diff options
| author | ph10 <ph10@2f5784b3-3f2a-0410-8824-cb99058d5e15> | 2011-09-11 14:31:21 +0000 |
|---|---|---|
| committer | ph10 <ph10@2f5784b3-3f2a-0410-8824-cb99058d5e15> | 2011-09-11 14:31:21 +0000 |
| commit | 872e41011c69ee598dbdd32444dcde8fa30a23ee (patch) | |
| tree | bbc0b9c2afdae0e564bc94b160ebf1a9fbe1744f /doc/pcre.txt | |
| parent | 3e3345effab1548229f5cf368f19ace0b64d782b (diff) | |
| download | pcre-872e41011c69ee598dbdd32444dcde8fa30a23ee.tar.gz | |
Final source and document tidies for 8.20-RC1.
git-svn-id: svn://vcs.exim.org/pcre/code/trunk@691 2f5784b3-3f2a-0410-8824-cb99058d5e15
Diffstat (limited to 'doc/pcre.txt')
| -rw-r--r-- | doc/pcre.txt | 1593 |
1 files changed, 1002 insertions, 591 deletions
diff --git a/doc/pcre.txt b/doc/pcre.txt index e8d63f9..2a50c1f 100644 --- a/doc/pcre.txt +++ b/doc/pcre.txt @@ -120,8 +120,8 @@ REVISION Last updated: 24 August 2011 Copyright (c) 1997-2011 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREBUILD(3) PCREBUILD(3) @@ -217,6 +217,23 @@ UNICODE CHARACTER PROPERTY SUPPORT are supported. Details are given in the pcrepattern documentation. +JUST-IN-TIME COMPILER SUPPORT + + Just-in-time compiler support is included in the build by specifying + + --enable-jit + + 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 pcrejit documentation for a discussion of JIT + usage. When JIT support is enabled, pcregrep automatically makes use of + it, unless you add + + --disable-pcregrep-jit + + to the "configure" command. + + CODE VALUE OF NEWLINE By default, PCRE interprets the linefeed (LF) character as indicating @@ -464,11 +481,11 @@ AUTHOR REVISION - Last updated: 02 August 2011 + Last updated: 06 September 2011 Copyright (c) 1997-2011 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREMATCHING(3) PCREMATCHING(3) @@ -671,8 +688,8 @@ REVISION Last updated: 17 November 2010 Copyright (c) 1997-2010 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREAPI(3) PCREAPI(3) @@ -680,7 +697,7 @@ NAME PCRE - Perl-compatible regular expressions -PCRE NATIVE API +PCRE NATIVE API BASIC FUNCTIONS #include <pcre.h> @@ -696,10 +713,22 @@ PCRE NATIVE API pcre_extra *pcre_study(const pcre *code, int options, const char **errptr); + void pcre_free_study(pcre_extra *extra); + int pcre_exec(const pcre *code, const pcre_extra *extra, const char *subject, int length, int startoffset, int options, int *ovector, int ovecsize); + +PCRE NATIVE API AUXILIARY FUNCTIONS + + pcre_jit_stack *pcre_jit_stack_alloc(int startsize, int maxsize); + + void pcre_jit_stack_free(pcre_jit_stack *stack); + + void pcre_assign_jit_stack(pcre_extra *extra, + pcre_jit_callback callback, void *data); + int pcre_dfa_exec(const pcre *code, const pcre_extra *extra, const char *subject, int length, int startoffset, int options, int *ovector, int ovecsize, @@ -749,6 +778,9 @@ PCRE NATIVE API char *pcre_version(void); + +PCRE NATIVE API INDIRECTED FUNCTIONS + void *(*pcre_malloc)(size_t); void (*pcre_free)(void *); @@ -764,42 +796,53 @@ PCRE API OVERVIEW PCRE has its own native API, which is described in this document. There are also some wrapper functions that correspond to the POSIX regular - expression API. These are described in the pcreposix documentation. - Both of these APIs define a set of C function calls. A C++ wrapper is - distributed with PCRE. It is documented in the pcrecpp page. + expression API, but they do not give access to all the functionality. + They are described in the pcreposix documentation. Both of these APIs + define a set of C function calls. A C++ wrapper is also distributed + with PCRE. It is documented in the pcrecpp page. - The native API C function prototypes are defined in the header file - pcre.h, and on Unix systems the library itself is called libpcre. It + The native API C function prototypes are defined in the header file + pcre.h, and on Unix systems the library itself is called libpcre. It can normally be accessed by adding -lpcre 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 num- - bers for the library. Applications can use these to include support + PCRE_MAJOR and PCRE_MINOR to contain the major and minor release num- + bers for the library. Applications can use these to include support for different releases of PCRE. In a Windows environment, if you want to statically link an application - program against a non-dll pcre.a file, you must define PCRE_STATIC - before including pcre.h or pcrecpp.h, because otherwise the pcre_mal- + program against a non-dll pcre.a file, you must define PCRE_STATIC + before including pcre.h or pcrecpp.h, because otherwise the pcre_mal- loc() and pcre_free() exported functions will be declared __declspec(dllimport), with unwanted results. - The functions pcre_compile(), pcre_compile2(), pcre_study(), and - pcre_exec() are used for compiling and matching regular expressions in - a Perl-compatible manner. A sample program that demonstrates the sim- - plest way of using them is provided in the file called pcredemo.c in + The functions pcre_compile(), pcre_compile2(), pcre_study(), and + pcre_exec() are used for compiling and matching regular expressions in + a Perl-compatible manner. A sample program that demonstrates the sim- + plest way of using them is provided in the file called pcredemo.c in the PCRE source distribution. A listing of this program is given in the - pcredemo documentation, and the pcresample documentation describes how + pcredemo documentation, and the pcresample documentation describes how to compile and run it. + 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 pcre_jit_stack_alloc(), + pcre_jit_stack_free(), and pcre_assign_jit_stack() in order to control + the JIT code's memory usage. These functions are discussed in the + pcrejit documentation. + A second matching function, pcre_dfa_exec(), which is not Perl-compati- - ble, is also provided. This uses a different algorithm for the match- - ing. 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 pcrematching docu- + ble, is also provided. This uses a different algorithm for the match- + ing. 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 pcrematching docu- mentation. - In addition to the main compiling and matching functions, there are + 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 pcre_exec(). They are: @@ -814,102 +857,106 @@ PCRE API OVERVIEW pcre_free_substring() and pcre_free_substring_list() are also provided, to free the memory used for extracted strings. - The function pcre_maketables() is used to build a set of character - tables in the current locale for passing to pcre_compile(), - pcre_exec(), or pcre_dfa_exec(). 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 + The function pcre_maketables() is used to build a set of character + tables in the current locale for passing to pcre_compile(), + pcre_exec(), or pcre_dfa_exec(). 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. - The function pcre_fullinfo() is used to find out information about a - compiled pattern; pcre_info() is an obsolete version that returns only - some of the available information, but is retained for backwards com- - patibility. The function pcre_version() returns a pointer to a string + The function pcre_fullinfo() is used to find out information about a + compiled pattern; pcre_info() is an obsolete version that returns only + some of the available information, but is retained for backwards com- + patibility. The function pcre_version() returns a pointer to a string containing the version of PCRE and its date of release. - The function pcre_refcount() maintains a reference count in a data - block containing a compiled pattern. This is provided for the benefit + The function pcre_refcount() maintains a reference count in a data + block containing a compiled pattern. This is provided for the benefit of object-oriented applications. - The global variables pcre_malloc and pcre_free initially contain the - entry points of the standard malloc() and free() functions, respec- + The global variables pcre_malloc and pcre_free initially contain the + entry points of the standard malloc() and free() functions, respec- tively. PCRE calls the memory management functions via these variables, - so a calling program can replace them if it wishes to intercept the + so a calling program can replace them if it wishes to intercept the calls. This should be done before calling any PCRE functions. - The global variables pcre_stack_malloc and pcre_stack_free are also - indirections to memory management functions. These special functions - are used only when PCRE is compiled to use the heap for remembering + The global variables pcre_stack_malloc and pcre_stack_free 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 pcre_exec() - function. See the pcrebuild documentation for details of how to do - this. It is a non-standard way of building PCRE, for use in environ- - ments 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 are always called in a stack-like manner (last - obtained, first freed), and always for memory blocks of the same size. - There is a discussion about PCRE's stack usage in the pcrestack docu- + function. See the pcrebuild documentation for details of how to do + this. It is a non-standard way of building PCRE, for use in environ- + ments 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 are always called in a stack-like manner (last + obtained, first freed), and always for memory blocks of the same size. + There is a discussion about PCRE's stack usage in the pcrestack docu- mentation. The global variable pcre_callout 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 + by the caller to a "callout" function, which PCRE will then call at + specified points during a matching operation. Details are given in the pcrecallout documentation. NEWLINES - PCRE supports five different conventions for indicating line breaks in - strings: a single CR (carriage return) character, a single LF (line- + PCRE supports five different conventions for indicating line breaks in + strings: a single CR (carriage return) character, a single LF (line- feed) character, the two-character sequence CRLF, any of the three pre- - ceding, or any Unicode newline sequence. The Unicode newline sequences - are the three just mentioned, plus the single characters VT (vertical - tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line + ceding, or any Unicode newline sequence. The Unicode newline sequences + are the three just mentioned, plus the single characters VT (vertical + tab, U+000B), FF (formfeed, U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS (paragraph separator, U+2029). - 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 stan- - dard. When PCRE is run, the default can be overridden, either when a + 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 stan- + dard. When PCRE is run, the default can be overridden, either when a pattern is compiled, or when it is matched. At compile time, the newline convention can be specified by the options - argument of pcre_compile(), or it can be specified by special text at + argument of pcre_compile(), or it can be specified by special text at the start of the pattern itself; this overrides any other settings. See the pcrepattern page for details of the special character sequences. In the PCRE documentation the word "newline" is used to mean "the char- - acter or pair of characters that indicate a line break". The choice of - newline convention affects the handling of the dot, circumflex, and + acter 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 advance- + CRLF is a recognized line ending sequence, the match position advance- ment for a non-anchored pattern. There is more detail about this in the section on pcre_exec() options below. - The choice of newline convention does not affect the interpretation of - the \n or \r escape sequences, nor does it affect what \R matches, + 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. MULTITHREADING - The PCRE functions can be used in multi-threading applications, with + The PCRE functions can be used in multi-threading applications, with the proviso that the memory management functions pointed to by pcre_malloc, pcre_free, pcre_stack_malloc, and pcre_stack_free, and the callout function pointed to by pcre_callout, are shared by all threads. - The compiled form of a regular expression is not altered during match- + The compiled form of a regular expression is not altered during match- ing, so the same compiled pattern can safely be used by several threads at once. + If the just-in-time optimization feature is being used, it needs sepa- + rate memory stack areas for each thread. See the pcrejit documentation + for more details. + SAVING PRECOMPILED PATTERNS FOR LATER USE 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 - pcreprecompile documentation. However, compiling a regular expression - with one version of PCRE for use with a different version is not guar- + 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 + pcreprecompile documentation. However, compiling a regular expression + with one version of PCRE for use with a different version is not guar- anteed to work and may cause crashes. @@ -917,26 +964,31 @@ CHECKING BUILD-TIME OPTIONS int pcre_config(int what, void *where); - The function pcre_config() makes it possible for a PCRE client to dis- + The function pcre_config() makes it possible for a PCRE client to dis- cover which optional features have been compiled into the PCRE library. - The pcrebuild documentation has more details about these optional fea- + The pcrebuild documentation has more details about these optional fea- tures. - The first argument for pcre_config() is an integer, specifying which + The first argument for pcre_config() is an integer, specifying which information is required; the second argument is a pointer to a variable - into which the information is placed. The following information is + into which the information is placed. The following information is available: PCRE_CONFIG_UTF8 - The output is an integer that is set to one if UTF-8 support is avail- + The output is an integer that is set to one if UTF-8 support is avail- able; otherwise it is set to zero. PCRE_CONFIG_UNICODE_PROPERTIES - The output is an integer that is set to one if support for Unicode + The output is an integer that is set to one if support for Unicode character properties is available; otherwise it is set to zero. + PCRE_CONFIG_JIT + + 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. + PCRE_CONFIG_NEWLINE The output is an integer whose value specifies the default character @@ -1423,8 +1475,20 @@ STUDYING A PATTERN wants to pass any of the other fields to pcre_exec() or pcre_dfa_exec(), it must set up its own pcre_extra block. - The second argument of pcre_study() contains option bits. At present, - no options are defined, and this argument should always be zero. + The second argument of pcre_study() contains option bits. There is only + one option: PCRE_STUDY_JIT_COMPILE. If this is set, and the just-in- + time compiler is available, the pattern is further compiled into + machine code that executes much faster than the pcre_exec() matching + function. If the just-in-time compiler is not available, this option is + ignored. All other bits in the options argument must be zero. + + JIT compilation is a heavyweight optimization. It can take some time + for patterns to be analyzed, and for one-off matches and simple pat- + terns 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 + pcre_exec() interpreter. For more details, see the pcrejit documenta- + tion. The third argument for pcre_study() is a pointer for an error message. If studying succeeds (even if no data is returned), the variable it @@ -1433,13 +1497,29 @@ STUDYING A PATTERN must not try to free it. You should test the error pointer for NULL after calling pcre_study(), to be sure that it has run successfully. - This is a typical call to pcre_study(): + When you are finished with a pattern, you can free the memory used for + the study data by calling pcre_free_study(). This function was added to + the API for release 8.20. For earlier versions, the memory could be + freed with pcre_free(), just like the pattern itself. This will still + work in cases where PCRE_STUDY_JIT_COMPILE is not used, but it is + advisable to change to the new function when convenient. - pcre_extra *pe; - pe = pcre_study( + This is a typical way in which pcre_study() is used (except that in a + real application there should be tests for errors): + + 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 exist */ + 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); 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 @@ -1454,68 +1534,71 @@ STUDYING A PATTERN bytes is created. This speeds up finding a position in the subject at which to start matching. - The two optimizations just described can be disabled by setting the - PCRE_NO_START_OPTIMIZE option when calling pcre_exec() or - pcre_dfa_exec(). 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. See the discussion of PCRE_NO_START_OPTI- - MIZE below. + These two optimizations apply to both pcre_exec() and pcre_dfa_exec(). + However, they are not used by pcre_exec() if pcre_study() is called + with the PCRE_STUDY_JIT_COMPILE option, and just-in-time compiling is + successful. The optimizations can be disabled by setting the + PCRE_NO_START_OPTIMIZE option when calling pcre_exec() or + pcre_dfa_exec(). You might want to do this if your pattern contains + callouts or (*MARK) (which cannot be handled by the JIT compiler), and + you want to make use of these facilities in cases where matching fails. + See the discussion of PCRE_NO_START_OPTIMIZE below. LOCALE SUPPORT - PCRE handles caseless matching, and determines whether characters are - letters, digits, or whatever, by reference to a set of tables, indexed - by character value. When running in UTF-8 mode, this applies only to - characters with codes less than 128. By default, higher-valued codes + PCRE handles caseless matching, and determines whether characters are + letters, digits, or whatever, by reference to a set of tables, indexed + by character value. When running in UTF-8 mode, this applies only to + characters with codes less than 128. By default, higher-valued codes never match escapes such as \w or \d, but they can be tested with \p if - PCRE is built with Unicode character property support. Alternatively, - the PCRE_UCP option can be set at compile time; this causes \w and + PCRE is built with Unicode character property support. Alternatively, + the PCRE_UCP option can be set at compile time; this causes \w and friends to use Unicode property support instead of built-in tables. The use of locales with Unicode is discouraged. If you are handling charac- - ters with codes greater than 128, you should either use UTF-8 and Uni- + ters with codes greater than 128, you should either use UTF-8 and Uni- code, or use locales, but not try to mix the two. - PCRE contains an internal set of tables that are used when the final - argument of pcre_compile() is NULL. These are sufficient for many + PCRE contains an internal set of tables that are used when the final + argument of pcre_compile() is NULL. These are sufficient for many applications. Normally, the internal tables recognize only ASCII char- acters. However, when PCRE is built, it is possible to cause the inter- nal tables to be rebuilt in the default "C" locale of the local system, which may cause them to be different. - The internal tables can always be overridden by tables supplied by the + 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 Uni- + from the default. As more and more applications change to using Uni- code, the need for this locale support is expected to die away. - External tables are built by calling the pcre_maketables() function, - which has no arguments, in the relevant locale. The result can then be - passed to pcre_compile() or pcre_exec() 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 + External tables are built by calling the pcre_maketables() function, + which has no arguments, in the relevant locale. The result can then be + passed to pcre_compile() or pcre_exec() 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: setlocale(LC_CTYPE, "fr_FR"); tables = pcre_maketables(); re = pcre_compile(..., tables); - The locale name "fr_FR" is used on Linux and other Unix-like systems; + 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". - When pcre_maketables() runs, the tables are built in memory that is - obtained via pcre_malloc. It is the caller's responsibility to ensure - that the memory containing the tables remains available for as long as + When pcre_maketables() runs, the tables are built in memory that is + obtained via pcre_malloc. It is the caller's responsibility to ensure + that the memory containing the tables remains available for as long as it is needed. The pointer that is passed to pcre_compile() is saved with the compiled - pattern, and the same tables are used via this pointer by pcre_study() + pattern, and the same tables are used via this pointer by pcre_study() and normally also by pcre_exec(). Thus, by default, for any single pat- tern, compilation, studying and matching all happen in the same locale, but different patterns can be compiled in different locales. - It is possible to pass a table pointer or NULL (indicating the use of - the internal tables) to pcre_exec(). Although not intended for this - purpose, this facility could be used to match a pattern in a different + It is possible to pass a table pointer or NULL (indicating the use of + the internal tables) to pcre_exec(). Although not intended for this + purpose, this facility could be used to match a pattern in a different locale from the one in which it was compiled. Passing table pointers at run time is discussed below in the section on matching a pattern. @@ -1525,15 +1608,15 @@ INFORMATION ABOUT A PATTERN int pcre_fullinfo(const pcre *code, const pcre_extra *extra, int what, void *where); - The pcre_fullinfo() function returns information about a compiled pat- + The pcre_fullinfo() function returns information about a compiled pat- tern. It replaces the obsolete pcre_info() function, which is neverthe- less retained for backwards compability (and is documented below). - The first argument for pcre_fullinfo() is a pointer to the compiled - pattern. The second argument is the result of pcre_study(), 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 + The first argument for pcre_fullinfo() is a pointer to the compiled + pattern. The second argument is the result of pcre_study(), 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: PCRE_ERROR_NULL the argument code was NULL @@ -1541,144 +1624,154 @@ INFORMATION ABOUT A PATTERN PCRE_ERROR_BADMAGIC the "magic number" was not found PCRE_ERROR_BADOPTION the value of what was invalid - The "magic number" is placed at the start of each compiled pattern as - an simple check against passing an arbitrary memory pointer. Here is a - typical call of pcre_fullinfo(), to obtain the length of the compiled + The "magic number" is placed at the start of each compiled pattern as + an simple check against passing an arbitrary memory pointer. Here is a + typical call of pcre_fullinfo(), to obtain the length of the compiled pattern: int rc; size_t length; rc = pcre_fullinfo( re, /* result of pcre_compile() */ - pe, /* result of pcre_study(), or NULL */ + sd, /* result of pcre_study(), or NULL */ PCRE_INFO_SIZE, /* what is required */ &length); /* where to put the data */ - The possible values for the third argument are defined in pcre.h, and + The possible values for the third argument are defined in pcre.h, and are as follows: PCRE_INFO_BACKREFMAX - Return the number of the highest back reference in the pattern. The - fourth argument should point to an int variable. Zero is returned if + Return the number of the highest back reference in the pattern. The + fourth argument should point to an int variable. Zero is returned if there are no back references. PCRE_INFO_CAPTURECOUNT - Return the number of capturing subpatterns in the pattern. The fourth + Return the number of capturing subpatterns in the pattern. The fourth argument should point to an int variable. PCRE_INFO_DEFAULT_TABLES - Return a pointer to the internal default character tables within PCRE. - The fourth argument should point to an unsigned char * variable. This + Return a pointer to the internal default character tables within PCRE. + The fourth argument should point to an unsigned char * variable. This information call is provided for internal use by the pcre_study() func- - tion. External callers can cause PCRE to use its internal tables by + tion. External callers can cause PCRE to use its internal tables by passing a NULL table pointer. PCRE_INFO_FIRSTBYTE - Return information about the first byte of any matched string, for a - non-anchored pattern. The fourth argument should point to an int vari- - able. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name + Return information about the first byte of any matched string, for a + non-anchored pattern. The fourth argument should point to an int vari- + able. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name is still recognized for backwards compatibility.) - If there is a fixed first byte, for example, from a pattern such as + If there is a fixed first byte, for example, from a pattern such as (cat|cow|coyote), its value is returned. Otherwise, if either - (a) the pattern was compiled with the PCRE_MULTILINE option, and every + (a) the pattern was compiled with the PCRE_MULTILINE option, and every branch starts with "^", or (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set (if it were set, the pattern would be anchored), - -1 is returned, indicating that the pattern matches only at the start - of a subject string or after any newline within the string. Otherwise + -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. PCRE_INFO_FIRSTTABLE - If the pattern was studied, and this resulted in the construction of a + If the pattern was studied, and this resulted in the construction of a 256-bit table indicating a fixed set of bytes for the first byte in any - matching string, a pointer to the table is returned. Otherwise NULL is - returned. The fourth argument should point to an unsigned char * vari- + matching string, a pointer to the table is returned. Otherwise NULL is + returned. The fourth argument should point to an unsigned char * vari- able. PCRE_INFO_HASCRORLF - Return 1 if the pattern contains any explicit matches for CR or LF - characters, otherwise 0. The fourth argument should point to an int - variable. An explicit match is either a literal CR or LF character, or + Return 1 if the pattern contains any explicit matches for CR or LF + characters, otherwise 0. The fourth argument should point to an int + variable. An explicit match is either a literal CR or LF character, or \r or \n. PCRE_INFO_JCHANGED - Return 1 if the (?J) or (?-J) option setting is used in the pattern, - otherwise 0. The fourth argument should point to an int variable. (?J) + Return 1 if the (?J) or (?-J) option setting is used in the pattern, + otherwise 0. The fourth argument should point to an int variable. (?J) and (?-J) set and unset the local PCRE_DUPNAMES option, respectively. + PCRE_INFO_JIT + + Return 1 if the pattern was studied with the PCRE_STUDY_JIT_COMPILE + option, and just-in-time compiling was successful. The fourth argument + should point to an int 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 the PCRE_STUDY_JIT_COMPILE option, or that the JIT + compiler could not handle this particular pattern. See the pcrejit doc- + umentation for details of what can and cannot be handled. + PCRE_INFO_LASTLITERAL - Return the value of the rightmost literal byte that must exist in any - matched string, other than at its start, if such a byte has been + Return the value of the rightmost literal byte that must exist in any + matched string, other than at its start, if such a byte has been recorded. The fourth argument should point to an int variable. If there - is no such byte, -1 is returned. For anchored patterns, a last literal - byte is recorded only if it follows something of variable length. For + is no such byte, -1 is returned. For anchored patterns, a last literal + byte 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. PCRE_INFO_MINLENGTH - 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, not bytes (this may - be relevant in UTF-8 mode). The fourth argument should point to an int - 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 + 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, not bytes (this may + be relevant in UTF-8 mode). The fourth argument should point to an int + 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. PCRE_INFO_NAMECOUNT PCRE_INFO_NAMEENTRYSIZE PCRE_INFO_NAMETABLE - PCRE supports the use of named as well as numbered capturing parenthe- - ses. The names are just an additional way of identifying the parenthe- + PCRE supports the use of named as well as numbered capturing parenthe- + ses. The names are just an additional way of identifying the parenthe- ses, which still acquire numbers. Several convenience functions such as - pcre_get_named_substring() are provided for extracting captured sub- - strings 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 + pcre_get_named_substring() are provided for extracting captured sub- + strings 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 pcre_exec() below). To do - the conversion, you need to use the name-to-number map, which is + the conversion, you need to use the name-to-number map, which is described by these three values. 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 int 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 (a pointer to char). The + of each entry; both of these return an int 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 (a pointer to char). The first two bytes of each entry are the number of the capturing parenthe- - sis, most significant byte first. The rest of the entry is the corre- + sis, most significant byte first. The rest of the entry is the corre- sponding name, zero terminated. - The names are in alphabetical order. Duplicate names may appear if (?| + The names are in alphabetical order. Duplicate names may appear if (?| is used to create multiple groups with the same number, as described in - the section on duplicate subpattern numbers in the pcrepattern page. - Duplicate names for subpatterns with different numbers are permitted - only if PCRE_DUPNAMES is set. In all cases of duplicate names, they - appear in the table in the order in which they were found in the pat- - tern. In the absence of (?| this is the order of increasing number; + the section on duplicate subpattern numbers in the pcrepattern page. + Duplicate names for subpatterns with different numbers are permitted + only if PCRE_DUPNAMES is set. In all cases of duplicate names, they + appear in the table in the order in which they were found in the pat- + tern. In the absence of (?| this is the order of increasing number; when (?| is used this is not necessarily the case because later subpat- terns may have lower numbers. - As a simple example of the name/number table, consider the following - pattern (assume PCRE_EXTENDED is set, so white space - including new- + As a simple example of the name/number table, consider the following + pattern (assume PCRE_EXTENDED is set, so white space - including new- lines - is ignored): (?<date> (?<year>(\d\d)?\d\d) - (?<month>\d\d) - (?<day>\d\d) ) - 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, + 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 ??: @@ -1687,31 +1780,31 @@ INFORMATION ABOUT A PATTERN 00 04 m o n t h 00 00 02 y e a r 00 ?? - When writing code to extract data from named subpatterns using the - name-to-number map, remember that the length of the entries is likely + 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. PCRE_INFO_OKPARTIAL - Return 1 if the pattern can be used for partial matching with - pcre_exec(), otherwise 0. The fourth argument should point to an int - variable. From release 8.00, this always returns 1, because the - restrictions that previously applied to partial matching have been - lifted. The pcrepartial documentation gives details of partial match- + Return 1 if the pattern can be used for partial matching with + pcre_exec(), otherwise 0. The fourth argument should point to an int + variable. From release 8.00, this always returns 1, because the + restrictions that previously applied to partial matching have been + lifted. The pcrepartial documentation gives details of partial match- ing. PCRE_INFO_OPTIONS - Return a copy of the options with which the pattern was compiled. The - fourth argument should point to an unsigned long int variable. These + Return a copy of the options with which the pattern was compiled. The + fourth argument should point to an unsigned long int variable. These option bits are those specified in the call to pcre_compile(), 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, + 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. - A pattern is automatically anchored by PCRE if all of its top-level + A pattern is automatically anchored by PCRE if all of its top-level alternatives begin with one of the following: ^ unless PCRE_MULTILINE is set @@ -1725,7 +1818,7 @@ INFORMATION ABOUT A PATTERN PCRE_INFO_SIZE - Return the size of the compiled pattern, that is, the value that was + Return the size of the compiled pattern, that is, the value that was passed as the argument to pcre_malloc() when PCRE was getting memory in which to place the compiled data. The fourth argument should point to a size_t variable. @@ -1733,12 +1826,12 @@ INFORMATION ABOUT A PATTERN PCRE_INFO_STUDYSIZE Return the size of the data block pointed to by the study_data field in - a pcre_extra block. If pcre_extra is NULL, or there is no study data, - zero is returned. The fourth argument should point to a size_t vari- - able. The study_data field is set by pcre_study() to record informa- - tion that will speed up matching (see the section entitled "Studying a + a pcre_extra block. If pcre_extra is NULL, or there is no study data, + zero is returned. The fourth argument should point to a size_t vari- + able. The study_data field is set by pcre_study() to record informa- + tion that will speed up matching (see the section entitled "Studying a pattern" above). The format of the study_data block is private, but its - length is made available via this option so that it can be saved and + length is made available via this option so that it can be saved and restored (see the pcreprecompile documentation for details). @@ -1746,21 +1839,21 @@ OBSOLETE INFO FUNCTION int pcre_info(const pcre *code, int *optptr, int *firstcharptr); - The pcre_info() function is now obsolete because its interface is too - restrictive to return all the available data about a compiled pattern. - New programs should use pcre_fullinfo() instead. The yield of - pcre_info() is the number of capturing subpatterns, or one of the fol- + The pcre_info() function is now obsolete because its interface is too + restrictive to return all the available data about a compiled pattern. + New programs should use pcre_fullinfo() instead. The yield of + pcre_info() is the number of capturing subpatterns, or one of the fol- lowing negative numbers: PCRE_ERROR_NULL the argument code was NULL PCRE_ERROR_BADMAGIC the "magic number" was not found - If the optptr argument is not NULL, a copy of the options with which - the pattern was compiled is placed in the integer it points to (see + If the optptr argument is not NULL, a copy of the options with which + the pattern was compiled is placed in the integer it points to (see PCRE_INFO_OPTIONS above). - If the pattern is not anchored and the firstcharptr argument is not - NULL, it is used to pass back information about the first character of + If the pattern is not anchored and the firstcharptr argument is not + NULL, it is used to pass back information about the first character of any matched string (see PCRE_INFO_FIRSTBYTE above). @@ -1768,21 +1861,21 @@ REFERENCE COUNTS int pcre_refcount(pcre *code, int adjust); - The pcre_refcount() function is used to maintain a reference count in + The pcre_refcount() 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, + 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. 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 adjust value (which may be positive or negative) to it. The + zero. It is changed only by calling this function, whose action is to + add the adjust 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 constrained to lie between 0 and 65535, inclusive. If the new value is outside these limits, it is forced to the appropriate limit value. - 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 + 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.) @@ -1792,18 +1885,18 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION const char *subject, int length, int startoffset, int options, int *ovector, int ovecsize); - The function pcre_exec() is called to match a subject string against a - compiled pattern, which is passed in the code argument. If the pattern - was studied, the result of the study should be passed in the extra - argument. This function is the main matching facility of the library, + The function pcre_exec() is called to match a subject string against a + compiled pattern, which is passed in the code argument. If the pattern + was studied, the result of the study should be passed in the extra + argument. 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 below in the sec- + an alternative matching function, which is described below in the sec- tion about the pcre_dfa_exec() function. - In most applications, the pattern will have been compiled (and option- - ally studied) in the same process that calls pcre_exec(). However, it + In most applications, the pattern will have been compiled (and option- + ally studied) in the same process that calls pcre_exec(). 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 + later in different processes, possibly even on different hosts. For a discussion about this, see the pcreprecompile documentation. Here is an example of a simple call to pcre_exec(): @@ -1822,48 +1915,57 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION Extra data for pcre_exec() - If the extra argument is not NULL, it must point to a pcre_extra data - block. The pcre_study() function returns such a block (when it doesn't - return NULL), but you can also create one for yourself, and pass addi- - tional information in it. The pcre_extra block contains the following + If the extra argument is not NULL, it must point to a pcre_extra data + block. The pcre_study() function returns such a block (when it doesn't + return NULL), but you can also create one for yourself, and pass addi- + tional information in it. The pcre_extra block contains the following fields (not necessarily in this order): unsigned long int flags; void *study_data; + void *executable_jit; unsigned long int match_limit; unsigned long int match_limit_recursion; void *callout_data; const unsigned char *tables; unsigned char **mark; - The flags field is a bitmap that specifies which of the other fields + The flags field is a bitmap that specifies which of the other fields are set. The flag bits are: PCRE_EXTRA_STUDY_DATA + PCRE_EXTRA_EXECUTABLE_JIT PCRE_EXTRA_MATCH_LIMIT PCRE_EXTRA_MATCH_LIMIT_RECURSION PCRE_EXTRA_CALLOUT_DATA PCRE_EXTRA_TABLES PCRE_EXTRA_MARK - Other flag bits should be set to zero. The study_data field is set in - the pcre_extra block that is returned by pcre_study(), together with - the appropriate flag bit. You should not set this yourself, but you may - add to the block by setting the other fields and their corresponding - flag bits. + Other flag bits should be set to zero. The study_data field and some- + times the executable_jit field are set in the pcre_extra block that is + returned by pcre_study(), together with the appropriate flag bits. You + should not set these yourself, but you may add to the block by setting + the other fields and their corresponding flag bits. The match_limit 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 unlim- + 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 unlim- ited repeats. - Internally, PCRE uses a function called match() which it calls repeat- - edly (sometimes recursively). The limit set by match_limit 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. + Internally, pcre_exec() uses a function called match(), which it calls + repeatedly (sometimes recursively). The limit set by match_limit 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. + + When pcre_exec() is called with a pattern that was successfully studied + with the PCRE_STUDY_JIT_COMPILE 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 + match_limit value is also used in this case (but in a different way) to + limit how long the matching can continue. 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 @@ -1878,9 +1980,11 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION the total number of calls, because not all calls to match() are recur- sive. This limit is of use only if it is set smaller than match_limit. - Limiting the recursion depth limits the amount of 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. + 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, if the pattern was successfully + studied with PCRE_STUDY_JIT_COMPILE. The default value for match_limit_recursion can be set when PCRE is built; the default default is the same value as the default for @@ -1923,19 +2027,26 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and PCRE_PARTIAL_HARD. + If the pattern was successfully studied with the PCRE_STUDY_JIT_COMPILE + option, the only supported options for JIT execution are + PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and + PCRE_NOTEMPTY_ATSTART. Note in particular that partial matching is not + supported. If an unsupported option is used, JIT execution is disabled + and the normal interpretive code in pcre_exec() is run. + PCRE_ANCHORED - The PCRE_ANCHORED option limits pcre_exec() 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 + The PCRE_ANCHORED option limits pcre_exec() 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. PCRE_BSR_ANYCRLF PCRE_BSR_UNICODE 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 + 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. PCRE_NEWLINE_CR @@ -1944,319 +2055,335 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION PCRE_NEWLINE_ANYCRLF PCRE_NEWLINE_ANY - These options override the newline definition that was chosen or - defaulted when the pattern was compiled. For details, see the descrip- - tion of pcre_compile() above. During matching, the newline choice - affects the behaviour of the dot, circumflex, and dollar metacharac- - ters. It may also alter the way the match position is advanced after a + These options override the newline definition that was chosen or + defaulted when the pattern was compiled. For details, see the descrip- + tion of pcre_compile() above. During matching, the newline choice + affects the behaviour of the dot, circumflex, and dollar metacharac- + ters. It may also alter the way the match position is advanced after a match failure for an unanchored pattern. - When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is - set, and a match attempt for an unanchored pattern fails when the cur- - rent position is at a CRLF sequence, and the pattern contains no - explicit matches for CR or LF characters, the match position is + When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is + set, and a match attempt for an unanchored pattern fails when the cur- + rent 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. 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 + 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 con- + 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 con- tains an explicit CR or LF reference, and so advances only by one char- acter after the first failure. 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 + 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). - Notwithstanding the above, anomalous effects may still occur when CRLF + 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. PCRE_NOTBOL 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 behav- + 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 behav- iour of the circumflex metacharacter. It does not affect \A. PCRE_NOTEOL 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 with- + of a line, so the dollar metacharacter should not match it nor (except + in multiline mode) a newline immediately before it. Setting this with- out PCRE_MULTILINE (at compile time) causes dollar never to match. This - option affects only the behaviour of the dollar metacharacter. It does + option affects only the behaviour of the dollar metacharacter. It does not affect \Z or \z. PCRE_NOTEMPTY 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 + 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 a?b? - 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 + 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 occur- rences of "a" or "b". PCRE_NOTEMPTY_ATSTART - 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 + 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. - 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 split() function, and when using - the /g modifier. It is possible to emulate Perl's behaviour after + 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 split() 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 off- - set with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then if that + set with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then if that fails, by advancing the starting offset (see below) and trying an ordi- - nary match again. There is some code that demonstrates how to do this - in the pcredemo 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 + nary match again. There is some code that demonstrates how to do this + in the pcredemo 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. PCRE_NO_START_OPTIMIZE - There are a number of optimizations that pcre_exec() uses at the start - of a match, in order to speed up the process. For example, if it is + There are a number of optimizations that pcre_exec() 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. + 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 pat- - tern is not considered until after a suitable starting point for the - match has been found. When callouts or (*MARK) items are in use, these + tern is not considered until after a suitable starting point for the + match has been found. 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- + never actually used. The start-up optimizations are in effect a pre- scan of the subject that takes place before the pattern is run. - 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 + 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 + position in the subject string. If PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching time. - Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching + Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation. Consider the pattern (*COMMIT)ABC - 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 pat- - tern 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 opti- - mizations may be used. For example, a minimum length for the subject + 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 pat- + tern 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 opti- + mizations may be used. For example, a minimum length for the subject may be recorded. Consider the pattern (*MARK:A)(X|Y) - 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 + 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. PCRE_NO_UTF8_CHECK When PCRE_UTF8 is set at compile time, the validity of the subject as a - UTF-8 string is automatically checked when pcre_exec() is subsequently - called. The value of startoffset is also checked to ensure that it - points to the start of a UTF-8 character. There is a discussion about - the validity of UTF-8 strings in the section on UTF-8 support in the - main pcre page. If an invalid UTF-8 sequence of bytes is found, - pcre_exec() returns the error PCRE_ERROR_BADUTF8 or, if PCRE_PAR- - TIAL_HARD is set and the problem is a truncated UTF-8 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 Error return val- + UTF-8 string is automatically checked when pcre_exec() is subsequently + called. The value of startoffset is also checked to ensure that it + points to the start of a UTF-8 character. There is a discussion about + the validity of UTF-8 strings in the section on UTF-8 support in the + main pcre page. If an invalid UTF-8 sequence of bytes is found, + pcre_exec() returns the error PCRE_ERROR_BADUTF8 or, if PCRE_PAR- + TIAL_HARD is set and the problem is a truncated UTF-8 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 Error return val- ues from pcre_exec() below). If startoffset contains a value that does - not point to the start of a UTF-8 character (or to the end of the sub- + not point to the start of a UTF-8 character (or to the end of the sub- ject), PCRE_ERROR_BADUTF8_OFFSET is returned. - 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 pcre_exec(). You might want to - do this for the second and subsequent calls to pcre_exec() 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 startoffset - points to the start of a UTF-8 character (or the end of the subject). - When PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 - string as a subject or an invalid value of startoffset is undefined. + 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 pcre_exec(). You might want to + do this for the second and subsequent calls to pcre_exec() 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 startoffset + points to the start of a UTF-8 character (or the end of the subject). + When PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid UTF-8 + string as a subject or an invalid value of startoffset is undefined. Your program may crash. PCRE_PARTIAL_HARD PCRE_PARTIAL_SOFT - These options turn on the partial matching feature. For backwards com- - patibility, 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 + These options turn on the partial matching feature. For backwards com- + patibility, 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 + 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. - If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this - case, if a partial match is found, pcre_exec() immediately returns - PCRE_ERROR_PARTIAL, without considering any other alternatives. In - other words, when PCRE_PARTIAL_HARD is set, a partial match is consid- + If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this + case, if a partial match is found, pcre_exec() immediately returns + PCRE_ERROR_PARTIAL, without considering any other alternatives. In + other words, when PCRE_PARTIAL_HARD is set, a partial match is consid- ered to be more important that an alternative complete match. - In both cases, the portion of the string that was inspected when the + 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 + more detailed discussion of partial and multi-segment matching, with examples, in the pcrepartial documentation. The string to be matched by pcre_exec() - The subject string is passed to pcre_exec() as a pointer in subject, a + The subject string is passed to pcre_exec() as a pointer in subject, a length (in bytes) in length, and a starting byte offset in startoffset. - If this is negative or greater than the length of the subject, - pcre_exec() returns PCRE_ERROR_BADOFFSET. When the starting offset is - zero, the search for a match starts at the beginning of the subject, + If this is negative or greater than the length of the subject, + pcre_exec() 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 mode, the byte offset - must point to the start of a UTF-8 character (or the end of the sub- - ject). Unlike the pattern string, the subject may contain binary zero + must point to the start of a UTF-8 character (or the end of the sub- + ject). Unlike the pattern string, the subject may contain binary zero bytes. - A non-zero starting offset is useful when searching for another match - in the same subject by calling pcre_exec() again after a previous suc- - cess. Setting startoffset differs from just passing over a shortened - string and setting PCRE_NOTBOL in the case of a pattern that begins + A non-zero starting offset is useful when searching for another match + in the same subject by calling pcre_exec() again after a previous suc- + cess. Setting startoffset 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 \Biss\B - 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 pcre_exec() - finds the first occurrence. If pcre_exec() is called again with just - the remainder of the subject, namely "issipi", it does not match, + 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 pcre_exec() + finds the first occurrence. If pcre_exec() 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 pcre_exec() is passed the entire + to be a word boundary. However, if pcre_exec() is passed the entire string again, but with startoffset set to 4, it finds the second occur- - rence of "iss" because it is able to look behind the starting point to + rence of "iss" because it is able to look behind the starting point to discover that it is preceded by a letter. - Finding all the matches in a subject is tricky when the pattern can + 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 + 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 pcre- demo 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 + 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. - If a non-zero starting offset is passed when the pattern is anchored, + 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 + if the pattern does not require the match to be at the start of the subject. How pcre_exec() returns captured substrings - 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 sub- - string. PCRE supports several other kinds of parenthesized subpattern + 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 sub- + string. PCRE supports several other kinds of parenthesized subpattern that do not cause substrings to be captured. Captured substrings are returned to the caller via a vector of integers - whose address is passed in ovector. The number of elements in the vec- - tor is passed in ovecsize, which must be a non-negative number. Note: + whose address is passed in ovector. The number of elements in the vec- + tor is passed in ovecsize, which must be a non-negative number. Note: this argument is NOT the size of ovector in bytes. - The first two-thirds of the vector is used to pass back captured sub- - strings, each substring using a pair of integers. The remaining third - of the vector is used as workspace by pcre_exec() while matching cap- - turing subpatterns, and is not available for passing back information. - The number passed in ovecsize should always be a multiple of three. If + The first two-thirds of the vector is used to pass back captured sub- + strings, each substring using a pair of integers. The remaining third + of the vector is used as workspace by pcre_exec() while matching cap- + turing subpatterns, and is not available for passing back information. + The number passed in ovecsize should always be a multiple of three. If it is not, it is rounded down. - When a match is successful, information about captured substrings is - returned in pairs of integers, starting at the beginning of ovector, - and continuing up to two-thirds of its length at the most. The first - element of each pair is set to the byte offset of the first character - in a substring, and the second is set to the byte offset of the first - character after the end of a substring. Note: these values are always + When a match is successful, information about captured substrings is + returned in pairs of integers, starting at the beginning of ovector, + and continuing up to two-thirds of its length at the most. The first + element of each pair is set to the byte offset of the first character + in a substring, and the second is set to the byte offset of the first + character after the end of a substring. Note: these values are always byte offsets, even in UTF-8 mode. They are not character counts. - The first pair of integers, ovector[0] and ovector[1], 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 + The first pair of integers, ovector[0] and ovector[1], 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 pcre_exec() 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 + 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. If a capturing subpattern is matched repeatedly, it is the last portion of the string that it matched that is returned. - If the vector is too small to hold all the captured substring offsets, + 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 the substring offsets are not of - interest, pcre_exec() may be called with ovector passed as NULL and - ovecsize as zero. However, if the pattern contains back references and - the ovector is not big enough to remember the related substrings, PCRE - has to get additional memory for use during matching. Thus it is usu- - ally advisable to supply an ovector. + function returns a value of zero. If neither the actual string matched + not any captured substrings are of interest, pcre_exec() may be called + with ovector passed as NULL and ovecsize as zero. However, if the pat- + tern contains back references and the ovector 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 ovector + of reasonable size. + + There are some cases where zero is returned (indicating vector over- + flow) when in fact the vector is exactly the right size for the final + match. For example, consider the pattern + + (a)(?:(b)c|bd) + + If a vector of 6 elements (allowing for only 1 captured substring) is + given with subject string "abd", pcre_exec() 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 tem- + porary overflow, but the final number of used slots is actually less + than the maximum, a non-zero value is returned. The pcre_fullinfo() function can be used to find out how many capturing - subpatterns there are in a compiled pattern. The smallest size for - ovector that will allow for n captured substrings, in addition to the + subpatterns there are in a compiled pattern. The smallest size for + ovector that will allow for n captured substrings, in addition to the offsets of the substring matched by the whole pattern, is (n+1)*3. - It is possible for capturing subpattern number n+1 to match some part + It is possible for capturing subpattern number n+1 to match some part of the subject when subpattern n has not been used at all. For example, - if the string "abc" is matched against the pattern (a|(z))(bc) the + 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 corre- + 2 is not. When this happens, both values in the offset pairs corre- sponding to unused subpatterns are set to -1. - 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, + 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. - Note: Elements of ovector that do not correspond to capturing parenthe- - ses in the pattern are never changed. That is, if a pattern contains n - capturing parentheses, no more than ovector[0] to ovector[2n+1] are set - by pcre_exec(). The other elements retain whatever values they previ- - ously had. + Note: Elements in the first two-thirds of ovector that do not corre- + spond to capturing parentheses in the pattern are never changed. That + is, if a pattern contains n capturing parentheses, no more than ovec- + tor[0] to ovector[2n+1] are set by pcre_exec(). The other elements (in + the first two-thirds) retain whatever values they previously had. - Some convenience functions are provided for extracting the captured + Some convenience functions are provided for extracting the captured substrings as separate strings. These are described below. Error return values from pcre_exec() - If pcre_exec() fails, it returns a negative number. The following are + If pcre_exec() fails, it returns a negative number. The following are defined in the header file: PCRE_ERROR_NOMATCH (-1) @@ -2265,7 +2392,7 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION PCRE_ERROR_NULL (-2) - Either code or subject was passed as NULL, or ovector was NULL and + Either code or subject was passed as NULL, or ovector was NULL and ovecsize was not zero. PCRE_ERROR_BADOPTION (-3) @@ -2274,82 +2401,82 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION PCRE_ERROR_BADMAGIC (-4) - PCRE stores a 4-byte "magic number" at the start of the compiled code, + 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 + an environment with the other endianness. This is the error that PCRE gives when the magic number is not present. PCRE_ERROR_UNKNOWN_OPCODE (-5) 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 + compiled pattern. This error could be caused by a bug in PCRE or by overwriting of the compiled pattern. PCRE_ERROR_NOMEMORY (-6) - If a pattern contains back references, but the ovector that is passed + If a pattern contains back references, but the ovector that is passed to pcre_exec() 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 pcre_malloc() fails, this error is given. The + PCRE gets a block of memory at the start of matching to use for this + purpose. If the call via pcre_malloc() fails, this error is given. The memory is automatically freed at the end of matching. - This error is also given if pcre_stack_malloc() fails in pcre_exec(). - This can happen only when PCRE has been compiled with --disable-stack- + This error is also given if pcre_stack_malloc() fails in pcre_exec(). + This can happen only when PCRE has been compiled with --disable-stack- for-recursion. PCRE_ERROR_NOSUBSTRING (-7) - This error is used by the pcre_copy_substring(), pcre_get_substring(), + This error is used by the pcre_copy_substring(), pcre_get_substring(), and pcre_get_substring_list() functions (see below). It is never returned by pcre_exec(). PCRE_ERROR_MATCHLIMIT (-8) - The backtracking limit, as specified by the match_limit field in a - pcre_extra structure (or defaulted) was reached. See the description + The backtracking limit, as specified by the match_limit field in a + pcre_extra structure (or defaulted) was reached. See the description above. PCRE_ERROR_CALLOUT (-9) This error is never generated by pcre_exec() itself. It is provided for - use by callout functions that want to yield a distinctive error code. + use by callout functions that want to yield a distinctive error code. See the pcrecallout documentation for details. PCRE_ERROR_BADUTF8 (-10) - 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 (ovecsize) is at least 2, the byte offset to the - start of the the invalid UTF-8 character is placed in the first ele- - ment, and a reason code is placed in the second element. The reason + 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 (ovecsize) is at least 2, the byte offset to the + start of the the invalid UTF-8 character is placed in the first ele- + ment, and a reason code is placed in the second element. The reason codes are listed in the following section. For backward compatibility, - if PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8 char- - acter at the end of the subject (reason codes 1 to 5), + if PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8 char- + acter at the end of the subject (reason codes 1 to 5), PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8. PCRE_ERROR_BADUTF8_OFFSET (-11) - 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 startoffset did not point to the beginning of a UTF-8 charac- + 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 startoffset did not point to the beginning of a UTF-8 charac- ter or the end of the subject. PCRE_ERROR_PARTIAL (-12) - The subject string did not match, but it did match partially. See the + The subject string did not match, but it did match partially. See the pcrepartial documentation for details of partial matching. PCRE_ERROR_BADPARTIAL (-13) - 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 + 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. PCRE_ERROR_INTERNAL (-14) - An unexpected internal error has occurred. This error could be caused + An unexpected internal error has occurred. This error could be caused by a bug in PCRE or by overwriting of the compiled pattern. PCRE_ERROR_BADCOUNT (-15) @@ -2359,7 +2486,7 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION PCRE_ERROR_RECURSIONLIMIT (-21) The internal recursion limit, as specified by the match_limit_recursion - field in a pcre_extra structure (or defaulted) was reached. See the + field in a pcre_extra structure (or defaulted) was reached. See the description above. PCRE_ERROR_BADNEWLINE (-23) @@ -2373,24 +2500,31 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION PCRE_ERROR_SHORTUTF8 (-25) - 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 implementa- - tion of returned information; it is retained for backwards compatibil- + 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 implementa- + tion of returned information; it is retained for backwards compatibil- ity. PCRE_ERROR_RECURSELOOP (-26) This error is returned when pcre_exec() 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 + 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, + are detected and faulted at compile time, but more complicated cases, in particular mutual recursions between two different subpatterns, can- not be detected until run time. + PCRE_ERROR_JIT_STACKLIMIT (-27) + + This error is returned when a pattern that was successfully studied + using the PCRE_STUDY_JIT_COMPILE option is being matched, but the mem- + ory available for the just-in-time processing stack is not large + enough. See the pcrejit documentation for more details. + Error numbers -16 to -20 and -22 are not used by pcre_exec(). Reason codes for invalid UTF-8 strings @@ -2785,32 +2919,34 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION The strings are returned in reverse order of length; that is, the long- est matching string is given first. If there were too many matches to fit into ovector, the yield of the function is zero, and the vector is - filled with the longest matches. + filled with the longest matches. Unlike pcre_exec(), pcre_dfa_exec() + can use the entire ovector for returning matched strings. Error returns from pcre_dfa_exec() - The pcre_dfa_exec() function returns a negative number when it fails. - Many of the errors are the same as for pcre_exec(), and these are - described above. There are in addition the following errors that are + The pcre_dfa_exec() function returns a negative number when it fails. + Many of the errors are the same as for pcre_exec(), and these are + described above. There are in addition the following errors that are specific to pcre_dfa_exec(): PCRE_ERROR_DFA_UITEM (-16) - This return is given if pcre_dfa_exec() encounters an item in the pat- - tern that it does not support, for instance, the use of \C or a back + This return is given if pcre_dfa_exec() encounters an item in the pat- + tern that it does not support, for instance, the use of \C or a back reference. PCRE_ERROR_DFA_UCOND (-17) - This return is given if pcre_dfa_exec() encounters a condition item - that uses a back reference for the condition, or a test for recursion + This return is given if pcre_dfa_exec() 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. PCRE_ERROR_DFA_UMLIMIT (-18) - This return is given if pcre_dfa_exec() is called with an extra block - that contains a setting of the match_limit field. This is not supported - (it is meaningless). + This return is given if pcre_dfa_exec() is called with an extra block + that contains a setting of the match_limit or match_limit_recursion + fields. This is not supported (these fields are meaningless for DFA + matching). PCRE_ERROR_DFA_WSSIZE (-19) @@ -2840,11 +2976,11 @@ AUTHOR REVISION - Last updated: 13 August 2011 + Last updated: 06 September 2011 Copyright (c) 1997-2011 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCRECALLOUT(3) PCRECALLOUT(3) @@ -2888,6 +3024,10 @@ PCRE CALLOUTS pattern is matched. This is useful information when you are trying to optimize the performance of a particular pattern. + The use of callouts in a pattern makes it ineligible for optimization + by the just-in-time compiler. Studying such a pattern with the + PCRE_STUDY_JIT_COMPILE option always fails. + MISSING CALLOUTS @@ -3029,11 +3169,11 @@ AUTHOR REVISION - Last updated: 31 July 2011 + Last updated: 26 August 2011 Copyright (c) 1997-2011 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCRECOMPAT(3) PCRECOMPAT(3) @@ -3198,8 +3338,8 @@ REVISION Last updated: 24 August 2011 Copyright (c) 1997-2011 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREPATTERN(3) PCREPATTERN(3) @@ -5707,8 +5847,8 @@ REVISION Last updated: 24 August 2011 Copyright (c) 1997-2011 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCRESYNTAX(3) PCRESYNTAX(3) @@ -6077,8 +6217,8 @@ REVISION Last updated: 21 November 2010 Copyright (c) 1997-2010 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREUNICODE(3) PCREUNICODE(3) @@ -6150,64 +6290,71 @@ UTF-8 AND UNICODE PROPERTY SUPPORT If you pass an invalid UTF-8 string when PCRE_NO_UTF8_CHECK is set, what happens depends on why the string is invalid. If the string con- forms to the "old" definition of UTF-8 (RFC 2279), it is processed as a - string of characters in the range 0 to 0x7FFFFFFF. In other words, - apart from the initial validity test, PCRE (when in UTF-8 mode) handles - strings according to the more liberal rules of RFC 2279. However, if - the string does not even conform to RFC 2279, the result is undefined. - Your program may crash. + string of characters in the range 0 to 0x7FFFFFFF by pcre_dfa_exec() + and the interpreted version of pcre_exec(). In other words, apart from + the initial validity test, these functions (when in UTF-8 mode) handle + strings according to the more liberal rules of RFC 2279. However, the + just-in-time (JIT) optimization for pcre_exec() supports only RFC 3629. + If you are using JIT optimization, or if the string does not even con- + form to RFC 2279, the result is undefined. Your program may crash. If you want to process strings of values in the full range 0 to 0x7FFFFFFF, encoded in a UTF-8-like manner as per the old RFC, you can set PCRE_NO_UTF8_CHECK to bypass the more restrictive test. However, in - this situation, you will have to apply your own validity check. + this situation, you will have to apply your own validity check, and + avoid the use of JIT optimization. General comments about UTF-8 mode - 1. An unbraced hexadecimal escape sequence (such as \xb3) matches a + 1. An unbraced hexadecimal escape sequence (such as \xb3) matches a two-byte UTF-8 character if the value is greater than 127. - 2. Octal numbers up to \777 are recognized, and match two-byte UTF-8 + 2. Octal numbers up to \777 are recognized, and match two-byte UTF-8 characters for values greater than \177. - 3. Repeat quantifiers apply to complete UTF-8 characters, not to indi- + 3. Repeat quantifiers apply to complete UTF-8 characters, not to indi- vidual bytes, for example: \x{100}{3}. - 4. The dot metacharacter matches one UTF-8 character instead of a sin- + 4. The dot metacharacter matches one UTF-8 character instead of a sin- gle byte. - 5. The escape sequence \C can be used to match a single byte in UTF-8 - mode, but its use can lead to some strange effects. This facility is - not available in the alternative matching function, pcre_dfa_exec(). + 5. The escape sequence \C can be used to match a single byte in UTF-8 + mode, but its use can lead to some strange effects. This facility is + not available in the alternative matching function, pcre_dfa_exec(), + nor is it supported by the JIT optimization of pcre_exec(). If JIT + optimization is requested for a pattern that contains \C, it will not + succeed, and so the matching will be carried out by the normal inter- + pretive function. - 6. The character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly + 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 before, all with values less than 256. This remains true even - when PCRE is built to include Unicode property support, because to do + PCRE recognizes as digits, spaces, or word characters remain the same + set as before, 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}. Alterna- - tively, if you set the PCRE_UCP option, the way that the character - escapes work is changed so that Unicode properties are used to deter- - mine which characters match. There are more details in the section on + 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}. Alterna- + tively, if you set the PCRE_UCP option, the way that the character + escapes work is changed so that Unicode properties are used to deter- + mine which characters match. There are more details in the section on generic character types in the pcrepattern documentation. - 7. Similarly, characters that match the POSIX named character classes + 7. Similarly, characters that match the POSIX named character classes are all low-valued characters, unless the PCRE_UCP option is set. - 8. However, the horizontal and vertical whitespace matching escapes - (\h, \H, \v, and \V) do match all the appropriate Unicode characters, + 8. However, the horizontal and vertical whitespace matching escapes + (\h, \H, \v, and \V) do match all the appropriate Unicode characters, whether or not PCRE_UCP is set. - 9. Case-insensitive matching applies only to characters whose values - are less than 128, unless PCRE is built with Unicode property support. - Even when Unicode property support is available, PCRE still uses its - own character tables when checking the case of low-valued characters, - so as not to degrade performance. The Unicode property information is + 9. Case-insensitive matching applies only to characters whose values + are less than 128, unless PCRE is built with Unicode property support. + Even when Unicode property support is available, PCRE still uses its + own character tables when checking the case of low-valued characters, + so as not to degrade performance. The Unicode property information is used only for characters with higher values. Furthermore, PCRE supports - case-insensitive matching only when there is a one-to-one mapping - between a letter's cases. There are a small number of many-to-one map- + case-insensitive matching only when there is a one-to-one mapping + between a letter's cases. There are a small number of many-to-one map- pings in Unicode; these are not supported by PCRE. @@ -6220,14 +6367,262 @@ AUTHOR REVISION - Last updated: 24 August 2011 + Last updated: 06 September 2011 Copyright (c) 1997-2011 University of Cambridge. ------------------------------------------------------------------------------ - - + + +PCREJIT(3) PCREJIT(3) + + +NAME + PCRE - Perl-compatible regular expressions + + +PCRE JUST-IN-TIME COMPILER SUPPORT + + Just-in-time compiling is a heavyweight optimization that can greatly + speed up pattern matching. However, it comes at the cost of extra pro- + cessing 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 pcre_exec(); if the pattern is not + anchored, matching attempts may take place many times at various posi- + tions in the subject, even for a single call to pcre_exec(). If the + subject string is very long, it may still pay to use JIT for one-off + matches. + + JIT support applies only to the traditional matching function, + pcre_exec(). It does not apply when pcre_dfa_exec() is being used. The + code for this support was written by Zoltan Herczeg. + + +AVAILABILITY OF JIT SUPPORT + + 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: + + ARM v5, v7, and Thumb2 + Intel x86 32-bit and 64-bit + MIPS 32-bit + Power PC 32-bit and 64-bit + + If --enable-jit is set on an unsupported platform, compilation fails. + + A program can tell if JIT support is available by calling pcre_config() + 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 API is implemented in a way that falls back to + the ordinary PCRE code if JIT is not available. + + +SIMPLE USE OF JIT + + You have to do two things to make use of the JIT support in the sim- + plest way: + + (1) Call pcre_study() with the PCRE_STUDY_JIT_COMPILE option for + each compiled pattern, and pass the resulting pcre_extra block to + pcre_exec(). + + (2) Use pcre_free_study() to free the pcre_extra block when it is + no longer needed instead of just freeing it yourself. This + ensures that any JIT data is also freed. + + In some circumstances you may need to call additional functions. These + are described in the section entitled "Controlling the JIT stack" + below. + + If JIT support is not available, PCRE_STUDY_JIT_COMPILE is ignored, and + no JIT data is set up. 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 pcre_exec() is passed a + pcre_extra block containing a pointer to JIT code, it obeys that + instead of the normal code. The result is identical, but the code runs + much faster. + + There are some pcre_exec() options that are not supported for JIT exe- + cution. 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 the JIT compiler finds an unsupported item, no JIT data is gener- + ated. You can find out if JIT execution is available after studying a + pattern by calling pcre_fullinfo() with the PCRE_INFO_JIT option. A + result of 1 means that JIT compilationw was successful. A result of 0 + means that JIT support is not available, or the pattern was not studied + with PCRE_STUDY_JIT_COMPILE, or the JIT compiler was not able to handle + the pattern. + + +UNSUPPORTED OPTIONS AND PATTERN ITEMS + + The only pcre_exec() options that are supported for JIT execution are + PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and + PCRE_NOTEMPTY_ATSTART. Note in particular that partial matching is not + supported. + + The unsupported pattern items are: + + \C match a single byte, even in UTF-8 mode + (?Cn) callouts + (?(<name>)... conditional test on setting of a named subpattern + (?(R)... conditional test on whole pattern recursion + (?(Rn)... conditional test on recursion, by number + (?(R&name)... conditional test on recursion, by name + (*COMMIT) ) + (*MARK) ) + (*PRUNE) ) the backtracking control verbs + (*SKIP) ) + (*THEN) ) + + Support for some of these may be added in future. + + +RETURN VALUES FROM JIT EXECUTION + + When a pattern is matched using JIT execution, the return values are + the same as those given by the interpretive pcre_exec() 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 "Control- + ling the JIT stack" below for a discussion of JIT stack usage. For com- + patibility with the interpretive pcre_exec() code, no more than two- + thirds of the ovector argument is used for passing back captured sub- + strings. + + 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. + + +SAVING AND RESTORING COMPILED PATTERNS + + The code that is generated by the JIT compiler is architecture-spe- + cific, and is also position dependent. For those reasons it cannot be + saved and restored like the bytecode and other data of a compiled pat- + tern. You should be able run pcre_study() on a saved and restored pat- + tern, and thereby recreate the JIT data, but because JIT compilation + uses significant resources, it is probably not worth doing this. + + +CONTROLLING THE JIT STACK + + 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. + + The pcre_jit_stack_alloc() 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 pcre_jit_stack, or NULL if there is an error. + The pcre_jit_stack_free() 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.) + + 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. + + The pcre_assign_jit_stack() function specifies which stack JIT code + should use. Its arguments are as follows: + + pcre_extra *extra + pcre_jit_callback callback + void *data + + The extra argument must be the result of studying a pattern with + PCRE_STUDY_JIT_COMPILE. There are three cases for the values of the + other two options: + + (1) If callback is NULL and data is NULL, an internal 32K block + on the machine stack is used. + + (2) If callback is NULL and data is not NULL, data must be + a valid JIT stack, the result of calling pcre_jit_stack_alloc(). + + (3) If callback not NULL, it must point to a function that is called + with data 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 pcre_jit_stack_alloc(). + + You may safely assign the same JIT stack to more than one pattern, as + long as they are all matched sequentially in the same thread. In a mul- + tithread application, each thread must use its own JIT stack. + + Strictly speaking, even more is allowed. You can assign the same 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 inef- + ficient solution, and not recommended. + + This is a suggestion for how a typical multithreaded program might + operate: + + 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 + + All the functions described in this section do nothing if JIT is not + available, and pcre_assign_jit_stack() does nothing unless the extra + argument is non-NULL and points to a pcre_extra block that is the + result of a successful study with PCRE_STUDY_JIT_COMPILE. + + +EXAMPLE CODE + + This is a single-threaded example that specifies a JIT stack without + using a callback. + + 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); + + +SEE ALSO + + pcreapi(3) + + +AUTHOR + + Philip Hazel + University Computing Service + Cambridge CB2 3QH, England. + + +REVISION + + Last updated: 06 September 2011 + Copyright (c) 1997-2011 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREPARTIAL(3) PCREPARTIAL(3) @@ -6266,14 +6661,16 @@ PARTIAL MATCHING IN PCRE plete match, though the details differ between the two matching func- tions. If both options are set, PCRE_PARTIAL_HARD takes precedence. - Setting a partial matching option disables two of PCRE's optimizations. - PCRE remembers the last literal byte in a pattern, and abandons match- - ing immediately if such a byte 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. + Setting a partial matching option for pcre_exec() disables the use of + any just-in-time code that was set up by calling pcre_study() with the + PCRE_STUDY_JIT_COMPILE option. It also disables two of PCRE's standard + optimizations. PCRE remembers the last literal byte in a pattern, and + abandons matching immediately if such a byte is not present in the sub- + ject 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 dis- + abled for partial matching. PARTIAL MATCHING USING pcre_exec() @@ -6643,11 +7040,11 @@ AUTHOR REVISION - Last updated: 07 November 2010 - Copyright (c) 1997-2010 University of Cambridge. + Last updated: 26 August 2011 + Copyright (c) 1997-2011 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREPRECOMPILE(3) PCREPRECOMPILE(3) @@ -6662,7 +7059,9 @@ SAVING AND RE-USING PRECOMPILED PCRE PATTERNS form instead of having to compile them every time the application is run. If you are not using any private character tables (see the pcre_maketables() documentation), this is relatively straightforward. - If you are using private tables, it is a little bit more complicated. + If you are using private tables, it is a little bit more complicated. + However, if you are using the just-in-time optimization feature of + pcre_study(), it is not possible to save and reload the JIT data. If you save compiled patterns to a file, you can copy them to a differ- ent host and run them there. This works even if the new host has the @@ -6670,16 +7069,17 @@ SAVING AND RE-USING PRECOMPILED PCRE PATTERNS There may be a small performance penalty, but it should be insignifi- cant. However, compiling regular expressions with one version of PCRE for use with a different version is not guaranteed to work and may - cause crashes. + cause crashes, and saving and restoring a compiled pattern loses any + JIT optimization data. SAVING A COMPILED PATTERN The value returned by pcre_compile() 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 pcre_fullinfo() with an argu- - ment of PCRE_INFO_SIZE. You can then save the data in any appropriate - manner. Here is sample code that compiles a pattern and writes it to a + that holds the compiled pattern and associated data. You can find the + length of this block in bytes by calling pcre_fullinfo() with an argu- + ment of PCRE_INFO_SIZE. You can then save the data in any appropriate + manner. Here is sample code that compiles a pattern and writes it to a file. It assumes that the variable fd refers to a file that is open for output: @@ -6694,62 +7094,65 @@ SAVING A COMPILED PATTERN rc = fwrite(re, 1, size, fd); if (rc != size) { ... handle errors ... } - 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 + 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. - 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 pat- - tern with its length is probably the most straightforward approach. - Another possibility is to write out the data in hexadecimal instead of + 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 pat- + tern 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. - 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 + 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. - If the pattern has been studied, it is also possible to save the study - data in a similar way to the compiled pattern itself. When studying - generates additional information, pcre_study() returns a pointer to a - pcre_extra data block. Its format is defined in the section on matching - a pattern in the pcreapi documentation. The study_data field points to - the binary study data, and this is what you must save (not the - pcre_extra block itself). The length of the study data can be obtained - by calling pcre_fullinfo() with an argument of PCRE_INFO_STUDYSIZE. - Remember to check that pcre_study() did return a non-NULL value before - trying to save the study data. + 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 cre- + ated cannot be saved because it is too dependent on the current envi- + ronment. When studying generates additional information, pcre_study() + returns a pointer to a pcre_extra data block. Its format is defined in + the section on matching a pattern in the pcreapi documentation. The + study_data field points to the binary study data, and this is what you + must save (not the pcre_extra block itself). The length of the study + data can be obtained by calling pcre_fullinfo() with an argument of + PCRE_INFO_STUDYSIZE. Remember to check that pcre_study() did return a + non-NULL value before trying to save the study data. RE-USING A PRECOMPILED PATTERN - Re-using a precompiled pattern is straightforward. Having reloaded it - into main memory, you pass its pointer to pcre_exec() or - pcre_dfa_exec() in the usual way. This should work even on another - host, and even if that host has the opposite endianness to the one + Re-using a precompiled pattern is straightforward. Having reloaded it + into main memory, you pass its pointer to pcre_exec() or + pcre_dfa_exec() in the usual way. This should work even on another + host, and even if that host has the opposite endianness to the one where the pattern was compiled. - However, if you passed a pointer to custom character tables when the - pattern was compiled (the tableptr argument of pcre_compile()), you - must now pass a similar pointer to pcre_exec() or pcre_dfa_exec(), - because the value saved with the compiled pattern will obviously be + However, if you passed a pointer to custom character tables when the + pattern was compiled (the tableptr argument of pcre_compile()), you + must now pass a similar pointer to pcre_exec() or pcre_dfa_exec(), + because the value saved with the compiled pattern will obviously be nonsense. A field in a pcre_extra() block is used to pass this data, as - described in the section on matching a pattern in the pcreapi documen- + described in the section on matching a pattern in the pcreapi documen- tation. - If you did not provide custom character tables when the pattern was - compiled, the pointer in the compiled pattern is NULL, which causes - pcre_exec() to use PCRE's internal tables. Thus, you do not need to + If you did not provide custom character tables when the pattern was + compiled, the pointer in the compiled pattern is NULL, which causes + pcre_exec() to use PCRE's internal tables. Thus, you do not need to take any special action at run time in this case. - If you saved study data with the compiled pattern, you need to create + If you saved study data with the compiled pattern, you need to create your own pcre_extra data block and set the study_data field to point to - the reloaded study data. You must also set the PCRE_EXTRA_STUDY_DATA - bit in the flags field to indicate that study data is present. Then - pass the pcre_extra block to pcre_exec() or pcre_dfa_exec() in the - usual way. + the reloaded study data. You must also set the PCRE_EXTRA_STUDY_DATA + bit in the flags field to indicate that study data is present. Then + pass the pcre_extra block to pcre_exec() or pcre_dfa_exec() 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. COMPATIBILITY WITH DIFFERENT PCRE RELEASES @@ -6768,11 +7171,11 @@ AUTHOR REVISION - Last updated: 17 November 2010 - Copyright (c) 1997-2010 University of Cambridge. + Last updated: 26 August 2011 + Copyright (c) 1997-2011 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREPERFORM(3) PCREPERFORM(3) @@ -6939,8 +7342,8 @@ REVISION Last updated: 16 May 2010 Copyright (c) 1997-2010 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREPOSIX(3) PCREPOSIX(3) @@ -7202,8 +7605,8 @@ REVISION Last updated: 16 May 2010 Copyright (c) 1997-2010 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCRECPP(3) PCRECPP(3) @@ -7544,8 +7947,8 @@ REVISION Last updated: 17 March 2009 Minor typo fixed: 25 July 2011 ------------------------------------------------------------------------------ - - + + PCRESAMPLE(3) PCRESAMPLE(3) @@ -7679,8 +8082,8 @@ REVISION Last updated: 24 August 2011 Copyright (c) 1997-2011 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCRESTACK(3) PCRESTACK(3) @@ -7706,6 +8109,14 @@ PCRE DISCUSSION OF STACK USAGE result of the current call (a "tail recursion"), the function is just restarted instead. + The above comments apply when pcre_exec() is run in its normal inter- + pretive manner. If the pattern was studied with the PCRE_STUDY_JIT_COM- + PILE option, and just-in-time compiling was successful, and the options + passed to pcre_exec() were not incompatible, the matching process uses + the JIT-compiled code instead of the match() function. In this case, + the memory requirements are handled entirely differently. See the pcre- + jit documentation for details. + The pcre_dfa_exec() 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 asser- @@ -7717,7 +8128,7 @@ PCRE DISCUSSION OF STACK USAGE stack. At present, there is no protection against this. The comments that follow do NOT apply to pcre_dfa_exec(); they are rel- - evant only for pcre_exec(). + evant only for pcre_exec() without the JIT optimization. Reducing pcre_exec()'s stack usage @@ -7829,8 +8240,8 @@ AUTHOR REVISION - Last updated: 22 July 2011 + Last updated: 26 August 2011 Copyright (c) 1997-2011 University of Cambridge. ------------------------------------------------------------------------------ - - + + |