H is a hexadecimal digit. Note that the Xuc property does not match these
|
||||
sequences but the characters that they represent.)
|
||||
<a name="resetmatchstart"></a></P>
|
||||
<br><b>
|
||||
Resetting the match start
|
||||
</b><br>
|
||||
<P>
|
||||
The escape sequence \K causes any previously matched characters not to be
|
||||
included in the final matched sequence. For example, the pattern:
|
||||
<pre>
|
||||
foo\Kbar
|
||||
</pre>
|
||||
matches "foobar", but reports that it has matched "bar". This feature is
|
||||
similar to a lookbehind assertion
|
||||
<a href="#lookbehind">(described below).</a>
|
||||
However, in this case, the part of the subject before the real match does not
|
||||
have to be of fixed length, as lookbehind assertions do. The use of \K does
|
||||
not interfere with the setting of
|
||||
<a href="#subpattern">captured substrings.</a>
|
||||
For example, when the pattern
|
||||
<pre>
|
||||
(foo)\Kbar
|
||||
</pre>
|
||||
matches "foobar", the first substring is still set to "foo".
|
||||
</P>
|
||||
<P>
|
||||
Perl documents that the use of \K within assertions is "not well defined". In
|
||||
PCRE, \K is acted upon when it occurs inside positive assertions, but is
|
||||
ignored in negative assertions. Note that when a pattern such as (?=ab\K)
|
||||
matches, the reported start of the match can be greater than the end of the
|
||||
match.
|
||||
<a name="smallassertions"></a></P>
|
||||
<br><b>
|
||||
Simple assertions
|
||||
</b><br>
|
||||
<P>
|
||||
The final use of backslash is for certain simple assertions. An assertion
|
||||
specifies a condition that has to be met at a particular point in a match,
|
||||
without consuming any characters from the subject string. The use of
|
||||
subpatterns for more complicated assertions is described
|
||||
<a href="#bigassertions">below.</a>
|
||||
The backslashed assertions are:
|
||||
<pre>
|
||||
\b matches at a word boundary
|
||||
\B matches when not at a word boundary
|
||||
\A matches at the start of the subject
|
||||
\Z matches at the end of the subject
|
||||
also matches before a newline at the end of the subject
|
||||
\z matches only at the end of the subject
|
||||
\G matches at the first matching position in the subject
|
||||
</pre>
|
||||
Inside a character class, \b has a different meaning; it matches the backspace
|
||||
character. If any other of these assertions appears in a character class, by
|
||||
default it matches the corresponding literal character (for example, \B
|
||||
matches the letter B). However, if the PCRE_EXTRA option is set, an "invalid
|
||||
escape sequence" error is generated instead.
|
||||
</P>
|
||||
<P>
|
||||
A word boundary is a position in the subject string where the current character
|
||||
and the previous character do not both match \w or \W (i.e. one matches
|
||||
\w and the other matches \W), or the start or end of the string if the
|
||||
first or last character matches \w, respectively. In a UTF mode, the meanings
|
||||
of \w and \W can be changed by setting the PCRE_UCP option. When this is
|
||||
done, it also affects \b and \B. Neither PCRE nor Perl has a separate "start
|
||||
of word" or "end of word" metasequence. However, whatever follows \b normally
|
||||
determines which it is. For example, the fragment \ba matches "a" at the start
|
||||
of a word.
|
||||
</P>
|
||||
<P>
|
||||
The \A, \Z, and \z assertions differ from the traditional circumflex and
|
||||
dollar (described in the next section) in that they only ever match at the very
|
||||
start and end of the subject string, whatever options are set. Thus, they are
|
||||
independent of multiline mode. These three assertions are not affected by the
|
||||
PCRE_NOTBOL or PCRE_NOTEOL options, which affect only the behaviour of the
|
||||
circumflex and dollar metacharacters. However, if the <i>startoffset</i>
|
||||
argument of <b>pcre_exec()</b> is non-zero, indicating that matching is to start
|
||||
at a point other than the beginning of the subject, \A can never match. The
|
||||
difference between \Z and \z is that \Z matches before a newline at the end
|
||||
of the string as well as at the very end, whereas \z matches only at the end.
|
||||
</P>
|
||||
<P>
|
||||
The \G assertion is true only when the current matching position is at the
|
||||
start point of the match, as specified by the <i>startoffset</i> argument of
|
||||
<b>pcre_exec()</b>. It differs from \A when the value of <i>startoffset</i> is
|
||||
non-zero. By calling <b>pcre_exec()</b> multiple times with appropriate
|
||||
arguments, you can mimic Perl's /g option, and it is in this kind of
|
||||
implementation where \G can be useful.
|
||||
</P>
|
||||
<P>
|
||||
Note, however, that PCRE's interpretation of \G, as the start of the current
|
||||
match, is subtly different from Perl's, which defines it as the end of the
|
||||
previous match. In Perl, these can be different when the previously matched
|
||||
string was empty. Because PCRE does just one match at a time, it cannot
|
||||
reproduce this behaviour.
|
||||
</P>
|
||||
<P>
|
||||
If all the alternatives of a pattern begin with \G, the expression is anchored
|
||||
to the starting match position, and the "anchored" flag is set in the compiled
|
||||
regular expression.
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">CIRCUMFLEX AND DOLLAR</a><br>
|
||||
<P>
|
||||
The circumflex and dollar metacharacters are zero-width assertions. That is,
|
||||
they test for a particular condition being true without consuming any
|
||||
characters from the subject string.
|
||||
</P>
|
||||
<P>
|
||||
Outside a character class, in the default matching mode, the circumflex
|
||||
character is an assertion that is true only if the current matching point is at
|
||||
the start of the subject string. If the <i>startoffset</i> argument of
|
||||
<b>pcre_exec()</b> is non-zero, circumflex can never match if the PCRE_MULTILINE
|
||||
option is unset. Inside a character class, circumflex has an entirely different
|
||||
meaning
|
||||
<a href="#characterclass">(see below).</a>
|
||||
</P>
|
||||
<P>
|
||||
Circumflex need not be the first character of the pattern if a number of
|
||||
alternatives are involved, but it should be the first thing in each alternative
|
||||
in which it appears if the pattern is ever to match that branch. If all
|
||||
possible alternatives start with a circumflex, that is, if the pattern is
|
||||
constrained to match only at the start of the subject, it is said to be an
|
||||
"anchored" pattern. (There are also other constructs that can cause a pattern
|
||||
to be anchored.)
|
||||
</P>
|
||||
<P>
|
||||
The dollar character is an assertion that is true only if the current matching
|
||||
point is at the end of the subject string, or immediately before a newline at
|
||||
the end of the string (by default). Note, however, that it does not actually
|
||||
match the newline. Dollar need not be the last character of the pattern if a
|
||||
number of alternatives are involved, but it should be the last item in any
|
||||
branch in which it appears. Dollar has no special meaning in a character class.
|
||||
</P>
|
||||
<P>
|
||||
The meaning of dollar can be changed so that it matches only at the very end of
|
||||
the string, by setting the PCRE_DOLLAR_ENDONLY option at compile time. This
|
||||
does not affect the \Z assertion.
|
||||
</P>
|
||||
<P>
|
||||
The meanings of the circumflex and dollar characters are changed if the
|
||||
PCRE_MULTILINE option is set. When this is the case, a circumflex matches
|
||||
immediately after internal newlines as well as at the start of the subject
|
||||
string. It does not match after a newline that ends the string. A dollar
|
||||
matches before any newlines in the string, as well as at the very end, when
|
||||
PCRE_MULTILINE is set. When newline is specified as the two-character
|
||||
sequence CRLF, isolated CR and LF characters do not indicate newlines.
|
||||
</P>
|
||||
<P>
|
||||
For example, the pattern /^abc$/ matches the subject string "def\nabc" (where
|
||||
\n represents a newline) in multiline mode, but not otherwise. Consequently,
|
||||
patterns that are anchored in single line mode because all branches start with
|
||||
^ are not anchored in multiline mode, and a match for circumflex is possible
|
||||
when the <i>startoffset</i> argument of <b>pcre_exec()</b> is non-zero. The
|
||||
PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is set.
|
||||
</P>
|
||||
<P>
|
||||
Note that the sequences \A, \Z, and \z can be used to match the start and
|
||||
end of the subject in both modes, and if all branches of a pattern start with
|
||||
\A it is always anchored, whether or not PCRE_MULTILINE is set.
|
||||
<a name="fullstopdot"></a></P>
|
||||
<br><a name="SEC7" href="#TOC1">FULL STOP (PERIOD, DOT) AND \N</a><br>
|
||||
<P>
|
||||
Outside a character class, a dot in the pattern matches any one character in
|
||||
the subject string except (by default) a character that signifies the end of a
|
||||
line.
|
||||
</P>
|
||||
<P>
|
||||
When a line ending is defined as a single character, dot never matches that
|
||||
character; when the two-character sequence CRLF is used, dot does not match CR
|
||||
if it is immediately followed by LF, but otherwise it matches all characters
|
||||
(including isolated CRs and LFs). When any Unicode line endings are being
|
||||
recognized, dot does not match CR or LF or any of the other line ending
|
||||
characters.
|
||||
</P>
|
||||
<P>
|
||||
The behaviour of dot with regard to newlines can be changed. If the PCRE_DOTALL
|
||||
option is set, a dot matches any one character, without exception. If the
|
||||
two-character sequence CRLF is present in the subject string, it takes two dots
|
||||
to match it.
|
||||
</P>
|
||||
<P>
|
||||
The handling of dot is entirely independent of the handling of circumflex and
|
||||
dollar, the only relationship being that they both involve newlines. Dot has no
|
||||
special meaning in a character class.
|
||||
</P>
|
||||
<P>
|
||||
The escape sequence \N behaves like a dot, except that it is not affected by
|
||||
the PCRE_DOTALL option. In other words, it matches any character except one
|
||||
that signifies the end of a line. Perl also uses \N to match characters by
|
||||
name; PCRE does not support this.
|
||||
</P>
|
||||
<br><a name="SEC8" href="#TOC1">MATCHING A SINGLE DATA UNIT</a><br>
|
||||
<P>
|
||||
Outside a character class, the escape sequence \C matches any one data unit,
|
||||
whether or not a UTF mode is set. In the 8-bit library, one data unit is one
|
||||
byte; in the 16-bit library it is a 16-bit unit; in the 32-bit library it is
|
||||
a 32-bit unit. Unlike a dot, \C always
|
||||
matches line-ending characters. The feature is provided in Perl in order to
|
||||
match individual bytes in UTF-8 mode, but it is unclear how it can usefully be
|
||||
used. Because \C breaks up characters into individual data units, matching one
|
||||
unit with \C in a UTF mode means that the rest of the string may start with a
|
||||
malformed UTF character. This has undefined results, because PCRE assumes that
|
||||
it is dealing with valid UTF strings (and by default it checks this at the
|
||||
start of processing unless the PCRE_NO_UTF8_CHECK, PCRE_NO_UTF16_CHECK or
|
||||
PCRE_NO_UTF32_CHECK option is used).
|
||||
</P>
|
||||
<P>
|
||||
PCRE does not allow \C to appear in lookbehind assertions
|
||||
<a href="#lookbehind">(described below)</a>
|
||||
in a UTF mode, because this would make it impossible to calculate the length of
|
||||
the lookbehind.
|
||||
</P>
|
||||
<P>
|
||||
In general, the \C escape sequence is best avoided. However, one
|
||||
way of using it that avoids the problem of malformed UTF characters is to use a
|
||||
lookahead to check the length of the next character, as in this pattern, which
|
||||
could be used with a UTF-8 string (ignore white space and line breaks):
|
||||
<pre>
|
||||
(?| (?=[\x00-\x7f])(\C) |
|
||||
(?=[\x80-\x{7ff}])(\C)(\C) |
|
||||
(?=[\x{800}-\x{ffff}])(\C)(\C)(\C) |
|
||||
(?=[\x{10000}-\x{1fffff}])(\C)(\C)(\C)(\C))
|
||||
</pre>
|
||||
A group that starts with (?| resets the capturing parentheses numbers in each
|
||||
alternative (see
|
||||
<a href="#dupsubpatternnumber">"Duplicate Subpattern Numbers"</a>
|
||||
below). The assertions at the start of each branch check the next UTF-8
|
||||
character for values whose encoding uses 1, 2, 3, or 4 bytes, respectively. The
|
||||
character's individual bytes are then captured by the appropriate number of
|
||||
groups.
|
||||
<a name="characterclass"></a></P>
|
||||
<br><a name="SEC9" href="#TOC1">SQUARE BRACKETS AND CHARACTER CLASSES</a><br>
|
||||
<P>
|
||||
An opening square bracket introduces a character class, terminated by a closing
|
||||
square bracket. A closing square bracket on its own is not special by default.
|
||||
However, if the PCRE_JAVASCRIPT_COMPAT option is set, a lone closing square
|
||||
bracket causes a compile-time error. If a closing square bracket is required as
|
||||
a member of the class, it should be the first data character in the class
|
||||
(after an initial circumflex, if present) or escaped with a backslash.
|
||||
</P>
|
||||
<P>
|
||||
A character class matches a single character in the subject. In a UTF mode, the
|
||||
character may be more than one data unit long. A matched character must be in
|
||||
the set of characters defined by the class, unless the first character in the
|
||||
class definition is a circumflex, in which case the subject character must not
|
||||
be in the set defined by the class. If a circumflex is actually required as a
|
||||
member of the class, ensure it is not the first character, or escape it with a
|
||||
backslash.
|
||||
</P>
|
||||
<P>
|
||||
For example, the character class [aeiou] matches any lower case vowel, while
|
||||
[^aeiou] matches any character that is not a lower case vowel. Note that a
|
||||
circumflex is just a convenient notation for specifying the characters that
|
||||
are in the class by enumerating those that are not. A class that starts with a
|
||||
circumflex is not an assertion; it still consumes a character from the subject
|
||||
string, and therefore it fails if the current pointer is at the end of the
|
||||
string.
|
||||
</P>
|
||||
<P>
|
||||
In UTF-8 (UTF-16, UTF-32) mode, characters with values greater than 255 (0xffff)
|
||||
can be included in a class as a literal string of data units, or by using the
|
||||
\x{ escaping mechanism.
|
||||
</P>
|
||||
<P>
|
||||
When caseless matching is set, any letters in a class represent both their
|
||||
upper case and lower case versions, so for example, a caseless [aeiou] matches
|
||||
"A" as well as "a", and a caseless [^aeiou] does not match "A", whereas a
|
||||
caseful version would. In a UTF mode, PCRE always understands the concept of
|
||||
case for characters whose values are less than 128, so caseless matching is
|
||||
always possible. For characters with higher values, the concept of case is
|
||||
supported if PCRE is compiled with Unicode property support, but not otherwise.
|
||||
If you want to use caseless matching in a UTF mode for characters 128 and
|
||||
above, you must ensure that PCRE is compiled with Unicode property support as
|
||||
well as with UTF support.
|
||||
</P>
|
||||
<P>
|
||||
Characters that might indicate line breaks are never treated in any special way
|
||||
when matching character classes, whatever line-ending sequence is in use, and
|
||||
whatever setting of the PCRE_DOTALL and PCRE_MULTILINE options is used. A class
|
||||
such as [^a] always matches one of these characters.
|
||||
</P>
|
||||
<P>
|
||||
The minus (hyphen) character can be used to specify a range of characters in a
|
||||
character class. For example, [d-m] matches any letter between d and m,
|
||||
inclusive. If a minus character is required in a class, it must be escaped with
|
||||
a backslash or appear in a position where it cannot be interpreted as
|
||||
indicating a range, typically as the first or last character in the class, or
|
||||
immediately after a range. For example, [b-d-z] matches letters in the range b
|
||||
to d, a hyphen character, or z.
|
||||
</P>
|
||||
<P>
|
||||
It is not possible to have the literal character "]" as the end character of a
|
||||
range. A pattern such as [W-]46] is interpreted as a class of two characters
|
||||
("W" and "-") followed by a literal string "46]", so it would match "W46]" or
|
||||
"-46]". However, if the "]" is escaped with a backslash it is interpreted as
|
||||
the end of range, so [W-\]46] is interpreted as a class containing a range
|
||||
followed by two other characters. The octal or hexadecimal representation of
|
||||
"]" can also be used to end a range.
|
||||
</P>
|
||||
<P>
|
||||
An error is generated if a POSIX character class (see below) or an escape
|
||||
sequence other than one that defines a single character appears at a point
|
||||
where a range ending character is expected. For example, [z-\xff] is valid,
|
||||
but [A-\d] and [A-[:digit:]] are not.
|
||||
</P>
|
||||
<P>
|
||||
Ranges operate in the collating sequence of character values. They can also be
|
||||
used for characters specified numerically, for example [\000-\037]. Ranges
|
||||
can include any characters that are valid for the current mode.
|
||||
</P>
|
||||
<P>
|
||||
If a range that includes letters is used when caseless matching is set, it
|
||||
matches the letters in either case. For example, [W-c] is equivalent to
|
||||
[][\\^_`wxyzabc], matched caselessly, and in a non-UTF mode, if character
|
||||
tables for a French locale are in use, [\xc8-\xcb] matches accented E
|
||||
characters in both cases. In UTF modes, PCRE supports the concept of case for
|
||||
characters with values greater than 128 only when it is compiled with Unicode
|
||||
property support.
|
||||
</P>
|
||||
<P>
|
||||
The character escape sequences \d, \D, \h, \H, \p, \P, \s, \S, \v,
|
||||
\V, \w, and \W may appear in a character class, and add the characters that
|
||||
they match to the class. For example, [\dABCDEF] matches any hexadecimal
|
||||
digit. In UTF modes, the PCRE_UCP option affects the meanings of \d, \s, \w
|
||||
and their upper case partners, just as it does when they appear outside a
|
||||
character class, as described in the section entitled
|
||||
<a href="#genericchartypes">"Generic character types"</a>
|
||||
above. The escape sequence \b has a different meaning inside a character
|
||||
class; it matches the backspace character. The sequences \B, \N, \R, and \X
|
||||
are not special inside a character class. Like any other unrecognized escape
|
||||
sequences, they are treated as the literal characters "B", "N", "R", and "X" by
|
||||
default, but cause an error if the PCRE_EXTRA option is set.
|
||||
</P>
|
||||
<P>
|
||||
A circumflex can conveniently be used with the upper case character types to
|
||||
specify a more restricted set of characters than the matching lower case type.
|
||||
For example, the class [^\W_] matches any letter or digit, but not underscore,
|
||||
whereas [\w] includes underscore. A positive character class should be read as
|
||||
"something OR something OR ..." and a negative class as "NOT something AND NOT
|
||||
something AND NOT ...".
|
||||
</P>
|
||||
<P>
|
||||
The only metacharacters that are recognized in character classes are backslash,
|
||||
hyphen (only where it can be interpreted as specifying a range), circumflex
|
||||
(only at the start), opening square bracket (only when it can be interpreted as
|
||||
introducing a POSIX class name, or for a special compatibility feature - see
|
||||
the next two sections), and the terminating closing square bracket. However,
|
||||
escaping other non-alphanumeric characters does no harm.
|
||||
</P>
|
||||
<br><a name="SEC10" href="#TOC1">POSIX CHARACTER CLASSES</a><br>
|
||||
<P>
|
||||
Perl supports the POSIX notation for character classes. This uses names
|
||||
enclosed by [: and :] within the enclosing square brackets. PCRE also supports
|
||||
this notation. For example,
|
||||
<pre>
|
||||
[01[:alpha:]%]
|
||||
</pre>
|
||||
matches "0", "1", any alphabetic character, or "%". The supported class names
|
||||
are:
|
||||
<pre>
|
||||
alnum letters and digits
|
||||
alpha letters
|
||||
ascii character codes 0 - 127
|
||||
blank space or tab only
|
||||
cntrl control characters
|
||||
digit decimal digits (same as \d)
|
||||
graph printing characters, excluding space
|
||||
lower lower case letters
|
||||
print printing characters, including space
|
||||
punct printing characters, excluding letters and digits and space
|
||||
space white space (the same as \s from PCRE 8.34)
|
||||
upper upper case letters
|
||||
word "word" characters (same as \w)
|
||||
xdigit hexadecimal digits
|
||||
</pre>
|
||||
The default "space" characters are HT (9), LF (10), VT (11), FF (12), CR (13),
|
||||
and space (32). If locale-specific matching is taking place, the list of space
|
||||
characters may be different; there may be fewer or more of them. "Space" used
|
||||
to be different to \s, which did not include VT, for Perl compatibility.
|
||||
However, Perl changed at release 5.18, and PCRE followed at release 8.34.
|
||||
"Space" and \s now match the same set of characters.
|
||||
</P>
|
||||
<P>
|
||||
The name "word" is a Perl extension, and "blank" is a GNU extension from Perl
|
||||
5.8. Another Perl extension is negation, which is indicated by a ^ character
|
||||
after the colon. For example,
|
||||
<pre>
|
||||
[12[:^digit:]]
|
||||
</pre>
|
||||
matches "1", "2", or any non-digit. PCRE (and Perl) also recognize the POSIX
|
||||
syntax [.ch.] and [=ch=] where "ch" is a "collating element", but these are not
|
||||
supported, and an error is given if they are encountered.
|
||||
</P>
|
||||
<P>
|
||||
By default, characters with values greater than 128 do not match any of the
|
||||
POSIX character classes. However, if the PCRE_UCP option is passed to
|
||||
<b>pcre_compile()</b>, some of the classes are changed so that Unicode character
|
||||
properties are used. This is achieved by replacing certain POSIX classes by
|
||||
other sequences, as follows:
|
||||
<pre>
|
||||
[:alnum:] becomes \p{Xan}
|
||||
[:alpha:] becomes \p{L}
|
||||
[:blank:] becomes \h
|
||||
[:digit:] becomes \p{Nd}
|
||||
[:lower:] becomes \p{Ll}
|
||||
[:space:] becomes \p{Xps}
|
||||
[:upper:] becomes \p{Lu}
|
||||
[:word:] becomes \p{Xwd}
|
||||
</pre>
|
||||
Negated versions, such as [:^alpha:] use \P instead of \p. Three other POSIX
|
||||
classes are handled specially in UCP mode:
|
||||
</P>
|
||||
<P>
|
||||
[:graph:]
|
||||
This matches characters that have glyphs that mark the page when printed. In
|
||||
Unicode property terms, it matches all characters with the L, M, N, P, S, or Cf
|
||||
properties, except for:
|
||||
<pre>
|
||||
U+061C Arabic Letter Mark
|
||||
U+180E Mongolian Vowel Separator
|
||||
U+2066 - U+2069 Various "isolate"s
|
||||
|
||||
</PRE>
|
||||
</P>
|
||||
<P>
|
||||
[:print:]
|
||||
This matches the same characters as [:graph:] plus space characters that are
|
||||
not controls, that is, characters with the Zs property.
|
||||
</P>
|
||||
<P>
|
||||
[:punct:]
|
||||
This matches all characters that have the Unicode P (punctuation) property,
|
||||
plus those characters whose code points are less than 128 that have the S
|
||||
(Symbol) property.
|
||||
</P>
|
||||
<P>
|
||||
The other POSIX classes are unchanged, and match only characters with code
|
||||
points less than 128.
|
||||
</P>
|
||||
<br><a name="SEC11" href="#TOC1">COMPATIBILITY FEATURE FOR WORD BOUNDARIES</a><br>
|
||||
<P>
|
||||
In the POSIX.2 compliant library that was included in 4.4BSD Unix, the ugly
|
||||
syntax [[:<:]] and [[:>:]] is used for matching "start of word" and "end of
|
||||
word". PCRE treats these items as follows:
|
||||
<pre>
|
||||
[[:<:]] is converted to \b(?=\w)
|
||||
[[:>:]] is converted to \b(?<=\w)
|
||||
</pre>
|
||||
Only these exact character sequences are recognized. A sequence such as
|
||||
[a[:<:]b] provokes error for an unrecognized POSIX class name. This support is
|
||||
not compatible with Perl. It is provided to help migrations from other
|
||||
environments, and is best not used in any new patterns. Note that \b matches
|
||||
at the start and the end of a word (see
|
||||
<a href="#smallassertions">"Simple assertions"</a>
|
||||
above), and in a Perl-style pattern the preceding or following character
|
||||
normally shows which is wanted, without the need for the assertions that are
|
||||
used above in order to give exactly the POSIX behaviour.
|
||||
</P>
|
||||
<br><a name="SEC12" href="#TOC1">VERTICAL BAR</a><br>
|
||||
<P>
|
||||
Vertical bar characters are used to separate alternative patterns. For example,
|
||||
the pattern
|
||||
<pre>
|
||||
gilbert|sullivan
|
||||
</pre>
|
||||
matches either "gilbert" or "sullivan". Any number of alternatives may appear,
|
||||
and an empty alternative is permitted (matching the empty string). The matching
|
||||
process tries each alternative in turn, from left to right, and the first one
|
||||
that succeeds is used. If the alternatives are within a subpattern
|
||||
<a href="#subpattern">(defined below),</a>
|
||||
"succeeds" means matching the rest of the main pattern as well as the
|
||||
alternative in the subpattern.
|
||||
</P>
|
||||
<br><a name="SEC13" href="#TOC1">INTERNAL OPTION SETTING</a><br>
|
||||
<P>
|
||||
The settings of the PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, and
|
||||
PCRE_EXTENDED options (which are Perl-compatible) can be changed from within
|
||||
the pattern by a sequence of Perl option letters enclosed between "(?" and ")".
|
||||
The option letters are
|
||||
<pre>
|
||||
i for PCRE_CASELESS
|
||||
m for PCRE_MULTILINE
|
||||
s for PCRE_DOTALL
|
||||
x for PCRE_EXTENDED
|
||||
</pre>
|
||||
For example, (?im) sets caseless, multiline matching. It is also possible to
|
||||
unset these options by preceding the letter with a hyphen, and a combined
|
||||
setting and unsetting such as (?im-sx), which sets PCRE_CASELESS and
|
||||
PCRE_MULTILINE while unsetting PCRE_DOTALL and PCRE_EXTENDED, is also
|
||||
permitted. If a letter appears both before and after the hyphen, the option is
|
||||
unset.
|
||||
</P>
|
||||
<P>
|
||||
The PCRE-specific options PCRE_DUPNAMES, PCRE_UNGREEDY, and PCRE_EXTRA can be
|
||||
changed in the same way as the Perl-compatible options by using the characters
|
||||
J, U and X respectively.
|
||||
</P>
|
||||
<P>
|
||||
When one of these option changes occurs at top level (that is, not inside
|
||||
subpattern parentheses), the change applies to the remainder of the pattern
|
||||
that follows. An option change within a subpattern (see below for a description
|
||||
of subpatterns) affects only that part of the subpattern that follows it, so
|
||||
<pre>
|
||||
(a(?i)b)c
|
||||
</pre>
|
||||
matches abc and aBc and no other strings (assuming PCRE_CASELESS is not used).
|
||||
By this means, options can be made to have different settings in different
|
||||
parts of the pattern. Any changes made in one alternative do carry on
|
||||
into subsequent branches within the same subpattern. For example,
|
||||
<pre>
|
||||
(a(?i)b|c)
|
||||
</pre>
|
||||
matches "ab", "aB", "c", and "C", even though when matching "C" the first
|
||||
branch is abandoned before the option setting. This is because the effects of
|
||||
option settings happen at compile time. There would be some very weird
|
||||
behaviour otherwise.
|
||||
</P>
|
||||
<P>
|
||||
<b>Note:</b> There are other PCRE-specific options that can be set by the
|
||||
application when the compiling or matching functions are called. In some cases
|
||||
the pattern can contain special leading sequences such as (*CRLF) to override
|
||||
what the application has set or what has been defaulted. Details are given in
|
||||
the section entitled
|
||||
<a href="#newlineseq">"Newline sequences"</a>
|
||||
above. There are also the (*UTF8), (*UTF16),(*UTF32), and (*UCP) leading
|
||||
sequences that can be used to set UTF and Unicode property modes; they are
|
||||
equivalent to setting the PCRE_UTF8, PCRE_UTF16, PCRE_UTF32 and the PCRE_UCP
|
||||
options, respectively. The (*UTF) sequence is a generic version that can be
|
||||
used with any of the libraries. However, the application can set the
|
||||
PCRE_NEVER_UTF option, which locks out the use of the (*UTF) sequences.
|
||||
<a name="subpattern"></a></P>
|
||||
<br><a name="SEC14" href="#TOC1">SUBPATTERNS</a><br>
|
||||
<P>
|
||||
Subpatterns are delimited by parentheses (round brackets), which can be nested.
|
||||
Turning part of a pattern into a subpattern does two things:
|
||||
<br>
|
||||
<br>
|
||||
1. It localizes a set of alternatives. For example, the pattern
|
||||
<pre>
|
||||
cat(aract|erpillar|)
|
||||
</pre>
|
||||
matches "cataract", "caterpillar", or "cat". Without the parentheses, it would
|
||||
match "cataract", "erpillar" or an empty string.
|
||||
<br>
|
||||
<br>
|
||||
2. It sets up the subpattern as a capturing subpattern. This means that, when
|
||||
the whole pattern matches, that portion of the subject string that matched the
|
||||
subpattern is passed back to the caller via the <i>ovector</i> argument of the
|
||||
matching function. (This applies only to the traditional matching functions;
|
||||
the DFA matching functions do not support capturing.)
|
||||
</P>
|
||||
<P>
|
||||
Opening parentheses are counted from left to right (starting from 1) to obtain
|
||||
numbers for the capturing subpatterns. For example, if the string "the red
|
||||
king" is matched against the pattern
|
||||
<pre>
|
||||
the ((red|white) (king|queen))
|
||||
</pre>
|
||||
the captured substrings are "red king", "red", and "king", and are numbered 1,
|
||||
2, and 3, respectively.
|
||||
</P>
|
||||
<P>
|
||||
The fact that plain parentheses fulfil two functions is not always helpful.
|
||||
There are often times when a grouping subpattern is required without a
|
||||
capturing requirement. If an opening parenthesis is followed by a question mark
|
||||
and a colon, the subpattern does not do any capturing, and is not counted when
|
||||
computing the number of any subsequent capturing subpatterns. For example, if
|
||||
the string "the white queen" is matched against the pattern
|
||||
<pre>
|
||||
the ((?:red|white) (king|queen))
|
||||
</pre>
|
||||
the captured substrings are "white queen" and "queen", and are numbered 1 and
|
||||
2. The maximum number of capturing subpatterns is 65535.
|
||||
</P>
|
||||
<P>
|
||||
As a convenient shorthand, if any option settings are required at the start of
|
||||
a non-capturing subpattern, the option letters may appear between the "?" and
|
||||
the ":". Thus the two patterns
|
||||
<pre>
|
||||
(?i:saturday|sunday)
|
||||
(?:(?i)saturday|sunday)
|
||||
</pre>
|
||||
match exactly the same set of strings. Because alternative branches are tried
|
||||
from left to right, and options are not reset until the end of the subpattern
|
||||
is reached, an option setting in one branch does affect subsequent branches, so
|
||||
the above patterns match "SUNDAY" as well as "Saturday".
|
||||
<a name="dupsubpatternnumber"></a></P>
|
||||
<br><a name="SEC15" href="#TOC1">DUPLICATE SUBPATTERN NUMBERS</a><br>
|
||||
<P>
|
||||
Perl 5.10 introduced a feature whereby each alternative in a subpattern uses
|
||||
the same numbers for its capturing parentheses. Such a subpattern starts with
|
||||
(?| and is itself a non-capturing subpattern. For example, consider this
|
||||
pattern:
|
||||
<pre>
|
||||
(?|(Sat)ur|(Sun))day
|
||||
</pre>
|
||||
Because the two alternatives are inside a (?| group, both sets of capturing
|
||||
parentheses are numbered one. Thus, when the pattern matches, you can look
|
||||
at captured substring number one, whichever alternative matched. This construct
|
||||
is useful when you want to capture part, but not all, of one of a number of
|
||||
alternatives. Inside a (?| group, parentheses are numbered as usual, but the
|
||||
number is reset at the start of each branch. The numbers of any capturing
|
||||
parentheses that follow the subpattern start after the highest number used in
|
||||
any branch. The following example is taken from the Perl documentation. The
|
||||
numbers underneath show in which buffer the captured content will be stored.
|
||||
<pre>
|
||||
# before ---------------branch-reset----------- after
|
||||
/ ( a ) (?| x ( y ) z | (p (q) r) | (t) u (v) ) ( z ) /x
|
||||
# 1 2 2 3 2 3 4
|
||||
</pre>
|
||||
A back reference to a numbered subpattern uses the most recent value that is
|
||||
set for that number by any subpattern. The following pattern matches "abcabc"
|
||||
or "defdef":
|
||||
<pre>
|
||||
/(?|(abc)|(def))\1/
|
||||
</pre>
|
||||
In contrast, a subroutine call to a numbered subpattern always refers to the
|
||||
first one in the pattern with the given number. The following pattern matches
|
||||
"abcabc" or "defabc":
|
||||
<pre>
|
||||
/(?|(abc)|(def))(?1)/
|
||||
</pre>
|
||||
If a
|
||||
<a href="#conditions">condition test</a>
|
||||
for a subpattern's having matched refers to a non-unique number, the test is
|
||||
true if any of the subpatterns of that number have matched.
|
||||
</P>
|
||||
<P>
|
||||
An alternative approach to using this "branch reset" feature is to use
|
||||
duplicate named subpatterns, as described in the next section.
|
||||
</P>
|
||||
<br><a name="SEC16" href="#TOC1">NAMED SUBPATTERNS</a><br>
|
||||
<P>
|
||||
Identifying capturing parentheses by number is simple, but it can be very hard
|
||||
to keep track of the numbers in complicated regular expressions. Furthermore,
|
||||
if an expression is modified, the numbers may change. To help with this
|
||||
difficulty, PCRE supports the naming of subpatterns. This feature was not
|
||||
added to Perl until release 5.10. Python had the feature earlier, and PCRE
|
||||
introduced it at release 4.0, using the Python syntax. PCRE now supports both
|
||||
the Perl and the Python syntax. Perl allows identically numbered subpatterns to
|
||||
have different names, but PCRE does not.
|
||||
</P>
|
||||
<P>
|
||||
In PCRE, a subpattern can be named in one of three ways: (?<name>...) or
|
||||
(?'name'...) as in Perl, or (?P<name>...) as in Python. References to capturing
|
||||
parentheses from other parts of the pattern, such as
|
||||
<a href="#backreferences">back references,</a>
|
||||
<a href="#recursion">recursion,</a>
|
||||
and
|
||||
<a href="#conditions">conditions,</a>
|
||||
can be made by name as well as by number.
|
||||
</P>
|
||||
<P>
|
||||
Names consist of up to 32 alphanumeric characters and underscores, but must
|
||||
start with a non-digit. Named capturing parentheses are still allocated numbers
|
||||
as well as names, exactly as if the names were not present. The PCRE API
|
||||
provides function calls for extracting the name-to-number translation table
|
||||
from a compiled pattern. There is also a convenience function for extracting a
|
||||
captured substring by name.
|
||||
</P>
|
||||
<P>
|
||||
By default, a name must be unique within a pattern, but it is possible to relax
|
||||
this constraint by setting the PCRE_DUPNAMES option at compile time. (Duplicate
|
||||
names are also always permitted for subpatterns with the same number, set up as
|
||||
described in the previous section.) Duplicate names can be useful for patterns
|
||||
where only one instance of the named parentheses can match. Suppose you want to
|
||||
match the name of a weekday, either as a 3-letter abbreviation or as the full
|
||||
name, and in both cases you want to extract the abbreviation. This pattern
|
||||
(ignoring the line breaks) does the job:
|
||||
<pre>
|
||||
(?<DN>Mon|Fri|Sun)(?:day)?|
|
||||
(?<DN>Tue)(?:sday)?|
|
||||
(?<DN>Wed)(?:nesday)?|
|
||||
(?<DN>Thu)(?:rsday)?|
|
||||
(?<DN>Sat)(?:urday)?
|
||||
</pre>
|
||||
There are five capturing substrings, but only one is ever set after a match.
|
||||
(An alternative way of solving this problem is to use a "branch reset"
|
||||
subpattern, as described in the previous section.)
|
||||
</P>
|
||||
<P>
|
||||
The convenience function for extracting the data by name returns the substring
|
||||
for the first (and in this example, the only) subpattern of that name that
|
||||
matched. This saves searching to find which numbered subpattern it was.
|
||||
</P>
|
||||
<P>
|
||||
If you make a back reference to a non-unique named subpattern from elsewhere in
|
||||
the pattern, the subpatterns to which the name refers are checked in the order
|
||||
in which they appear in the overall pattern. The first one that is set is used
|
||||
for the reference. For example, this pattern matches both "foofoo" and
|
||||
"barbar" but not "foobar" or "barfoo":
|
||||
<pre>
|
||||
(?:(?<n>foo)|(?<n>bar))\k<n>
|
||||
|
||||
</PRE>
|
||||
</P>
|
||||
<P>
|
||||
If you make a subroutine call to a non-unique named subpattern, the one that
|
||||
corresponds to the first occurrence of the name is used. In the absence of
|
||||
duplicate numbers (see the previous section) this is the one with the lowest
|
||||
number.
|
||||
</P>
|
||||
<P>
|
||||
If you use a named reference in a condition
|
||||
test (see the
|
||||
<a href="#conditions">section about conditions</a>
|
||||
below), either to check whether a subpattern has matched, or to check for
|
||||
recursion, all subpatterns with the same name are tested. If the condition is
|
||||
true for any one of them, the overall condition is true. This is the same
|
||||
behaviour as testing by number. For further details of the interfaces for
|
||||
handling named subpatterns, see the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
<b>Warning:</b> You cannot use different names to distinguish between two
|
||||
subpatterns with the same number because PCRE uses only the numbers when
|
||||
matching. For this reason, an error is given at compile time if different names
|
||||
are given to subpatterns with the same number. However, you can always give the
|
||||
same name to subpatterns with the same number, even when PCRE_DUPNAMES is not
|
||||
set.
|
||||
</P>
|
||||
<br><a name="SEC17" href="#TOC1">REPETITION</a><br>
|
||||
<P>
|
||||
Repetition is specified by quantifiers, which can follow any of the following
|
||||
items:
|
||||
<pre>
|
||||
a literal data character
|
||||
the dot metacharacter
|
||||
the \C escape sequence
|
||||
the \X escape sequence
|
||||
the \R escape sequence
|
||||
an escape such as \d or \pL that matches a single character
|
||||
a character class
|
||||
a back reference (see next section)
|
||||
a parenthesized subpattern (including assertions)
|
||||
a subroutine call to a subpattern (recursive or otherwise)
|
||||
</pre>
|
||||
The general repetition quantifier specifies a minimum and maximum number of
|
||||
permitted matches, by giving the two numbers in curly brackets (braces),
|
||||
separated by a comma. The numbers must be less than 65536, and the first must
|
||||
be less than or equal to the second. For example:
|
||||
<pre>
|
||||
z{2,4}
|
||||
</pre>
|
||||
matches "zz", "zzz", or "zzzz". A closing brace on its own is not a special
|
||||
character. If the second number is omitted, but the comma is present, there is
|
||||
no upper limit; if the second number and the comma are both omitted, the
|
||||
quantifier specifies an exact number of required matches. Thus
|
||||
<pre>
|
||||
[aeiou]{3,}
|
||||
</pre>
|
||||
matches at least 3 successive vowels, but may match many more, while
|
||||
<pre>
|
||||
\d{8}
|
||||
</pre>
|
||||
matches exactly 8 digits. An opening curly bracket that appears in a position
|
||||
where a quantifier is not allowed, or one that does not match the syntax of a
|
||||
quantifier, is taken as a literal character. For example, {,6} is not a
|
||||
quantifier, but a literal string of four characters.
|
||||
</P>
|
||||
<P>
|
||||
In UTF modes, quantifiers apply to characters rather than to individual data
|
||||
units. Thus, for example, \x{100}{2} matches two characters, each of
|
||||
which is represented by a two-byte sequence in a UTF-8 string. Similarly,
|
||||
\X{3} matches three Unicode extended grapheme clusters, each of which may be
|
||||
several data units long (and they may be of different lengths).
|
||||
</P>
|
||||
<P>
|
||||
The quantifier {0} is permitted, causing the expression to behave as if the
|
||||
previous item and the quantifier were not present. This may be useful for
|
||||
subpatterns that are referenced as
|
||||
<a href="#subpatternsassubroutines">subroutines</a>
|
||||
from elsewhere in the pattern (but see also the section entitled
|
||||
<a href="#subdefine">"Defining subpatterns for use by reference only"</a>
|
||||
below). Items other than subpatterns that have a {0} quantifier are omitted
|
||||
from the compiled pattern.
|
||||
</P>
|
||||
<P>
|
||||
For convenience, the three most common quantifiers have single-character
|
||||
abbreviations:
|
||||
<pre>
|
||||
* is equivalent to {0,}
|
||||
+ is equivalent to {1,}
|
||||
? is equivalent to {0,1}
|
||||
</pre>
|
||||
It is possible to construct infinite loops by following a subpattern that can
|
||||
match no characters with a quantifier that has no upper limit, for example:
|
||||
<pre>
|
||||
(a?)*
|
||||
</pre>
|
||||
Earlier versions of Perl and PCRE used to give an error at compile time for
|
||||
such patterns. However, because there are cases where this can be useful, such
|
||||
patterns are now accepted, but if any repetition of the subpattern does in fact
|
||||
match no characters, the loop is forcibly broken.
|
||||
</P>
|
||||
<P>
|
||||
By default, the quantifiers are "greedy", that is, they match as much as
|
||||
possible (up to the maximum number of permitted times), without causing the
|
||||
rest of the pattern to fail. The classic example of where this gives problems
|
||||
is in trying to match comments in C programs. These appear between /* and */
|
||||
and within the comment, individual * and / characters may appear. An attempt to
|
||||
match C comments by applying the pattern
|
||||
<pre>
|
||||
/\*.*\*/
|
||||
</pre>
|
||||
to the string
|
||||
<pre>
|
||||
/* first comment */ not comment /* second comment */
|
||||
</pre>
|
||||
fails, because it matches the entire string owing to the greediness of the .*
|
||||
item.
|
||||
</P>
|
||||
<P>
|
||||
However, if a quantifier is followed by a question mark, it ceases to be
|
||||
greedy, and instead matches the minimum number of times possible, so the
|
||||
pattern
|
||||
<pre>
|
||||
/\*.*?\*/
|
||||
</pre>
|
||||
does the right thing with the C comments. The meaning of the various
|
||||
quantifiers is not otherwise changed, just the preferred number of matches.
|
||||
Do not confuse this use of question mark with its use as a quantifier in its
|
||||
own right. Because it has two uses, it can sometimes appear doubled, as in
|
||||
<pre>
|
||||
\d??\d
|
||||
</pre>
|
||||
which matches one digit by preference, but can match two if that is the only
|
||||
way the rest of the pattern matches.
|
||||
</P>
|
||||
<P>
|
||||
If the PCRE_UNGREEDY option is set (an option that is not available in Perl),
|
||||
the quantifiers are not greedy by default, but individual ones can be made
|
||||
greedy by following them with a question mark. In other words, it inverts the
|
||||
default behaviour.
|
||||
</P>
|
||||
<P>
|
||||
When a parenthesized subpattern is quantified with a minimum repeat count that
|
||||
is greater than 1 or with a limited maximum, more memory is required for the
|
||||
compiled pattern, in proportion to the size of the minimum or maximum.
|
||||
</P>
|
||||
<P>
|
||||
If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equivalent
|
||||
to Perl's /s) is set, thus allowing the dot to match newlines, the pattern is
|
||||
implicitly anchored, because whatever follows will be tried against every
|
||||
character position in the subject string, so there is no point in retrying the
|
||||
overall match at any position after the first. PCRE normally treats such a
|
||||
pattern as though it were preceded by \A.
|
||||
</P>
|
||||
<P>
|
||||
In cases where it is known that the subject string contains no newlines, it is
|
||||
worth setting PCRE_DOTALL in order to obtain this optimization, or
|
||||
alternatively using ^ to indicate anchoring explicitly.
|
||||
</P>
|
||||
<P>
|
||||
However, there are some cases where the optimization cannot be used. When .*
|
||||
is inside capturing parentheses that are the subject of a back reference
|
||||
elsewhere in the pattern, a match at the start may fail where a later one
|
||||
succeeds. Consider, for example:
|
||||
<pre>
|
||||
(.*)abc\1
|
||||
</pre>
|
||||
If the subject is "xyz123abc123" the match point is the fourth character. For
|
||||
this reason, such a pattern is not implicitly anchored.
|
||||
</P>
|
||||
<P>
|
||||
Another case where implicit anchoring is not applied is when the leading .* is
|
||||
inside an atomic group. Once again, a match at the start may fail where a later
|
||||
one succeeds. Consider this pattern:
|
||||
<pre>
|
||||
(?>.*?a)b
|
||||
</pre>
|
||||
It matches "ab" in the subject "aab". The use of the backtracking control verbs
|
||||
(*PRUNE) and (*SKIP) also disable this optimization.
|
||||
</P>
|
||||
<P>
|
||||
When a capturing subpattern is repeated, the value captured is the substring
|
||||
that matched the final iteration. For example, after
|
||||
<pre>
|
||||
(tweedle[dume]{3}\s*)+
|
||||
</pre>
|
||||
has matched "tweedledum tweedledee" the value of the captured substring is
|
||||
"tweedledee". However, if there are nested capturing subpatterns, the
|
||||
corresponding captured values may have been set in previous iterations. For
|
||||
example, after
|
||||
<pre>
|
||||
/(a|(b))+/
|
||||
</pre>
|
||||
matches "aba" the value of the second captured substring is "b".
|
||||
<a name="atomicgroup"></a></P>
|
||||
<br><a name="SEC18" href="#TOC1">ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS</a><br>
|
||||
<P>
|
||||
With both maximizing ("greedy") and minimizing ("ungreedy" or "lazy")
|
||||
repetition, failure of what follows normally causes the repeated item to be
|
||||
re-evaluated to see if a different number of repeats allows the rest of the
|
||||
pattern to match. Sometimes it is useful to prevent this, either to change the
|
||||
nature of the match, or to cause it fail earlier than it otherwise might, when
|
||||
the author of the pattern knows there is no point in carrying on.
|
||||
</P>
|
||||
<P>
|
||||
Consider, for example, the pattern \d+foo when applied to the subject line
|
||||
<pre>
|
||||
123456bar
|
||||
</pre>
|
||||
After matching all 6 digits and then failing to match "foo", the normal
|
||||
action of the matcher is to try again with only 5 digits matching the \d+
|
||||
item, and then with 4, and so on, before ultimately failing. "Atomic grouping"
|
||||
(a term taken from Jeffrey Friedl's book) provides the means for specifying
|
||||
that once a subpattern has matched, it is not to be re-evaluated in this way.
|
||||
</P>
|
||||
<P>
|
||||
If we use atomic grouping for the previous example, the matcher gives up
|
||||
immediately on failing to match "foo" the first time. The notation is a kind of
|
||||
special parenthesis, starting with (?> as in this example:
|
||||
<pre>
|
||||
(?>\d+)foo
|
||||
</pre>
|
||||
This kind of parenthesis "locks up" the part of the pattern it contains once
|
||||
it has matched, and a failure further into the pattern is prevented from
|
||||
backtracking into it. Backtracking past it to previous items, however, works as
|
||||
normal.
|
||||
</P>
|
||||
<P>
|
||||
An alternative description is that a subpattern of this type matches the string
|
||||
of characters that an identical standalone pattern would match, if anchored at
|
||||
the current point in the subject string.
|
||||
</P>
|
||||
<P>
|
||||
Atomic grouping subpatterns are not capturing subpatterns. Simple cases such as
|
||||
the above example can be thought of as a maximizing repeat that must swallow
|
||||
everything it can. So, while both \d+ and \d+? are prepared to adjust the
|
||||
number of digits they match in order to make the rest of the pattern match,
|
||||
(?>\d+) can only match an entire sequence of digits.
|
||||
</P>
|
||||
<P>
|
||||
Atomic groups in general can of course contain arbitrarily complicated
|
||||
subpatterns, and can be nested. However, when the subpattern for an atomic
|
||||
group is just a single repeated item, as in the example above, a simpler
|
||||
notation, called a "possessive quantifier" can be used. This consists of an
|
||||
additional + character following a quantifier. Using this notation, the
|
||||
previous example can be rewritten as
|
||||
<pre>
|
||||
\d++foo
|
||||
</pre>
|
||||
Note that a possessive quantifier can be used with an entire group, for
|
||||
example:
|
||||
<pre>
|
||||
(abc|xyz){2,3}+
|
||||
</pre>
|
||||
Possessive quantifiers are always greedy; the setting of the PCRE_UNGREEDY
|
||||
option is ignored. They are a convenient notation for the simpler forms of
|
||||
atomic group. However, there is no difference in the meaning of a possessive
|
||||
quantifier and the equivalent atomic group, though there may be a performance
|
||||
difference; possessive quantifiers should be slightly faster.
|
||||
</P>
|
||||
<P>
|
||||
The possessive quantifier syntax is an extension to the Perl 5.8 syntax.
|
||||
Jeffrey Friedl originated the idea (and the name) in the first edition of his
|
||||
book. Mike McCloskey liked it, so implemented it when he built Sun's Java
|
||||
package, and PCRE copied it from there. It ultimately found its way into Perl
|
||||
at release 5.10.
|
||||
</P>
|
||||
<P>
|
||||
PCRE has an optimization that automatically "possessifies" certain simple
|
||||
pattern constructs. For example, the sequence A+B is treated as A++B because
|
||||
there is no point in backtracking into a sequence of A's when B must follow.
|
||||
</P>
|
||||
<P>
|
||||
When a pattern contains an unlimited repeat inside a subpattern that can itself
|
||||
be repeated an unlimited number of times, the use of an atomic group is the
|
||||
only way to avoid some failing matches taking a very long time indeed. The
|
||||
pattern
|
||||
<pre>
|
||||
(\D+|<\d+>)*[!?]
|
||||
</pre>
|
||||
matches an unlimited number of substrings that either consist of non-digits, or
|
||||
digits enclosed in <>, followed by either ! or ?. When it matches, it runs
|
||||
quickly. However, if it is applied to
|
||||
<pre>
|
||||
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
|
||||
</pre>
|
||||
it takes a long time before reporting failure. This is because the string can
|
||||
be divided between the internal \D+ repeat and the external * repeat in a
|
||||
large number of ways, and all have to be tried. (The example uses [!?] rather
|
||||
than a single character at the end, because both PCRE and Perl have an
|
||||
optimization that allows for fast failure when a single character is used. They
|
||||
remember the last single character that is required for a match, and fail early
|
||||
if it is not present in the string.) If the pattern is changed so that it uses
|
||||
an atomic group, like this:
|
||||
<pre>
|
||||
((?>\D+)|<\d+>)*[!?]
|
||||
</pre>
|
||||
sequences of non-digits cannot be broken, and failure happens quickly.
|
||||
<a name="backreferences"></a></P>
|
||||
<br><a name="SEC19" href="#TOC1">BACK REFERENCES</a><br>
|
||||
<P>
|
||||
Outside a character class, a backslash followed by a digit greater than 0 (and
|
||||
possibly further digits) is a back reference to a capturing subpattern earlier
|
||||
(that is, to its left) in the pattern, provided there have been that many
|
||||
previous capturing left parentheses.
|
||||
</P>
|
||||
<P>
|
||||
However, if the decimal number following the backslash is less than 10, it is
|
||||
always taken as a back reference, and causes an error only if there are not
|
||||
that many capturing left parentheses in the entire pattern. In other words, the
|
||||
parentheses that are referenced need not be to the left of the reference for
|
||||
numbers less than 10. A "forward back reference" of this type can make sense
|
||||
when a repetition is involved and the subpattern to the right has participated
|
||||
in an earlier iteration.
|
||||
</P>
|
||||
<P>
|
||||
It is not possible to have a numerical "forward back reference" to a subpattern
|
||||
whose number is 10 or more using this syntax because a sequence such as \50 is
|
||||
interpreted as a character defined in octal. See the subsection entitled
|
||||
"Non-printing characters"
|
||||
<a href="#digitsafterbackslash">above</a>
|
||||
for further details of the handling of digits following a backslash. There is
|
||||
no such problem when named parentheses are used. A back reference to any
|
||||
subpattern is possible using named parentheses (see below).
|
||||
</P>
|
||||
<P>
|
||||
Another way of avoiding the ambiguity inherent in the use of digits following a
|
||||
backslash is to use the \g escape sequence. This escape must be followed by an
|
||||
unsigned number or a negative number, optionally enclosed in braces. These
|
||||
examples are all identical:
|
||||
<pre>
|
||||
(ring), \1
|
||||
(ring), \g1
|
||||
(ring), \g{1}
|
||||
</pre>
|
||||
An unsigned number specifies an absolute reference without the ambiguity that
|
||||
is present in the older syntax. It is also useful when literal digits follow
|
||||
the reference. A negative number is a relative reference. Consider this
|
||||
example:
|
||||
<pre>
|
||||
(abc(def)ghi)\g{-1}
|
||||
</pre>
|
||||
The sequence \g{-1} is a reference to the most recently started capturing
|
||||
subpattern before \g, that is, is it equivalent to \2 in this example.
|
||||
Similarly, \g{-2} would be equivalent to \1. The use of relative references
|
||||
can be helpful in long patterns, and also in patterns that are created by
|
||||
joining together fragments that contain references within themselves.
|
||||
</P>
|
||||
<P>
|
||||
A back reference matches whatever actually matched the capturing subpattern in
|
||||
the current subject string, rather than anything matching the subpattern
|
||||
itself (see
|
||||
<a href="#subpatternsassubroutines">"Subpatterns as subroutines"</a>
|
||||
below for a way of doing that). So the pattern
|
||||
<pre>
|
||||
(sens|respons)e and \1ibility
|
||||
</pre>
|
||||
matches "sense and sensibility" and "response and responsibility", but not
|
||||
"sense and responsibility". If caseful matching is in force at the time of the
|
||||
back reference, the case of letters is relevant. For example,
|
||||
<pre>
|
||||
((?i)rah)\s+\1
|
||||
</pre>
|
||||
matches "rah rah" and "RAH RAH", but not "RAH rah", even though the original
|
||||
capturing subpattern is matched caselessly.
|
||||
</P>
|
||||
<P>
|
||||
There are several different ways of writing back references to named
|
||||
subpatterns. The .NET syntax \k{name} and the Perl syntax \k<name> or
|
||||
\k'name' are supported, as is the Python syntax (?P=name). Perl 5.10's unified
|
||||
back reference syntax, in which \g can be used for both numeric and named
|
||||
references, is also supported. We could rewrite the above example in any of
|
||||
the following ways:
|
||||
<pre>
|
||||
(?<p1>(?i)rah)\s+\k<p1>
|
||||
(?'p1'(?i)rah)\s+\k{p1}
|
||||
(?P<p1>(?i)rah)\s+(?P=p1)
|
||||
(?<p1>(?i)rah)\s+\g{p1}
|
||||
</pre>
|
||||
A subpattern that is referenced by name may appear in the pattern before or
|
||||
after the reference.
|
||||
</P>
|
||||
<P>
|
||||
There may be more than one back reference to the same subpattern. If a
|
||||
subpattern has not actually been used in a particular match, any back
|
||||
references to it always fail by default. For example, the pattern
|
||||
<pre>
|
||||
(a|(bc))\2
|
||||
</pre>
|
||||
always fails if it starts to match "a" rather than "bc". However, if the
|
||||
PCRE_JAVASCRIPT_COMPAT option is set at compile time, a back reference to an
|
||||
unset value matches an empty string.
|
||||
</P>
|
||||
<P>
|
||||
Because there may be many capturing parentheses in a pattern, all digits
|
||||
following a backslash are taken as part of a potential back reference number.
|
||||
If the pattern continues with a digit character, some delimiter must be used to
|
||||
terminate the back reference. If the PCRE_EXTENDED option is set, this can be
|
||||
white space. Otherwise, the \g{ syntax or an empty comment (see
|
||||
<a href="#comments">"Comments"</a>
|
||||
below) can be used.
|
||||
</P>
|
||||
<br><b>
|
||||
Recursive back references
|
||||
</b><br>
|
||||
<P>
|
||||
A back reference that occurs inside the parentheses to which it refers fails
|
||||
when the subpattern is first used, so, for example, (a\1) never matches.
|
||||
However, such references can be useful inside repeated subpatterns. For
|
||||
example, the pattern
|
||||
<pre>
|
||||
(a|b\1)+
|
||||
</pre>
|
||||
matches any number of "a"s and also "aba", "ababbaa" etc. At each iteration of
|
||||
the subpattern, the back reference matches the character string corresponding
|
||||
to the previous iteration. In order for this to work, the pattern must be such
|
||||
that the first iteration does not need to match the back reference. This can be
|
||||
done using alternation, as in the example above, or by a quantifier with a
|
||||
minimum of zero.
|
||||
</P>
|
||||
<P>
|
||||
Back references of this type cause the group that they reference to be treated
|
||||
as an
|
||||
<a href="#atomicgroup">atomic group.</a>
|
||||
Once the whole group has been matched, a subsequent matching failure cannot
|
||||
cause backtracking into the middle of the group.
|
||||
<a name="bigassertions"></a></P>
|
||||
<br><a name="SEC20" href="#TOC1">ASSERTIONS</a><br>
|
||||
<P>
|
||||
An assertion is a test on the characters following or preceding the current
|
||||
matching point that does not actually consume any characters. The simple
|
||||
assertions coded as \b, \B, \A, \G, \Z, \z, ^ and $ are described
|
||||
<a href="#smallassertions">above.</a>
|
||||
</P>
|
||||
<P>
|
||||
More complicated assertions are coded as subpatterns. There are two kinds:
|
||||
those that look ahead of the current position in the subject string, and those
|
||||
that look behind it. An assertion subpattern is matched in the normal way,
|
||||
except that it does not cause the current matching position to be changed.
|
||||
</P>
|
||||
<P>
|
||||
Assertion subpatterns are not capturing subpatterns. If such an assertion
|
||||
contains capturing subpatterns within it, these are counted for the purposes of
|
||||
numbering the capturing subpatterns in the whole pattern. However, substring
|
||||
capturing is carried out only for positive assertions. (Perl sometimes, but not
|
||||
always, does do capturing in negative assertions.)
|
||||
</P>
|
||||
<P>
|
||||
WARNING: If a positive assertion containing one or more capturing subpatterns
|
||||
succeeds, but failure to match later in the pattern causes backtracking over
|
||||
this assertion, the captures within the assertion are reset only if no higher
|
||||
numbered captures are already set. This is, unfortunately, a fundamental
|
||||
limitation of the current implementation, and as PCRE1 is now in
|
||||
maintenance-only status, it is unlikely ever to change.
|
||||
</P>
|
||||
<P>
|
||||
For compatibility with Perl, assertion subpatterns may be repeated; though
|
||||
it makes no sense to assert the same thing several times, the side effect of
|
||||
capturing parentheses may occasionally be useful. In practice, there only three
|
||||
cases:
|
||||
<br>
|
||||
<br>
|
||||
(1) If the quantifier is {0}, the assertion is never obeyed during matching.
|
||||
However, it may contain internal capturing parenthesized groups that are called
|
||||
from elsewhere via the
|
||||
<a href="#subpatternsassubroutines">subroutine mechanism.</a>
|
||||
<br>
|
||||
<br>
|
||||
(2) If quantifier is {0,n} where n is greater than zero, it is treated as if it
|
||||
were {0,1}. At run time, the rest of the pattern match is tried with and
|
||||
without the assertion, the order depending on the greediness of the quantifier.
|
||||
<br>
|
||||
<br>
|
||||
(3) If the minimum repetition is greater than zero, the quantifier is ignored.
|
||||
The assertion is obeyed just once when encountered during matching.
|
||||
</P>
|
||||
<br><b>
|
||||
Lookahead assertions
|
||||
</b><br>
|
||||
<P>
|
||||
Lookahead assertions start with (?= for positive assertions and (?! for
|
||||
negative assertions. For example,
|
||||
<pre>
|
||||
\w+(?=;)
|
||||
</pre>
|
||||
matches a word followed by a semicolon, but does not include the semicolon in
|
||||
the match, and
|
||||
<pre>
|
||||
foo(?!bar)
|
||||
</pre>
|
||||
matches any occurrence of "foo" that is not followed by "bar". Note that the
|
||||
apparently similar pattern
|
||||
<pre>
|
||||
(?!foo)bar
|
||||
</pre>
|
||||
does not find an occurrence of "bar" that is preceded by something other than
|
||||
"foo"; it finds any occurrence of "bar" whatsoever, because the assertion
|
||||
(?!foo) is always true when the next three characters are "bar". A
|
||||
lookbehind assertion is needed to achieve the other effect.
|
||||
</P>
|
||||
<P>
|
||||
If you want to force a matching failure at some point in a pattern, the most
|
||||
convenient way to do it is with (?!) because an empty string always matches, so
|
||||
an assertion that requires there not to be an empty string must always fail.
|
||||
The backtracking control verb (*FAIL) or (*F) is a synonym for (?!).
|
||||
<a name="lookbehind"></a></P>
|
||||
<br><b>
|
||||
Lookbehind assertions
|
||||
</b><br>
|
||||
<P>
|
||||
Lookbehind assertions start with (?<= for positive assertions and (?<! for
|
||||
negative assertions. For example,
|
||||
<pre>
|
||||
(?<!foo)bar
|
||||
</pre>
|
||||
does find an occurrence of "bar" that is not preceded by "foo". The contents of
|
||||
a lookbehind assertion are restricted such that all the strings it matches must
|
||||
have a fixed length. However, if there are several top-level alternatives, they
|
||||
do not all have to have the same fixed length. Thus
|
||||
<pre>
|
||||
(?<=bullock|donkey)
|
||||
</pre>
|
||||
is permitted, but
|
||||
<pre>
|
||||
(?<!dogs?|cats?)
|
||||
</pre>
|
||||
causes an error at compile time. Branches that match different length strings
|
||||
are permitted only at the top level of a lookbehind assertion. This is an
|
||||
extension compared with Perl, which requires all branches to match the same
|
||||
length of string. An assertion such as
|
||||
<pre>
|
||||
(?<=ab(c|de))
|
||||
</pre>
|
||||
is not permitted, because its single top-level branch can match two different
|
||||
lengths, but it is acceptable to PCRE if rewritten to use two top-level
|
||||
branches:
|
||||
<pre>
|
||||
(?<=abc|abde)
|
||||
</pre>
|
||||
In some cases, the escape sequence \K
|
||||
<a href="#resetmatchstart">(see above)</a>
|
||||
can be used instead of a lookbehind assertion to get round the fixed-length
|
||||
restriction.
|
||||
</P>
|
||||
<P>
|
||||
The implementation of lookbehind assertions is, for each alternative, to
|
||||
temporarily move the current position back by the fixed length and then try to
|
||||
match. If there are insufficient characters before the current position, the
|
||||
assertion fails.
|
||||
</P>
|
||||
<P>
|
||||
In a UTF mode, PCRE does not allow the \C escape (which matches a single data
|
||||
unit even in a UTF mode) to appear in lookbehind assertions, because it makes
|
||||
it impossible to calculate the length of the lookbehind. The \X and \R
|
||||
escapes, which can match different numbers of data units, are also not
|
||||
permitted.
|
||||
</P>
|
||||
<P>
|
||||
<a href="#subpatternsassubroutines">"Subroutine"</a>
|
||||
calls (see below) such as (?2) or (?&X) are permitted in lookbehinds, as long
|
||||
as the subpattern matches a fixed-length string.
|
||||
<a href="#recursion">Recursion,</a>
|
||||
however, is not supported.
|
||||
</P>
|
||||
<P>
|
||||
Possessive quantifiers can be used in conjunction with lookbehind assertions to
|
||||
specify efficient matching of fixed-length strings at the end of subject
|
||||
strings. Consider a simple pattern such as
|
||||
<pre>
|
||||
abcd$
|
||||
</pre>
|
||||
when applied to a long string that does not match. Because matching proceeds
|
||||
from left to right, PCRE will look for each "a" in the subject and then see if
|
||||
what follows matches the rest of the pattern. If the pattern is specified as
|
||||
<pre>
|
||||
^.*abcd$
|
||||
</pre>
|
||||
the initial .* matches the entire string at first, but when this fails (because
|
||||
there is no following "a"), it backtracks to match all but the last character,
|
||||
then all but the last two characters, and so on. Once again the search for "a"
|
||||
covers the entire string, from right to left, so we are no better off. However,
|
||||
if the pattern is written as
|
||||
<pre>
|
||||
^.*+(?<=abcd)
|
||||
</pre>
|
||||
there can be no backtracking for the .*+ item; it can match only the entire
|
||||
string. The subsequent lookbehind assertion does a single test on the last four
|
||||
characters. If it fails, the match fails immediately. For long strings, this
|
||||
approach makes a significant difference to the processing time.
|
||||
</P>
|
||||
<br><b>
|
||||
Using multiple assertions
|
||||
</b><br>
|
||||
<P>
|
||||
Several assertions (of any sort) may occur in succession. For example,
|
||||
<pre>
|
||||
(?<=\d{3})(?<!999)foo
|
||||
</pre>
|
||||
matches "foo" preceded by three digits that are not "999". Notice that each of
|
||||
the assertions is applied independently at the same point in the subject
|
||||
string. First there is a check that the previous three characters are all
|
||||
digits, and then there is a check that the same three characters are not "999".
|
||||
This pattern does <i>not</i> match "foo" preceded by six characters, the first
|
||||
of which are digits and the last three of which are not "999". For example, it
|
||||
doesn't match "123abcfoo". A pattern to do that is
|
||||
<pre>
|
||||
(?<=\d{3}...)(?<!999)foo
|
||||
</pre>
|
||||
This time the first assertion looks at the preceding six characters, checking
|
||||
that the first three are digits, and then the second assertion checks that the
|
||||
preceding three characters are not "999".
|
||||
</P>
|
||||
<P>
|
||||
Assertions can be nested in any combination. For example,
|
||||
<pre>
|
||||
(?<=(?<!foo)bar)baz
|
||||
</pre>
|
||||
matches an occurrence of "baz" that is preceded by "bar" which in turn is not
|
||||
preceded by "foo", while
|
||||
<pre>
|
||||
(?<=\d{3}(?!999)...)foo
|
||||
</pre>
|
||||
is another pattern that matches "foo" preceded by three digits and any three
|
||||
characters that are not "999".
|
||||
<a name="conditions"></a></P>
|
||||
<br><a name="SEC21" href="#TOC1">CONDITIONAL SUBPATTERNS</a><br>
|
||||
<P>
|
||||
It is possible to cause the matching process to obey a subpattern
|
||||
conditionally or to choose between two alternative subpatterns, depending on
|
||||
the result of an assertion, or whether a specific capturing subpattern has
|
||||
already been matched. The two possible forms of conditional subpattern are:
|
||||
<pre>
|
||||
(?(condition)yes-pattern)
|
||||
(?(condition)yes-pattern|no-pattern)
|
||||
</pre>
|
||||
If the condition is satisfied, the yes-pattern is used; otherwise the
|
||||
no-pattern (if present) is used. If there are more than two alternatives in the
|
||||
subpattern, a compile-time error occurs. Each of the two alternatives may
|
||||
itself contain nested subpatterns of any form, including conditional
|
||||
subpatterns; the restriction to two alternatives applies only at the level of
|
||||
the condition. This pattern fragment is an example where the alternatives are
|
||||
complex:
|
||||
<pre>
|
||||
(?(1) (A|B|C) | (D | (?(2)E|F) | E) )
|
||||
|
||||
</PRE>
|
||||
</P>
|
||||
<P>
|
||||
There are four kinds of condition: references to subpatterns, references to
|
||||
recursion, a pseudo-condition called DEFINE, and assertions.
|
||||
</P>
|
||||
<br><b>
|
||||
Checking for a used subpattern by number
|
||||
</b><br>
|
||||
<P>
|
||||
If the text between the parentheses consists of a sequence of digits, the
|
||||
condition is true if a capturing subpattern of that number has previously
|
||||
matched. If there is more than one capturing subpattern with the same number
|
||||
(see the earlier
|
||||
<a href="#recursion">section about duplicate subpattern numbers),</a>
|
||||
the condition is true if any of them have matched. An alternative notation is
|
||||
to precede the digits with a plus or minus sign. In this case, the subpattern
|
||||
number is relative rather than absolute. The most recently opened parentheses
|
||||
can be referenced by (?(-1), the next most recent by (?(-2), and so on. Inside
|
||||
loops it can also make sense to refer to subsequent groups. The next
|
||||
parentheses to be opened can be referenced as (?(+1), and so on. (The value
|
||||
zero in any of these forms is not used; it provokes a compile-time error.)
|
||||
</P>
|
||||
<P>
|
||||
Consider the following pattern, which contains non-significant white space to
|
||||
make it more readable (assume the PCRE_EXTENDED option) and to divide it into
|
||||
three parts for ease of discussion:
|
||||
<pre>
|
||||
( \( )? [^()]+ (?(1) \) )
|
||||
</pre>
|
||||
The first part matches an optional opening parenthesis, and if that
|
||||
character is present, sets it as the first captured substring. The second part
|
||||
matches one or more characters that are not parentheses. The third part is a
|
||||
conditional subpattern that tests whether or not the first set of parentheses
|
||||
matched. If they did, that is, if subject started with an opening parenthesis,
|
||||
the condition is true, and so the yes-pattern is executed and a closing
|
||||
parenthesis is required. Otherwise, since no-pattern is not present, the
|
||||
subpattern matches nothing. In other words, this pattern matches a sequence of
|
||||
non-parentheses, optionally enclosed in parentheses.
|
||||
</P>
|
||||
<P>
|
||||
If you were embedding this pattern in a larger one, you could use a relative
|
||||
reference:
|
||||
<pre>
|
||||
...other stuff... ( \( )? [^()]+ (?(-1) \) ) ...
|
||||
</pre>
|
||||
This makes the fragment independent of the parentheses in the larger pattern.
|
||||
</P>
|
||||
<br><b>
|
||||
Checking for a used subpattern by name
|
||||
</b><br>
|
||||
<P>
|
||||
Perl uses the syntax (?(<name>)...) or (?('name')...) to test for a used
|
||||
subpattern by name. For compatibility with earlier versions of PCRE, which had
|
||||
this facility before Perl, the syntax (?(name)...) is also recognized.
|
||||
</P>
|
||||
<P>
|
||||
Rewriting the above example to use a named subpattern gives this:
|
||||
<pre>
|
||||
(?<OPEN> \( )? [^()]+ (?(<OPEN>) \) )
|
||||
</pre>
|
||||
If the name used in a condition of this kind is a duplicate, the test is
|
||||
applied to all subpatterns of the same name, and is true if any one of them has
|
||||
matched.
|
||||
</P>
|
||||
<br><b>
|
||||
Checking for pattern recursion
|
||||
</b><br>
|
||||
<P>
|
||||
If the condition is the string (R), and there is no subpattern with the name R,
|
||||
the condition is true if a recursive call to the whole pattern or any
|
||||
subpattern has been made. If digits or a name preceded by ampersand follow the
|
||||
letter R, for example:
|
||||
<pre>
|
||||
(?(R3)...) or (?(R&name)...)
|
||||
</pre>
|
||||
the condition is true if the most recent recursion is into a subpattern whose
|
||||
number or name is given. This condition does not check the entire recursion
|
||||
stack. If the name used in a condition of this kind is a duplicate, the test is
|
||||
applied to all subpatterns of the same name, and is true if any one of them is
|
||||
the most recent recursion.
|
||||
</P>
|
||||
<P>
|
||||
At "top level", all these recursion test conditions are false.
|
||||
<a href="#recursion">The syntax for recursive patterns</a>
|
||||
is described below.
|
||||
<a name="subdefine"></a></P>
|
||||
<br><b>
|
||||
Defining subpatterns for use by reference only
|
||||
</b><br>
|
||||
<P>
|
||||
If the condition is the string (DEFINE), and there is no subpattern with the
|
||||
name DEFINE, the condition is always false. In this case, there may be only one
|
||||
alternative in the subpattern. It is always skipped if control reaches this
|
||||
point in the pattern; the idea of DEFINE is that it can be used to define
|
||||
subroutines that can be referenced from elsewhere. (The use of
|
||||
<a href="#subpatternsassubroutines">subroutines</a>
|
||||
is described below.) For example, a pattern to match an IPv4 address such as
|
||||
"192.168.23.245" could be written like this (ignore white space and line
|
||||
breaks):
|
||||
<pre>
|
||||
(?(DEFINE) (?<byte> 2[0-4]\d | 25[0-5] | 1\d\d | [1-9]?\d) )
|
||||
\b (?&byte) (\.(?&byte)){3} \b
|
||||
</pre>
|
||||
The first part of the pattern is a DEFINE group inside which a another group
|
||||
named "byte" is defined. This matches an individual component of an IPv4
|
||||
address (a number less than 256). When matching takes place, this part of the
|
||||
pattern is skipped because DEFINE acts like a false condition. The rest of the
|
||||
pattern uses references to the named group to match the four dot-separated
|
||||
components of an IPv4 address, insisting on a word boundary at each end.
|
||||
</P>
|
||||
<br><b>
|
||||
Assertion conditions
|
||||
</b><br>
|
||||
<P>
|
||||
If the condition is not in any of the above formats, it must be an assertion.
|
||||
This may be a positive or negative lookahead or lookbehind assertion. Consider
|
||||
this pattern, again containing non-significant white space, and with the two
|
||||
alternatives on the second line:
|
||||
<pre>
|
||||
(?(?=[^a-z]*[a-z])
|
||||
\d{2}-[a-z]{3}-\d{2} | \d{2}-\d{2}-\d{2} )
|
||||
</pre>
|
||||
The condition is a positive lookahead assertion that matches an optional
|
||||
sequence of non-letters followed by a letter. In other words, it tests for the
|
||||
presence of at least one letter in the subject. If a letter is found, the
|
||||
subject is matched against the first alternative; otherwise it is matched
|
||||
against the second. This pattern matches strings in one of the two forms
|
||||
dd-aaa-dd or dd-dd-dd, where aaa are letters and dd are digits.
|
||||
<a name="comments"></a></P>
|
||||
<br><a name="SEC22" href="#TOC1">COMMENTS</a><br>
|
||||
<P>
|
||||
There are two ways of including comments in patterns that are processed by
|
||||
PCRE. In both cases, the start of the comment must not be in a character class,
|
||||
nor in the middle of any other sequence of related characters such as (?: or a
|
||||
subpattern name or number. The characters that make up a comment play no part
|
||||
in the pattern matching.
|
||||
</P>
|
||||
<P>
|
||||
The sequence (?# marks the start of a comment that continues up to the next
|
||||
closing parenthesis. Nested parentheses are not permitted. If the PCRE_EXTENDED
|
||||
option is set, an unescaped # character also introduces a comment, which in
|
||||
this case continues to immediately after the next newline character or
|
||||
character sequence in the pattern. Which characters are interpreted as newlines
|
||||
is controlled by the options passed to a compiling function or by a special
|
||||
sequence at the start of the pattern, as described in the section entitled
|
||||
<a href="#newlines">"Newline conventions"</a>
|
||||
above. Note that the end of this type of comment is a literal newline sequence
|
||||
in the pattern; escape sequences that happen to represent a newline do not
|
||||
count. For example, consider this pattern when PCRE_EXTENDED is set, and the
|
||||
default newline convention is in force:
|
||||
<pre>
|
||||
abc #comment \n still comment
|
||||
</pre>
|
||||
On encountering the # character, <b>pcre_compile()</b> skips along, looking for
|
||||
a newline in the pattern. The sequence \n is still literal at this stage, so
|
||||
it does not terminate the comment. Only an actual character with the code value
|
||||
0x0a (the default newline) does so.
|
||||
<a name="recursion"></a></P>
|
||||
<br><a name="SEC23" href="#TOC1">RECURSIVE PATTERNS</a><br>
|
||||
<P>
|
||||
Consider the problem of matching a string in parentheses, allowing for
|
||||
unlimited nested parentheses. Without the use of recursion, the best that can
|
||||
be done is to use a pattern that matches up to some fixed depth of nesting. It
|
||||
is not possible to handle an arbitrary nesting depth.
|
||||
</P>
|
||||
<P>
|
||||
For some time, Perl has provided a facility that allows regular expressions to
|
||||
recurse (amongst other things). It does this by interpolating Perl code in the
|
||||
expression at run time, and the code can refer to the expression itself. A Perl
|
||||
pattern using code interpolation to solve the parentheses problem can be
|
||||
created like this:
|
||||
<pre>
|
||||
$re = qr{\( (?: (?>[^()]+) | (?p{$re}) )* \)}x;
|
||||
</pre>
|
||||
The (?p{...}) item interpolates Perl code at run time, and in this case refers
|
||||
recursively to the pattern in which it appears.
|
||||
</P>
|
||||
<P>
|
||||
Obviously, PCRE cannot support the interpolation of Perl code. Instead, it
|
||||
supports special syntax for recursion of the entire pattern, and also for
|
||||
individual subpattern recursion. After its introduction in PCRE and Python,
|
||||
this kind of recursion was subsequently introduced into Perl at release 5.10.
|
||||
</P>
|
||||
<P>
|
||||
A special item that consists of (? followed by a number greater than zero and a
|
||||
closing parenthesis is a recursive subroutine call of the subpattern of the
|
||||
given number, provided that it occurs inside that subpattern. (If not, it is a
|
||||
<a href="#subpatternsassubroutines">non-recursive subroutine</a>
|
||||
call, which is described in the next section.) The special item (?R) or (?0) is
|
||||
a recursive call of the entire regular expression.
|
||||
</P>
|
||||
<P>
|
||||
This PCRE pattern solves the nested parentheses problem (assume the
|
||||
PCRE_EXTENDED option is set so that white space is ignored):
|
||||
<pre>
|
||||
\( ( [^()]++ | (?R) )* \)
|
||||
</pre>
|
||||
First it matches an opening parenthesis. Then it matches any number of
|
||||
substrings which can either be a sequence of non-parentheses, or a recursive
|
||||
match of the pattern itself (that is, a correctly parenthesized substring).
|
||||
Finally there is a closing parenthesis. Note the use of a possessive quantifier
|
||||
to avoid backtracking into sequences of non-parentheses.
|
||||
</P>
|
||||
<P>
|
||||
If this were part of a larger pattern, you would not want to recurse the entire
|
||||
pattern, so instead you could use this:
|
||||
<pre>
|
||||
( \( ( [^()]++ | (?1) )* \) )
|
||||
</pre>
|
||||
We have put the pattern into parentheses, and caused the recursion to refer to
|
||||
them instead of the whole pattern.
|
||||
</P>
|
||||
<P>
|
||||
In a larger pattern, keeping track of parenthesis numbers can be tricky. This
|
||||
is made easier by the use of relative references. Instead of (?1) in the
|
||||
pattern above you can write (?-2) to refer to the second most recently opened
|
||||
parentheses preceding the recursion. In other words, a negative number counts
|
||||
capturing parentheses leftwards from the point at which it is encountered.
|
||||
</P>
|
||||
<P>
|
||||
It is also possible to refer to subsequently opened parentheses, by writing
|
||||
references such as (?+2). However, these cannot be recursive because the
|
||||
reference is not inside the parentheses that are referenced. They are always
|
||||
<a href="#subpatternsassubroutines">non-recursive subroutine</a>
|
||||
calls, as described in the next section.
|
||||
</P>
|
||||
<P>
|
||||
An alternative approach is to use named parentheses instead. The Perl syntax
|
||||
for this is (?&name); PCRE's earlier syntax (?P>name) is also supported. We
|
||||
could rewrite the above example as follows:
|
||||
<pre>
|
||||
(?<pn> \( ( [^()]++ | (?&pn) )* \) )
|
||||
</pre>
|
||||
If there is more than one subpattern with the same name, the earliest one is
|
||||
used.
|
||||
</P>
|
||||
<P>
|
||||
This particular example pattern that we have been looking at contains nested
|
||||
unlimited repeats, and so the use of a possessive quantifier for matching
|
||||
strings of non-parentheses is important when applying the pattern to strings
|
||||
that do not match. For example, when this pattern is applied to
|
||||
<pre>
|
||||
(aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()
|
||||
</pre>
|
||||
it yields "no match" quickly. However, if a possessive quantifier is not used,
|
||||
the match runs for a very long time indeed because there are so many different
|
||||
ways the + and * repeats can carve up the subject, and all have to be tested
|
||||
before failure can be reported.
|
||||
</P>
|
||||
<P>
|
||||
At the end of a match, the values of capturing parentheses are those from
|
||||
the outermost level. If you want to obtain intermediate values, a callout
|
||||
function can be used (see below and the
|
||||
<a href="pcrecallout.html"><b>pcrecallout</b></a>
|
||||
documentation). If the pattern above is matched against
|
||||
<pre>
|
||||
(ab(cd)ef)
|
||||
</pre>
|
||||
the value for the inner capturing parentheses (numbered 2) is "ef", which is
|
||||
the last value taken on at the top level. If a capturing subpattern is not
|
||||
matched at the top level, its final captured value is unset, even if it was
|
||||
(temporarily) set at a deeper level during the matching process.
|
||||
</P>
|
||||
<P>
|
||||
If there are more than 15 capturing parentheses in a pattern, PCRE has to
|
||||
obtain extra memory to store data during a recursion, which it does by using
|
||||
<b>pcre_malloc</b>, freeing it via <b>pcre_free</b> afterwards. If no memory can
|
||||
be obtained, the match fails with the PCRE_ERROR_NOMEMORY error.
|
||||
</P>
|
||||
<P>
|
||||
Do not confuse the (?R) item with the condition (R), which tests for recursion.
|
||||
Consider this pattern, which matches text in angle brackets, allowing for
|
||||
arbitrary nesting. Only digits are allowed in nested brackets (that is, when
|
||||
recursing), whereas any characters are permitted at the outer level.
|
||||
<pre>
|
||||
< (?: (?(R) \d++ | [^<>]*+) | (?R)) * >
|
||||
</pre>
|
||||
In this pattern, (?(R) is the start of a conditional subpattern, with two
|
||||
different alternatives for the recursive and non-recursive cases. The (?R) item
|
||||
is the actual recursive call.
|
||||
<a name="recursiondifference"></a></P>
|
||||
<br><b>
|
||||
Differences in recursion processing between PCRE and Perl
|
||||
</b><br>
|
||||
<P>
|
||||
Recursion processing in PCRE differs from Perl in two important ways. In PCRE
|
||||
(like Python, but unlike Perl), a recursive subpattern call is always treated
|
||||
as an atomic group. That is, once it has matched some of the subject string, it
|
||||
is never re-entered, even if it contains untried alternatives and there is a
|
||||
subsequent matching failure. This can be illustrated by the following pattern,
|
||||
which purports to match a palindromic string that contains an odd number of
|
||||
characters (for example, "a", "aba", "abcba", "abcdcba"):
|
||||
<pre>
|
||||
^(.|(.)(?1)\2)$
|
||||
</pre>
|
||||
The idea is that it either matches a single character, or two identical
|
||||
characters surrounding a sub-palindrome. In Perl, this pattern works; in PCRE
|
||||
it does not if the pattern is longer than three characters. Consider the
|
||||
subject string "abcba":
|
||||
</P>
|
||||
<P>
|
||||
At the top level, the first character is matched, but as it is not at the end
|
||||
of the string, the first alternative fails; the second alternative is taken
|
||||
and the recursion kicks in. The recursive call to subpattern 1 successfully
|
||||
matches the next character ("b"). (Note that the beginning and end of line
|
||||
tests are not part of the recursion).
|
||||
</P>
|
||||
<P>
|
||||
Back at the top level, the next character ("c") is compared with what
|
||||
subpattern 2 matched, which was "a". This fails. Because the recursion is
|
||||
treated as an atomic group, there are now no backtracking points, and so the
|
||||
entire match fails. (Perl is able, at this point, to re-enter the recursion and
|
||||
try the second alternative.) However, if the pattern is written with the
|
||||
alternatives in the other order, things are different:
|
||||
<pre>
|
||||
^((.)(?1)\2|.)$
|
||||
</pre>
|
||||
This time, the recursing alternative is tried first, and continues to recurse
|
||||
until it runs out of characters, at which point the recursion fails. But this
|
||||
time we do have another alternative to try at the higher level. That is the big
|
||||
difference: in the previous case the remaining alternative is at a deeper
|
||||
recursion level, which PCRE cannot use.
|
||||
</P>
|
||||
<P>
|
||||
To change the pattern so that it matches all palindromic strings, not just
|
||||
those with an odd number of characters, it is tempting to change the pattern to
|
||||
this:
|
||||
<pre>
|
||||
^((.)(?1)\2|.?)$
|
||||
</pre>
|
||||
Again, this works in Perl, but not in PCRE, and for the same reason. When a
|
||||
deeper recursion has matched a single character, it cannot be entered again in
|
||||
order to match an empty string. The solution is to separate the two cases, and
|
||||
write out the odd and even cases as alternatives at the higher level:
|
||||
<pre>
|
||||
^(?:((.)(?1)\2|)|((.)(?3)\4|.))
|
||||
</pre>
|
||||
If you want to match typical palindromic phrases, the pattern has to ignore all
|
||||
non-word characters, which can be done like this:
|
||||
<pre>
|
||||
^\W*+(?:((.)\W*+(?1)\W*+\2|)|((.)\W*+(?3)\W*+\4|\W*+.\W*+))\W*+$
|
||||
</pre>
|
||||
If run with the PCRE_CASELESS option, this pattern matches phrases such as "A
|
||||
man, a plan, a canal: Panama!" and it works well in both PCRE and Perl. Note
|
||||
the use of the possessive quantifier *+ to avoid backtracking into sequences of
|
||||
non-word characters. Without this, PCRE takes a great deal longer (ten times or
|
||||
more) to match typical phrases, and Perl takes so long that you think it has
|
||||
gone into a loop.
|
||||
</P>
|
||||
<P>
|
||||
<b>WARNING</b>: The palindrome-matching patterns above work only if the subject
|
||||
string does not start with a palindrome that is shorter than the entire string.
|
||||
For example, although "abcba" is correctly matched, if the subject is "ababa",
|
||||
PCRE finds the palindrome "aba" at the start, then fails at top level because
|
||||
the end of the string does not follow. Once again, it cannot jump back into the
|
||||
recursion to try other alternatives, so the entire match fails.
|
||||
</P>
|
||||
<P>
|
||||
The second way in which PCRE and Perl differ in their recursion processing is
|
||||
in the handling of captured values. In Perl, when a subpattern is called
|
||||
recursively or as a subpattern (see the next section), it has no access to any
|
||||
values that were captured outside the recursion, whereas in PCRE these values
|
||||
can be referenced. Consider this pattern:
|
||||
<pre>
|
||||
^(.)(\1|a(?2))
|
||||
</pre>
|
||||
In PCRE, this pattern matches "bab". The first capturing parentheses match "b",
|
||||
then in the second group, when the back reference \1 fails to match "b", the
|
||||
second alternative matches "a" and then recurses. In the recursion, \1 does
|
||||
now match "b" and so the whole match succeeds. In Perl, the pattern fails to
|
||||
match because inside the recursive call \1 cannot access the externally set
|
||||
value.
|
||||
<a name="subpatternsassubroutines"></a></P>
|
||||
<br><a name="SEC24" href="#TOC1">SUBPATTERNS AS SUBROUTINES</a><br>
|
||||
<P>
|
||||
If the syntax for a recursive subpattern call (either by number or by
|
||||
name) is used outside the parentheses to which it refers, it operates like a
|
||||
subroutine in a programming language. The called subpattern may be defined
|
||||
before or after the reference. A numbered reference can be absolute or
|
||||
relative, as in these examples:
|
||||
<pre>
|
||||
(...(absolute)...)...(?2)...
|
||||
(...(relative)...)...(?-1)...
|
||||
(...(?+1)...(relative)...
|
||||
</pre>
|
||||
An earlier example pointed out that the pattern
|
||||
<pre>
|
||||
(sens|respons)e and \1ibility
|
||||
</pre>
|
||||
matches "sense and sensibility" and "response and responsibility", but not
|
||||
"sense and responsibility". If instead the pattern
|
||||
<pre>
|
||||
(sens|respons)e and (?1)ibility
|
||||
</pre>
|
||||
is used, it does match "sense and responsibility" as well as the other two
|
||||
strings. Another example is given in the discussion of DEFINE above.
|
||||
</P>
|
||||
<P>
|
||||
All subroutine calls, whether recursive or not, are always treated as atomic
|
||||
groups. That is, once a subroutine has matched some of the subject string, it
|
||||
is never re-entered, even if it contains untried alternatives and there is a
|
||||
subsequent matching failure. Any capturing parentheses that are set during the
|
||||
subroutine call revert to their previous values afterwards.
|
||||
</P>
|
||||
<P>
|
||||
Processing options such as case-independence are fixed when a subpattern is
|
||||
defined, so if it is used as a subroutine, such options cannot be changed for
|
||||
different calls. For example, consider this pattern:
|
||||
<pre>
|
||||
(abc)(?i:(?-1))
|
||||
</pre>
|
||||
It matches "abcabc". It does not match "abcABC" because the change of
|
||||
processing option does not affect the called subpattern.
|
||||
<a name="onigurumasubroutines"></a></P>
|
||||
<br><a name="SEC25" href="#TOC1">ONIGURUMA SUBROUTINE SYNTAX</a><br>
|
||||
<P>
|
||||
For compatibility with Oniguruma, the non-Perl syntax \g followed by a name or
|
||||
a number enclosed either in angle brackets or single quotes, is an alternative
|
||||
syntax for referencing a subpattern as a subroutine, possibly recursively. Here
|
||||
are two of the examples used above, rewritten using this syntax:
|
||||
<pre>
|
||||
(?<pn> \( ( (?>[^()]+) | \g<pn> )* \) )
|
||||
(sens|respons)e and \g'1'ibility
|
||||
</pre>
|
||||
PCRE supports an extension to Oniguruma: if a number is preceded by a
|
||||
plus or a minus sign it is taken as a relative reference. For example:
|
||||
<pre>
|
||||
(abc)(?i:\g<-1>)
|
||||
</pre>
|
||||
Note that \g{...} (Perl syntax) and \g<...> (Oniguruma syntax) are <i>not</i>
|
||||
synonymous. The former is a back reference; the latter is a subroutine call.
|
||||
</P>
|
||||
<br><a name="SEC26" href="#TOC1">CALLOUTS</a><br>
|
||||
<P>
|
||||
Perl has a feature whereby using the sequence (?{...}) causes arbitrary Perl
|
||||
code to be obeyed in the middle of matching a regular expression. This makes it
|
||||
possible, amongst other things, to extract different substrings that match the
|
||||
same pair of parentheses when there is a repetition.
|
||||
</P>
|
||||
<P>
|
||||
PCRE provides a similar feature, but of course it cannot obey arbitrary Perl
|
||||
code. The feature is called "callout". The caller of PCRE provides an external
|
||||
function by putting its entry point in the global variable <i>pcre_callout</i>
|
||||
(8-bit library) or <i>pcre[16|32]_callout</i> (16-bit or 32-bit library).
|
||||
By default, this variable contains NULL, which disables all calling out.
|
||||
</P>
|
||||
<P>
|
||||
Within a regular expression, (?C) indicates the points at which the external
|
||||
function is to be called. If you want to identify different callout points, you
|
||||
can put a number less than 256 after the letter C. The default value is zero.
|
||||
For example, this pattern has two callout points:
|
||||
<pre>
|
||||
(?C1)abc(?C2)def
|
||||
</pre>
|
||||
If the PCRE_AUTO_CALLOUT flag is passed to a compiling function, callouts are
|
||||
automatically installed before each item in the pattern. They are all numbered
|
||||
255. If there is a conditional group in the pattern whose condition is an
|
||||
assertion, an additional callout is inserted just before the condition. An
|
||||
explicit callout may also be set at this position, as in this example:
|
||||
<pre>
|
||||
(?(?C9)(?=a)abc|def)
|
||||
</pre>
|
||||
Note that this applies only to assertion conditions, not to other types of
|
||||
condition.
|
||||
</P>
|
||||
<P>
|
||||
During matching, when PCRE reaches a callout point, the external function is
|
||||
called. It is provided with the number of the callout, the position in the
|
||||
pattern, and, optionally, one item of data originally supplied by the caller of
|
||||
the matching function. The callout function may cause matching to proceed, to
|
||||
backtrack, or to fail altogether.
|
||||
</P>
|
||||
<P>
|
||||
By default, PCRE implements a number of optimizations at compile time and
|
||||
matching time, and one side-effect is that sometimes callouts are skipped. If
|
||||
you need all possible callouts to happen, you need to set options that disable
|
||||
the relevant optimizations. More details, and a complete description of the
|
||||
interface to the callout function, are given in the
|
||||
<a href="pcrecallout.html"><b>pcrecallout</b></a>
|
||||
documentation.
|
||||
<a name="backtrackcontrol"></a></P>
|
||||
<br><a name="SEC27" href="#TOC1">BACKTRACKING CONTROL</a><br>
|
||||
<P>
|
||||
Perl 5.10 introduced a number of "Special Backtracking Control Verbs", which
|
||||
are still described in the Perl documentation as "experimental and subject to
|
||||
change or removal in a future version of Perl". It goes on to say: "Their usage
|
||||
in production code should be noted to avoid problems during upgrades." The same
|
||||
remarks apply to the PCRE features described in this section.
|
||||
</P>
|
||||
<P>
|
||||
The new verbs make use of what was previously invalid syntax: an opening
|
||||
parenthesis followed by an asterisk. They are generally of the form
|
||||
(*VERB) or (*VERB:NAME). Some may take either form, possibly behaving
|
||||
differently depending on whether or not a name is present. A name is any
|
||||
sequence of characters that does not include a closing parenthesis. The maximum
|
||||
length of name is 255 in the 8-bit library and 65535 in the 16-bit and 32-bit
|
||||
libraries. If the name is empty, that is, if the closing parenthesis
|
||||
immediately follows the colon, the effect is as if the colon were not there.
|
||||
Any number of these verbs may occur in a pattern.
|
||||
</P>
|
||||
<P>
|
||||
Since these verbs are specifically related to backtracking, most of them can be
|
||||
used only when the pattern is to be matched using one of the traditional
|
||||
matching functions, because these use a backtracking algorithm. With the
|
||||
exception of (*FAIL), which behaves like a failing negative assertion, the
|
||||
backtracking control verbs cause an error if encountered by a DFA matching
|
||||
function.
|
||||
</P>
|
||||
<P>
|
||||
The behaviour of these verbs in
|
||||
<a href="#btrepeat">repeated groups,</a>
|
||||
<a href="#btassert">assertions,</a>
|
||||
and in
|
||||
<a href="#btsub">subpatterns called as subroutines</a>
|
||||
(whether or not recursively) is documented below.
|
||||
<a name="nooptimize"></a></P>
|
||||
<br><b>
|
||||
Optimizations that affect backtracking verbs
|
||||
</b><br>
|
||||
<P>
|
||||
PCRE contains some optimizations that are used to speed up matching by running
|
||||
some checks at the start of each match attempt. For example, it may know the
|
||||
minimum length of matching subject, or that a particular character must be
|
||||
present. When one of these optimizations bypasses the running of a match, any
|
||||
included backtracking verbs will not, of course, be processed. You can suppress
|
||||
the start-of-match optimizations by setting the PCRE_NO_START_OPTIMIZE option
|
||||
when calling <b>pcre_compile()</b> or <b>pcre_exec()</b>, or by starting the
|
||||
pattern with (*NO_START_OPT). There is more discussion of this option in the
|
||||
section entitled
|
||||
<a href="pcreapi.html#execoptions">"Option bits for <b>pcre_exec()</b>"</a>
|
||||
in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
Experiments with Perl suggest that it too has similar optimizations, sometimes
|
||||
leading to anomalous results.
|
||||
</P>
|
||||
<br><b>
|
||||
Verbs that act immediately
|
||||
</b><br>
|
||||
<P>
|
||||
The following verbs act as soon as they are encountered. They may not be
|
||||
followed by a name.
|
||||
<pre>
|
||||
(*ACCEPT)
|
||||
</pre>
|
||||
This verb causes the match to end successfully, skipping the remainder of the
|
||||
pattern. However, when it is inside a subpattern that is called as a
|
||||
subroutine, only that subpattern is ended successfully. Matching then continues
|
||||
at the outer level. If (*ACCEPT) in triggered in a positive assertion, the
|
||||
assertion succeeds; in a negative assertion, the assertion fails.
|
||||
</P>
|
||||
<P>
|
||||
If (*ACCEPT) is inside capturing parentheses, the data so far is captured. For
|
||||
example:
|
||||
<pre>
|
||||
A((?:A|B(*ACCEPT)|C)D)
|
||||
</pre>
|
||||
This matches "AB", "AAD", or "ACD"; when it matches "AB", "B" is captured by
|
||||
the outer parentheses.
|
||||
<pre>
|
||||
(*FAIL) or (*F)
|
||||
</pre>
|
||||
This verb causes a matching failure, forcing backtracking to occur. It is
|
||||
equivalent to (?!) but easier to read. The Perl documentation notes that it is
|
||||
probably useful only when combined with (?{}) or (??{}). Those are, of course,
|
||||
Perl features that are not present in PCRE. The nearest equivalent is the
|
||||
callout feature, as for example in this pattern:
|
||||
<pre>
|
||||
a+(?C)(*FAIL)
|
||||
</pre>
|
||||
A match with the string "aaaa" always fails, but the callout is taken before
|
||||
each backtrack happens (in this example, 10 times).
|
||||
</P>
|
||||
<br><b>
|
||||
Recording which path was taken
|
||||
</b><br>
|
||||
<P>
|
||||
There is one verb whose main purpose is to track how a match was arrived at,
|
||||
though it also has a secondary use in conjunction with advancing the match
|
||||
starting point (see (*SKIP) below).
|
||||
<pre>
|
||||
(*MARK:NAME) or (*:NAME)
|
||||
</pre>
|
||||
A name is always required with this verb. There may be as many instances of
|
||||
(*MARK) as you like in a pattern, and their names do not have to be unique.
|
||||
</P>
|
||||
<P>
|
||||
When a match succeeds, the name of the last-encountered (*MARK:NAME),
|
||||
(*PRUNE:NAME), or (*THEN:NAME) on the matching path is passed back to the
|
||||
caller as described in the section entitled
|
||||
<a href="pcreapi.html#extradata">"Extra data for <b>pcre_exec()</b>"</a>
|
||||
in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
documentation. Here is an example of <b>pcretest</b> output, where the /K
|
||||
modifier requests the retrieval and outputting of (*MARK) data:
|
||||
<pre>
|
||||
re> /X(*MARK:A)Y|X(*MARK:B)Z/K
|
||||
data> XY
|
||||
0: XY
|
||||
MK: A
|
||||
XZ
|
||||
0: XZ
|
||||
MK: B
|
||||
</pre>
|
||||
The (*MARK) name is tagged with "MK:" in this output, and in this example it
|
||||
indicates which of the two alternatives matched. This is a more efficient way
|
||||
of obtaining this information than putting each alternative in its own
|
||||
capturing parentheses.
|
||||
</P>
|
||||
<P>
|
||||
If a verb with a name is encountered in a positive assertion that is true, the
|
||||
name is recorded and passed back if it is the last-encountered. This does not
|
||||
happen for negative assertions or failing positive assertions.
|
||||
</P>
|
||||
<P>
|
||||
After a partial match or a failed match, the last encountered name in the
|
||||
entire match process is returned. For example:
|
||||
<pre>
|
||||
re> /X(*MARK:A)Y|X(*MARK:B)Z/K
|
||||
data> XP
|
||||
No match, mark = B
|
||||
</pre>
|
||||
Note that in this unanchored example the mark is retained from the match
|
||||
attempt that started at the letter "X" in the subject. Subsequent match
|
||||
attempts starting at "P" and then with an empty string do not get as far as the
|
||||
(*MARK) item, but nevertheless do not reset it.
|
||||
</P>
|
||||
<P>
|
||||
If you are interested in (*MARK) values after failed matches, you should
|
||||
probably set the PCRE_NO_START_OPTIMIZE option
|
||||
<a href="#nooptimize">(see above)</a>
|
||||
to ensure that the match is always attempted.
|
||||
</P>
|
||||
<br><b>
|
||||
Verbs that act after backtracking
|
||||
</b><br>
|
||||
<P>
|
||||
The following verbs do nothing when they are encountered. Matching continues
|
||||
with what follows, but if there is no subsequent match, causing a backtrack to
|
||||
the verb, a failure is forced. That is, backtracking cannot pass to the left of
|
||||
the verb. However, when one of these verbs appears inside an atomic group or an
|
||||
assertion that is true, its effect is confined to that group, because once the
|
||||
group has been matched, there is never any backtracking into it. In this
|
||||
situation, backtracking can "jump back" to the left of the entire atomic group
|
||||
or assertion. (Remember also, as stated above, that this localization also
|
||||
applies in subroutine calls.)
|
||||
</P>
|
||||
<P>
|
||||
These verbs differ in exactly what kind of failure occurs when backtracking
|
||||
reaches them. The behaviour described below is what happens when the verb is
|
||||
not in a subroutine or an assertion. Subsequent sections cover these special
|
||||
cases.
|
||||
<pre>
|
||||
(*COMMIT)
|
||||
</pre>
|
||||
This verb, which may not be followed by a name, causes the whole match to fail
|
||||
outright if there is a later matching failure that causes backtracking to reach
|
||||
it. Even if the pattern is unanchored, no further attempts to find a match by
|
||||
advancing the starting point take place. If (*COMMIT) is the only backtracking
|
||||
verb that is encountered, once it has been passed <b>pcre_exec()</b> is
|
||||
committed to finding a match at the current starting point, or not at all. For
|
||||
example:
|
||||
<pre>
|
||||
a+(*COMMIT)b
|
||||
</pre>
|
||||
This matches "xxaab" but not "aacaab". It can be thought of as a kind of
|
||||
dynamic anchor, or "I've started, so I must finish." The name of the most
|
||||
recently passed (*MARK) in the path is passed back when (*COMMIT) forces a
|
||||
match failure.
|
||||
</P>
|
||||
<P>
|
||||
If there is more than one backtracking verb in a pattern, a different one that
|
||||
follows (*COMMIT) may be triggered first, so merely passing (*COMMIT) during a
|
||||
match does not always guarantee that a match must be at this starting point.
|
||||
</P>
|
||||
<P>
|
||||
Note that (*COMMIT) at the start of a pattern is not the same as an anchor,
|
||||
unless PCRE's start-of-match optimizations are turned off, as shown in this
|
||||
output from <b>pcretest</b>:
|
||||
<pre>
|
||||
re> /(*COMMIT)abc/
|
||||
data> xyzabc
|
||||
0: abc
|
||||
data> xyzabc\Y
|
||||
No match
|
||||
</pre>
|
||||
For this pattern, PCRE knows that any match must start with "a", so the
|
||||
optimization skips along the subject to "a" before applying the pattern to the
|
||||
first set of data. The match attempt then succeeds. In the second set of data,
|
||||
the escape sequence \Y is interpreted by the <b>pcretest</b> program. It causes
|
||||
the PCRE_NO_START_OPTIMIZE option to be set when <b>pcre_exec()</b> is called.
|
||||
This disables the optimization that skips along to the first character. The
|
||||
pattern is now applied starting at "x", and so the (*COMMIT) causes the match
|
||||
to fail without trying any other starting points.
|
||||
<pre>
|
||||
(*PRUNE) or (*PRUNE:NAME)
|
||||
</pre>
|
||||
This verb causes the match to fail at the current starting position in the
|
||||
subject if there is a later matching failure that causes backtracking to reach
|
||||
it. If the pattern is unanchored, the normal "bumpalong" advance to the next
|
||||
starting character then happens. Backtracking can occur as usual to the left of
|
||||
(*PRUNE), before it is reached, or when matching to the right of (*PRUNE), but
|
||||
if there is no match to the right, backtracking cannot cross (*PRUNE). In
|
||||
simple cases, the use of (*PRUNE) is just an alternative to an atomic group or
|
||||
possessive quantifier, but there are some uses of (*PRUNE) that cannot be
|
||||
expressed in any other way. In an anchored pattern (*PRUNE) has the same effect
|
||||
as (*COMMIT).
|
||||
</P>
|
||||
<P>
|
||||
The behaviour of (*PRUNE:NAME) is the not the same as (*MARK:NAME)(*PRUNE).
|
||||
It is like (*MARK:NAME) in that the name is remembered for passing back to the
|
||||
caller. However, (*SKIP:NAME) searches only for names set with (*MARK).
|
||||
<pre>
|
||||
(*SKIP)
|
||||
</pre>
|
||||
This verb, when given without a name, is like (*PRUNE), except that if the
|
||||
pattern is unanchored, the "bumpalong" advance is not to the next character,
|
||||
but to the position in the subject where (*SKIP) was encountered. (*SKIP)
|
||||
signifies that whatever text was matched leading up to it cannot be part of a
|
||||
successful match. Consider:
|
||||
<pre>
|
||||
a+(*SKIP)b
|
||||
</pre>
|
||||
If the subject is "aaaac...", after the first match attempt fails (starting at
|
||||
the first character in the string), the starting point skips on to start the
|
||||
next attempt at "c". Note that a possessive quantifer does not have the same
|
||||
effect as this example; although it would suppress backtracking during the
|
||||
first match attempt, the second attempt would start at the second character
|
||||
instead of skipping on to "c".
|
||||
<pre>
|
||||
(*SKIP:NAME)
|
||||
</pre>
|
||||
When (*SKIP) has an associated name, its behaviour is modified. When it is
|
||||
triggered, the previous path through the pattern is searched for the most
|
||||
recent (*MARK) that has the same name. If one is found, the "bumpalong" advance
|
||||
is to the subject position that corresponds to that (*MARK) instead of to where
|
||||
(*SKIP) was encountered. If no (*MARK) with a matching name is found, the
|
||||
(*SKIP) is ignored.
|
||||
</P>
|
||||
<P>
|
||||
Note that (*SKIP:NAME) searches only for names set by (*MARK:NAME). It ignores
|
||||
names that are set by (*PRUNE:NAME) or (*THEN:NAME).
|
||||
<pre>
|
||||
(*THEN) or (*THEN:NAME)
|
||||
</pre>
|
||||
This verb causes a skip to the next innermost alternative when backtracking
|
||||
reaches it. That is, it cancels any further backtracking within the current
|
||||
alternative. Its name comes from the observation that it can be used for a
|
||||
pattern-based if-then-else block:
|
||||
<pre>
|
||||
( COND1 (*THEN) FOO | COND2 (*THEN) BAR | COND3 (*THEN) BAZ ) ...
|
||||
</pre>
|
||||
If the COND1 pattern matches, FOO is tried (and possibly further items after
|
||||
the end of the group if FOO succeeds); on failure, the matcher skips to the
|
||||
second alternative and tries COND2, without backtracking into COND1. If that
|
||||
succeeds and BAR fails, COND3 is tried. If subsequently BAZ fails, there are no
|
||||
more alternatives, so there is a backtrack to whatever came before the entire
|
||||
group. If (*THEN) is not inside an alternation, it acts like (*PRUNE).
|
||||
</P>
|
||||
<P>
|
||||
The behaviour of (*THEN:NAME) is the not the same as (*MARK:NAME)(*THEN).
|
||||
It is like (*MARK:NAME) in that the name is remembered for passing back to the
|
||||
caller. However, (*SKIP:NAME) searches only for names set with (*MARK).
|
||||
</P>
|
||||
<P>
|
||||
A subpattern that does not contain a | character is just a part of the
|
||||
enclosing alternative; it is not a nested alternation with only one
|
||||
alternative. The effect of (*THEN) extends beyond such a subpattern to the
|
||||
enclosing alternative. Consider this pattern, where A, B, etc. are complex
|
||||
pattern fragments that do not contain any | characters at this level:
|
||||
<pre>
|
||||
A (B(*THEN)C) | D
|
||||
</pre>
|
||||
If A and B are matched, but there is a failure in C, matching does not
|
||||
backtrack into A; instead it moves to the next alternative, that is, D.
|
||||
However, if the subpattern containing (*THEN) is given an alternative, it
|
||||
behaves differently:
|
||||
<pre>
|
||||
A (B(*THEN)C | (*FAIL)) | D
|
||||
</pre>
|
||||
The effect of (*THEN) is now confined to the inner subpattern. After a failure
|
||||
in C, matching moves to (*FAIL), which causes the whole subpattern to fail
|
||||
because there are no more alternatives to try. In this case, matching does now
|
||||
backtrack into A.
|
||||
</P>
|
||||
<P>
|
||||
Note that a conditional subpattern is not considered as having two
|
||||
alternatives, because only one is ever used. In other words, the | character in
|
||||
a conditional subpattern has a different meaning. Ignoring white space,
|
||||
consider:
|
||||
<pre>
|
||||
^.*? (?(?=a) a | b(*THEN)c )
|
||||
</pre>
|
||||
If the subject is "ba", this pattern does not match. Because .*? is ungreedy,
|
||||
it initially matches zero characters. The condition (?=a) then fails, the
|
||||
character "b" is matched, but "c" is not. At this point, matching does not
|
||||
backtrack to .*? as might perhaps be expected from the presence of the |
|
||||
character. The conditional subpattern is part of the single alternative that
|
||||
comprises the whole pattern, and so the match fails. (If there was a backtrack
|
||||
into .*?, allowing it to match "b", the match would succeed.)
|
||||
</P>
|
||||
<P>
|
||||
The verbs just described provide four different "strengths" of control when
|
||||
subsequent matching fails. (*THEN) is the weakest, carrying on the match at the
|
||||
next alternative. (*PRUNE) comes next, failing the match at the current
|
||||
starting position, but allowing an advance to the next character (for an
|
||||
unanchored pattern). (*SKIP) is similar, except that the advance may be more
|
||||
than one character. (*COMMIT) is the strongest, causing the entire match to
|
||||
fail.
|
||||
</P>
|
||||
<br><b>
|
||||
More than one backtracking verb
|
||||
</b><br>
|
||||
<P>
|
||||
If more than one backtracking verb is present in a pattern, the one that is
|
||||
backtracked onto first acts. For example, consider this pattern, where A, B,
|
||||
etc. are complex pattern fragments:
|
||||
<pre>
|
||||
(A(*COMMIT)B(*THEN)C|ABD)
|
||||
</pre>
|
||||
If A matches but B fails, the backtrack to (*COMMIT) causes the entire match to
|
||||
fail. However, if A and B match, but C fails, the backtrack to (*THEN) causes
|
||||
the next alternative (ABD) to be tried. This behaviour is consistent, but is
|
||||
not always the same as Perl's. It means that if two or more backtracking verbs
|
||||
appear in succession, all the the last of them has no effect. Consider this
|
||||
example:
|
||||
<pre>
|
||||
...(*COMMIT)(*PRUNE)...
|
||||
</pre>
|
||||
If there is a matching failure to the right, backtracking onto (*PRUNE) causes
|
||||
it to be triggered, and its action is taken. There can never be a backtrack
|
||||
onto (*COMMIT).
|
||||
<a name="btrepeat"></a></P>
|
||||
<br><b>
|
||||
Backtracking verbs in repeated groups
|
||||
</b><br>
|
||||
<P>
|
||||
PCRE differs from Perl in its handling of backtracking verbs in repeated
|
||||
groups. For example, consider:
|
||||
<pre>
|
||||
/(a(*COMMIT)b)+ac/
|
||||
</pre>
|
||||
If the subject is "abac", Perl matches, but PCRE fails because the (*COMMIT) in
|
||||
the second repeat of the group acts.
|
||||
<a name="btassert"></a></P>
|
||||
<br><b>
|
||||
Backtracking verbs in assertions
|
||||
</b><br>
|
||||
<P>
|
||||
(*FAIL) in an assertion has its normal effect: it forces an immediate backtrack.
|
||||
</P>
|
||||
<P>
|
||||
(*ACCEPT) in a positive assertion causes the assertion to succeed without any
|
||||
further processing. In a negative assertion, (*ACCEPT) causes the assertion to
|
||||
fail without any further processing.
|
||||
</P>
|
||||
<P>
|
||||
The other backtracking verbs are not treated specially if they appear in a
|
||||
positive assertion. In particular, (*THEN) skips to the next alternative in the
|
||||
innermost enclosing group that has alternations, whether or not this is within
|
||||
the assertion.
|
||||
</P>
|
||||
<P>
|
||||
Negative assertions are, however, different, in order to ensure that changing a
|
||||
positive assertion into a negative assertion changes its result. Backtracking
|
||||
into (*COMMIT), (*SKIP), or (*PRUNE) causes a negative assertion to be true,
|
||||
without considering any further alternative branches in the assertion.
|
||||
Backtracking into (*THEN) causes it to skip to the next enclosing alternative
|
||||
within the assertion (the normal behaviour), but if the assertion does not have
|
||||
such an alternative, (*THEN) behaves like (*PRUNE).
|
||||
<a name="btsub"></a></P>
|
||||
<br><b>
|
||||
Backtracking verbs in subroutines
|
||||
</b><br>
|
||||
<P>
|
||||
These behaviours occur whether or not the subpattern is called recursively.
|
||||
Perl's treatment of subroutines is different in some cases.
|
||||
</P>
|
||||
<P>
|
||||
(*FAIL) in a subpattern called as a subroutine has its normal effect: it forces
|
||||
an immediate backtrack.
|
||||
</P>
|
||||
<P>
|
||||
(*ACCEPT) in a subpattern called as a subroutine causes the subroutine match to
|
||||
succeed without any further processing. Matching then continues after the
|
||||
subroutine call.
|
||||
</P>
|
||||
<P>
|
||||
(*COMMIT), (*SKIP), and (*PRUNE) in a subpattern called as a subroutine cause
|
||||
the subroutine match to fail.
|
||||
</P>
|
||||
<P>
|
||||
(*THEN) skips to the next alternative in the innermost enclosing group within
|
||||
the subpattern that has alternatives. If there is no such group within the
|
||||
subpattern, (*THEN) causes the subroutine match to fail.
|
||||
</P>
|
||||
<br><a name="SEC28" href="#TOC1">SEE ALSO</a><br>
|
||||
<P>
|
||||
<b>pcreapi</b>(3), <b>pcrecallout</b>(3), <b>pcrematching</b>(3),
|
||||
<b>pcresyntax</b>(3), <b>pcre</b>(3), <b>pcre16(3)</b>, <b>pcre32(3)</b>.
|
||||
</P>
|
||||
<br><a name="SEC29" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC30" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 23 October 2016
|
||||
<br>
|
||||
Copyright © 1997-2016 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,195 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcreperform specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcreperform man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
PCRE PERFORMANCE
|
||||
</b><br>
|
||||
<P>
|
||||
Two aspects of performance are discussed below: memory usage and processing
|
||||
time. The way you express your pattern as a regular expression can affect both
|
||||
of them.
|
||||
</P>
|
||||
<br><b>
|
||||
COMPILED PATTERN MEMORY USAGE
|
||||
</b><br>
|
||||
<P>
|
||||
Patterns are compiled by PCRE into a reasonably efficient interpretive code, so
|
||||
that most simple patterns do not use much memory. However, there is one case
|
||||
where the memory usage of a compiled pattern can be unexpectedly large. If a
|
||||
parenthesized subpattern has a quantifier with a minimum greater than 1 and/or
|
||||
a limited maximum, the whole subpattern is repeated in the compiled code. For
|
||||
example, the pattern
|
||||
<pre>
|
||||
(abc|def){2,4}
|
||||
</pre>
|
||||
is compiled as if it were
|
||||
<pre>
|
||||
(abc|def)(abc|def)((abc|def)(abc|def)?)?
|
||||
</pre>
|
||||
(Technical aside: It is done this way so that backtrack points within each of
|
||||
the repetitions can be independently maintained.)
|
||||
</P>
|
||||
<P>
|
||||
For regular expressions whose quantifiers use only small numbers, this is not
|
||||
usually a problem. However, if the numbers are large, and particularly if such
|
||||
repetitions are nested, the memory usage can become an embarrassment. For
|
||||
example, the very simple pattern
|
||||
<pre>
|
||||
((ab){1,1000}c){1,3}
|
||||
</pre>
|
||||
uses 51K bytes when compiled using the 8-bit library. When PCRE is compiled
|
||||
with its default internal pointer size of two bytes, the size limit on a
|
||||
compiled pattern is 64K data units, and this is reached with the above pattern
|
||||
if the outer repetition is increased from 3 to 4. PCRE can be compiled to use
|
||||
larger internal pointers and thus handle larger compiled patterns, but it is
|
||||
better to try to rewrite your pattern to use less memory if you can.
|
||||
</P>
|
||||
<P>
|
||||
One way of reducing the memory usage for such patterns is to make use of PCRE's
|
||||
<a href="pcrepattern.html#subpatternsassubroutines">"subroutine"</a>
|
||||
facility. Re-writing the above pattern as
|
||||
<pre>
|
||||
((ab)(?2){0,999}c)(?1){0,2}
|
||||
</pre>
|
||||
reduces the memory requirements to 18K, and indeed it remains under 20K even
|
||||
with the outer repetition increased to 100. However, this pattern is not
|
||||
exactly equivalent, because the "subroutine" calls are treated as
|
||||
<a href="pcrepattern.html#atomicgroup">atomic groups</a>
|
||||
into which there can be no backtracking if there is a subsequent matching
|
||||
failure. Therefore, PCRE cannot do this kind of rewriting automatically.
|
||||
Furthermore, there is a noticeable loss of speed when executing the modified
|
||||
pattern. Nevertheless, if the atomic grouping is not a problem and the loss of
|
||||
speed is acceptable, this kind of rewriting will allow you to process patterns
|
||||
that PCRE cannot otherwise handle.
|
||||
</P>
|
||||
<br><b>
|
||||
STACK USAGE AT RUN TIME
|
||||
</b><br>
|
||||
<P>
|
||||
When <b>pcre_exec()</b> or <b>pcre[16|32]_exec()</b> is used for matching, certain
|
||||
kinds of pattern can cause it to use large amounts of the process stack. In
|
||||
some environments the default process stack is quite small, and if it runs out
|
||||
the result is often SIGSEGV. This issue is probably the most frequently raised
|
||||
problem with PCRE. Rewriting your pattern can often help. The
|
||||
<a href="pcrestack.html"><b>pcrestack</b></a>
|
||||
documentation discusses this issue in detail.
|
||||
</P>
|
||||
<br><b>
|
||||
PROCESSING TIME
|
||||
</b><br>
|
||||
<P>
|
||||
Certain items in regular expression patterns are processed more efficiently
|
||||
than others. It is more efficient to use a character class like [aeiou] than a
|
||||
set of single-character alternatives such as (a|e|i|o|u). In general, the
|
||||
simplest construction that provides the required behaviour is usually the most
|
||||
efficient. Jeffrey Friedl's book contains a lot of useful general discussion
|
||||
about optimizing regular expressions for efficient performance. This document
|
||||
contains a few observations about PCRE.
|
||||
</P>
|
||||
<P>
|
||||
Using Unicode character properties (the \p, \P, and \X escapes) is slow,
|
||||
because PCRE has to use a multi-stage table lookup whenever it needs a
|
||||
character's property. If you can find an alternative pattern that does not use
|
||||
character properties, it will probably be faster.
|
||||
</P>
|
||||
<P>
|
||||
By default, the escape sequences \b, \d, \s, and \w, and the POSIX
|
||||
character classes such as [:alpha:] do not use Unicode properties, partly for
|
||||
backwards compatibility, and partly for performance reasons. However, you can
|
||||
set PCRE_UCP if you want Unicode character properties to be used. This can
|
||||
double the matching time for items such as \d, when matched with
|
||||
a traditional matching function; the performance loss is less with
|
||||
a DFA matching function, and in both cases there is not much difference for
|
||||
\b.
|
||||
</P>
|
||||
<P>
|
||||
When a pattern begins with .* not in parentheses, or in parentheses that are
|
||||
not the subject of a backreference, and the PCRE_DOTALL option is set, the
|
||||
pattern is implicitly anchored by PCRE, since it can match only at the start of
|
||||
a subject string. However, if PCRE_DOTALL is not set, PCRE cannot make this
|
||||
optimization, because the . metacharacter does not then match a newline, and if
|
||||
the subject string contains newlines, the pattern may match from the character
|
||||
immediately following one of them instead of from the very start. For example,
|
||||
the pattern
|
||||
<pre>
|
||||
.*second
|
||||
</pre>
|
||||
matches the subject "first\nand second" (where \n stands for a newline
|
||||
character), with the match starting at the seventh character. In order to do
|
||||
this, PCRE has to retry the match starting after every newline in the subject.
|
||||
</P>
|
||||
<P>
|
||||
If you are using such a pattern with subject strings that do not contain
|
||||
newlines, the best performance is obtained by setting PCRE_DOTALL, or starting
|
||||
the pattern with ^.* or ^.*? to indicate explicit anchoring. That saves PCRE
|
||||
from having to scan along the subject looking for a newline to restart at.
|
||||
</P>
|
||||
<P>
|
||||
Beware of patterns that contain nested indefinite repeats. These can take a
|
||||
long time to run when applied to a string that does not match. Consider the
|
||||
pattern fragment
|
||||
<pre>
|
||||
^(a+)*
|
||||
</pre>
|
||||
This can match "aaaa" in 16 different ways, and this number increases very
|
||||
rapidly as the string gets longer. (The * repeat can match 0, 1, 2, 3, or 4
|
||||
times, and for each of those cases other than 0 or 4, the + repeats can match
|
||||
different numbers of times.) When the remainder of the pattern is such that the
|
||||
entire match is going to fail, PCRE has in principle to try every possible
|
||||
variation, and this can take an extremely long time, even for relatively short
|
||||
strings.
|
||||
</P>
|
||||
<P>
|
||||
An optimization catches some of the more simple cases such as
|
||||
<pre>
|
||||
(a+)*b
|
||||
</pre>
|
||||
where a literal character follows. Before embarking on the standard matching
|
||||
procedure, PCRE checks that there is a "b" later in the subject string, and if
|
||||
there is not, it fails the match immediately. However, when there is no
|
||||
following literal this optimization cannot be used. You can see the difference
|
||||
by comparing the behaviour of
|
||||
<pre>
|
||||
(a+)*\d
|
||||
</pre>
|
||||
with the pattern above. The former gives a failure almost instantly when
|
||||
applied to a whole line of "a" characters, whereas the latter takes an
|
||||
appreciable time with strings longer than about 20 characters.
|
||||
</P>
|
||||
<P>
|
||||
In many cases, the solution to this kind of performance issue is to use an
|
||||
atomic group or a possessive quantifier.
|
||||
</P>
|
||||
<br><b>
|
||||
AUTHOR
|
||||
</b><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><b>
|
||||
REVISION
|
||||
</b><br>
|
||||
<P>
|
||||
Last updated: 25 August 2012
|
||||
<br>
|
||||
Copyright © 1997-2012 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,290 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcreposix specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcreposix man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
|
||||
<li><a name="TOC2" href="#SEC2">DESCRIPTION</a>
|
||||
<li><a name="TOC3" href="#SEC3">COMPILING A PATTERN</a>
|
||||
<li><a name="TOC4" href="#SEC4">MATCHING NEWLINE CHARACTERS</a>
|
||||
<li><a name="TOC5" href="#SEC5">MATCHING A PATTERN</a>
|
||||
<li><a name="TOC6" href="#SEC6">ERROR MESSAGES</a>
|
||||
<li><a name="TOC7" href="#SEC7">MEMORY USAGE</a>
|
||||
<li><a name="TOC8" href="#SEC8">AUTHOR</a>
|
||||
<li><a name="TOC9" href="#SEC9">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
|
||||
<P>
|
||||
<b>#include <pcreposix.h></b>
|
||||
</P>
|
||||
<P>
|
||||
<b>int regcomp(regex_t *<i>preg</i>, const char *<i>pattern</i>,</b>
|
||||
<b> int <i>cflags</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>int regexec(regex_t *<i>preg</i>, const char *<i>string</i>,</b>
|
||||
<b> size_t <i>nmatch</i>, regmatch_t <i>pmatch</i>[], int <i>eflags</i>);</b>
|
||||
<b> size_t regerror(int <i>errcode</i>, const regex_t *<i>preg</i>,</b>
|
||||
<b> char *<i>errbuf</i>, size_t <i>errbuf_size</i>);</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>void regfree(regex_t *<i>preg</i>);</b>
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">DESCRIPTION</a><br>
|
||||
<P>
|
||||
This set of functions provides a POSIX-style API for the PCRE regular
|
||||
expression 8-bit library. See the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
documentation for a description of PCRE's native API, which contains much
|
||||
additional functionality. There is no POSIX-style wrapper for PCRE's 16-bit
|
||||
and 32-bit library.
|
||||
</P>
|
||||
<P>
|
||||
The functions described here are just wrapper functions that ultimately call
|
||||
the PCRE native API. Their prototypes are defined in the <b>pcreposix.h</b>
|
||||
header file, and on Unix systems the library itself is called
|
||||
<b>pcreposix.a</b>, so can be accessed by adding <b>-lpcreposix</b> to the
|
||||
command for linking an application that uses them. Because the POSIX functions
|
||||
call the native ones, it is also necessary to add <b>-lpcre</b>.
|
||||
</P>
|
||||
<P>
|
||||
I have implemented only those POSIX option bits that can be reasonably mapped
|
||||
to PCRE native options. In addition, the option REG_EXTENDED is defined with
|
||||
the value zero. This has no effect, but since programs that are written to the
|
||||
POSIX interface often use it, this makes it easier to slot in PCRE as a
|
||||
replacement library. Other POSIX options are not even defined.
|
||||
</P>
|
||||
<P>
|
||||
There are also some other options that are not defined by POSIX. These have
|
||||
been added at the request of users who want to make use of certain
|
||||
PCRE-specific features via the POSIX calling interface.
|
||||
</P>
|
||||
<P>
|
||||
When PCRE is called via these functions, it is only the API that is POSIX-like
|
||||
in style. The syntax and semantics of the regular expressions themselves are
|
||||
still those of Perl, subject to the setting of various PCRE options, as
|
||||
described below. "POSIX-like in style" means that the API approximates to the
|
||||
POSIX definition; it is not fully POSIX-compatible, and in multi-byte encoding
|
||||
domains it is probably even less compatible.
|
||||
</P>
|
||||
<P>
|
||||
The header for these functions is supplied as <b>pcreposix.h</b> to avoid any
|
||||
potential clash with other POSIX libraries. It can, of course, be renamed or
|
||||
aliased as <b>regex.h</b>, which is the "correct" name. It provides two
|
||||
structure types, <i>regex_t</i> for compiled internal forms, and
|
||||
<i>regmatch_t</i> for returning captured substrings. It also defines some
|
||||
constants whose names start with "REG_"; these are used for setting options and
|
||||
identifying error codes.
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">COMPILING A PATTERN</a><br>
|
||||
<P>
|
||||
The function <b>regcomp()</b> is called to compile a pattern into an
|
||||
internal form. The pattern is a C string terminated by a binary zero, and
|
||||
is passed in the argument <i>pattern</i>. The <i>preg</i> argument is a pointer
|
||||
to a <b>regex_t</b> structure that is used as a base for storing information
|
||||
about the compiled regular expression.
|
||||
</P>
|
||||
<P>
|
||||
The argument <i>cflags</i> is either zero, or contains one or more of the bits
|
||||
defined by the following macros:
|
||||
<pre>
|
||||
REG_DOTALL
|
||||
</pre>
|
||||
The PCRE_DOTALL option is set when the regular expression is passed for
|
||||
compilation to the native function. Note that REG_DOTALL is not part of the
|
||||
POSIX standard.
|
||||
<pre>
|
||||
REG_ICASE
|
||||
</pre>
|
||||
The PCRE_CASELESS option is set when the regular expression is passed for
|
||||
compilation to the native function.
|
||||
<pre>
|
||||
REG_NEWLINE
|
||||
</pre>
|
||||
The PCRE_MULTILINE option is set when the regular expression is passed for
|
||||
compilation to the native function. Note that this does <i>not</i> mimic the
|
||||
defined POSIX behaviour for REG_NEWLINE (see the following section).
|
||||
<pre>
|
||||
REG_NOSUB
|
||||
</pre>
|
||||
The PCRE_NO_AUTO_CAPTURE option is set when the regular expression is passed
|
||||
for compilation to the native function. In addition, when a pattern that is
|
||||
compiled with this flag is passed to <b>regexec()</b> for matching, the
|
||||
<i>nmatch</i> and <i>pmatch</i> arguments are ignored, and no captured strings
|
||||
are returned.
|
||||
<pre>
|
||||
REG_UCP
|
||||
</pre>
|
||||
The PCRE_UCP option is set when the regular expression is passed for
|
||||
compilation to the native function. This causes PCRE to use Unicode properties
|
||||
when matchine \d, \w, etc., instead of just recognizing ASCII values. Note
|
||||
that REG_UTF8 is not part of the POSIX standard.
|
||||
<pre>
|
||||
REG_UNGREEDY
|
||||
</pre>
|
||||
The PCRE_UNGREEDY option is set when the regular expression is passed for
|
||||
compilation to the native function. Note that REG_UNGREEDY is not part of the
|
||||
POSIX standard.
|
||||
<pre>
|
||||
REG_UTF8
|
||||
</pre>
|
||||
The PCRE_UTF8 option is set when the regular expression is passed for
|
||||
compilation to the native function. This causes the pattern itself and all data
|
||||
strings used for matching it to be treated as UTF-8 strings. Note that REG_UTF8
|
||||
is not part of the POSIX standard.
|
||||
</P>
|
||||
<P>
|
||||
In the absence of these flags, no options are passed to the native function.
|
||||
This means the the regex is compiled with PCRE default semantics. In
|
||||
particular, the way it handles newline characters in the subject string is the
|
||||
Perl way, not the POSIX way. Note that setting PCRE_MULTILINE has only
|
||||
<i>some</i> of the effects specified for REG_NEWLINE. It does not affect the way
|
||||
newlines are matched by . (they are not) or by a negative class such as [^a]
|
||||
(they are).
|
||||
</P>
|
||||
<P>
|
||||
The yield of <b>regcomp()</b> is zero on success, and non-zero otherwise. The
|
||||
<i>preg</i> structure is filled in on success, and one member of the structure
|
||||
is public: <i>re_nsub</i> contains the number of capturing subpatterns in
|
||||
the regular expression. Various error codes are defined in the header file.
|
||||
</P>
|
||||
<P>
|
||||
NOTE: If the yield of <b>regcomp()</b> is non-zero, you must not attempt to
|
||||
use the contents of the <i>preg</i> structure. If, for example, you pass it to
|
||||
<b>regexec()</b>, the result is undefined and your program is likely to crash.
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">MATCHING NEWLINE CHARACTERS</a><br>
|
||||
<P>
|
||||
This area is not simple, because POSIX and Perl take different views of things.
|
||||
It is not possible to get PCRE to obey POSIX semantics, but then PCRE was never
|
||||
intended to be a POSIX engine. The following table lists the different
|
||||
possibilities for matching newline characters in PCRE:
|
||||
<pre>
|
||||
Default Change with
|
||||
|
||||
. matches newline no PCRE_DOTALL
|
||||
newline matches [^a] yes not changeable
|
||||
$ matches \n at end yes PCRE_DOLLARENDONLY
|
||||
$ matches \n in middle no PCRE_MULTILINE
|
||||
^ matches \n in middle no PCRE_MULTILINE
|
||||
</pre>
|
||||
This is the equivalent table for POSIX:
|
||||
<pre>
|
||||
Default Change with
|
||||
|
||||
. matches newline yes REG_NEWLINE
|
||||
newline matches [^a] yes REG_NEWLINE
|
||||
$ matches \n at end no REG_NEWLINE
|
||||
$ matches \n in middle no REG_NEWLINE
|
||||
^ matches \n in middle no REG_NEWLINE
|
||||
</pre>
|
||||
PCRE's behaviour is the same as Perl's, except that there is no equivalent for
|
||||
PCRE_DOLLAR_ENDONLY in Perl. In both PCRE and Perl, there is no way to stop
|
||||
newline from matching [^a].
|
||||
</P>
|
||||
<P>
|
||||
The default POSIX newline handling can be obtained by setting PCRE_DOTALL and
|
||||
PCRE_DOLLAR_ENDONLY, but there is no way to make PCRE behave exactly as for the
|
||||
REG_NEWLINE action.
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">MATCHING A PATTERN</a><br>
|
||||
<P>
|
||||
The function <b>regexec()</b> is called to match a compiled pattern <i>preg</i>
|
||||
against a given <i>string</i>, which is by default terminated by a zero byte
|
||||
(but see REG_STARTEND below), subject to the options in <i>eflags</i>. These can
|
||||
be:
|
||||
<pre>
|
||||
REG_NOTBOL
|
||||
</pre>
|
||||
The PCRE_NOTBOL option is set when calling the underlying PCRE matching
|
||||
function.
|
||||
<pre>
|
||||
REG_NOTEMPTY
|
||||
</pre>
|
||||
The PCRE_NOTEMPTY option is set when calling the underlying PCRE matching
|
||||
function. Note that REG_NOTEMPTY is not part of the POSIX standard. However,
|
||||
setting this option can give more POSIX-like behaviour in some situations.
|
||||
<pre>
|
||||
REG_NOTEOL
|
||||
</pre>
|
||||
The PCRE_NOTEOL option is set when calling the underlying PCRE matching
|
||||
function.
|
||||
<pre>
|
||||
REG_STARTEND
|
||||
</pre>
|
||||
The string is considered to start at <i>string</i> + <i>pmatch[0].rm_so</i> and
|
||||
to have a terminating NUL located at <i>string</i> + <i>pmatch[0].rm_eo</i>
|
||||
(there need not actually be a NUL at that location), regardless of the value of
|
||||
<i>nmatch</i>. This is a BSD extension, compatible with but not specified by
|
||||
IEEE Standard 1003.2 (POSIX.2), and should be used with caution in software
|
||||
intended to be portable to other systems. Note that a non-zero <i>rm_so</i> does
|
||||
not imply REG_NOTBOL; REG_STARTEND affects only the location of the string, not
|
||||
how it is matched.
|
||||
</P>
|
||||
<P>
|
||||
If the pattern was compiled with the REG_NOSUB flag, no data about any matched
|
||||
strings is returned. The <i>nmatch</i> and <i>pmatch</i> arguments of
|
||||
<b>regexec()</b> are ignored.
|
||||
</P>
|
||||
<P>
|
||||
If the value of <i>nmatch</i> is zero, or if the value <i>pmatch</i> is NULL,
|
||||
no data about any matched strings is returned.
|
||||
</P>
|
||||
<P>
|
||||
Otherwise,the portion of the string that was matched, and also any captured
|
||||
substrings, are returned via the <i>pmatch</i> argument, which points to an
|
||||
array of <i>nmatch</i> structures of type <i>regmatch_t</i>, containing the
|
||||
members <i>rm_so</i> and <i>rm_eo</i>. These contain the offset to the first
|
||||
character of each substring and the offset to the first character after the end
|
||||
of each substring, respectively. The 0th element of the vector relates to the
|
||||
entire portion of <i>string</i> that was matched; subsequent elements relate to
|
||||
the capturing subpatterns of the regular expression. Unused entries in the
|
||||
array have both structure members set to -1.
|
||||
</P>
|
||||
<P>
|
||||
A successful match yields a zero return; various error codes are defined in the
|
||||
header file, of which REG_NOMATCH is the "expected" failure code.
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">ERROR MESSAGES</a><br>
|
||||
<P>
|
||||
The <b>regerror()</b> function maps a non-zero errorcode from either
|
||||
<b>regcomp()</b> or <b>regexec()</b> to a printable message. If <i>preg</i> is not
|
||||
NULL, the error should have arisen from the use of that structure. A message
|
||||
terminated by a binary zero is placed in <i>errbuf</i>. The length of the
|
||||
message, including the zero, is limited to <i>errbuf_size</i>. The yield of the
|
||||
function is the size of buffer needed to hold the whole message.
|
||||
</P>
|
||||
<br><a name="SEC7" href="#TOC1">MEMORY USAGE</a><br>
|
||||
<P>
|
||||
Compiling a regular expression causes memory to be allocated and associated
|
||||
with the <i>preg</i> structure. The function <b>regfree()</b> frees all such
|
||||
memory, after which <i>preg</i> may no longer be used as a compiled expression.
|
||||
</P>
|
||||
<br><a name="SEC8" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC9" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 09 January 2012
|
||||
<br>
|
||||
Copyright © 1997-2012 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,163 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcreprecompile specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcreprecompile man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">SAVING AND RE-USING PRECOMPILED PCRE PATTERNS</a>
|
||||
<li><a name="TOC2" href="#SEC2">SAVING A COMPILED PATTERN</a>
|
||||
<li><a name="TOC3" href="#SEC3">RE-USING A PRECOMPILED PATTERN</a>
|
||||
<li><a name="TOC4" href="#SEC4">COMPATIBILITY WITH DIFFERENT PCRE RELEASES</a>
|
||||
<li><a name="TOC5" href="#SEC5">AUTHOR</a>
|
||||
<li><a name="TOC6" href="#SEC6">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">SAVING AND RE-USING PRECOMPILED PCRE PATTERNS</a><br>
|
||||
<P>
|
||||
If you are running an application that uses a large number of regular
|
||||
expression patterns, it may be useful to store them in a precompiled form
|
||||
instead of having to compile them every time the application is run.
|
||||
If you are not using any private character tables (see the
|
||||
<a href="pcre_maketables.html"><b>pcre_maketables()</b></a>
|
||||
documentation), this is relatively straightforward. If you are using private
|
||||
tables, it is a little bit more complicated. However, if you are using the
|
||||
just-in-time optimization feature, it is not possible to save and reload the
|
||||
JIT data.
|
||||
</P>
|
||||
<P>
|
||||
If you save compiled patterns to a file, you can copy them to a different host
|
||||
and run them there. If the two hosts have different endianness (byte order),
|
||||
you should run the <b>pcre[16|32]_pattern_to_host_byte_order()</b> function on the
|
||||
new host before trying to match the pattern. The matching functions return
|
||||
PCRE_ERROR_BADENDIANNESS if they detect a pattern with the wrong endianness.
|
||||
</P>
|
||||
<P>
|
||||
Compiling regular expressions with one version of PCRE for use with a different
|
||||
version is not guaranteed to work and may cause crashes, and saving and
|
||||
restoring a compiled pattern loses any JIT optimization data.
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">SAVING A COMPILED PATTERN</a><br>
|
||||
<P>
|
||||
The value returned by <b>pcre[16|32]_compile()</b> points to a single block of
|
||||
memory that holds the compiled pattern and associated data. You can find the
|
||||
length of this block in bytes by calling <b>pcre[16|32]_fullinfo()</b> with an
|
||||
argument of PCRE_INFO_SIZE. You can then save the data in any appropriate
|
||||
manner. Here is sample code for the 8-bit library that compiles a pattern and
|
||||
writes it to a file. It assumes that the variable <i>fd</i> refers to a file
|
||||
that is open for output:
|
||||
<pre>
|
||||
int erroroffset, rc, size;
|
||||
char *error;
|
||||
pcre *re;
|
||||
|
||||
re = pcre_compile("my pattern", 0, &error, &erroroffset, NULL);
|
||||
if (re == NULL) { ... handle errors ... }
|
||||
rc = pcre_fullinfo(re, NULL, PCRE_INFO_SIZE, &size);
|
||||
if (rc < 0) { ... handle errors ... }
|
||||
rc = fwrite(re, 1, size, fd);
|
||||
if (rc != size) { ... handle errors ... }
|
||||
</pre>
|
||||
In this example, the bytes that comprise the compiled pattern are copied
|
||||
exactly. Note that this is binary data that may contain any of the 256 possible
|
||||
byte values. On systems that make a distinction between binary and non-binary
|
||||
data, be sure that the file is opened for binary output.
|
||||
</P>
|
||||
<P>
|
||||
If you want to write more than one pattern to a file, you will have to devise a
|
||||
way of separating them. For binary data, preceding each pattern with its length
|
||||
is probably the most straightforward approach. Another possibility is to write
|
||||
out the data in hexadecimal instead of binary, one pattern to a line.
|
||||
</P>
|
||||
<P>
|
||||
Saving compiled patterns in a file is only one possible way of storing them for
|
||||
later use. They could equally well be saved in a database, or in the memory of
|
||||
some daemon process that passes them via sockets to the processes that want
|
||||
them.
|
||||
</P>
|
||||
<P>
|
||||
If the pattern has been studied, it is also possible to save the normal study
|
||||
data in a similar way to the compiled pattern itself. However, if the
|
||||
PCRE_STUDY_JIT_COMPILE was used, the just-in-time data that is created cannot
|
||||
be saved because it is too dependent on the current environment. When studying
|
||||
generates additional information, <b>pcre[16|32]_study()</b> returns a pointer to a
|
||||
<b>pcre[16|32]_extra</b> data block. Its format is defined in the
|
||||
<a href="pcreapi.html#extradata">section on matching a pattern</a>
|
||||
in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
documentation. The <i>study_data</i> field points to the binary study data, and
|
||||
this is what you must save (not the <b>pcre[16|32]_extra</b> block itself). The
|
||||
length of the study data can be obtained by calling <b>pcre[16|32]_fullinfo()</b>
|
||||
with an argument of PCRE_INFO_STUDYSIZE. Remember to check that
|
||||
<b>pcre[16|32]_study()</b> did return a non-NULL value before trying to save the
|
||||
study data.
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">RE-USING A PRECOMPILED PATTERN</a><br>
|
||||
<P>
|
||||
Re-using a precompiled pattern is straightforward. Having reloaded it into main
|
||||
memory, called <b>pcre[16|32]_pattern_to_host_byte_order()</b> if necessary, you
|
||||
pass its pointer to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b> in
|
||||
the usual way.
|
||||
</P>
|
||||
<P>
|
||||
However, if you passed a pointer to custom character tables when the pattern
|
||||
was compiled (the <i>tableptr</i> argument of <b>pcre[16|32]_compile()</b>), you
|
||||
must now pass a similar pointer to <b>pcre[16|32]_exec()</b> or
|
||||
<b>pcre[16|32]_dfa_exec()</b>, because the value saved with the compiled pattern
|
||||
will obviously be nonsense. A field in a <b>pcre[16|32]_extra()</b> block is used
|
||||
to pass this data, as described in the
|
||||
<a href="pcreapi.html#extradata">section on matching a pattern</a>
|
||||
in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
<b>Warning:</b> The tables that <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b> use
|
||||
must be the same as those that were used when the pattern was compiled. If this
|
||||
is not the case, the behaviour is undefined.
|
||||
</P>
|
||||
<P>
|
||||
If you did not provide custom character tables when the pattern was compiled,
|
||||
the pointer in the compiled pattern is NULL, which causes the matching
|
||||
functions to use PCRE's internal tables. Thus, you do not need to take any
|
||||
special action at run time in this case.
|
||||
</P>
|
||||
<P>
|
||||
If you saved study data with the compiled pattern, you need to create your own
|
||||
<b>pcre[16|32]_extra</b> data block and set the <i>study_data</i> field to point
|
||||
to the reloaded study data. You must also set the PCRE_EXTRA_STUDY_DATA bit in
|
||||
the <i>flags</i> field to indicate that study data is present. Then pass the
|
||||
<b>pcre[16|32]_extra</b> block to the matching function in the usual way. If the
|
||||
pattern was studied for just-in-time optimization, that data cannot be saved,
|
||||
and so is lost by a save/restore cycle.
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">COMPATIBILITY WITH DIFFERENT PCRE RELEASES</a><br>
|
||||
<P>
|
||||
In general, it is safest to recompile all saved patterns when you update to a
|
||||
new PCRE release, though not all updates actually require this.
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 12 November 2013
|
||||
<br>
|
||||
Copyright © 1997-2013 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,110 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcresample specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcresample man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
PCRE SAMPLE PROGRAM
|
||||
</b><br>
|
||||
<P>
|
||||
A simple, complete demonstration program, to get you started with using PCRE,
|
||||
is supplied in the file <i>pcredemo.c</i> in the PCRE distribution. A listing of
|
||||
this program is given in the
|
||||
<a href="pcredemo.html"><b>pcredemo</b></a>
|
||||
documentation. If you do not have a copy of the PCRE distribution, you can save
|
||||
this listing to re-create <i>pcredemo.c</i>.
|
||||
</P>
|
||||
<P>
|
||||
The demonstration program, which uses the original PCRE 8-bit library, compiles
|
||||
the regular expression that is its first argument, and matches it against the
|
||||
subject string in its second argument. No PCRE options are set, and default
|
||||
character tables are used. If matching succeeds, the program outputs the
|
||||
portion of the subject that matched, together with the contents of any captured
|
||||
substrings.
|
||||
</P>
|
||||
<P>
|
||||
If the -g option is given on the command line, the program then goes on to
|
||||
check for further matches of the same regular expression in the same subject
|
||||
string. The logic is a little bit tricky because of the possibility of matching
|
||||
an empty string. Comments in the code explain what is going on.
|
||||
</P>
|
||||
<P>
|
||||
If PCRE is installed in the standard include and library directories for your
|
||||
operating system, you should be able to compile the demonstration program using
|
||||
this command:
|
||||
<pre>
|
||||
gcc -o pcredemo pcredemo.c -lpcre
|
||||
</pre>
|
||||
If PCRE is installed elsewhere, you may need to add additional options to the
|
||||
command line. For example, on a Unix-like system that has PCRE installed in
|
||||
<i>/usr/local</i>, you can compile the demonstration program using a command
|
||||
like this:
|
||||
<pre>
|
||||
gcc -o pcredemo -I/usr/local/include pcredemo.c -L/usr/local/lib -lpcre
|
||||
</pre>
|
||||
In a Windows environment, if you want to statically link the program against a
|
||||
non-dll <b>pcre.a</b> file, you must uncomment the line that defines PCRE_STATIC
|
||||
before including <b>pcre.h</b>, because otherwise the <b>pcre_malloc()</b> and
|
||||
<b>pcre_free()</b> exported functions will be declared
|
||||
<b>__declspec(dllimport)</b>, with unwanted results.
|
||||
</P>
|
||||
<P>
|
||||
Once you have compiled and linked the demonstration program, you can run simple
|
||||
tests like this:
|
||||
<pre>
|
||||
./pcredemo 'cat|dog' 'the cat sat on the mat'
|
||||
./pcredemo -g 'cat|dog' 'the dog sat on the cat'
|
||||
</pre>
|
||||
Note that there is a much more comprehensive test program, called
|
||||
<a href="pcretest.html"><b>pcretest</b>,</a>
|
||||
which supports many more facilities for testing regular expressions and both
|
||||
PCRE libraries. The
|
||||
<a href="pcredemo.html"><b>pcredemo</b></a>
|
||||
program is provided as a simple coding example.
|
||||
</P>
|
||||
<P>
|
||||
If you try to run
|
||||
<a href="pcredemo.html"><b>pcredemo</b></a>
|
||||
when PCRE is not installed in the standard library directory, you may get an
|
||||
error like this on some operating systems (e.g. Solaris):
|
||||
<pre>
|
||||
ld.so.1: a.out: fatal: libpcre.so.0: open failed: No such file or directory
|
||||
</pre>
|
||||
This is caused by the way shared library support works on those systems. You
|
||||
need to add
|
||||
<pre>
|
||||
-R/usr/local/lib
|
||||
</pre>
|
||||
(for example) to the compile command to get round this problem.
|
||||
</P>
|
||||
<br><b>
|
||||
AUTHOR
|
||||
</b><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><b>
|
||||
REVISION
|
||||
</b><br>
|
||||
<P>
|
||||
Last updated: 10 January 2012
|
||||
<br>
|
||||
Copyright © 1997-2012 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,225 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcrestack specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcrestack man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
PCRE DISCUSSION OF STACK USAGE
|
||||
</b><br>
|
||||
<P>
|
||||
When you call <b>pcre[16|32]_exec()</b>, it makes use of an internal function
|
||||
called <b>match()</b>. This calls itself recursively at branch points in the
|
||||
pattern, in order to remember the state of the match so that it can back up and
|
||||
try a different alternative if the first one fails. As matching proceeds deeper
|
||||
and deeper into the tree of possibilities, the recursion depth increases. The
|
||||
<b>match()</b> function is also called in other circumstances, for example,
|
||||
whenever a parenthesized sub-pattern is entered, and in certain cases of
|
||||
repetition.
|
||||
</P>
|
||||
<P>
|
||||
Not all calls of <b>match()</b> increase the recursion depth; for an item such
|
||||
as a* it may be called several times at the same level, after matching
|
||||
different numbers of a's. Furthermore, in a number of cases where the result of
|
||||
the recursive call would immediately be passed back as the result of the
|
||||
current call (a "tail recursion"), the function is just restarted instead.
|
||||
</P>
|
||||
<P>
|
||||
The above comments apply when <b>pcre[16|32]_exec()</b> is run in its normal
|
||||
interpretive manner. If the pattern was studied with the
|
||||
PCRE_STUDY_JIT_COMPILE option, and just-in-time compiling was successful, and
|
||||
the options passed to <b>pcre[16|32]_exec()</b> were not incompatible, the matching
|
||||
process uses the JIT-compiled code instead of the <b>match()</b> function. In
|
||||
this case, the memory requirements are handled entirely differently. See the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
documentation for details.
|
||||
</P>
|
||||
<P>
|
||||
The <b>pcre[16|32]_dfa_exec()</b> function operates in an entirely different way,
|
||||
and uses recursion only when there is a regular expression recursion or
|
||||
subroutine call in the pattern. This includes the processing of assertion and
|
||||
"once-only" subpatterns, which are handled like subroutine calls. Normally,
|
||||
these are never very deep, and the limit on the complexity of
|
||||
<b>pcre[16|32]_dfa_exec()</b> is controlled by the amount of workspace it is given.
|
||||
However, it is possible to write patterns with runaway infinite recursions;
|
||||
such patterns will cause <b>pcre[16|32]_dfa_exec()</b> to run out of stack. At
|
||||
present, there is no protection against this.
|
||||
</P>
|
||||
<P>
|
||||
The comments that follow do NOT apply to <b>pcre[16|32]_dfa_exec()</b>; they are
|
||||
relevant only for <b>pcre[16|32]_exec()</b> without the JIT optimization.
|
||||
</P>
|
||||
<br><b>
|
||||
Reducing <b>pcre[16|32]_exec()</b>'s stack usage
|
||||
</b><br>
|
||||
<P>
|
||||
Each time that <b>match()</b> is actually called recursively, it uses memory
|
||||
from the process stack. For certain kinds of pattern and data, very large
|
||||
amounts of stack may be needed, despite the recognition of "tail recursion".
|
||||
You can often reduce the amount of recursion, and therefore the amount of stack
|
||||
used, by modifying the pattern that is being matched. Consider, for example,
|
||||
this pattern:
|
||||
<pre>
|
||||
([^<]|<(?!inet))+
|
||||
</pre>
|
||||
It matches from wherever it starts until it encounters "<inet" or the end of
|
||||
the data, and is the kind of pattern that might be used when processing an XML
|
||||
file. Each iteration of the outer parentheses matches either one character that
|
||||
is not "<" or a "<" that is not followed by "inet". However, each time a
|
||||
parenthesis is processed, a recursion occurs, so this formulation uses a stack
|
||||
frame for each matched character. For a long string, a lot of stack is
|
||||
required. Consider now this rewritten pattern, which matches exactly the same
|
||||
strings:
|
||||
<pre>
|
||||
([^<]++|<(?!inet))+
|
||||
</pre>
|
||||
This uses very much less stack, because runs of characters that do not contain
|
||||
"<" are "swallowed" in one item inside the parentheses. Recursion happens only
|
||||
when a "<" character that is not followed by "inet" is encountered (and we
|
||||
assume this is relatively rare). A possessive quantifier is used to stop any
|
||||
backtracking into the runs of non-"<" characters, but that is not related to
|
||||
stack usage.
|
||||
</P>
|
||||
<P>
|
||||
This example shows that one way of avoiding stack problems when matching long
|
||||
subject strings is to write repeated parenthesized subpatterns to match more
|
||||
than one character whenever possible.
|
||||
</P>
|
||||
<br><b>
|
||||
Compiling PCRE to use heap instead of stack for <b>pcre[16|32]_exec()</b>
|
||||
</b><br>
|
||||
<P>
|
||||
In environments where stack memory is constrained, you might want to compile
|
||||
PCRE to use heap memory instead of stack for remembering back-up points when
|
||||
<b>pcre[16|32]_exec()</b> is running. This makes it run a lot more slowly, however.
|
||||
Details of how to do this are given in the
|
||||
<a href="pcrebuild.html"><b>pcrebuild</b></a>
|
||||
documentation. When built in this way, instead of using the stack, PCRE obtains
|
||||
and frees memory by calling the functions that are pointed to by the
|
||||
<b>pcre[16|32]_stack_malloc</b> and <b>pcre[16|32]_stack_free</b> variables. By
|
||||
default, these point to <b>malloc()</b> and <b>free()</b>, but you can replace
|
||||
the pointers to cause PCRE to use your own functions. Since the block sizes are
|
||||
always the same, and are always freed in reverse order, it may be possible to
|
||||
implement customized memory handlers that are more efficient than the standard
|
||||
functions.
|
||||
</P>
|
||||
<br><b>
|
||||
Limiting <b>pcre[16|32]_exec()</b>'s stack usage
|
||||
</b><br>
|
||||
<P>
|
||||
You can set limits on the number of times that <b>match()</b> is called, both in
|
||||
total and recursively. If a limit is exceeded, <b>pcre[16|32]_exec()</b> returns an
|
||||
error code. Setting suitable limits should prevent it from running out of
|
||||
stack. The default values of the limits are very large, and unlikely ever to
|
||||
operate. They can be changed when PCRE is built, and they can also be set when
|
||||
<b>pcre[16|32]_exec()</b> is called. For details of these interfaces, see the
|
||||
<a href="pcrebuild.html"><b>pcrebuild</b></a>
|
||||
documentation and the
|
||||
<a href="pcreapi.html#extradata">section on extra data for <b>pcre[16|32]_exec()</b></a>
|
||||
in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
As a very rough rule of thumb, you should reckon on about 500 bytes per
|
||||
recursion. Thus, if you want to limit your stack usage to 8Mb, you should set
|
||||
the limit at 16000 recursions. A 64Mb stack, on the other hand, can support
|
||||
around 128000 recursions.
|
||||
</P>
|
||||
<P>
|
||||
In Unix-like environments, the <b>pcretest</b> test program has a command line
|
||||
option (<b>-S</b>) that can be used to increase the size of its stack. As long
|
||||
as the stack is large enough, another option (<b>-M</b>) can be used to find the
|
||||
smallest limits that allow a particular pattern to match a given subject
|
||||
string. This is done by calling <b>pcre[16|32]_exec()</b> repeatedly with different
|
||||
limits.
|
||||
</P>
|
||||
<br><b>
|
||||
Obtaining an estimate of stack usage
|
||||
</b><br>
|
||||
<P>
|
||||
The actual amount of stack used per recursion can vary quite a lot, depending
|
||||
on the compiler that was used to build PCRE and the optimization or debugging
|
||||
options that were set for it. The rule of thumb value of 500 bytes mentioned
|
||||
above may be larger or smaller than what is actually needed. A better
|
||||
approximation can be obtained by running this command:
|
||||
<pre>
|
||||
pcretest -m -C
|
||||
</pre>
|
||||
The <b>-C</b> option causes <b>pcretest</b> to output information about the
|
||||
options with which PCRE was compiled. When <b>-m</b> is also given (before
|
||||
<b>-C</b>), information about stack use is given in a line like this:
|
||||
<pre>
|
||||
Match recursion uses stack: approximate frame size = 640 bytes
|
||||
</pre>
|
||||
The value is approximate because some recursions need a bit more (up to perhaps
|
||||
16 more bytes).
|
||||
</P>
|
||||
<P>
|
||||
If the above command is given when PCRE is compiled to use the heap instead of
|
||||
the stack for recursion, the value that is output is the size of each block
|
||||
that is obtained from the heap.
|
||||
</P>
|
||||
<br><b>
|
||||
Changing stack size in Unix-like systems
|
||||
</b><br>
|
||||
<P>
|
||||
In Unix-like environments, there is not often a problem with the stack unless
|
||||
very long strings are involved, though the default limit on stack size varies
|
||||
from system to system. Values from 8Mb to 64Mb are common. You can find your
|
||||
default limit by running the command:
|
||||
<pre>
|
||||
ulimit -s
|
||||
</pre>
|
||||
Unfortunately, the effect of running out of stack is often SIGSEGV, though
|
||||
sometimes a more explicit error message is given. You can normally increase the
|
||||
limit on stack size by code such as this:
|
||||
<pre>
|
||||
struct rlimit rlim;
|
||||
getrlimit(RLIMIT_STACK, &rlim);
|
||||
rlim.rlim_cur = 100*1024*1024;
|
||||
setrlimit(RLIMIT_STACK, &rlim);
|
||||
</pre>
|
||||
This reads the current limits (soft and hard) using <b>getrlimit()</b>, then
|
||||
attempts to increase the soft limit to 100Mb using <b>setrlimit()</b>. You must
|
||||
do this before calling <b>pcre[16|32]_exec()</b>.
|
||||
</P>
|
||||
<br><b>
|
||||
Changing stack size in Mac OS X
|
||||
</b><br>
|
||||
<P>
|
||||
Using <b>setrlimit()</b>, as described above, should also work on Mac OS X. It
|
||||
is also possible to set a stack size when linking a program. There is a
|
||||
discussion about stack sizes in Mac OS X at this web site:
|
||||
<a href="http://developer.apple.com/qa/qa2005/qa1419.html">http://developer.apple.com/qa/qa2005/qa1419.html.</a>
|
||||
</P>
|
||||
<br><b>
|
||||
AUTHOR
|
||||
</b><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><b>
|
||||
REVISION
|
||||
</b><br>
|
||||
<P>
|
||||
Last updated: 24 June 2012
|
||||
<br>
|
||||
Copyright © 1997-2012 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,561 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcresyntax specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcresyntax man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">PCRE REGULAR EXPRESSION SYNTAX SUMMARY</a>
|
||||
<li><a name="TOC2" href="#SEC2">QUOTING</a>
|
||||
<li><a name="TOC3" href="#SEC3">CHARACTERS</a>
|
||||
<li><a name="TOC4" href="#SEC4">CHARACTER TYPES</a>
|
||||
<li><a name="TOC5" href="#SEC5">GENERAL CATEGORY PROPERTIES FOR \p and \P</a>
|
||||
<li><a name="TOC6" href="#SEC6">PCRE SPECIAL CATEGORY PROPERTIES FOR \p and \P</a>
|
||||
<li><a name="TOC7" href="#SEC7">SCRIPT NAMES FOR \p AND \P</a>
|
||||
<li><a name="TOC8" href="#SEC8">CHARACTER CLASSES</a>
|
||||
<li><a name="TOC9" href="#SEC9">QUANTIFIERS</a>
|
||||
<li><a name="TOC10" href="#SEC10">ANCHORS AND SIMPLE ASSERTIONS</a>
|
||||
<li><a name="TOC11" href="#SEC11">MATCH POINT RESET</a>
|
||||
<li><a name="TOC12" href="#SEC12">ALTERNATION</a>
|
||||
<li><a name="TOC13" href="#SEC13">CAPTURING</a>
|
||||
<li><a name="TOC14" href="#SEC14">ATOMIC GROUPS</a>
|
||||
<li><a name="TOC15" href="#SEC15">COMMENT</a>
|
||||
<li><a name="TOC16" href="#SEC16">OPTION SETTING</a>
|
||||
<li><a name="TOC17" href="#SEC17">NEWLINE CONVENTION</a>
|
||||
<li><a name="TOC18" href="#SEC18">WHAT \R MATCHES</a>
|
||||
<li><a name="TOC19" href="#SEC19">LOOKAHEAD AND LOOKBEHIND ASSERTIONS</a>
|
||||
<li><a name="TOC20" href="#SEC20">BACKREFERENCES</a>
|
||||
<li><a name="TOC21" href="#SEC21">SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)</a>
|
||||
<li><a name="TOC22" href="#SEC22">CONDITIONAL PATTERNS</a>
|
||||
<li><a name="TOC23" href="#SEC23">BACKTRACKING CONTROL</a>
|
||||
<li><a name="TOC24" href="#SEC24">CALLOUTS</a>
|
||||
<li><a name="TOC25" href="#SEC25">SEE ALSO</a>
|
||||
<li><a name="TOC26" href="#SEC26">AUTHOR</a>
|
||||
<li><a name="TOC27" href="#SEC27">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">PCRE REGULAR EXPRESSION SYNTAX SUMMARY</a><br>
|
||||
<P>
|
||||
The full syntax and semantics of the regular expressions that are supported by
|
||||
PCRE are described in the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
documentation. This document contains a quick-reference summary of the syntax.
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">QUOTING</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
\x where x is non-alphanumeric is a literal x
|
||||
\Q...\E treat enclosed characters as literal
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">CHARACTERS</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
\a alarm, that is, the BEL character (hex 07)
|
||||
\cx "control-x", where x is any ASCII character
|
||||
\e escape (hex 1B)
|
||||
\f form feed (hex 0C)
|
||||
\n newline (hex 0A)
|
||||
\r carriage return (hex 0D)
|
||||
\t tab (hex 09)
|
||||
\0dd character with octal code 0dd
|
||||
\ddd character with octal code ddd, or backreference
|
||||
\o{ddd..} character with octal code ddd..
|
||||
\xhh character with hex code hh
|
||||
\x{hhh..} character with hex code hhh..
|
||||
</pre>
|
||||
Note that \0dd is always an octal code, and that \8 and \9 are the literal
|
||||
characters "8" and "9".
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">CHARACTER TYPES</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
. any character except newline;
|
||||
in dotall mode, any character whatsoever
|
||||
\C one data unit, even in UTF mode (best avoided)
|
||||
\d a decimal digit
|
||||
\D a character that is not a decimal digit
|
||||
\h a horizontal white space character
|
||||
\H a character that is not a horizontal white space character
|
||||
\N a character that is not a newline
|
||||
\p{<i>xx</i>} a character with the <i>xx</i> property
|
||||
\P{<i>xx</i>} a character without the <i>xx</i> property
|
||||
\R a newline sequence
|
||||
\s a white space character
|
||||
\S a character that is not a white space character
|
||||
\v a vertical white space character
|
||||
\V a character that is not a vertical white space character
|
||||
\w a "word" character
|
||||
\W a "non-word" character
|
||||
\X a Unicode extended grapheme cluster
|
||||
</pre>
|
||||
By default, \d, \s, and \w match only ASCII characters, even in UTF-8 mode
|
||||
or in the 16- bit and 32-bit libraries. However, if locale-specific matching is
|
||||
happening, \s and \w may also match characters with code points in the range
|
||||
128-255. If the PCRE_UCP option is set, the behaviour of these escape sequences
|
||||
is changed to use Unicode properties and they match many more characters.
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">GENERAL CATEGORY PROPERTIES FOR \p and \P</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
C Other
|
||||
Cc Control
|
||||
Cf Format
|
||||
Cn Unassigned
|
||||
Co Private use
|
||||
Cs Surrogate
|
||||
|
||||
L Letter
|
||||
Ll Lower case letter
|
||||
Lm Modifier letter
|
||||
Lo Other letter
|
||||
Lt Title case letter
|
||||
Lu Upper case letter
|
||||
L& Ll, Lu, or Lt
|
||||
|
||||
M Mark
|
||||
Mc Spacing mark
|
||||
Me Enclosing mark
|
||||
Mn Non-spacing mark
|
||||
|
||||
N Number
|
||||
Nd Decimal number
|
||||
Nl Letter number
|
||||
No Other number
|
||||
|
||||
P Punctuation
|
||||
Pc Connector punctuation
|
||||
Pd Dash punctuation
|
||||
Pe Close punctuation
|
||||
Pf Final punctuation
|
||||
Pi Initial punctuation
|
||||
Po Other punctuation
|
||||
Ps Open punctuation
|
||||
|
||||
S Symbol
|
||||
Sc Currency symbol
|
||||
Sk Modifier symbol
|
||||
Sm Mathematical symbol
|
||||
So Other symbol
|
||||
|
||||
Z Separator
|
||||
Zl Line separator
|
||||
Zp Paragraph separator
|
||||
Zs Space separator
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">PCRE SPECIAL CATEGORY PROPERTIES FOR \p and \P</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
Xan Alphanumeric: union of properties L and N
|
||||
Xps POSIX space: property Z or tab, NL, VT, FF, CR
|
||||
Xsp Perl space: property Z or tab, NL, VT, FF, CR
|
||||
Xuc Univerally-named character: one that can be
|
||||
represented by a Universal Character Name
|
||||
Xwd Perl word: property Xan or underscore
|
||||
</pre>
|
||||
Perl and POSIX space are now the same. Perl added VT to its space character set
|
||||
at release 5.18 and PCRE changed at release 8.34.
|
||||
</P>
|
||||
<br><a name="SEC7" href="#TOC1">SCRIPT NAMES FOR \p AND \P</a><br>
|
||||
<P>
|
||||
Arabic,
|
||||
Armenian,
|
||||
Avestan,
|
||||
Balinese,
|
||||
Bamum,
|
||||
Bassa_Vah,
|
||||
Batak,
|
||||
Bengali,
|
||||
Bopomofo,
|
||||
Brahmi,
|
||||
Braille,
|
||||
Buginese,
|
||||
Buhid,
|
||||
Canadian_Aboriginal,
|
||||
Carian,
|
||||
Caucasian_Albanian,
|
||||
Chakma,
|
||||
Cham,
|
||||
Cherokee,
|
||||
Common,
|
||||
Coptic,
|
||||
Cuneiform,
|
||||
Cypriot,
|
||||
Cyrillic,
|
||||
Deseret,
|
||||
Devanagari,
|
||||
Duployan,
|
||||
Egyptian_Hieroglyphs,
|
||||
Elbasan,
|
||||
Ethiopic,
|
||||
Georgian,
|
||||
Glagolitic,
|
||||
Gothic,
|
||||
Grantha,
|
||||
Greek,
|
||||
Gujarati,
|
||||
Gurmukhi,
|
||||
Han,
|
||||
Hangul,
|
||||
Hanunoo,
|
||||
Hebrew,
|
||||
Hiragana,
|
||||
Imperial_Aramaic,
|
||||
Inherited,
|
||||
Inscriptional_Pahlavi,
|
||||
Inscriptional_Parthian,
|
||||
Javanese,
|
||||
Kaithi,
|
||||
Kannada,
|
||||
Katakana,
|
||||
Kayah_Li,
|
||||
Kharoshthi,
|
||||
Khmer,
|
||||
Khojki,
|
||||
Khudawadi,
|
||||
Lao,
|
||||
Latin,
|
||||
Lepcha,
|
||||
Limbu,
|
||||
Linear_A,
|
||||
Linear_B,
|
||||
Lisu,
|
||||
Lycian,
|
||||
Lydian,
|
||||
Mahajani,
|
||||
Malayalam,
|
||||
Mandaic,
|
||||
Manichaean,
|
||||
Meetei_Mayek,
|
||||
Mende_Kikakui,
|
||||
Meroitic_Cursive,
|
||||
Meroitic_Hieroglyphs,
|
||||
Miao,
|
||||
Modi,
|
||||
Mongolian,
|
||||
Mro,
|
||||
Myanmar,
|
||||
Nabataean,
|
||||
New_Tai_Lue,
|
||||
Nko,
|
||||
Ogham,
|
||||
Ol_Chiki,
|
||||
Old_Italic,
|
||||
Old_North_Arabian,
|
||||
Old_Permic,
|
||||
Old_Persian,
|
||||
Old_South_Arabian,
|
||||
Old_Turkic,
|
||||
Oriya,
|
||||
Osmanya,
|
||||
Pahawh_Hmong,
|
||||
Palmyrene,
|
||||
Pau_Cin_Hau,
|
||||
Phags_Pa,
|
||||
Phoenician,
|
||||
Psalter_Pahlavi,
|
||||
Rejang,
|
||||
Runic,
|
||||
Samaritan,
|
||||
Saurashtra,
|
||||
Sharada,
|
||||
Shavian,
|
||||
Siddham,
|
||||
Sinhala,
|
||||
Sora_Sompeng,
|
||||
Sundanese,
|
||||
Syloti_Nagri,
|
||||
Syriac,
|
||||
Tagalog,
|
||||
Tagbanwa,
|
||||
Tai_Le,
|
||||
Tai_Tham,
|
||||
Tai_Viet,
|
||||
Takri,
|
||||
Tamil,
|
||||
Telugu,
|
||||
Thaana,
|
||||
Thai,
|
||||
Tibetan,
|
||||
Tifinagh,
|
||||
Tirhuta,
|
||||
Ugaritic,
|
||||
Vai,
|
||||
Warang_Citi,
|
||||
Yi.
|
||||
</P>
|
||||
<br><a name="SEC8" href="#TOC1">CHARACTER CLASSES</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
[...] positive character class
|
||||
[^...] negative character class
|
||||
[x-y] range (can be used for hex characters)
|
||||
[[:xxx:]] positive POSIX named set
|
||||
[[:^xxx:]] negative POSIX named set
|
||||
|
||||
alnum alphanumeric
|
||||
alpha alphabetic
|
||||
ascii 0-127
|
||||
blank space or tab
|
||||
cntrl control character
|
||||
digit decimal digit
|
||||
graph printing, excluding space
|
||||
lower lower case letter
|
||||
print printing, including space
|
||||
punct printing, excluding alphanumeric
|
||||
space white space
|
||||
upper upper case letter
|
||||
word same as \w
|
||||
xdigit hexadecimal digit
|
||||
</pre>
|
||||
In PCRE, POSIX character set names recognize only ASCII characters by default,
|
||||
but some of them use Unicode properties if PCRE_UCP is set. You can use
|
||||
\Q...\E inside a character class.
|
||||
</P>
|
||||
<br><a name="SEC9" href="#TOC1">QUANTIFIERS</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
? 0 or 1, greedy
|
||||
?+ 0 or 1, possessive
|
||||
?? 0 or 1, lazy
|
||||
* 0 or more, greedy
|
||||
*+ 0 or more, possessive
|
||||
*? 0 or more, lazy
|
||||
+ 1 or more, greedy
|
||||
++ 1 or more, possessive
|
||||
+? 1 or more, lazy
|
||||
{n} exactly n
|
||||
{n,m} at least n, no more than m, greedy
|
||||
{n,m}+ at least n, no more than m, possessive
|
||||
{n,m}? at least n, no more than m, lazy
|
||||
{n,} n or more, greedy
|
||||
{n,}+ n or more, possessive
|
||||
{n,}? n or more, lazy
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC10" href="#TOC1">ANCHORS AND SIMPLE ASSERTIONS</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
\b word boundary
|
||||
\B not a word boundary
|
||||
^ start of subject
|
||||
also after internal newline in multiline mode
|
||||
\A start of subject
|
||||
$ end of subject
|
||||
also before newline at end of subject
|
||||
also before internal newline in multiline mode
|
||||
\Z end of subject
|
||||
also before newline at end of subject
|
||||
\z end of subject
|
||||
\G first matching position in subject
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC11" href="#TOC1">MATCH POINT RESET</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
\K reset start of match
|
||||
</pre>
|
||||
\K is honoured in positive assertions, but ignored in negative ones.
|
||||
</P>
|
||||
<br><a name="SEC12" href="#TOC1">ALTERNATION</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
expr|expr|expr...
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC13" href="#TOC1">CAPTURING</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
(...) capturing group
|
||||
(?<name>...) named capturing group (Perl)
|
||||
(?'name'...) named capturing group (Perl)
|
||||
(?P<name>...) named capturing group (Python)
|
||||
(?:...) non-capturing group
|
||||
(?|...) non-capturing group; reset group numbers for
|
||||
capturing groups in each alternative
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC14" href="#TOC1">ATOMIC GROUPS</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
(?>...) atomic, non-capturing group
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC15" href="#TOC1">COMMENT</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
(?#....) comment (not nestable)
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC16" href="#TOC1">OPTION SETTING</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
(?i) caseless
|
||||
(?J) allow duplicate names
|
||||
(?m) multiline
|
||||
(?s) single line (dotall)
|
||||
(?U) default ungreedy (lazy)
|
||||
(?x) extended (ignore white space)
|
||||
(?-...) unset option(s)
|
||||
</pre>
|
||||
The following are recognized only at the very start of a pattern or after one
|
||||
of the newline or \R options with similar syntax. More than one of them may
|
||||
appear.
|
||||
<pre>
|
||||
(*LIMIT_MATCH=d) set the match limit to d (decimal number)
|
||||
(*LIMIT_RECURSION=d) set the recursion limit to d (decimal number)
|
||||
(*NO_AUTO_POSSESS) no auto-possessification (PCRE_NO_AUTO_POSSESS)
|
||||
(*NO_START_OPT) no start-match optimization (PCRE_NO_START_OPTIMIZE)
|
||||
(*UTF8) set UTF-8 mode: 8-bit library (PCRE_UTF8)
|
||||
(*UTF16) set UTF-16 mode: 16-bit library (PCRE_UTF16)
|
||||
(*UTF32) set UTF-32 mode: 32-bit library (PCRE_UTF32)
|
||||
(*UTF) set appropriate UTF mode for the library in use
|
||||
(*UCP) set PCRE_UCP (use Unicode properties for \d etc)
|
||||
</pre>
|
||||
Note that LIMIT_MATCH and LIMIT_RECURSION can only reduce the value of the
|
||||
limits set by the caller of pcre_exec(), not increase them.
|
||||
</P>
|
||||
<br><a name="SEC17" href="#TOC1">NEWLINE CONVENTION</a><br>
|
||||
<P>
|
||||
These are recognized only at the very start of the pattern or after option
|
||||
settings with a similar syntax.
|
||||
<pre>
|
||||
(*CR) carriage return only
|
||||
(*LF) linefeed only
|
||||
(*CRLF) carriage return followed by linefeed
|
||||
(*ANYCRLF) all three of the above
|
||||
(*ANY) any Unicode newline sequence
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC18" href="#TOC1">WHAT \R MATCHES</a><br>
|
||||
<P>
|
||||
These are recognized only at the very start of the pattern or after option
|
||||
setting with a similar syntax.
|
||||
<pre>
|
||||
(*BSR_ANYCRLF) CR, LF, or CRLF
|
||||
(*BSR_UNICODE) any Unicode newline sequence
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC19" href="#TOC1">LOOKAHEAD AND LOOKBEHIND ASSERTIONS</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
(?=...) positive look ahead
|
||||
(?!...) negative look ahead
|
||||
(?<=...) positive look behind
|
||||
(?<!...) negative look behind
|
||||
</pre>
|
||||
Each top-level branch of a look behind must be of a fixed length.
|
||||
</P>
|
||||
<br><a name="SEC20" href="#TOC1">BACKREFERENCES</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
\n reference by number (can be ambiguous)
|
||||
\gn reference by number
|
||||
\g{n} reference by number
|
||||
\g{-n} relative reference by number
|
||||
\k<name> reference by name (Perl)
|
||||
\k'name' reference by name (Perl)
|
||||
\g{name} reference by name (Perl)
|
||||
\k{name} reference by name (.NET)
|
||||
(?P=name) reference by name (Python)
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC21" href="#TOC1">SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
(?R) recurse whole pattern
|
||||
(?n) call subpattern by absolute number
|
||||
(?+n) call subpattern by relative number
|
||||
(?-n) call subpattern by relative number
|
||||
(?&name) call subpattern by name (Perl)
|
||||
(?P>name) call subpattern by name (Python)
|
||||
\g<name> call subpattern by name (Oniguruma)
|
||||
\g'name' call subpattern by name (Oniguruma)
|
||||
\g<n> call subpattern by absolute number (Oniguruma)
|
||||
\g'n' call subpattern by absolute number (Oniguruma)
|
||||
\g<+n> call subpattern by relative number (PCRE extension)
|
||||
\g'+n' call subpattern by relative number (PCRE extension)
|
||||
\g<-n> call subpattern by relative number (PCRE extension)
|
||||
\g'-n' call subpattern by relative number (PCRE extension)
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC22" href="#TOC1">CONDITIONAL PATTERNS</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
(?(condition)yes-pattern)
|
||||
(?(condition)yes-pattern|no-pattern)
|
||||
|
||||
(?(n)... absolute reference condition
|
||||
(?(+n)... relative reference condition
|
||||
(?(-n)... relative reference condition
|
||||
(?(<name>)... named reference condition (Perl)
|
||||
(?('name')... named reference condition (Perl)
|
||||
(?(name)... named reference condition (PCRE)
|
||||
(?(R)... overall recursion condition
|
||||
(?(Rn)... specific group recursion condition
|
||||
(?(R&name)... specific recursion condition
|
||||
(?(DEFINE)... define subpattern for reference
|
||||
(?(assert)... assertion condition
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC23" href="#TOC1">BACKTRACKING CONTROL</a><br>
|
||||
<P>
|
||||
The following act immediately they are reached:
|
||||
<pre>
|
||||
(*ACCEPT) force successful match
|
||||
(*FAIL) force backtrack; synonym (*F)
|
||||
(*MARK:NAME) set name to be passed back; synonym (*:NAME)
|
||||
</pre>
|
||||
The following act only when a subsequent match failure causes a backtrack to
|
||||
reach them. They all force a match failure, but they differ in what happens
|
||||
afterwards. Those that advance the start-of-match point do so only if the
|
||||
pattern is not anchored.
|
||||
<pre>
|
||||
(*COMMIT) overall failure, no advance of starting point
|
||||
(*PRUNE) advance to next starting character
|
||||
(*PRUNE:NAME) equivalent to (*MARK:NAME)(*PRUNE)
|
||||
(*SKIP) advance to current matching position
|
||||
(*SKIP:NAME) advance to position corresponding to an earlier
|
||||
(*MARK:NAME); if not found, the (*SKIP) is ignored
|
||||
(*THEN) local failure, backtrack to next alternation
|
||||
(*THEN:NAME) equivalent to (*MARK:NAME)(*THEN)
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC24" href="#TOC1">CALLOUTS</a><br>
|
||||
<P>
|
||||
<pre>
|
||||
(?C) callout
|
||||
(?Cn) callout with data n
|
||||
</PRE>
|
||||
</P>
|
||||
<br><a name="SEC25" href="#TOC1">SEE ALSO</a><br>
|
||||
<P>
|
||||
<b>pcrepattern</b>(3), <b>pcreapi</b>(3), <b>pcrecallout</b>(3),
|
||||
<b>pcrematching</b>(3), <b>pcre</b>(3).
|
||||
</P>
|
||||
<br><a name="SEC26" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC27" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 08 January 2014
|
||||
<br>
|
||||
Copyright © 1997-2014 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,1163 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcretest specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcretest man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<ul>
|
||||
<li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
|
||||
<li><a name="TOC2" href="#SEC2">INPUT DATA FORMAT</a>
|
||||
<li><a name="TOC3" href="#SEC3">PCRE's 8-BIT, 16-BIT AND 32-BIT LIBRARIES</a>
|
||||
<li><a name="TOC4" href="#SEC4">COMMAND LINE OPTIONS</a>
|
||||
<li><a name="TOC5" href="#SEC5">DESCRIPTION</a>
|
||||
<li><a name="TOC6" href="#SEC6">PATTERN MODIFIERS</a>
|
||||
<li><a name="TOC7" href="#SEC7">DATA LINES</a>
|
||||
<li><a name="TOC8" href="#SEC8">THE ALTERNATIVE MATCHING FUNCTION</a>
|
||||
<li><a name="TOC9" href="#SEC9">DEFAULT OUTPUT FROM PCRETEST</a>
|
||||
<li><a name="TOC10" href="#SEC10">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a>
|
||||
<li><a name="TOC11" href="#SEC11">RESTARTING AFTER A PARTIAL MATCH</a>
|
||||
<li><a name="TOC12" href="#SEC12">CALLOUTS</a>
|
||||
<li><a name="TOC13" href="#SEC13">NON-PRINTING CHARACTERS</a>
|
||||
<li><a name="TOC14" href="#SEC14">SAVING AND RELOADING COMPILED PATTERNS</a>
|
||||
<li><a name="TOC15" href="#SEC15">SEE ALSO</a>
|
||||
<li><a name="TOC16" href="#SEC16">AUTHOR</a>
|
||||
<li><a name="TOC17" href="#SEC17">REVISION</a>
|
||||
</ul>
|
||||
<br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
|
||||
<P>
|
||||
<b>pcretest [options] [input file [output file]]</b>
|
||||
<br>
|
||||
<br>
|
||||
<b>pcretest</b> was written as a test program for the PCRE regular expression
|
||||
library itself, but it can also be used for experimenting with regular
|
||||
expressions. This document describes the features of the test program; for
|
||||
details of the regular expressions themselves, see the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
documentation. For details of the PCRE library function calls and their
|
||||
options, see the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
,
|
||||
<a href="pcre16.html"><b>pcre16</b></a>
|
||||
and
|
||||
<a href="pcre32.html"><b>pcre32</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
The input for <b>pcretest</b> is a sequence of regular expression patterns and
|
||||
strings to be matched, as described below. The output shows the result of each
|
||||
match. Options on the command line and the patterns control PCRE options and
|
||||
exactly what is output.
|
||||
</P>
|
||||
<P>
|
||||
As PCRE has evolved, it has acquired many different features, and as a result,
|
||||
<b>pcretest</b> now has rather a lot of obscure options for testing every
|
||||
possible feature. Some of these options are specifically designed for use in
|
||||
conjunction with the test script and data files that are distributed as part of
|
||||
PCRE, and are unlikely to be of use otherwise. They are all documented here,
|
||||
but without much justification.
|
||||
</P>
|
||||
<br><a name="SEC2" href="#TOC1">INPUT DATA FORMAT</a><br>
|
||||
<P>
|
||||
Input to <b>pcretest</b> is processed line by line, either by calling the C
|
||||
library's <b>fgets()</b> function, or via the <b>libreadline</b> library (see
|
||||
below). In Unix-like environments, <b>fgets()</b> treats any bytes other than
|
||||
newline as data characters. However, in some Windows environments character 26
|
||||
(hex 1A) causes an immediate end of file, and no further data is read. For
|
||||
maximum portability, therefore, it is safest to use only ASCII characters in
|
||||
<b>pcretest</b> input files.
|
||||
</P>
|
||||
<P>
|
||||
The input is processed using using C's string functions, so must not
|
||||
contain binary zeroes, even though in Unix-like environments, <b>fgets()</b>
|
||||
treats any bytes other than newline as data characters.
|
||||
</P>
|
||||
<br><a name="SEC3" href="#TOC1">PCRE's 8-BIT, 16-BIT AND 32-BIT LIBRARIES</a><br>
|
||||
<P>
|
||||
From release 8.30, two separate PCRE libraries can be built. The original one
|
||||
supports 8-bit character strings, whereas the newer 16-bit library supports
|
||||
character strings encoded in 16-bit units. From release 8.32, a third library
|
||||
can be built, supporting character strings encoded in 32-bit units. The
|
||||
<b>pcretest</b> program can be used to test all three libraries. However, it is
|
||||
itself still an 8-bit program, reading 8-bit input and writing 8-bit output.
|
||||
When testing the 16-bit or 32-bit library, the patterns and data strings are
|
||||
converted to 16- or 32-bit format before being passed to the PCRE library
|
||||
functions. Results are converted to 8-bit for output.
|
||||
</P>
|
||||
<P>
|
||||
References to functions and structures of the form <b>pcre[16|32]_xx</b> below
|
||||
mean "<b>pcre_xx</b> when using the 8-bit library, <b>pcre16_xx</b> when using
|
||||
the 16-bit library, or <b>pcre32_xx</b> when using the 32-bit library".
|
||||
</P>
|
||||
<br><a name="SEC4" href="#TOC1">COMMAND LINE OPTIONS</a><br>
|
||||
<P>
|
||||
<b>-8</b>
|
||||
If both the 8-bit library has been built, this option causes the 8-bit library
|
||||
to be used (which is the default); if the 8-bit library has not been built,
|
||||
this option causes an error.
|
||||
</P>
|
||||
<P>
|
||||
<b>-16</b>
|
||||
If both the 8-bit or the 32-bit, and the 16-bit libraries have been built, this
|
||||
option causes the 16-bit library to be used. If only the 16-bit library has been
|
||||
built, this is the default (so has no effect). If only the 8-bit or the 32-bit
|
||||
library has been built, this option causes an error.
|
||||
</P>
|
||||
<P>
|
||||
<b>-32</b>
|
||||
If both the 8-bit or the 16-bit, and the 32-bit libraries have been built, this
|
||||
option causes the 32-bit library to be used. If only the 32-bit library has been
|
||||
built, this is the default (so has no effect). If only the 8-bit or the 16-bit
|
||||
library has been built, this option causes an error.
|
||||
</P>
|
||||
<P>
|
||||
<b>-b</b>
|
||||
Behave as if each pattern has the <b>/B</b> (show byte code) modifier; the
|
||||
internal form is output after compilation.
|
||||
</P>
|
||||
<P>
|
||||
<b>-C</b>
|
||||
Output the version number of the PCRE library, and all available information
|
||||
about the optional features that are included, and then exit with zero exit
|
||||
code. All other options are ignored.
|
||||
</P>
|
||||
<P>
|
||||
<b>-C</b> <i>option</i>
|
||||
Output information about a specific build-time option, then exit. This
|
||||
functionality is intended for use in scripts such as <b>RunTest</b>. The
|
||||
following options output the value and set the exit code as indicated:
|
||||
<pre>
|
||||
ebcdic-nl the code for LF (= NL) in an EBCDIC environment:
|
||||
0x15 or 0x25
|
||||
0 if used in an ASCII environment
|
||||
exit code is always 0
|
||||
linksize the configured internal link size (2, 3, or 4)
|
||||
exit code is set to the link size
|
||||
newline the default newline setting:
|
||||
CR, LF, CRLF, ANYCRLF, or ANY
|
||||
exit code is always 0
|
||||
bsr the default setting for what \R matches:
|
||||
ANYCRLF or ANY
|
||||
exit code is always 0
|
||||
</pre>
|
||||
The following options output 1 for true or 0 for false, and set the exit code
|
||||
to the same value:
|
||||
<pre>
|
||||
ebcdic compiled for an EBCDIC environment
|
||||
jit just-in-time support is available
|
||||
pcre16 the 16-bit library was built
|
||||
pcre32 the 32-bit library was built
|
||||
pcre8 the 8-bit library was built
|
||||
ucp Unicode property support is available
|
||||
utf UTF-8 and/or UTF-16 and/or UTF-32 support
|
||||
is available
|
||||
</pre>
|
||||
If an unknown option is given, an error message is output; the exit code is 0.
|
||||
</P>
|
||||
<P>
|
||||
<b>-d</b>
|
||||
Behave as if each pattern has the <b>/D</b> (debug) modifier; the internal
|
||||
form and information about the compiled pattern is output after compilation;
|
||||
<b>-d</b> is equivalent to <b>-b -i</b>.
|
||||
</P>
|
||||
<P>
|
||||
<b>-dfa</b>
|
||||
Behave as if each data line contains the \D escape sequence; this causes the
|
||||
alternative matching function, <b>pcre[16|32]_dfa_exec()</b>, to be used instead
|
||||
of the standard <b>pcre[16|32]_exec()</b> function (more detail is given below).
|
||||
</P>
|
||||
<P>
|
||||
<b>-help</b>
|
||||
Output a brief summary these options and then exit.
|
||||
</P>
|
||||
<P>
|
||||
<b>-i</b>
|
||||
Behave as if each pattern has the <b>/I</b> modifier; information about the
|
||||
compiled pattern is given after compilation.
|
||||
</P>
|
||||
<P>
|
||||
<b>-M</b>
|
||||
Behave as if each data line contains the \M escape sequence; this causes
|
||||
PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by
|
||||
calling <b>pcre[16|32]_exec()</b> repeatedly with different limits.
|
||||
</P>
|
||||
<P>
|
||||
<b>-m</b>
|
||||
Output the size of each compiled pattern after it has been compiled. This is
|
||||
equivalent to adding <b>/M</b> to each regular expression. The size is given in
|
||||
bytes for both libraries.
|
||||
</P>
|
||||
<P>
|
||||
<b>-O</b>
|
||||
Behave as if each pattern has the <b>/O</b> modifier, that is disable
|
||||
auto-possessification for all patterns.
|
||||
</P>
|
||||
<P>
|
||||
<b>-o</b> <i>osize</i>
|
||||
Set the number of elements in the output vector that is used when calling
|
||||
<b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b> to be <i>osize</i>. The
|
||||
default value is 45, which is enough for 14 capturing subexpressions for
|
||||
<b>pcre[16|32]_exec()</b> or 22 different matches for
|
||||
<b>pcre[16|32]_dfa_exec()</b>.
|
||||
The vector size can be changed for individual matching calls by including \O
|
||||
in the data line (see below).
|
||||
</P>
|
||||
<P>
|
||||
<b>-p</b>
|
||||
Behave as if each pattern has the <b>/P</b> modifier; the POSIX wrapper API is
|
||||
used to call PCRE. None of the other options has any effect when <b>-p</b> is
|
||||
set. This option can be used only with the 8-bit library.
|
||||
</P>
|
||||
<P>
|
||||
<b>-q</b>
|
||||
Do not output the version number of <b>pcretest</b> at the start of execution.
|
||||
</P>
|
||||
<P>
|
||||
<b>-S</b> <i>size</i>
|
||||
On Unix-like systems, set the size of the run-time stack to <i>size</i>
|
||||
megabytes.
|
||||
</P>
|
||||
<P>
|
||||
<b>-s</b> or <b>-s+</b>
|
||||
Behave as if each pattern has the <b>/S</b> modifier; in other words, force each
|
||||
pattern to be studied. If <b>-s+</b> is used, all the JIT compile options are
|
||||
passed to <b>pcre[16|32]_study()</b>, causing just-in-time optimization to be set
|
||||
up if it is available, for both full and partial matching. Specific JIT compile
|
||||
options can be selected by following <b>-s+</b> with a digit in the range 1 to
|
||||
7, which selects the JIT compile modes as follows:
|
||||
<pre>
|
||||
1 normal match only
|
||||
2 soft partial match only
|
||||
3 normal match and soft partial match
|
||||
4 hard partial match only
|
||||
6 soft and hard partial match
|
||||
7 all three modes (default)
|
||||
</pre>
|
||||
If <b>-s++</b> is used instead of <b>-s+</b> (with or without a following digit),
|
||||
the text "(JIT)" is added to the first output line after a match or no match
|
||||
when JIT-compiled code was actually used.
|
||||
<br>
|
||||
<br>
|
||||
Note that there are pattern options that can override <b>-s</b>, either
|
||||
specifying no studying at all, or suppressing JIT compilation.
|
||||
<br>
|
||||
<br>
|
||||
If the <b>/I</b> or <b>/D</b> option is present on a pattern (requesting output
|
||||
about the compiled pattern), information about the result of studying is not
|
||||
included when studying is caused only by <b>-s</b> and neither <b>-i</b> nor
|
||||
<b>-d</b> is present on the command line. This behaviour means that the output
|
||||
from tests that are run with and without <b>-s</b> should be identical, except
|
||||
when options that output information about the actual running of a match are
|
||||
set.
|
||||
<br>
|
||||
<br>
|
||||
The <b>-M</b>, <b>-t</b>, and <b>-tm</b> options, which give information about
|
||||
resources used, are likely to produce different output with and without
|
||||
<b>-s</b>. Output may also differ if the <b>/C</b> option is present on an
|
||||
individual pattern. This uses callouts to trace the the matching process, and
|
||||
this may be different between studied and non-studied patterns. If the pattern
|
||||
contains (*MARK) items there may also be differences, for the same reason. The
|
||||
<b>-s</b> command line option can be overridden for specific patterns that
|
||||
should never be studied (see the <b>/S</b> pattern modifier below).
|
||||
</P>
|
||||
<P>
|
||||
<b>-t</b>
|
||||
Run each compile, study, and match many times with a timer, and output the
|
||||
resulting times per compile, study, or match (in milliseconds). Do not set
|
||||
<b>-m</b> with <b>-t</b>, because you will then get the size output a zillion
|
||||
times, and the timing will be distorted. You can control the number of
|
||||
iterations that are used for timing by following <b>-t</b> with a number (as a
|
||||
separate item on the command line). For example, "-t 1000" iterates 1000 times.
|
||||
The default is to iterate 500000 times.
|
||||
</P>
|
||||
<P>
|
||||
<b>-tm</b>
|
||||
This is like <b>-t</b> except that it times only the matching phase, not the
|
||||
compile or study phases.
|
||||
</P>
|
||||
<P>
|
||||
<b>-T</b> <b>-TM</b>
|
||||
These behave like <b>-t</b> and <b>-tm</b>, but in addition, at the end of a run,
|
||||
the total times for all compiles, studies, and matches are output.
|
||||
</P>
|
||||
<br><a name="SEC5" href="#TOC1">DESCRIPTION</a><br>
|
||||
<P>
|
||||
If <b>pcretest</b> is given two filename arguments, it reads from the first and
|
||||
writes to the second. If it is given only one filename argument, it reads from
|
||||
that file and writes to stdout. Otherwise, it reads from stdin and writes to
|
||||
stdout, and prompts for each line of input, using "re>" to prompt for regular
|
||||
expressions, and "data>" to prompt for data lines.
|
||||
</P>
|
||||
<P>
|
||||
When <b>pcretest</b> is built, a configuration option can specify that it should
|
||||
be linked with the <b>libreadline</b> library. When this is done, if the input
|
||||
is from a terminal, it is read using the <b>readline()</b> function. This
|
||||
provides line-editing and history facilities. The output from the <b>-help</b>
|
||||
option states whether or not <b>readline()</b> will be used.
|
||||
</P>
|
||||
<P>
|
||||
The program handles any number of sets of input on a single input file. Each
|
||||
set starts with a regular expression, and continues with any number of data
|
||||
lines to be matched against that pattern.
|
||||
</P>
|
||||
<P>
|
||||
Each data line is matched separately and independently. If you want to do
|
||||
multi-line matches, you have to use the \n escape sequence (or \r or \r\n,
|
||||
etc., depending on the newline setting) in a single line of input to encode the
|
||||
newline sequences. There is no limit on the length of data lines; the input
|
||||
buffer is automatically extended if it is too small.
|
||||
</P>
|
||||
<P>
|
||||
An empty line signals the end of the data lines, at which point a new regular
|
||||
expression is read. The regular expressions are given enclosed in any
|
||||
non-alphanumeric delimiters other than backslash, for example:
|
||||
<pre>
|
||||
/(a|bc)x+yz/
|
||||
</pre>
|
||||
White space before the initial delimiter is ignored. A regular expression may
|
||||
be continued over several input lines, in which case the newline characters are
|
||||
included within it. It is possible to include the delimiter within the pattern
|
||||
by escaping it, for example
|
||||
<pre>
|
||||
/abc\/def/
|
||||
</pre>
|
||||
If you do so, the escape and the delimiter form part of the pattern, but since
|
||||
delimiters are always non-alphanumeric, this does not affect its interpretation.
|
||||
If the terminating delimiter is immediately followed by a backslash, for
|
||||
example,
|
||||
<pre>
|
||||
/abc/\
|
||||
</pre>
|
||||
then a backslash is added to the end of the pattern. This is done to provide a
|
||||
way of testing the error condition that arises if a pattern finishes with a
|
||||
backslash, because
|
||||
<pre>
|
||||
/abc\/
|
||||
</pre>
|
||||
is interpreted as the first line of a pattern that starts with "abc/", causing
|
||||
pcretest to read the next line as a continuation of the regular expression.
|
||||
</P>
|
||||
<br><a name="SEC6" href="#TOC1">PATTERN MODIFIERS</a><br>
|
||||
<P>
|
||||
A pattern may be followed by any number of modifiers, which are mostly single
|
||||
characters, though some of these can be qualified by further characters.
|
||||
Following Perl usage, these are referred to below as, for example, "the
|
||||
<b>/i</b> modifier", even though the delimiter of the pattern need not always be
|
||||
a slash, and no slash is used when writing modifiers. White space may appear
|
||||
between the final pattern delimiter and the first modifier, and between the
|
||||
modifiers themselves. For reference, here is a complete list of modifiers. They
|
||||
fall into several groups that are described in detail in the following
|
||||
sections.
|
||||
<pre>
|
||||
<b>/8</b> set UTF mode
|
||||
<b>/9</b> set PCRE_NEVER_UTF (locks out UTF mode)
|
||||
<b>/?</b> disable UTF validity check
|
||||
<b>/+</b> show remainder of subject after match
|
||||
<b>/=</b> show all captures (not just those that are set)
|
||||
|
||||
<b>/A</b> set PCRE_ANCHORED
|
||||
<b>/B</b> show compiled code
|
||||
<b>/C</b> set PCRE_AUTO_CALLOUT
|
||||
<b>/D</b> same as <b>/B</b> plus <b>/I</b>
|
||||
<b>/E</b> set PCRE_DOLLAR_ENDONLY
|
||||
<b>/F</b> flip byte order in compiled pattern
|
||||
<b>/f</b> set PCRE_FIRSTLINE
|
||||
<b>/G</b> find all matches (shorten string)
|
||||
<b>/g</b> find all matches (use startoffset)
|
||||
<b>/I</b> show information about pattern
|
||||
<b>/i</b> set PCRE_CASELESS
|
||||
<b>/J</b> set PCRE_DUPNAMES
|
||||
<b>/K</b> show backtracking control names
|
||||
<b>/L</b> set locale
|
||||
<b>/M</b> show compiled memory size
|
||||
<b>/m</b> set PCRE_MULTILINE
|
||||
<b>/N</b> set PCRE_NO_AUTO_CAPTURE
|
||||
<b>/O</b> set PCRE_NO_AUTO_POSSESS
|
||||
<b>/P</b> use the POSIX wrapper
|
||||
<b>/Q</b> test external stack check function
|
||||
<b>/S</b> study the pattern after compilation
|
||||
<b>/s</b> set PCRE_DOTALL
|
||||
<b>/T</b> select character tables
|
||||
<b>/U</b> set PCRE_UNGREEDY
|
||||
<b>/W</b> set PCRE_UCP
|
||||
<b>/X</b> set PCRE_EXTRA
|
||||
<b>/x</b> set PCRE_EXTENDED
|
||||
<b>/Y</b> set PCRE_NO_START_OPTIMIZE
|
||||
<b>/Z</b> don't show lengths in <b>/B</b> output
|
||||
|
||||
<b>/<any></b> set PCRE_NEWLINE_ANY
|
||||
<b>/<anycrlf></b> set PCRE_NEWLINE_ANYCRLF
|
||||
<b>/<cr></b> set PCRE_NEWLINE_CR
|
||||
<b>/<crlf></b> set PCRE_NEWLINE_CRLF
|
||||
<b>/<lf></b> set PCRE_NEWLINE_LF
|
||||
<b>/<bsr_anycrlf></b> set PCRE_BSR_ANYCRLF
|
||||
<b>/<bsr_unicode></b> set PCRE_BSR_UNICODE
|
||||
<b>/<JS></b> set PCRE_JAVASCRIPT_COMPAT
|
||||
|
||||
</PRE>
|
||||
</P>
|
||||
<br><b>
|
||||
Perl-compatible modifiers
|
||||
</b><br>
|
||||
<P>
|
||||
The <b>/i</b>, <b>/m</b>, <b>/s</b>, and <b>/x</b> modifiers set the PCRE_CASELESS,
|
||||
PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
|
||||
<b>pcre[16|32]_compile()</b> is called. These four modifier letters have the same
|
||||
effect as they do in Perl. For example:
|
||||
<pre>
|
||||
/caseless/i
|
||||
|
||||
</PRE>
|
||||
</P>
|
||||
<br><b>
|
||||
Modifiers for other PCRE options
|
||||
</b><br>
|
||||
<P>
|
||||
The following table shows additional modifiers for setting PCRE compile-time
|
||||
options that do not correspond to anything in Perl:
|
||||
<pre>
|
||||
<b>/8</b> PCRE_UTF8 ) when using the 8-bit
|
||||
<b>/?</b> PCRE_NO_UTF8_CHECK ) library
|
||||
|
||||
<b>/8</b> PCRE_UTF16 ) when using the 16-bit
|
||||
<b>/?</b> PCRE_NO_UTF16_CHECK ) library
|
||||
|
||||
<b>/8</b> PCRE_UTF32 ) when using the 32-bit
|
||||
<b>/?</b> PCRE_NO_UTF32_CHECK ) library
|
||||
|
||||
<b>/9</b> PCRE_NEVER_UTF
|
||||
<b>/A</b> PCRE_ANCHORED
|
||||
<b>/C</b> PCRE_AUTO_CALLOUT
|
||||
<b>/E</b> PCRE_DOLLAR_ENDONLY
|
||||
<b>/f</b> PCRE_FIRSTLINE
|
||||
<b>/J</b> PCRE_DUPNAMES
|
||||
<b>/N</b> PCRE_NO_AUTO_CAPTURE
|
||||
<b>/O</b> PCRE_NO_AUTO_POSSESS
|
||||
<b>/U</b> PCRE_UNGREEDY
|
||||
<b>/W</b> PCRE_UCP
|
||||
<b>/X</b> PCRE_EXTRA
|
||||
<b>/Y</b> PCRE_NO_START_OPTIMIZE
|
||||
<b>/<any></b> PCRE_NEWLINE_ANY
|
||||
<b>/<anycrlf></b> PCRE_NEWLINE_ANYCRLF
|
||||
<b>/<cr></b> PCRE_NEWLINE_CR
|
||||
<b>/<crlf></b> PCRE_NEWLINE_CRLF
|
||||
<b>/<lf></b> PCRE_NEWLINE_LF
|
||||
<b>/<bsr_anycrlf></b> PCRE_BSR_ANYCRLF
|
||||
<b>/<bsr_unicode></b> PCRE_BSR_UNICODE
|
||||
<b>/<JS></b> PCRE_JAVASCRIPT_COMPAT
|
||||
</pre>
|
||||
The modifiers that are enclosed in angle brackets are literal strings as shown,
|
||||
including the angle brackets, but the letters within can be in either case.
|
||||
This example sets multiline matching with CRLF as the line ending sequence:
|
||||
<pre>
|
||||
/^abc/m<CRLF>
|
||||
</pre>
|
||||
As well as turning on the PCRE_UTF8/16/32 option, the <b>/8</b> modifier causes
|
||||
all non-printing characters in output strings to be printed using the
|
||||
\x{hh...} notation. Otherwise, those less than 0x100 are output in hex without
|
||||
the curly brackets.
|
||||
</P>
|
||||
<P>
|
||||
Full details of the PCRE options are given in the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<br><b>
|
||||
Finding all matches in a string
|
||||
</b><br>
|
||||
<P>
|
||||
Searching for all possible matches within each subject string can be requested
|
||||
by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
|
||||
again to search the remainder of the subject string. The difference between
|
||||
<b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
|
||||
<b>pcre[16|32]_exec()</b> to start searching at a new point within the entire
|
||||
string (which is in effect what Perl does), whereas the latter passes over a
|
||||
shortened substring. This makes a difference to the matching process if the
|
||||
pattern begins with a lookbehind assertion (including \b or \B).
|
||||
</P>
|
||||
<P>
|
||||
If any call to <b>pcre[16|32]_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches
|
||||
an empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
|
||||
PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
|
||||
same point. If this second match fails, the start offset is advanced, and the
|
||||
normal match is retried. This imitates the way Perl handles such cases when
|
||||
using the <b>/g</b> modifier or the <b>split()</b> function. Normally, the start
|
||||
offset is advanced by one character, but if the newline convention recognizes
|
||||
CRLF as a newline, and the current character is CR followed by LF, an advance
|
||||
of two is used.
|
||||
</P>
|
||||
<br><b>
|
||||
Other modifiers
|
||||
</b><br>
|
||||
<P>
|
||||
There are yet more modifiers for controlling the way <b>pcretest</b>
|
||||
operates.
|
||||
</P>
|
||||
<P>
|
||||
The <b>/+</b> modifier requests that as well as outputting the substring that
|
||||
matched the entire pattern, <b>pcretest</b> should in addition output the
|
||||
remainder of the subject string. This is useful for tests where the subject
|
||||
contains multiple copies of the same substring. If the <b>+</b> modifier appears
|
||||
twice, the same action is taken for captured substrings. In each case the
|
||||
remainder is output on the following line with a plus character following the
|
||||
capture number. Note that this modifier must not immediately follow the /S
|
||||
modifier because /S+ and /S++ have other meanings.
|
||||
</P>
|
||||
<P>
|
||||
The <b>/=</b> modifier requests that the values of all potential captured
|
||||
parentheses be output after a match. By default, only those up to the highest
|
||||
one actually used in the match are output (corresponding to the return code
|
||||
from <b>pcre[16|32]_exec()</b>). Values in the offsets vector corresponding to
|
||||
higher numbers should be set to -1, and these are output as "<unset>". This
|
||||
modifier gives a way of checking that this is happening.
|
||||
</P>
|
||||
<P>
|
||||
The <b>/B</b> modifier is a debugging feature. It requests that <b>pcretest</b>
|
||||
output a representation of the compiled code after compilation. Normally this
|
||||
information contains length and offset values; however, if <b>/Z</b> is also
|
||||
present, this data is replaced by spaces. This is a special feature for use in
|
||||
the automatic test scripts; it ensures that the same output is generated for
|
||||
different internal link sizes.
|
||||
</P>
|
||||
<P>
|
||||
The <b>/D</b> modifier is a PCRE debugging feature, and is equivalent to
|
||||
<b>/BI</b>, that is, both the <b>/B</b> and the <b>/I</b> modifiers.
|
||||
</P>
|
||||
<P>
|
||||
The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the
|
||||
2-byte and 4-byte fields in the compiled pattern. This facility is for testing
|
||||
the feature in PCRE that allows it to execute patterns that were compiled on a
|
||||
host with a different endianness. This feature is not available when the POSIX
|
||||
interface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
|
||||
specified. See also the section about saving and reloading compiled patterns
|
||||
below.
|
||||
</P>
|
||||
<P>
|
||||
The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
|
||||
compiled pattern (whether it is anchored, has a fixed first character, and
|
||||
so on). It does this by calling <b>pcre[16|32]_fullinfo()</b> after compiling a
|
||||
pattern. If the pattern is studied, the results of that are also output. In
|
||||
this output, the word "char" means a non-UTF character, that is, the value of a
|
||||
single data item (8-bit, 16-bit, or 32-bit, depending on the library that is
|
||||
being tested).
|
||||
</P>
|
||||
<P>
|
||||
The <b>/K</b> modifier requests <b>pcretest</b> to show names from backtracking
|
||||
control verbs that are returned from calls to <b>pcre[16|32]_exec()</b>. It causes
|
||||
<b>pcretest</b> to create a <b>pcre[16|32]_extra</b> block if one has not already
|
||||
been created by a call to <b>pcre[16|32]_study()</b>, and to set the
|
||||
PCRE_EXTRA_MARK flag and the <b>mark</b> field within it, every time that
|
||||
<b>pcre[16|32]_exec()</b> is called. If the variable that the <b>mark</b> field
|
||||
points to is non-NULL for a match, non-match, or partial match, <b>pcretest</b>
|
||||
prints the string to which it points. For a match, this is shown on a line by
|
||||
itself, tagged with "MK:". For a non-match it is added to the message.
|
||||
</P>
|
||||
<P>
|
||||
The <b>/L</b> modifier must be followed directly by the name of a locale, for
|
||||
example,
|
||||
<pre>
|
||||
/pattern/Lfr_FR
|
||||
</pre>
|
||||
For this reason, it must be the last modifier. The given locale is set,
|
||||
<b>pcre[16|32]_maketables()</b> is called to build a set of character tables for
|
||||
the locale, and this is then passed to <b>pcre[16|32]_compile()</b> when compiling
|
||||
the regular expression. Without an <b>/L</b> (or <b>/T</b>) modifier, NULL is
|
||||
passed as the tables pointer; that is, <b>/L</b> applies only to the expression
|
||||
on which it appears.
|
||||
</P>
|
||||
<P>
|
||||
The <b>/M</b> modifier causes the size in bytes of the memory block used to hold
|
||||
the compiled pattern to be output. This does not include the size of the
|
||||
<b>pcre[16|32]</b> block; it is just the actual compiled data. If the pattern is
|
||||
successfully studied with the PCRE_STUDY_JIT_COMPILE option, the size of the
|
||||
JIT compiled code is also output.
|
||||
</P>
|
||||
<P>
|
||||
The <b>/Q</b> modifier is used to test the use of <b>pcre_stack_guard</b>. It
|
||||
must be followed by '0' or '1', specifying the return code to be given from an
|
||||
external function that is passed to PCRE and used for stack checking during
|
||||
compilation (see the
|
||||
<a href="pcreapi.html"><b>pcreapi</b></a>
|
||||
documentation for details).
|
||||
</P>
|
||||
<P>
|
||||
The <b>/S</b> modifier causes <b>pcre[16|32]_study()</b> to be called after the
|
||||
expression has been compiled, and the results used when the expression is
|
||||
matched. There are a number of qualifying characters that may follow <b>/S</b>.
|
||||
They may appear in any order.
|
||||
</P>
|
||||
<P>
|
||||
If <b>/S</b> is followed by an exclamation mark, <b>pcre[16|32]_study()</b> is
|
||||
called with the PCRE_STUDY_EXTRA_NEEDED option, causing it always to return a
|
||||
<b>pcre_extra</b> block, even when studying discovers no useful information.
|
||||
</P>
|
||||
<P>
|
||||
If <b>/S</b> is followed by a second S character, it suppresses studying, even
|
||||
if it was requested externally by the <b>-s</b> command line option. This makes
|
||||
it possible to specify that certain patterns are always studied, and others are
|
||||
never studied, independently of <b>-s</b>. This feature is used in the test
|
||||
files in a few cases where the output is different when the pattern is studied.
|
||||
</P>
|
||||
<P>
|
||||
If the <b>/S</b> modifier is followed by a + character, the call to
|
||||
<b>pcre[16|32]_study()</b> is made with all the JIT study options, requesting
|
||||
just-in-time optimization support if it is available, for both normal and
|
||||
partial matching. If you want to restrict the JIT compiling modes, you can
|
||||
follow <b>/S+</b> with a digit in the range 1 to 7:
|
||||
<pre>
|
||||
1 normal match only
|
||||
2 soft partial match only
|
||||
3 normal match and soft partial match
|
||||
4 hard partial match only
|
||||
6 soft and hard partial match
|
||||
7 all three modes (default)
|
||||
</pre>
|
||||
If <b>/S++</b> is used instead of <b>/S+</b> (with or without a following digit),
|
||||
the text "(JIT)" is added to the first output line after a match or no match
|
||||
when JIT-compiled code was actually used.
|
||||
</P>
|
||||
<P>
|
||||
Note that there is also an independent <b>/+</b> modifier; it must not be given
|
||||
immediately after <b>/S</b> or <b>/S+</b> because this will be misinterpreted.
|
||||
</P>
|
||||
<P>
|
||||
If JIT studying is successful, the compiled JIT code will automatically be used
|
||||
when <b>pcre[16|32]_exec()</b> is run, except when incompatible run-time options
|
||||
are specified. For more details, see the
|
||||
<a href="pcrejit.html"><b>pcrejit</b></a>
|
||||
documentation. See also the <b>\J</b> escape sequence below for a way of
|
||||
setting the size of the JIT stack.
|
||||
</P>
|
||||
<P>
|
||||
Finally, if <b>/S</b> is followed by a minus character, JIT compilation is
|
||||
suppressed, even if it was requested externally by the <b>-s</b> command line
|
||||
option. This makes it possible to specify that JIT is never to be used for
|
||||
certain patterns.
|
||||
</P>
|
||||
<P>
|
||||
The <b>/T</b> modifier must be followed by a single digit. It causes a specific
|
||||
set of built-in character tables to be passed to <b>pcre[16|32]_compile()</b>. It
|
||||
is used in the standard PCRE tests to check behaviour with different character
|
||||
tables. The digit specifies the tables as follows:
|
||||
<pre>
|
||||
0 the default ASCII tables, as distributed in
|
||||
pcre_chartables.c.dist
|
||||
1 a set of tables defining ISO 8859 characters
|
||||
</pre>
|
||||
In table 1, some characters whose codes are greater than 128 are identified as
|
||||
letters, digits, spaces, etc.
|
||||
</P>
|
||||
<br><b>
|
||||
Using the POSIX wrapper API
|
||||
</b><br>
|
||||
<P>
|
||||
The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
|
||||
API rather than its native API. This supports only the 8-bit library. When
|
||||
<b>/P</b> is set, the following modifiers set options for the <b>regcomp()</b>
|
||||
function:
|
||||
<pre>
|
||||
/i REG_ICASE
|
||||
/m REG_NEWLINE
|
||||
/N REG_NOSUB
|
||||
/s REG_DOTALL )
|
||||
/U REG_UNGREEDY ) These options are not part of
|
||||
/W REG_UCP ) the POSIX standard
|
||||
/8 REG_UTF8 )
|
||||
</pre>
|
||||
The <b>/+</b> modifier works as described above. All other modifiers are
|
||||
ignored.
|
||||
</P>
|
||||
<br><b>
|
||||
Locking out certain modifiers
|
||||
</b><br>
|
||||
<P>
|
||||
PCRE can be compiled with or without support for certain features such as
|
||||
UTF-8/16/32 or Unicode properties. Accordingly, the standard tests are split up
|
||||
into a number of different files that are selected for running depending on
|
||||
which features are available. When updating the tests, it is all too easy to
|
||||
put a new test into the wrong file by mistake; for example, to put a test that
|
||||
requires UTF support into a file that is used when it is not available. To help
|
||||
detect such mistakes as early as possible, there is a facility for locking out
|
||||
specific modifiers. If an input line for <b>pcretest</b> starts with the string
|
||||
"< forbid " the following sequence of characters is taken as a list of
|
||||
forbidden modifiers. For example, in the test files that must not use UTF or
|
||||
Unicode property support, this line appears:
|
||||
<pre>
|
||||
< forbid 8W
|
||||
</pre>
|
||||
This locks out the /8 and /W modifiers. An immediate error is given if they are
|
||||
subsequently encountered. If the character string contains < but not >, all the
|
||||
multi-character modifiers that begin with < are locked out. Otherwise, such
|
||||
modifiers must be explicitly listed, for example:
|
||||
<pre>
|
||||
< forbid <JS><cr>
|
||||
</pre>
|
||||
There must be a single space between < and "forbid" for this feature to be
|
||||
recognised. If there is not, the line is interpreted either as a request to
|
||||
re-load a pre-compiled pattern (see "SAVING AND RELOADING COMPILED PATTERNS"
|
||||
below) or, if there is a another < character, as a pattern that uses < as its
|
||||
delimiter.
|
||||
</P>
|
||||
<br><a name="SEC7" href="#TOC1">DATA LINES</a><br>
|
||||
<P>
|
||||
Before each data line is passed to <b>pcre[16|32]_exec()</b>, leading and trailing
|
||||
white space is removed, and it is then scanned for \ escapes. Some of these
|
||||
are pretty esoteric features, intended for checking out some of the more
|
||||
complicated features of PCRE. If you are just testing "ordinary" regular
|
||||
expressions, you probably don't need any of these. The following escapes are
|
||||
recognized:
|
||||
<pre>
|
||||
\a alarm (BEL, \x07)
|
||||
\b backspace (\x08)
|
||||
\e escape (\x27)
|
||||
\f form feed (\x0c)
|
||||
\n newline (\x0a)
|
||||
\qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
|
||||
\r carriage return (\x0d)
|
||||
\t tab (\x09)
|
||||
\v vertical tab (\x0b)
|
||||
\nnn octal character (up to 3 octal digits); always
|
||||
a byte unless > 255 in UTF-8 or 16-bit or 32-bit mode
|
||||
\o{dd...} octal character (any number of octal digits}
|
||||
\xhh hexadecimal byte (up to 2 hex digits)
|
||||
\x{hh...} hexadecimal character (any number of hex digits)
|
||||
\A pass the PCRE_ANCHORED option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
|
||||
\B pass the PCRE_NOTBOL option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
|
||||
\Cdd call pcre[16|32]_copy_substring() for substring dd after a successful match (number less than 32)
|
||||
\Cname call pcre[16|32]_copy_named_substring() for substring "name" after a successful match (name termin-
|
||||
ated by next non alphanumeric character)
|
||||
\C+ show the current captured substrings at callout time
|
||||
\C- do not supply a callout function
|
||||
\C!n return 1 instead of 0 when callout number n is reached
|
||||
\C!n!m return 1 instead of 0 when callout number n is reached for the nth time
|
||||
\C*n pass the number n (may be negative) as callout data; this is used as the callout return value
|
||||
\D use the <b>pcre[16|32]_dfa_exec()</b> match function
|
||||
\F only shortest match for <b>pcre[16|32]_dfa_exec()</b>
|
||||
\Gdd call pcre[16|32]_get_substring() for substring dd after a successful match (number less than 32)
|
||||
\Gname call pcre[16|32]_get_named_substring() for substring "name" after a successful match (name termin-
|
||||
ated by next non-alphanumeric character)
|
||||
\Jdd set up a JIT stack of dd kilobytes maximum (any number of digits)
|
||||
\L call pcre[16|32]_get_substringlist() after a successful match
|
||||
\M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
|
||||
\N pass the PCRE_NOTEMPTY option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>; if used twice, pass the
|
||||
PCRE_NOTEMPTY_ATSTART option
|
||||
\Odd set the size of the output vector passed to <b>pcre[16|32]_exec()</b> to dd (any number of digits)
|
||||
\P pass the PCRE_PARTIAL_SOFT option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>; if used twice, pass the
|
||||
PCRE_PARTIAL_HARD option
|
||||
\Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
|
||||
\R pass the PCRE_DFA_RESTART option to <b>pcre[16|32]_dfa_exec()</b>
|
||||
\S output details of memory get/free calls during matching
|
||||
\Y pass the PCRE_NO_START_OPTIMIZE option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
|
||||
\Z pass the PCRE_NOTEOL option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
|
||||
\? pass the PCRE_NO_UTF[8|16|32]_CHECK option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
|
||||
\>dd start the match at offset dd (optional "-"; then any number of digits); this sets the <i>startoffset</i>
|
||||
argument for <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
|
||||
\<cr> pass the PCRE_NEWLINE_CR option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
|
||||
\<lf> pass the PCRE_NEWLINE_LF option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
|
||||
\<crlf> pass the PCRE_NEWLINE_CRLF option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
|
||||
\<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
|
||||
\<any> pass the PCRE_NEWLINE_ANY option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b>
|
||||
</pre>
|
||||
The use of \x{hh...} is not dependent on the use of the <b>/8</b> modifier on
|
||||
the pattern. It is recognized always. There may be any number of hexadecimal
|
||||
digits inside the braces; invalid values provoke error messages.
|
||||
</P>
|
||||
<P>
|
||||
Note that \xhh specifies one byte rather than one character in UTF-8 mode;
|
||||
this makes it possible to construct invalid UTF-8 sequences for testing
|
||||
purposes. On the other hand, \x{hh} is interpreted as a UTF-8 character in
|
||||
UTF-8 mode, generating more than one byte if the value is greater than 127.
|
||||
When testing the 8-bit library not in UTF-8 mode, \x{hh} generates one byte
|
||||
for values less than 256, and causes an error for greater values.
|
||||
</P>
|
||||
<P>
|
||||
In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it
|
||||
possible to construct invalid UTF-16 sequences for testing purposes.
|
||||
</P>
|
||||
<P>
|
||||
In UTF-32 mode, all 4- to 8-digit \x{...} values are accepted. This makes it
|
||||
possible to construct invalid UTF-32 sequences for testing purposes.
|
||||
</P>
|
||||
<P>
|
||||
The escapes that specify line ending sequences are literal strings, exactly as
|
||||
shown. No more than one newline setting should be present in any data line.
|
||||
</P>
|
||||
<P>
|
||||
A backslash followed by anything else just escapes the anything else. If
|
||||
the very last character is a backslash, it is ignored. This gives a way of
|
||||
passing an empty line as data, since a real empty line terminates the data
|
||||
input.
|
||||
</P>
|
||||
<P>
|
||||
The <b>\J</b> escape provides a way of setting the maximum stack size that is
|
||||
used by the just-in-time optimization code. It is ignored if JIT optimization
|
||||
is not being used. Providing a stack that is larger than the default 32K is
|
||||
necessary only for very complicated patterns.
|
||||
</P>
|
||||
<P>
|
||||
If \M is present, <b>pcretest</b> calls <b>pcre[16|32]_exec()</b> several times,
|
||||
with different values in the <i>match_limit</i> and <i>match_limit_recursion</i>
|
||||
fields of the <b>pcre[16|32]_extra</b> data structure, until it finds the minimum
|
||||
numbers for each parameter that allow <b>pcre[16|32]_exec()</b> to complete without
|
||||
error. Because this is testing a specific feature of the normal interpretive
|
||||
<b>pcre[16|32]_exec()</b> execution, the use of any JIT optimization that might
|
||||
have been set up by the <b>/S+</b> qualifier of <b>-s+</b> option is disabled.
|
||||
</P>
|
||||
<P>
|
||||
The <i>match_limit</i> number is a measure of the amount of backtracking
|
||||
that takes place, and checking it out can be instructive. For most simple
|
||||
matches, the number is quite small, but for patterns with very large numbers of
|
||||
matching possibilities, it can become large very quickly with increasing length
|
||||
of subject string. The <i>match_limit_recursion</i> number is a measure of how
|
||||
much stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is
|
||||
needed to complete the match attempt.
|
||||
</P>
|
||||
<P>
|
||||
When \O is used, the value specified may be higher or lower than the size set
|
||||
by the <b>-O</b> command line option (or defaulted to 45); \O applies only to
|
||||
the call of <b>pcre[16|32]_exec()</b> for the line in which it appears.
|
||||
</P>
|
||||
<P>
|
||||
If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper
|
||||
API to be used, the only option-setting sequences that have any effect are \B,
|
||||
\N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively,
|
||||
to be passed to <b>regexec()</b>.
|
||||
</P>
|
||||
<br><a name="SEC8" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br>
|
||||
<P>
|
||||
By default, <b>pcretest</b> uses the standard PCRE matching function,
|
||||
<b>pcre[16|32]_exec()</b> to match each data line. PCRE also supports an
|
||||
alternative matching function, <b>pcre[16|32]_dfa_test()</b>, which operates in a
|
||||
different way, and has some restrictions. The differences between the two
|
||||
functions are described in the
|
||||
<a href="pcrematching.html"><b>pcrematching</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
If a data line contains the \D escape sequence, or if the command line
|
||||
contains the <b>-dfa</b> option, the alternative matching function is used.
|
||||
This function finds all possible matches at a given point. If, however, the \F
|
||||
escape sequence is present in the data line, it stops after the first match is
|
||||
found. This is always the shortest possible match.
|
||||
</P>
|
||||
<br><a name="SEC9" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br>
|
||||
<P>
|
||||
This section describes the output when the normal matching function,
|
||||
<b>pcre[16|32]_exec()</b>, is being used.
|
||||
</P>
|
||||
<P>
|
||||
When a match succeeds, <b>pcretest</b> outputs the list of captured substrings
|
||||
that <b>pcre[16|32]_exec()</b> returns, starting with number 0 for the string that
|
||||
matched the whole pattern. Otherwise, it outputs "No match" when the return is
|
||||
PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
|
||||
substring when <b>pcre[16|32]_exec()</b> returns PCRE_ERROR_PARTIAL. (Note that
|
||||
this is the entire substring that was inspected during the partial match; it
|
||||
may include characters before the actual match start if a lookbehind assertion,
|
||||
\K, \b, or \B was involved.) For any other return, <b>pcretest</b> outputs
|
||||
the PCRE negative error number and a short descriptive phrase. If the error is
|
||||
a failed UTF string check, the offset of the start of the failing character and
|
||||
the reason code are also output, provided that the size of the output vector is
|
||||
at least two. Here is an example of an interactive <b>pcretest</b> run.
|
||||
<pre>
|
||||
$ pcretest
|
||||
PCRE version 8.13 2011-04-30
|
||||
|
||||
re> /^abc(\d+)/
|
||||
data> abc123
|
||||
0: abc123
|
||||
1: 123
|
||||
data> xyz
|
||||
No match
|
||||
</pre>
|
||||
Unset capturing substrings that are not followed by one that is set are not
|
||||
returned by <b>pcre[16|32]_exec()</b>, and are not shown by <b>pcretest</b>. In the
|
||||
following example, there are two capturing substrings, but when the first data
|
||||
line is matched, the second, unset substring is not shown. An "internal" unset
|
||||
substring is shown as "<unset>", as for the second data line.
|
||||
<pre>
|
||||
re> /(a)|(b)/
|
||||
data> a
|
||||
0: a
|
||||
1: a
|
||||
data> b
|
||||
0: b
|
||||
1: <unset>
|
||||
2: b
|
||||
</pre>
|
||||
If the strings contain any non-printing characters, they are output as \xhh
|
||||
escapes if the value is less than 256 and UTF mode is not set. Otherwise they
|
||||
are output as \x{hh...} escapes. See below for the definition of non-printing
|
||||
characters. If the pattern has the <b>/+</b> modifier, the output for substring
|
||||
0 is followed by the the rest of the subject string, identified by "0+" like
|
||||
this:
|
||||
<pre>
|
||||
re> /cat/+
|
||||
data> cataract
|
||||
0: cat
|
||||
0+ aract
|
||||
</pre>
|
||||
If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
|
||||
matching attempts are output in sequence, like this:
|
||||
<pre>
|
||||
re> /\Bi(\w\w)/g
|
||||
data> Mississippi
|
||||
0: iss
|
||||
1: ss
|
||||
0: iss
|
||||
1: ss
|
||||
0: ipp
|
||||
1: pp
|
||||
</pre>
|
||||
"No match" is output only if the first match attempt fails. Here is an example
|
||||
of a failure message (the offset 4 that is specified by \>4 is past the end of
|
||||
the subject string):
|
||||
<pre>
|
||||
re> /xyz/
|
||||
data> xyz\>4
|
||||
Error -24 (bad offset value)
|
||||
</PRE>
|
||||
</P>
|
||||
<P>
|
||||
If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> are present in a
|
||||
data line that is successfully matched, the substrings extracted by the
|
||||
convenience functions are output with C, G, or L after the string number
|
||||
instead of a colon. This is in addition to the normal full list. The string
|
||||
length (that is, the return from the extraction function) is given in
|
||||
parentheses after each string for <b>\C</b> and <b>\G</b>.
|
||||
</P>
|
||||
<P>
|
||||
Note that whereas patterns can be continued over several lines (a plain ">"
|
||||
prompt is used for continuations), data lines may not. However newlines can be
|
||||
included in data by means of the \n escape (or \r, \r\n, etc., depending on
|
||||
the newline sequence setting).
|
||||
</P>
|
||||
<br><a name="SEC10" href="#TOC1">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a><br>
|
||||
<P>
|
||||
When the alternative matching function, <b>pcre[16|32]_dfa_exec()</b>, is used (by
|
||||
means of the \D escape sequence or the <b>-dfa</b> command line option), the
|
||||
output consists of a list of all the matches that start at the first point in
|
||||
the subject where there is at least one match. For example:
|
||||
<pre>
|
||||
re> /(tang|tangerine|tan)/
|
||||
data> yellow tangerine\D
|
||||
0: tangerine
|
||||
1: tang
|
||||
2: tan
|
||||
</pre>
|
||||
(Using the normal matching function on this data finds only "tang".) The
|
||||
longest matching string is always given first (and numbered zero). After a
|
||||
PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
|
||||
partially matching substring. (Note that this is the entire substring that was
|
||||
inspected during the partial match; it may include characters before the actual
|
||||
match start if a lookbehind assertion, \K, \b, or \B was involved.)
|
||||
</P>
|
||||
<P>
|
||||
If <b>/g</b> is present on the pattern, the search for further matches resumes
|
||||
at the end of the longest match. For example:
|
||||
<pre>
|
||||
re> /(tang|tangerine|tan)/g
|
||||
data> yellow tangerine and tangy sultana\D
|
||||
0: tangerine
|
||||
1: tang
|
||||
2: tan
|
||||
0: tang
|
||||
1: tan
|
||||
0: tan
|
||||
</pre>
|
||||
Since the matching function does not support substring capture, the escape
|
||||
sequences that are concerned with captured substrings are not relevant.
|
||||
</P>
|
||||
<br><a name="SEC11" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br>
|
||||
<P>
|
||||
When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
|
||||
indicating that the subject partially matched the pattern, you can restart the
|
||||
match with additional subject data by means of the \R escape sequence. For
|
||||
example:
|
||||
<pre>
|
||||
re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
|
||||
data> 23ja\P\D
|
||||
Partial match: 23ja
|
||||
data> n05\R\D
|
||||
0: n05
|
||||
</pre>
|
||||
For further information about partial matching, see the
|
||||
<a href="pcrepartial.html"><b>pcrepartial</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<br><a name="SEC12" href="#TOC1">CALLOUTS</a><br>
|
||||
<P>
|
||||
If the pattern contains any callout requests, <b>pcretest</b>'s callout function
|
||||
is called during matching. This works with both matching functions. By default,
|
||||
the called function displays the callout number, the start and current
|
||||
positions in the text at the callout time, and the next pattern item to be
|
||||
tested. For example:
|
||||
<pre>
|
||||
--->pqrabcdef
|
||||
0 ^ ^ \d
|
||||
</pre>
|
||||
This output indicates that callout number 0 occurred for a match attempt
|
||||
starting at the fourth character of the subject string, when the pointer was at
|
||||
the seventh character of the data, and when the next pattern item was \d. Just
|
||||
one circumflex is output if the start and current positions are the same.
|
||||
</P>
|
||||
<P>
|
||||
Callouts numbered 255 are assumed to be automatic callouts, inserted as a
|
||||
result of the <b>/C</b> pattern modifier. In this case, instead of showing the
|
||||
callout number, the offset in the pattern, preceded by a plus, is output. For
|
||||
example:
|
||||
<pre>
|
||||
re> /\d?[A-E]\*/C
|
||||
data> E*
|
||||
--->E*
|
||||
+0 ^ \d?
|
||||
+3 ^ [A-E]
|
||||
+8 ^^ \*
|
||||
+10 ^ ^
|
||||
0: E*
|
||||
</pre>
|
||||
If a pattern contains (*MARK) items, an additional line is output whenever
|
||||
a change of latest mark is passed to the callout function. For example:
|
||||
<pre>
|
||||
re> /a(*MARK:X)bc/C
|
||||
data> abc
|
||||
--->abc
|
||||
+0 ^ a
|
||||
+1 ^^ (*MARK:X)
|
||||
+10 ^^ b
|
||||
Latest Mark: X
|
||||
+11 ^ ^ c
|
||||
+12 ^ ^
|
||||
0: abc
|
||||
</pre>
|
||||
The mark changes between matching "a" and "b", but stays the same for the rest
|
||||
of the match, so nothing more is output. If, as a result of backtracking, the
|
||||
mark reverts to being unset, the text "<unset>" is output.
|
||||
</P>
|
||||
<P>
|
||||
The callout function in <b>pcretest</b> returns zero (carry on matching) by
|
||||
default, but you can use a \C item in a data line (as described above) to
|
||||
change this and other parameters of the callout.
|
||||
</P>
|
||||
<P>
|
||||
Inserting callouts can be helpful when using <b>pcretest</b> to check
|
||||
complicated regular expressions. For further information about callouts, see
|
||||
the
|
||||
<a href="pcrecallout.html"><b>pcrecallout</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<br><a name="SEC13" href="#TOC1">NON-PRINTING CHARACTERS</a><br>
|
||||
<P>
|
||||
When <b>pcretest</b> is outputting text in the compiled version of a pattern,
|
||||
bytes other than 32-126 are always treated as non-printing characters are are
|
||||
therefore shown as hex escapes.
|
||||
</P>
|
||||
<P>
|
||||
When <b>pcretest</b> is outputting text that is a matched part of a subject
|
||||
string, it behaves in the same way, unless a different locale has been set for
|
||||
the pattern (using the <b>/L</b> modifier). In this case, the <b>isprint()</b>
|
||||
function to distinguish printing and non-printing characters.
|
||||
</P>
|
||||
<br><a name="SEC14" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br>
|
||||
<P>
|
||||
The facilities described in this section are not available when the POSIX
|
||||
interface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
|
||||
specified.
|
||||
</P>
|
||||
<P>
|
||||
When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a
|
||||
compiled pattern to a file, by following the modifiers with > and a file name.
|
||||
For example:
|
||||
<pre>
|
||||
/pattern/im >/some/file
|
||||
</pre>
|
||||
See the
|
||||
<a href="pcreprecompile.html"><b>pcreprecompile</b></a>
|
||||
documentation for a discussion about saving and re-using compiled patterns.
|
||||
Note that if the pattern was successfully studied with JIT optimization, the
|
||||
JIT data cannot be saved.
|
||||
</P>
|
||||
<P>
|
||||
The data that is written is binary. The first eight bytes are the length of the
|
||||
compiled pattern data followed by the length of the optional study data, each
|
||||
written as four bytes in big-endian order (most significant byte first). If
|
||||
there is no study data (either the pattern was not studied, or studying did not
|
||||
return any data), the second length is zero. The lengths are followed by an
|
||||
exact copy of the compiled pattern. If there is additional study data, this
|
||||
(excluding any JIT data) follows immediately after the compiled pattern. After
|
||||
writing the file, <b>pcretest</b> expects to read a new pattern.
|
||||
</P>
|
||||
<P>
|
||||
A saved pattern can be reloaded into <b>pcretest</b> by specifying < and a file
|
||||
name instead of a pattern. There must be no space between < and the file name,
|
||||
which must not contain a < character, as otherwise <b>pcretest</b> will
|
||||
interpret the line as a pattern delimited by < characters. For example:
|
||||
<pre>
|
||||
re> </some/file
|
||||
Compiled pattern loaded from /some/file
|
||||
No study data
|
||||
</pre>
|
||||
If the pattern was previously studied with the JIT optimization, the JIT
|
||||
information cannot be saved and restored, and so is lost. When the pattern has
|
||||
been loaded, <b>pcretest</b> proceeds to read data lines in the usual way.
|
||||
</P>
|
||||
<P>
|
||||
You can copy a file written by <b>pcretest</b> to a different host and reload it
|
||||
there, even if the new host has opposite endianness to the one on which the
|
||||
pattern was compiled. For example, you can compile on an i86 machine and run on
|
||||
a SPARC machine. When a pattern is reloaded on a host with different
|
||||
endianness, the confirmation message is changed to:
|
||||
<pre>
|
||||
Compiled pattern (byte-inverted) loaded from /some/file
|
||||
</pre>
|
||||
The test suite contains some saved pre-compiled patterns with different
|
||||
endianness. These are reloaded using "<!" instead of just "<". This suppresses
|
||||
the "(byte-inverted)" text so that the output is the same on all hosts. It also
|
||||
forces debugging output once the pattern has been reloaded.
|
||||
</P>
|
||||
<P>
|
||||
File names for saving and reloading can be absolute or relative, but note that
|
||||
the shell facility of expanding a file name that starts with a tilde (~) is not
|
||||
available.
|
||||
</P>
|
||||
<P>
|
||||
The ability to save and reload files in <b>pcretest</b> is intended for testing
|
||||
and experimentation. It is not intended for production use because only a
|
||||
single pattern can be written to a file. Furthermore, there is no facility for
|
||||
supplying custom character tables for use with a reloaded pattern. If the
|
||||
original pattern was compiled with custom tables, an attempt to match a subject
|
||||
string using a reloaded pattern is likely to cause <b>pcretest</b> to crash.
|
||||
Finally, if you attempt to load a file that is not in the correct format, the
|
||||
result is undefined.
|
||||
</P>
|
||||
<br><a name="SEC15" href="#TOC1">SEE ALSO</a><br>
|
||||
<P>
|
||||
<b>pcre</b>(3), <b>pcre16</b>(3), <b>pcre32</b>(3), <b>pcreapi</b>(3),
|
||||
<b>pcrecallout</b>(3),
|
||||
<b>pcrejit</b>, <b>pcrematching</b>(3), <b>pcrepartial</b>(d),
|
||||
<b>pcrepattern</b>(3), <b>pcreprecompile</b>(3).
|
||||
</P>
|
||||
<br><a name="SEC16" href="#TOC1">AUTHOR</a><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><a name="SEC17" href="#TOC1">REVISION</a><br>
|
||||
<P>
|
||||
Last updated: 23 February 2017
|
||||
<br>
|
||||
Copyright © 1997-2017 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
@@ -0,0 +1,262 @@
|
||||
<html>
|
||||
<head>
|
||||
<title>pcreunicode specification</title>
|
||||
</head>
|
||||
<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
|
||||
<h1>pcreunicode man page</h1>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
<p>
|
||||
This page is part of the PCRE HTML documentation. It was generated automatically
|
||||
from the original man page. If there is any nonsense in it, please consult the
|
||||
man page, in case the conversion went wrong.
|
||||
<br>
|
||||
<br><b>
|
||||
UTF-8, UTF-16, UTF-32, AND UNICODE PROPERTY SUPPORT
|
||||
</b><br>
|
||||
<P>
|
||||
As well as UTF-8 support, PCRE also supports UTF-16 (from release 8.30) and
|
||||
UTF-32 (from release 8.32), by means of two additional libraries. They can be
|
||||
built as well as, or instead of, the 8-bit library.
|
||||
</P>
|
||||
<br><b>
|
||||
UTF-8 SUPPORT
|
||||
</b><br>
|
||||
<P>
|
||||
In order process UTF-8 strings, you must build PCRE's 8-bit library with UTF
|
||||
support, and, in addition, you must call
|
||||
<a href="pcre_compile.html"><b>pcre_compile()</b></a>
|
||||
with the PCRE_UTF8 option flag, or the pattern must start with the sequence
|
||||
(*UTF8) or (*UTF). When either of these is the case, both the pattern and any
|
||||
subject strings that are matched against it are treated as UTF-8 strings
|
||||
instead of strings of individual 1-byte characters.
|
||||
</P>
|
||||
<br><b>
|
||||
UTF-16 AND UTF-32 SUPPORT
|
||||
</b><br>
|
||||
<P>
|
||||
In order process UTF-16 or UTF-32 strings, you must build PCRE's 16-bit or
|
||||
32-bit library with UTF support, and, in addition, you must call
|
||||
<a href="pcre16_compile.html"><b>pcre16_compile()</b></a>
|
||||
or
|
||||
<a href="pcre32_compile.html"><b>pcre32_compile()</b></a>
|
||||
with the PCRE_UTF16 or PCRE_UTF32 option flag, as appropriate. Alternatively,
|
||||
the pattern must start with the sequence (*UTF16), (*UTF32), as appropriate, or
|
||||
(*UTF), which can be used with either library. When UTF mode is set, both the
|
||||
pattern and any subject strings that are matched against it are treated as
|
||||
UTF-16 or UTF-32 strings instead of strings of individual 16-bit or 32-bit
|
||||
characters.
|
||||
</P>
|
||||
<br><b>
|
||||
UTF SUPPORT OVERHEAD
|
||||
</b><br>
|
||||
<P>
|
||||
If you compile PCRE with UTF support, but do not use it at run time, the
|
||||
library will be a bit bigger, but the additional run time overhead is limited
|
||||
to testing the PCRE_UTF[8|16|32] flag occasionally, so should not be very big.
|
||||
</P>
|
||||
<br><b>
|
||||
UNICODE PROPERTY SUPPORT
|
||||
</b><br>
|
||||
<P>
|
||||
If PCRE is built with Unicode character property support (which implies UTF
|
||||
support), the escape sequences \p{..}, \P{..}, and \X can be used.
|
||||
The available properties that can be tested are limited to the general
|
||||
category properties such as Lu for an upper case letter or Nd for a decimal
|
||||
number, the Unicode script names such as Arabic or Han, and the derived
|
||||
properties Any and L&. Full lists is given in the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
and
|
||||
<a href="pcresyntax.html"><b>pcresyntax</b></a>
|
||||
documentation. Only the short names for properties are supported. For example,
|
||||
\p{L} matches a letter. Its Perl synonym, \p{Letter}, is not supported.
|
||||
Furthermore, in Perl, many properties may optionally be prefixed by "Is", for
|
||||
compatibility with Perl 5.6. PCRE does not support this.
|
||||
<a name="utf8strings"></a></P>
|
||||
<br><b>
|
||||
Validity of UTF-8 strings
|
||||
</b><br>
|
||||
<P>
|
||||
When you set the PCRE_UTF8 flag, the byte strings passed as patterns and
|
||||
subjects are (by default) checked for validity on entry to the relevant
|
||||
functions. The entire string is checked before any other processing takes
|
||||
place. From release 7.3 of PCRE, the check is according the rules of RFC 3629,
|
||||
which are themselves derived from the Unicode specification. Earlier releases
|
||||
of PCRE followed the rules of RFC 2279, which allows the full range of 31-bit
|
||||
values (0 to 0x7FFFFFFF). The current check allows only values in the range U+0
|
||||
to U+10FFFF, excluding the surrogate area. (From release 8.33 the so-called
|
||||
"non-character" code points are no longer excluded because Unicode corrigendum
|
||||
#9 makes it clear that they should not be.)
|
||||
</P>
|
||||
<P>
|
||||
Characters in the "Surrogate Area" of Unicode are reserved for use by UTF-16,
|
||||
where they are used in pairs to encode codepoints with values greater than
|
||||
0xFFFF. The code points that are encoded by UTF-16 pairs are available
|
||||
independently in the UTF-8 and UTF-32 encodings. (In other words, the whole
|
||||
surrogate thing is a fudge for UTF-16 which unfortunately messes up UTF-8 and
|
||||
UTF-32.)
|
||||
</P>
|
||||
<P>
|
||||
If an invalid UTF-8 string is passed to PCRE, an error return is given. At
|
||||
compile time, the only additional information is the offset to the first byte
|
||||
of the failing character. The run-time functions <b>pcre_exec()</b> and
|
||||
<b>pcre_dfa_exec()</b> also pass back this information, as well as a more
|
||||
detailed reason code if the caller has provided memory in which to do this.
|
||||
</P>
|
||||
<P>
|
||||
In some situations, you may already know that your strings are valid, and
|
||||
therefore want to skip these checks in order to improve performance, for
|
||||
example in the case of a long subject string that is being scanned repeatedly.
|
||||
If you set the PCRE_NO_UTF8_CHECK flag at compile time or at run time, PCRE
|
||||
assumes that the pattern or subject it is given (respectively) contains only
|
||||
valid UTF-8 codes. In this case, it does not diagnose an invalid UTF-8 string.
|
||||
</P>
|
||||
<P>
|
||||
Note that passing PCRE_NO_UTF8_CHECK to <b>pcre_compile()</b> just disables the
|
||||
check for the pattern; it does not also apply to subject strings. If you want
|
||||
to disable the check for a subject string you must pass this option to
|
||||
<b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>.
|
||||
</P>
|
||||
<P>
|
||||
If you pass an invalid UTF-8 string when PCRE_NO_UTF8_CHECK is set, the result
|
||||
is undefined and your program may crash.
|
||||
<a name="utf16strings"></a></P>
|
||||
<br><b>
|
||||
Validity of UTF-16 strings
|
||||
</b><br>
|
||||
<P>
|
||||
When you set the PCRE_UTF16 flag, the strings of 16-bit data units that are
|
||||
passed as patterns and subjects are (by default) checked for validity on entry
|
||||
to the relevant functions. Values other than those in the surrogate range
|
||||
U+D800 to U+DFFF are independent code points. Values in the surrogate range
|
||||
must be used in pairs in the correct manner.
|
||||
</P>
|
||||
<P>
|
||||
If an invalid UTF-16 string is passed to PCRE, an error return is given. At
|
||||
compile time, the only additional information is the offset to the first data
|
||||
unit of the failing character. The run-time functions <b>pcre16_exec()</b> and
|
||||
<b>pcre16_dfa_exec()</b> also pass back this information, as well as a more
|
||||
detailed reason code if the caller has provided memory in which to do this.
|
||||
</P>
|
||||
<P>
|
||||
In some situations, you may already know that your strings are valid, and
|
||||
therefore want to skip these checks in order to improve performance. If you set
|
||||
the PCRE_NO_UTF16_CHECK flag at compile time or at run time, PCRE assumes that
|
||||
the pattern or subject it is given (respectively) contains only valid UTF-16
|
||||
sequences. In this case, it does not diagnose an invalid UTF-16 string.
|
||||
However, if an invalid string is passed, the result is undefined.
|
||||
<a name="utf32strings"></a></P>
|
||||
<br><b>
|
||||
Validity of UTF-32 strings
|
||||
</b><br>
|
||||
<P>
|
||||
When you set the PCRE_UTF32 flag, the strings of 32-bit data units that are
|
||||
passed as patterns and subjects are (by default) checked for validity on entry
|
||||
to the relevant functions. This check allows only values in the range U+0
|
||||
to U+10FFFF, excluding the surrogate area U+D800 to U+DFFF.
|
||||
</P>
|
||||
<P>
|
||||
If an invalid UTF-32 string is passed to PCRE, an error return is given. At
|
||||
compile time, the only additional information is the offset to the first data
|
||||
unit of the failing character. The run-time functions <b>pcre32_exec()</b> and
|
||||
<b>pcre32_dfa_exec()</b> also pass back this information, as well as a more
|
||||
detailed reason code if the caller has provided memory in which to do this.
|
||||
</P>
|
||||
<P>
|
||||
In some situations, you may already know that your strings are valid, and
|
||||
therefore want to skip these checks in order to improve performance. If you set
|
||||
the PCRE_NO_UTF32_CHECK flag at compile time or at run time, PCRE assumes that
|
||||
the pattern or subject it is given (respectively) contains only valid UTF-32
|
||||
sequences. In this case, it does not diagnose an invalid UTF-32 string.
|
||||
However, if an invalid string is passed, the result is undefined.
|
||||
</P>
|
||||
<br><b>
|
||||
General comments about UTF modes
|
||||
</b><br>
|
||||
<P>
|
||||
1. Codepoints less than 256 can be specified in patterns by either braced or
|
||||
unbraced hexadecimal escape sequences (for example, \x{b3} or \xb3). Larger
|
||||
values have to use braced sequences.
|
||||
</P>
|
||||
<P>
|
||||
2. Octal numbers up to \777 are recognized, and in UTF-8 mode they match
|
||||
two-byte characters for values greater than \177.
|
||||
</P>
|
||||
<P>
|
||||
3. Repeat quantifiers apply to complete UTF characters, not to individual
|
||||
data units, for example: \x{100}{3}.
|
||||
</P>
|
||||
<P>
|
||||
4. The dot metacharacter matches one UTF character instead of a single data
|
||||
unit.
|
||||
</P>
|
||||
<P>
|
||||
5. The escape sequence \C can be used to match a single byte in UTF-8 mode, or
|
||||
a single 16-bit data unit in UTF-16 mode, or a single 32-bit data unit in
|
||||
UTF-32 mode, but its use can lead to some strange effects because it breaks up
|
||||
multi-unit characters (see the description of \C in the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
documentation). The use of \C is not supported in the alternative matching
|
||||
function <b>pcre[16|32]_dfa_exec()</b>, nor is it supported in UTF mode by the
|
||||
JIT optimization of <b>pcre[16|32]_exec()</b>. If JIT optimization is requested
|
||||
for a UTF pattern that contains \C, it will not succeed, and so the matching
|
||||
will be carried out by the normal interpretive function.
|
||||
</P>
|
||||
<P>
|
||||
6. The character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly
|
||||
test characters of any code value, but, by default, the characters that PCRE
|
||||
recognizes as digits, spaces, or word characters remain the same set as in
|
||||
non-UTF mode, all with values less than 256. This remains true even when PCRE
|
||||
is built to include Unicode property support, because to do otherwise would
|
||||
slow down PCRE in many common cases. Note in particular that this applies to
|
||||
\b and \B, because they are defined in terms of \w and \W. If you really
|
||||
want to test for a wider sense of, say, "digit", you can use explicit Unicode
|
||||
property tests such as \p{Nd}. Alternatively, if you set the PCRE_UCP option,
|
||||
the way that the character escapes work is changed so that Unicode properties
|
||||
are used to determine which characters match. There are more details in the
|
||||
section on
|
||||
<a href="pcrepattern.html#genericchartypes">generic character types</a>
|
||||
in the
|
||||
<a href="pcrepattern.html"><b>pcrepattern</b></a>
|
||||
documentation.
|
||||
</P>
|
||||
<P>
|
||||
7. Similarly, characters that match the POSIX named character classes are all
|
||||
low-valued characters, unless the PCRE_UCP option is set.
|
||||
</P>
|
||||
<P>
|
||||
8. However, the horizontal and vertical white space matching escapes (\h, \H,
|
||||
\v, and \V) do match all the appropriate Unicode characters, whether or not
|
||||
PCRE_UCP is set.
|
||||
</P>
|
||||
<P>
|
||||
9. Case-insensitive matching applies only to characters whose values are less
|
||||
than 128, unless PCRE is built with Unicode property support. A few Unicode
|
||||
characters such as Greek sigma have more than two codepoints that are
|
||||
case-equivalent. Up to and including PCRE release 8.31, only one-to-one case
|
||||
mappings were supported, but later releases (with Unicode property support) do
|
||||
treat as case-equivalent all versions of characters such as Greek sigma.
|
||||
</P>
|
||||
<br><b>
|
||||
AUTHOR
|
||||
</b><br>
|
||||
<P>
|
||||
Philip Hazel
|
||||
<br>
|
||||
University Computing Service
|
||||
<br>
|
||||
Cambridge CB2 3QH, England.
|
||||
<br>
|
||||
</P>
|
||||
<br><b>
|
||||
REVISION
|
||||
</b><br>
|
||||
<P>
|
||||
Last updated: 27 February 2013
|
||||
<br>
|
||||
Copyright © 1997-2013 University of Cambridge.
|
||||
<br>
|
||||
<p>
|
||||
Return to the <a href="index.html">PCRE index page</a>.
|
||||
</p>
|
||||
Reference in New Issue
Block a user