| <html> |
| <head> |
| <title>pcreapi specification</title> |
| </head> |
| <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB"> |
| <h1>pcreapi man page</h1> |
| <p> |
| Return to the <a href="index.html">PCRE index page</a>. |
| </p> |
| <p> |
| This page is part of the PCRE HTML documentation. It was generated automatically |
| from the original man page. If there is any nonsense in it, please consult the |
| man page, in case the conversion went wrong. |
| <br> |
| <ul> |
| <li><a name="TOC1" href="#SEC1">PCRE NATIVE API BASIC FUNCTIONS</a> |
| <li><a name="TOC2" href="#SEC2">PCRE NATIVE API AUXILIARY FUNCTIONS</a> |
| <li><a name="TOC3" href="#SEC3">PCRE NATIVE API INDIRECTED FUNCTIONS</a> |
| <li><a name="TOC4" href="#SEC4">PCRE API OVERVIEW</a> |
| <li><a name="TOC5" href="#SEC5">NEWLINES</a> |
| <li><a name="TOC6" href="#SEC6">MULTITHREADING</a> |
| <li><a name="TOC7" href="#SEC7">SAVING PRECOMPILED PATTERNS FOR LATER USE</a> |
| <li><a name="TOC8" href="#SEC8">CHECKING BUILD-TIME OPTIONS</a> |
| <li><a name="TOC9" href="#SEC9">COMPILING A PATTERN</a> |
| <li><a name="TOC10" href="#SEC10">COMPILATION ERROR CODES</a> |
| <li><a name="TOC11" href="#SEC11">STUDYING A PATTERN</a> |
| <li><a name="TOC12" href="#SEC12">LOCALE SUPPORT</a> |
| <li><a name="TOC13" href="#SEC13">INFORMATION ABOUT A PATTERN</a> |
| <li><a name="TOC14" href="#SEC14">OBSOLETE INFO FUNCTION</a> |
| <li><a name="TOC15" href="#SEC15">REFERENCE COUNTS</a> |
| <li><a name="TOC16" href="#SEC16">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a> |
| <li><a name="TOC17" href="#SEC17">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a> |
| <li><a name="TOC18" href="#SEC18">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a> |
| <li><a name="TOC19" href="#SEC19">DUPLICATE SUBPATTERN NAMES</a> |
| <li><a name="TOC20" href="#SEC20">FINDING ALL POSSIBLE MATCHES</a> |
| <li><a name="TOC21" href="#SEC21">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a> |
| <li><a name="TOC22" href="#SEC22">SEE ALSO</a> |
| <li><a name="TOC23" href="#SEC23">AUTHOR</a> |
| <li><a name="TOC24" href="#SEC24">REVISION</a> |
| </ul> |
| <br><a name="SEC1" href="#TOC1">PCRE NATIVE API BASIC FUNCTIONS</a><br> |
| <P> |
| <b>#include <pcre.h></b> |
| </P> |
| <P> |
| <b>pcre *pcre_compile(const char *<i>pattern</i>, int <i>options</i>,</b> |
| <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b> |
| <b>const unsigned char *<i>tableptr</i>);</b> |
| </P> |
| <P> |
| <b>pcre *pcre_compile2(const char *<i>pattern</i>, int <i>options</i>,</b> |
| <b>int *<i>errorcodeptr</i>,</b> |
| <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b> |
| <b>const unsigned char *<i>tableptr</i>);</b> |
| </P> |
| <P> |
| <b>pcre_extra *pcre_study(const pcre *<i>code</i>, int <i>options</i>,</b> |
| <b>const char **<i>errptr</i>);</b> |
| </P> |
| <P> |
| <b>void pcre_free_study(pcre_extra *<i>extra</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b> |
| <b>const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b> |
| <b>int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>);</b> |
| </P> |
| <br><a name="SEC2" href="#TOC1">PCRE NATIVE API AUXILIARY FUNCTIONS</a><br> |
| <P> |
| <b>pcre_jit_stack *pcre_jit_stack_alloc(int <i>startsize</i>, int <i>maxsize</i>);</b> |
| </P> |
| <P> |
| <b>void pcre_jit_stack_free(pcre_jit_stack *<i>stack</i>);</b> |
| </P> |
| <P> |
| <b>void pcre_assign_jit_stack(pcre_extra *<i>extra</i>,</b> |
| <b>pcre_jit_callback <i>callback</i>, void *<i>data</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_dfa_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b> |
| <b>const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b> |
| <b>int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b> |
| <b>int *<i>workspace</i>, int <i>wscount</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b> |
| <b>const char *<i>subject</i>, int *<i>ovector</i>,</b> |
| <b>int <i>stringcount</i>, const char *<i>stringname</i>,</b> |
| <b>char *<i>buffer</i>, int <i>buffersize</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_copy_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b> |
| <b>int <i>stringcount</i>, int <i>stringnumber</i>, char *<i>buffer</i>,</b> |
| <b>int <i>buffersize</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_get_named_substring(const pcre *<i>code</i>,</b> |
| <b>const char *<i>subject</i>, int *<i>ovector</i>,</b> |
| <b>int <i>stringcount</i>, const char *<i>stringname</i>,</b> |
| <b>const char **<i>stringptr</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b> |
| <b>const char *<i>name</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b> |
| <b>const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_get_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b> |
| <b>int <i>stringcount</i>, int <i>stringnumber</i>,</b> |
| <b>const char **<i>stringptr</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_get_substring_list(const char *<i>subject</i>,</b> |
| <b>int *<i>ovector</i>, int <i>stringcount</i>, const char ***<i>listptr</i>);</b> |
| </P> |
| <P> |
| <b>void pcre_free_substring(const char *<i>stringptr</i>);</b> |
| </P> |
| <P> |
| <b>void pcre_free_substring_list(const char **<i>stringptr</i>);</b> |
| </P> |
| <P> |
| <b>const unsigned char *pcre_maketables(void);</b> |
| </P> |
| <P> |
| <b>int pcre_fullinfo(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b> |
| <b>int <i>what</i>, void *<i>where</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_info(const pcre *<i>code</i>, int *<i>optptr</i>, int</b> |
| <b>*<i>firstcharptr</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_refcount(pcre *<i>code</i>, int <i>adjust</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_config(int <i>what</i>, void *<i>where</i>);</b> |
| </P> |
| <P> |
| <b>char *pcre_version(void);</b> |
| </P> |
| <br><a name="SEC3" href="#TOC1">PCRE NATIVE API INDIRECTED FUNCTIONS</a><br> |
| <P> |
| <b>void *(*pcre_malloc)(size_t);</b> |
| </P> |
| <P> |
| <b>void (*pcre_free)(void *);</b> |
| </P> |
| <P> |
| <b>void *(*pcre_stack_malloc)(size_t);</b> |
| </P> |
| <P> |
| <b>void (*pcre_stack_free)(void *);</b> |
| </P> |
| <P> |
| <b>int (*pcre_callout)(pcre_callout_block *);</b> |
| </P> |
| <br><a name="SEC4" href="#TOC1">PCRE API OVERVIEW</a><br> |
| <P> |
| PCRE has its own native API, which is described in this document. There are |
| also some wrapper functions that correspond to the POSIX regular expression |
| API, but they do not give access to all the functionality. They are described |
| in the |
| <a href="pcreposix.html"><b>pcreposix</b></a> |
| documentation. Both of these APIs define a set of C function calls. A C++ |
| wrapper is also distributed with PCRE. It is documented in the |
| <a href="pcrecpp.html"><b>pcrecpp</b></a> |
| page. |
| </P> |
| <P> |
| The native API C function prototypes are defined in the header file |
| <b>pcre.h</b>, and on Unix systems the library itself is called <b>libpcre</b>. |
| It can normally be accessed by adding <b>-lpcre</b> to the command for linking |
| an application that uses PCRE. The header file defines the macros PCRE_MAJOR |
| and PCRE_MINOR to contain the major and minor release numbers for the library. |
| Applications can use these to include support for different releases of PCRE. |
| </P> |
| <P> |
| In a Windows environment, if you want to statically link an application program |
| against a non-dll <b>pcre.a</b> file, you must define PCRE_STATIC before |
| including <b>pcre.h</b> or <b>pcrecpp.h</b>, because otherwise the |
| <b>pcre_malloc()</b> and <b>pcre_free()</b> exported functions will be declared |
| <b>__declspec(dllimport)</b>, with unwanted results. |
| </P> |
| <P> |
| The functions <b>pcre_compile()</b>, <b>pcre_compile2()</b>, <b>pcre_study()</b>, |
| and <b>pcre_exec()</b> are used for compiling and matching regular expressions |
| in a Perl-compatible manner. A sample program that demonstrates the simplest |
| way of using them is provided in the file called <i>pcredemo.c</i> in the PCRE |
| source distribution. A listing of this program is given in the |
| <a href="pcredemo.html"><b>pcredemo</b></a> |
| documentation, and the |
| <a href="pcresample.html"><b>pcresample</b></a> |
| documentation describes how to compile and run it. |
| </P> |
| <P> |
| Just-in-time compiler support is an optional feature of PCRE that can be built |
| in appropriate hardware environments. It greatly speeds up the matching |
| performance of many patterns. Simple programs can easily request that it be |
| used if available, by setting an option that is ignored when it is not |
| relevant. More complicated programs might need to make use of the functions |
| <b>pcre_jit_stack_alloc()</b>, <b>pcre_jit_stack_free()</b>, and |
| <b>pcre_assign_jit_stack()</b> in order to control the JIT code's memory usage. |
| These functions are discussed in the |
| <a href="pcrejit.html"><b>pcrejit</b></a> |
| documentation. |
| </P> |
| <P> |
| A second matching function, <b>pcre_dfa_exec()</b>, which is not |
| Perl-compatible, is also provided. This uses a different algorithm for the |
| matching. The alternative algorithm finds all possible matches (at a given |
| point in the subject), and scans the subject just once (unless there are |
| lookbehind assertions). However, this algorithm does not return captured |
| substrings. A description of the two matching algorithms and their advantages |
| and disadvantages is given in the |
| <a href="pcrematching.html"><b>pcrematching</b></a> |
| documentation. |
| </P> |
| <P> |
| In addition to the main compiling and matching functions, there are convenience |
| functions for extracting captured substrings from a subject string that is |
| matched by <b>pcre_exec()</b>. They are: |
| <pre> |
| <b>pcre_copy_substring()</b> |
| <b>pcre_copy_named_substring()</b> |
| <b>pcre_get_substring()</b> |
| <b>pcre_get_named_substring()</b> |
| <b>pcre_get_substring_list()</b> |
| <b>pcre_get_stringnumber()</b> |
| <b>pcre_get_stringtable_entries()</b> |
| </pre> |
| <b>pcre_free_substring()</b> and <b>pcre_free_substring_list()</b> are also |
| provided, to free the memory used for extracted strings. |
| </P> |
| <P> |
| The function <b>pcre_maketables()</b> is used to build a set of character tables |
| in the current locale for passing to <b>pcre_compile()</b>, <b>pcre_exec()</b>, |
| or <b>pcre_dfa_exec()</b>. This is an optional facility that is provided for |
| specialist use. Most commonly, no special tables are passed, in which case |
| internal tables that are generated when PCRE is built are used. |
| </P> |
| <P> |
| The function <b>pcre_fullinfo()</b> is used to find out information about a |
| compiled pattern; <b>pcre_info()</b> is an obsolete version that returns only |
| some of the available information, but is retained for backwards compatibility. |
| The function <b>pcre_version()</b> returns a pointer to a string containing the |
| version of PCRE and its date of release. |
| </P> |
| <P> |
| The function <b>pcre_refcount()</b> maintains a reference count in a data block |
| containing a compiled pattern. This is provided for the benefit of |
| object-oriented applications. |
| </P> |
| <P> |
| The global variables <b>pcre_malloc</b> and <b>pcre_free</b> initially contain |
| the entry points of the standard <b>malloc()</b> and <b>free()</b> functions, |
| respectively. PCRE calls the memory management functions via these variables, |
| so a calling program can replace them if it wishes to intercept the calls. This |
| should be done before calling any PCRE functions. |
| </P> |
| <P> |
| The global variables <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> are also |
| indirections to memory management functions. These special functions are used |
| only when PCRE is compiled to use the heap for remembering data, instead of |
| recursive function calls, when running the <b>pcre_exec()</b> function. See the |
| <a href="pcrebuild.html"><b>pcrebuild</b></a> |
| documentation for details of how to do this. It is a non-standard way of |
| building PCRE, for use in environments that have limited stacks. Because of the |
| greater use of memory management, it runs more slowly. Separate functions are |
| provided so that special-purpose external code can be used for this case. When |
| used, these functions 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 |
| <a href="pcrestack.html"><b>pcrestack</b></a> |
| documentation. |
| </P> |
| <P> |
| The global variable <b>pcre_callout</b> initially contains NULL. It can be set |
| by the caller to a "callout" function, which PCRE will then call at specified |
| points during a matching operation. Details are given in the |
| <a href="pcrecallout.html"><b>pcrecallout</b></a> |
| documentation. |
| <a name="newlines"></a></P> |
| <br><a name="SEC5" href="#TOC1">NEWLINES</a><br> |
| <P> |
| PCRE supports five different conventions for indicating line breaks in |
| strings: a single CR (carriage return) character, a single LF (linefeed) |
| character, the two-character sequence CRLF, any of the three preceding, or any |
| Unicode newline sequence. The Unicode newline sequences are the three just |
| mentioned, plus the single characters VT (vertical tab, U+000B), FF (formfeed, |
| U+000C), NEL (next line, U+0085), LS (line separator, U+2028), and PS |
| (paragraph separator, U+2029). |
| </P> |
| <P> |
| Each of the first three conventions is used by at least one operating system as |
| its standard newline sequence. When PCRE is built, a default can be specified. |
| The default default is LF, which is the Unix standard. When PCRE is run, the |
| default can be overridden, either when a pattern is compiled, or when it is |
| matched. |
| </P> |
| <P> |
| At compile time, the newline convention can be specified by the <i>options</i> |
| argument of <b>pcre_compile()</b>, or it can be specified by special text at the |
| start of the pattern itself; this overrides any other settings. See the |
| <a href="pcrepattern.html"><b>pcrepattern</b></a> |
| page for details of the special character sequences. |
| </P> |
| <P> |
| In the PCRE documentation the word "newline" is used to mean "the character or |
| pair of characters that indicate a line break". The choice of newline |
| convention affects the handling of the dot, circumflex, and dollar |
| metacharacters, the handling of #-comments in /x mode, and, when CRLF is a |
| recognized line ending sequence, the match position advancement for a |
| non-anchored pattern. There is more detail about this in the |
| <a href="#execoptions">section on <b>pcre_exec()</b> options</a> |
| below. |
| </P> |
| <P> |
| The choice of newline convention does not affect the interpretation of |
| the \n or \r escape sequences, nor does it affect what \R matches, which is |
| controlled in a similar way, but by separate options. |
| </P> |
| <br><a name="SEC6" href="#TOC1">MULTITHREADING</a><br> |
| <P> |
| The PCRE functions can be used in multi-threading applications, with the |
| proviso that the memory management functions pointed to by <b>pcre_malloc</b>, |
| <b>pcre_free</b>, <b>pcre_stack_malloc</b>, and <b>pcre_stack_free</b>, and the |
| callout function pointed to by <b>pcre_callout</b>, are shared by all threads. |
| </P> |
| <P> |
| The compiled form of a regular expression is not altered during matching, so |
| the same compiled pattern can safely be used by several threads at once. |
| </P> |
| <P> |
| If the just-in-time optimization feature is being used, it needs separate |
| memory stack areas for each thread. See the |
| <a href="pcrejit.html"><b>pcrejit</b></a> |
| documentation for more details. |
| </P> |
| <br><a name="SEC7" href="#TOC1">SAVING PRECOMPILED PATTERNS FOR LATER USE</a><br> |
| <P> |
| The compiled form of a regular expression can be saved and re-used at a later |
| time, possibly by a different program, and even on a host other than the one on |
| which it was compiled. Details are given in the |
| <a href="pcreprecompile.html"><b>pcreprecompile</b></a> |
| documentation. However, compiling a regular expression with one version of PCRE |
| for use with a different version is not guaranteed to work and may cause |
| crashes. |
| </P> |
| <br><a name="SEC8" href="#TOC1">CHECKING BUILD-TIME OPTIONS</a><br> |
| <P> |
| <b>int pcre_config(int <i>what</i>, void *<i>where</i>);</b> |
| </P> |
| <P> |
| The function <b>pcre_config()</b> makes it possible for a PCRE client to |
| discover which optional features have been compiled into the PCRE library. The |
| <a href="pcrebuild.html"><b>pcrebuild</b></a> |
| documentation has more details about these optional features. |
| </P> |
| <P> |
| The first argument for <b>pcre_config()</b> is an integer, specifying which |
| information is required; the second argument is a pointer to a variable into |
| which the information is placed. The following information is available: |
| <pre> |
| PCRE_CONFIG_UTF8 |
| </pre> |
| The output is an integer that is set to one if UTF-8 support is available; |
| otherwise it is set to zero. |
| <pre> |
| PCRE_CONFIG_UNICODE_PROPERTIES |
| </pre> |
| The output is an integer that is set to one if support for Unicode character |
| properties is available; otherwise it is set to zero. |
| <pre> |
| PCRE_CONFIG_JIT |
| </pre> |
| The output is an integer that is set to one if support for just-in-time |
| compiling is available; otherwise it is set to zero. |
| <pre> |
| PCRE_CONFIG_NEWLINE |
| </pre> |
| The output is an integer whose value specifies the default character sequence |
| that is recognized as meaning "newline". The four values that are supported |
| are: 10 for LF, 13 for CR, 3338 for CRLF, -2 for ANYCRLF, and -1 for ANY. |
| Though they are derived from ASCII, the same values are returned in EBCDIC |
| environments. The default should normally correspond to the standard sequence |
| for your operating system. |
| <pre> |
| PCRE_CONFIG_BSR |
| </pre> |
| The output is an integer whose value indicates what character sequences the \R |
| escape sequence matches by default. A value of 0 means that \R matches any |
| Unicode line ending sequence; a value of 1 means that \R matches only CR, LF, |
| or CRLF. The default can be overridden when a pattern is compiled or matched. |
| <pre> |
| PCRE_CONFIG_LINK_SIZE |
| </pre> |
| The output is an integer that contains the number of bytes used for internal |
| linkage in compiled regular expressions. The value is 2, 3, or 4. Larger values |
| allow larger regular expressions to be compiled, at the expense of slower |
| matching. The default value of 2 is sufficient for all but the most massive |
| patterns, since it allows the compiled pattern to be up to 64K in size. |
| <pre> |
| PCRE_CONFIG_POSIX_MALLOC_THRESHOLD |
| </pre> |
| The output is an integer that contains the threshold above which the POSIX |
| interface uses <b>malloc()</b> for output vectors. Further details are given in |
| the |
| <a href="pcreposix.html"><b>pcreposix</b></a> |
| documentation. |
| <pre> |
| PCRE_CONFIG_MATCH_LIMIT |
| </pre> |
| The output is a long integer that gives the default limit for the number of |
| internal matching function calls in a <b>pcre_exec()</b> execution. Further |
| details are given with <b>pcre_exec()</b> below. |
| <pre> |
| PCRE_CONFIG_MATCH_LIMIT_RECURSION |
| </pre> |
| The output is a long integer that gives the default limit for the depth of |
| recursion when calling the internal matching function in a <b>pcre_exec()</b> |
| execution. Further details are given with <b>pcre_exec()</b> below. |
| <pre> |
| PCRE_CONFIG_STACKRECURSE |
| </pre> |
| The output is an integer that is set to one if internal recursion when running |
| <b>pcre_exec()</b> is implemented by recursive function calls that use the stack |
| to remember their state. This is the usual way that PCRE is compiled. The |
| output is zero if PCRE was compiled to use blocks of data on the heap instead |
| of recursive function calls. In this case, <b>pcre_stack_malloc</b> and |
| <b>pcre_stack_free</b> are called to manage memory blocks on the heap, thus |
| avoiding the use of the stack. |
| </P> |
| <br><a name="SEC9" href="#TOC1">COMPILING A PATTERN</a><br> |
| <P> |
| <b>pcre *pcre_compile(const char *<i>pattern</i>, int <i>options</i>,</b> |
| <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b> |
| <b>const unsigned char *<i>tableptr</i>);</b> |
| <b>pcre *pcre_compile2(const char *<i>pattern</i>, int <i>options</i>,</b> |
| <b>int *<i>errorcodeptr</i>,</b> |
| <b>const char **<i>errptr</i>, int *<i>erroffset</i>,</b> |
| <b>const unsigned char *<i>tableptr</i>);</b> |
| </P> |
| <P> |
| Either of the functions <b>pcre_compile()</b> or <b>pcre_compile2()</b> can be |
| called to compile a pattern into an internal form. The only difference between |
| the two interfaces is that <b>pcre_compile2()</b> has an additional argument, |
| <i>errorcodeptr</i>, via which a numerical error code can be returned. To avoid |
| too much repetition, we refer just to <b>pcre_compile()</b> below, but the |
| information applies equally to <b>pcre_compile2()</b>. |
| </P> |
| <P> |
| The pattern is a C string terminated by a binary zero, and is passed in the |
| <i>pattern</i> argument. A pointer to a single block of memory that is obtained |
| via <b>pcre_malloc</b> is returned. This contains the compiled code and related |
| data. The <b>pcre</b> type is defined for the returned block; this is a typedef |
| for a structure whose contents are not externally defined. It is up to the |
| caller to free the memory (via <b>pcre_free</b>) when it is no longer required. |
| </P> |
| <P> |
| Although the compiled code of a PCRE regex is relocatable, that is, it does not |
| depend on memory location, the complete <b>pcre</b> data block is not |
| fully relocatable, because it may contain a copy of the <i>tableptr</i> |
| argument, which is an address (see below). |
| </P> |
| <P> |
| The <i>options</i> argument contains various bit settings that affect the |
| compilation. It should be zero if no options are required. The available |
| options are described below. Some of them (in particular, those that are |
| compatible with Perl, but some others as well) can also be set and unset from |
| within the pattern (see the detailed description in the |
| <a href="pcrepattern.html"><b>pcrepattern</b></a> |
| documentation). For those options that can be different in different parts of |
| the pattern, the contents of the <i>options</i> argument specifies their |
| settings at the start of compilation and execution. The PCRE_ANCHORED, |
| PCRE_BSR_<i>xxx</i>, PCRE_NEWLINE_<i>xxx</i>, PCRE_NO_UTF8_CHECK, and |
| PCRE_NO_START_OPT options can be set at the time of matching as well as at |
| compile time. |
| </P> |
| <P> |
| If <i>errptr</i> is NULL, <b>pcre_compile()</b> returns NULL immediately. |
| Otherwise, if compilation of a pattern fails, <b>pcre_compile()</b> returns |
| NULL, and sets the variable pointed to by <i>errptr</i> to point to a textual |
| error message. This is a static string that is part of the library. You must |
| not try to free it. Normally, the offset from the start of the pattern to the |
| byte that was being processed when the error was discovered is placed in the |
| variable pointed to by <i>erroffset</i>, which must not be NULL (if it is, an |
| immediate error is given). However, for an invalid UTF-8 string, the offset is |
| that of the first byte of the failing character. Also, some errors are not |
| detected until checks are carried out when the whole pattern has been scanned; |
| in these cases the offset passed back is the length of the pattern. |
| </P> |
| <P> |
| Note that the offset is in bytes, not characters, even in UTF-8 mode. It may |
| sometimes point into the middle of a UTF-8 character. |
| </P> |
| <P> |
| If <b>pcre_compile2()</b> is used instead of <b>pcre_compile()</b>, and the |
| <i>errorcodeptr</i> argument is not NULL, a non-zero error code number is |
| returned via this argument in the event of an error. This is in addition to the |
| textual error message. Error codes and messages are listed below. |
| </P> |
| <P> |
| If the final argument, <i>tableptr</i>, is NULL, PCRE uses a default set of |
| character tables that are built when PCRE is compiled, using the default C |
| locale. Otherwise, <i>tableptr</i> must be an address that is the result of a |
| call to <b>pcre_maketables()</b>. This value is stored with the compiled |
| pattern, and used again by <b>pcre_exec()</b>, unless another table pointer is |
| passed to it. For more discussion, see the section on locale support below. |
| </P> |
| <P> |
| This code fragment shows a typical straightforward call to <b>pcre_compile()</b>: |
| <pre> |
| pcre *re; |
| const char *error; |
| int erroffset; |
| re = pcre_compile( |
| "^A.*Z", /* the pattern */ |
| 0, /* default options */ |
| &error, /* for error message */ |
| &erroffset, /* for error offset */ |
| NULL); /* use default character tables */ |
| </pre> |
| The following names for option bits are defined in the <b>pcre.h</b> header |
| file: |
| <pre> |
| PCRE_ANCHORED |
| </pre> |
| If this bit is set, the pattern is forced to be "anchored", that is, it is |
| constrained to match only at the first matching point in the string that is |
| being searched (the "subject string"). This effect can also be achieved by |
| appropriate constructs in the pattern itself, which is the only way to do it in |
| Perl. |
| <pre> |
| PCRE_AUTO_CALLOUT |
| </pre> |
| If this bit is set, <b>pcre_compile()</b> automatically inserts callout items, |
| all with number 255, before each pattern item. For discussion of the callout |
| facility, see the |
| <a href="pcrecallout.html"><b>pcrecallout</b></a> |
| documentation. |
| <pre> |
| PCRE_BSR_ANYCRLF |
| PCRE_BSR_UNICODE |
| </pre> |
| These options (which are mutually exclusive) control what the \R escape |
| sequence matches. The choice is either to match only CR, LF, or CRLF, or to |
| match any Unicode newline sequence. The default is specified when PCRE is |
| built. It can be overridden from within the pattern, or by setting an option |
| when a compiled pattern is matched. |
| <pre> |
| PCRE_CASELESS |
| </pre> |
| If this bit is set, letters in the pattern match both upper and lower case |
| letters. It is equivalent to Perl's /i option, and it can be changed within a |
| pattern by a (?i) option setting. In UTF-8 mode, PCRE always understands the |
| concept of case for characters whose values are less than 128, so caseless |
| matching is always possible. For characters with higher values, the concept of |
| case is supported if PCRE is compiled with Unicode property support, but not |
| otherwise. If you want to use caseless matching for characters 128 and above, |
| you must ensure that PCRE is compiled with Unicode property support as well as |
| with UTF-8 support. |
| <pre> |
| PCRE_DOLLAR_ENDONLY |
| </pre> |
| If this bit is set, a dollar metacharacter in the pattern matches only at the |
| end of the subject string. Without this option, a dollar also matches |
| immediately before a newline at the end of the string (but not before any other |
| newlines). The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is set. |
| There is no equivalent to this option in Perl, and no way to set it within a |
| pattern. |
| <pre> |
| PCRE_DOTALL |
| </pre> |
| If this bit is set, a dot metacharacter in the pattern matches a character of |
| any value, including one that indicates a newline. However, it only ever |
| matches one character, even if newlines are coded as CRLF. Without this option, |
| a dot does not match when the current position is at a newline. This option is |
| equivalent to Perl's /s option, and it can be changed within a pattern by a |
| (?s) option setting. A negative class such as [^a] always matches newline |
| characters, independent of the setting of this option. |
| <pre> |
| PCRE_DUPNAMES |
| </pre> |
| If this bit is set, names used to identify capturing subpatterns need not be |
| unique. This can be helpful for certain types of pattern when it is known that |
| only one instance of the named subpattern can ever be matched. There are more |
| details of named subpatterns below; see also the |
| <a href="pcrepattern.html"><b>pcrepattern</b></a> |
| documentation. |
| <pre> |
| PCRE_EXTENDED |
| </pre> |
| If this bit is set, whitespace data characters in the pattern are totally |
| ignored except when escaped or inside a character class. Whitespace does not |
| include the VT character (code 11). In addition, characters between an |
| unescaped # outside a character class and the next newline, inclusive, are also |
| ignored. This is equivalent to Perl's /x option, and it can be changed within a |
| pattern by a (?x) option setting. |
| </P> |
| <P> |
| Which characters are interpreted as newlines is controlled by the options |
| passed to <b>pcre_compile()</b> or by a special sequence at the start of the |
| pattern, as described in the section entitled |
| <a href="pcrepattern.html#newlines">"Newline conventions"</a> |
| in the <b>pcrepattern</b> documentation. Note that the end of this type of |
| comment is a literal newline sequence in the pattern; escape sequences that |
| happen to represent a newline do not count. |
| </P> |
| <P> |
| This option makes it possible to include comments inside complicated patterns. |
| Note, however, that this applies only to data characters. Whitespace characters |
| may never appear within special character sequences in a pattern, for example |
| within the sequence (?( that introduces a conditional subpattern. |
| <pre> |
| PCRE_EXTRA |
| </pre> |
| This option was invented in order to turn on additional functionality of PCRE |
| that is incompatible with Perl, but it is currently of very little use. When |
| set, any backslash in a pattern that is followed by a letter that has no |
| special meaning causes an error, thus reserving these combinations for future |
| expansion. By default, as in Perl, a backslash followed by a letter with no |
| special meaning is treated as a literal. (Perl can, however, be persuaded to |
| give an error for this, by running it with the -w option.) There are at present |
| no other features controlled by this option. It can also be set by a (?X) |
| option setting within a pattern. |
| <pre> |
| PCRE_FIRSTLINE |
| </pre> |
| If this option is set, an unanchored pattern is required to match before or at |
| the first newline in the subject string, though the matched text may continue |
| over the newline. |
| <pre> |
| PCRE_JAVASCRIPT_COMPAT |
| </pre> |
| If this option is set, PCRE's behaviour is changed in some ways so that it is |
| compatible with JavaScript rather than Perl. The changes are as follows: |
| </P> |
| <P> |
| (1) A lone closing square bracket in a pattern causes a compile-time error, |
| because this is illegal in JavaScript (by default it is treated as a data |
| character). Thus, the pattern AB]CD becomes illegal when this option is set. |
| </P> |
| <P> |
| (2) At run time, a back reference to an unset subpattern group matches an empty |
| string (by default this causes the current matching alternative to fail). A |
| pattern such as (\1)(a) succeeds when this option is set (assuming it can find |
| an "a" in the subject), whereas it fails by default, for Perl compatibility. |
| </P> |
| <P> |
| (3) \U matches an upper case "U" character; by default \U causes a compile |
| time error (Perl uses \U to upper case subsequent characters). |
| </P> |
| <P> |
| (4) \u matches a lower case "u" character unless it is followed by four |
| hexadecimal digits, in which case the hexadecimal number defines the code point |
| to match. By default, \u causes a compile time error (Perl uses it to upper |
| case the following character). |
| </P> |
| <P> |
| (5) \x matches a lower case "x" character unless it is followed by two |
| hexadecimal digits, in which case the hexadecimal number defines the code point |
| to match. By default, as in Perl, a hexadecimal number is always expected after |
| \x, but it may have zero, one, or two digits (so, for example, \xz matches a |
| binary zero character followed by z). |
| <pre> |
| PCRE_MULTILINE |
| </pre> |
| By default, PCRE treats the subject string as consisting of a single line of |
| characters (even if it actually contains newlines). The "start of line" |
| metacharacter (^) matches only at the start of the string, while the "end of |
| line" metacharacter ($) matches only at the end of the string, or before a |
| terminating newline (unless PCRE_DOLLAR_ENDONLY is set). This is the same as |
| Perl. |
| </P> |
| <P> |
| When PCRE_MULTILINE it is set, the "start of line" and "end of line" constructs |
| match immediately following or immediately before internal newlines in the |
| subject string, respectively, as well as at the very start and end. This is |
| equivalent to Perl's /m option, and it can be changed within a pattern by a |
| (?m) option setting. If there are no newlines in a subject string, or no |
| occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect. |
| <pre> |
| PCRE_NEWLINE_CR |
| PCRE_NEWLINE_LF |
| PCRE_NEWLINE_CRLF |
| PCRE_NEWLINE_ANYCRLF |
| PCRE_NEWLINE_ANY |
| </pre> |
| These options override the default newline definition that was chosen when PCRE |
| was built. Setting the first or the second specifies that a newline is |
| indicated by a single character (CR or LF, respectively). Setting |
| PCRE_NEWLINE_CRLF specifies that a newline is indicated by the two-character |
| CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three |
| preceding sequences should be recognized. Setting PCRE_NEWLINE_ANY specifies |
| that any Unicode newline sequence should be recognized. 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). The last two are |
| recognized only in UTF-8 mode. |
| </P> |
| <P> |
| The newline setting in the options word uses three bits that are treated |
| as a number, giving eight possibilities. Currently only six are used (default |
| plus the five values above). This means that if you set more than one newline |
| option, the combination may or may not be sensible. For example, |
| PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to PCRE_NEWLINE_CRLF, but |
| other combinations may yield unused numbers and cause an error. |
| </P> |
| <P> |
| The only time that a line break in a pattern is specially recognized when |
| compiling is when PCRE_EXTENDED is set. CR and LF are whitespace characters, |
| and so are ignored in this mode. Also, an unescaped # outside a character class |
| indicates a comment that lasts until after the next line break sequence. In |
| other circumstances, line break sequences in patterns are treated as literal |
| data. |
| </P> |
| <P> |
| The newline option that is set at compile time becomes the default that is used |
| for <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, but it can be overridden. |
| <pre> |
| PCRE_NO_AUTO_CAPTURE |
| </pre> |
| If this option is set, it disables the use of numbered capturing parentheses in |
| the pattern. Any opening parenthesis that is not followed by ? behaves as if it |
| were followed by ?: but named parentheses can still be used for capturing (and |
| they acquire numbers in the usual way). There is no equivalent of this option |
| in Perl. |
| <pre> |
| NO_START_OPTIMIZE |
| </pre> |
| This is an option that acts at matching time; that is, it is really an option |
| for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>. If it is set at compile time, |
| it is remembered with the compiled pattern and assumed at matching time. For |
| details see the discussion of PCRE_NO_START_OPTIMIZE |
| <a href="#execoptions">below.</a> |
| <pre> |
| PCRE_UCP |
| </pre> |
| This option changes the way PCRE processes \B, \b, \D, \d, \S, \s, \W, |
| \w, and some of the POSIX character classes. By default, only ASCII characters |
| are recognized, but if PCRE_UCP is set, Unicode properties are used instead to |
| classify characters. More details are given in the section on |
| <a href="pcre.html#genericchartypes">generic character types</a> |
| in the |
| <a href="pcrepattern.html"><b>pcrepattern</b></a> |
| page. If you set PCRE_UCP, matching one of the items it affects takes much |
| longer. The option is available only if PCRE has been compiled with Unicode |
| property support. |
| <pre> |
| PCRE_UNGREEDY |
| </pre> |
| This option inverts the "greediness" of the quantifiers so that they are not |
| greedy by default, but become greedy if followed by "?". It is not compatible |
| with Perl. It can also be set by a (?U) option setting within the pattern. |
| <pre> |
| PCRE_UTF8 |
| </pre> |
| This option causes PCRE to regard both the pattern and the subject as strings |
| of UTF-8 characters instead of single-byte character strings. However, it is |
| available only when PCRE is built to include UTF-8 support. If not, the use |
| of this option provokes an error. Details of how this option changes the |
| behaviour of PCRE are given in the |
| <a href="pcreunicode.html"><b>pcreunicode</b></a> |
| page. |
| <pre> |
| PCRE_NO_UTF8_CHECK |
| </pre> |
| When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is |
| automatically checked. There is a discussion about the |
| <a href="pcre.html#utf8strings">validity of UTF-8 strings</a> |
| in the main |
| <a href="pcre.html"><b>pcre</b></a> |
| page. If an invalid UTF-8 sequence of bytes is found, <b>pcre_compile()</b> |
| returns an error. If you already know that your pattern is valid, and you want |
| to skip this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK |
| option. When it is set, the effect of passing an invalid UTF-8 string as a |
| pattern is undefined. It may cause your program to crash. Note that this option |
| can also be passed to <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, to suppress |
| the UTF-8 validity checking of subject strings. |
| </P> |
| <br><a name="SEC10" href="#TOC1">COMPILATION ERROR CODES</a><br> |
| <P> |
| The following table lists the error codes than may be returned by |
| <b>pcre_compile2()</b>, along with the error messages that may be returned by |
| both compiling functions. As PCRE has developed, some error codes have fallen |
| out of use. To avoid confusion, they have not been re-used. |
| <pre> |
| 0 no error |
| 1 \ at end of pattern |
| 2 \c at end of pattern |
| 3 unrecognized character follows \ |
| 4 numbers out of order in {} quantifier |
| 5 number too big in {} quantifier |
| 6 missing terminating ] for character class |
| 7 invalid escape sequence in character class |
| 8 range out of order in character class |
| 9 nothing to repeat |
| 10 [this code is not in use] |
| 11 internal error: unexpected repeat |
| 12 unrecognized character after (? or (?- |
| 13 POSIX named classes are supported only within a class |
| 14 missing ) |
| 15 reference to non-existent subpattern |
| 16 erroffset passed as NULL |
| 17 unknown option bit(s) set |
| 18 missing ) after comment |
| 19 [this code is not in use] |
| 20 regular expression is too large |
| 21 failed to get memory |
| 22 unmatched parentheses |
| 23 internal error: code overflow |
| 24 unrecognized character after (?< |
| 25 lookbehind assertion is not fixed length |
| 26 malformed number or name after (?( |
| 27 conditional group contains more than two branches |
| 28 assertion expected after (?( |
| 29 (?R or (?[+-]digits must be followed by ) |
| 30 unknown POSIX class name |
| 31 POSIX collating elements are not supported |
| 32 this version of PCRE is not compiled with PCRE_UTF8 support |
| 33 [this code is not in use] |
| 34 character value in \x{...} sequence is too large |
| 35 invalid condition (?(0) |
| 36 \C not allowed in lookbehind assertion |
| 37 PCRE does not support \L, \l, \N{name}, \U, or \u |
| 38 number after (?C is > 255 |
| 39 closing ) for (?C expected |
| 40 recursive call could loop indefinitely |
| 41 unrecognized character after (?P |
| 42 syntax error in subpattern name (missing terminator) |
| 43 two named subpatterns have the same name |
| 44 invalid UTF-8 string |
| 45 support for \P, \p, and \X has not been compiled |
| 46 malformed \P or \p sequence |
| 47 unknown property name after \P or \p |
| 48 subpattern name is too long (maximum 32 characters) |
| 49 too many named subpatterns (maximum 10000) |
| 50 [this code is not in use] |
| 51 octal value is greater than \377 (not in UTF-8 mode) |
| 52 internal error: overran compiling workspace |
| 53 internal error: previously-checked referenced subpattern |
| not found |
| 54 DEFINE group contains more than one branch |
| 55 repeating a DEFINE group is not allowed |
| 56 inconsistent NEWLINE options |
| 57 \g is not followed by a braced, angle-bracketed, or quoted |
| name/number or by a plain number |
| 58 a numbered reference must not be zero |
| 59 an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT) |
| 60 (*VERB) not recognized |
| 61 number is too big |
| 62 subpattern name expected |
| 63 digit expected after (?+ |
| 64 ] is an invalid data character in JavaScript compatibility mode |
| 65 different names for subpatterns of the same number are |
| not allowed |
| 66 (*MARK) must have an argument |
| 67 this version of PCRE is not compiled with PCRE_UCP support |
| 68 \c must be followed by an ASCII character |
| 69 \k is not followed by a braced, angle-bracketed, or quoted name |
| </pre> |
| The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may |
| be used if the limits were changed when PCRE was built. |
| <a name="studyingapattern"></a></P> |
| <br><a name="SEC11" href="#TOC1">STUDYING A PATTERN</a><br> |
| <P> |
| <b>pcre_extra *pcre_study(const pcre *<i>code</i>, int <i>options</i></b> |
| <b>const char **<i>errptr</i>);</b> |
| </P> |
| <P> |
| If a compiled pattern is going to be used several times, it is worth spending |
| more time analyzing it in order to speed up the time taken for matching. The |
| function <b>pcre_study()</b> takes a pointer to a compiled pattern as its first |
| argument. If studying the pattern produces additional information that will |
| help speed up matching, <b>pcre_study()</b> returns a pointer to a |
| <b>pcre_extra</b> block, in which the <i>study_data</i> field points to the |
| results of the study. |
| </P> |
| <P> |
| The returned value from <b>pcre_study()</b> can be passed directly to |
| <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>. However, a <b>pcre_extra</b> block |
| also contains other fields that can be set by the caller before the block is |
| passed; these are described |
| <a href="#extradata">below</a> |
| in the section on matching a pattern. |
| </P> |
| <P> |
| If studying the pattern does not produce any useful information, |
| <b>pcre_study()</b> returns NULL. In that circumstance, if the calling program |
| wants to pass any of the other fields to <b>pcre_exec()</b> or |
| <b>pcre_dfa_exec()</b>, it must set up its own <b>pcre_extra</b> block. |
| </P> |
| <P> |
| The second argument of <b>pcre_study()</b> 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 <b>pcre_exec()</b> matching function. If |
| the just-in-time compiler is not available, this option is ignored. All other |
| bits in the <i>options</i> argument must be zero. |
| </P> |
| <P> |
| JIT compilation is a heavyweight optimization. It can take some time for |
| patterns to be analyzed, and for one-off matches and simple patterns the |
| benefit of faster execution might be offset by a much slower study time. |
| Not all patterns can be optimized by the JIT compiler. For those that cannot be |
| handled, matching automatically falls back to the <b>pcre_exec()</b> |
| interpreter. For more details, see the |
| <a href="pcrejit.html"><b>pcrejit</b></a> |
| documentation. |
| </P> |
| <P> |
| The third argument for <b>pcre_study()</b> is a pointer for an error message. If |
| studying succeeds (even if no data is returned), the variable it points to is |
| set to NULL. Otherwise it is set to point to a textual error message. This is a |
| static string that is part of the library. You must not try to free it. You |
| should test the error pointer for NULL after calling <b>pcre_study()</b>, to be |
| sure that it has run successfully. |
| </P> |
| <P> |
| When you are finished with a pattern, you can free the memory used for the |
| study data by calling <b>pcre_free_study()</b>. This function was added to the |
| API for release 8.20. For earlier versions, the memory could be freed with |
| <b>pcre_free()</b>, just like the pattern itself. This will still work in cases |
| where PCRE_STUDY_JIT_COMPILE is not used, but it is advisable to change to the |
| new function when convenient. |
| </P> |
| <P> |
| This is a typical way in which <b>pcre_study</b>() is used (except that in a |
| real application there should be tests for errors): |
| <pre> |
| int rc; |
| pcre *re; |
| pcre_extra *sd; |
| re = pcre_compile("pattern", 0, &error, &erroroffset, NULL); |
| sd = pcre_study( |
| re, /* result of pcre_compile() */ |
| 0, /* no options */ |
| &error); /* set to NULL or points to a message */ |
| rc = pcre_exec( /* see below for details of pcre_exec() options */ |
| re, sd, "subject", 7, 0, 0, ovector, 30); |
| ... |
| pcre_free_study(sd); |
| pcre_free(re); |
| </pre> |
| Studying a pattern does two things: first, a lower bound for the length of |
| subject string that is needed to match the pattern is computed. This does not |
| mean that there are any strings of that length that match, but it does |
| guarantee that no shorter strings match. The value is used by |
| <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b> to avoid wasting time by trying to |
| match strings that are shorter than the lower bound. You can find out the value |
| in a calling program via the <b>pcre_fullinfo()</b> function. |
| </P> |
| <P> |
| Studying a pattern is also useful for non-anchored patterns that do not have a |
| single fixed starting character. A bitmap of possible starting bytes is |
| created. This speeds up finding a position in the subject at which to start |
| matching. |
| </P> |
| <P> |
| These two optimizations apply to both <b>pcre_exec()</b> and |
| <b>pcre_dfa_exec()</b>. However, they are not used by <b>pcre_exec()</b> if |
| <b>pcre_study()</b> 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 <b>pcre_exec()</b> or |
| <b>pcre_dfa_exec()</b>. 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 |
| <a href="#execoptions">below.</a> |
| <a name="localesupport"></a></P> |
| <br><a name="SEC12" href="#TOC1">LOCALE SUPPORT</a><br> |
| <P> |
| PCRE handles caseless matching, and determines whether characters are letters, |
| digits, or whatever, by reference to a set of tables, indexed by character |
| 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 friends to use Unicode property support instead of |
| built-in tables. The use of locales with Unicode is discouraged. If you are |
| handling characters with codes greater than 128, you should either use UTF-8 |
| and Unicode, or use locales, but not try to mix the two. |
| </P> |
| <P> |
| PCRE contains an internal set of tables that are used when the final argument |
| of <b>pcre_compile()</b> is NULL. These are sufficient for many applications. |
| Normally, the internal tables recognize only ASCII characters. However, when |
| PCRE is built, it is possible to cause the internal tables to be rebuilt in the |
| default "C" locale of the local system, which may cause them to be different. |
| </P> |
| <P> |
| The internal tables can always be overridden by tables supplied by the |
| application that calls PCRE. These may be created in a different locale from |
| the default. As more and more applications change to using Unicode, the need |
| for this locale support is expected to die away. |
| </P> |
| <P> |
| External tables are built by calling the <b>pcre_maketables()</b> function, |
| which has no arguments, in the relevant locale. The result can then be passed |
| to <b>pcre_compile()</b> or <b>pcre_exec()</b> as often as necessary. For |
| example, to build and use tables that are appropriate for the French locale |
| (where accented characters with values greater than 128 are treated as letters), |
| the following code could be used: |
| <pre> |
| setlocale(LC_CTYPE, "fr_FR"); |
| tables = pcre_maketables(); |
| re = pcre_compile(..., tables); |
| </pre> |
| The locale name "fr_FR" is used on Linux and other Unix-like systems; if you |
| are using Windows, the name for the French locale is "french". |
| </P> |
| <P> |
| When <b>pcre_maketables()</b> runs, the tables are built in memory that is |
| obtained via <b>pcre_malloc</b>. It is the caller's responsibility to ensure |
| that the memory containing the tables remains available for as long as it is |
| needed. |
| </P> |
| <P> |
| The pointer that is passed to <b>pcre_compile()</b> is saved with the compiled |
| pattern, and the same tables are used via this pointer by <b>pcre_study()</b> |
| and normally also by <b>pcre_exec()</b>. Thus, by default, for any single |
| pattern, compilation, studying and matching all happen in the same locale, but |
| different patterns can be compiled in different locales. |
| </P> |
| <P> |
| It is possible to pass a table pointer or NULL (indicating the use of the |
| internal tables) to <b>pcre_exec()</b>. 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. |
| <a name="infoaboutpattern"></a></P> |
| <br><a name="SEC13" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br> |
| <P> |
| <b>int pcre_fullinfo(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b> |
| <b>int <i>what</i>, void *<i>where</i>);</b> |
| </P> |
| <P> |
| The <b>pcre_fullinfo()</b> function returns information about a compiled |
| pattern. It replaces the obsolete <b>pcre_info()</b> function, which is |
| nevertheless retained for backwards compability (and is documented below). |
| </P> |
| <P> |
| The first argument for <b>pcre_fullinfo()</b> is a pointer to the compiled |
| pattern. The second argument is the result of <b>pcre_study()</b>, or NULL if |
| the pattern was not studied. The third argument specifies which piece of |
| information is required, and the fourth argument is a pointer to a variable |
| to receive the data. The yield of the function is zero for success, or one of |
| the following negative numbers: |
| <pre> |
| PCRE_ERROR_NULL the argument <i>code</i> was NULL |
| the argument <i>where</i> was NULL |
| PCRE_ERROR_BADMAGIC the "magic number" was not found |
| PCRE_ERROR_BADOPTION the value of <i>what</i> was invalid |
| </pre> |
| 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 |
| <b>pcre_fullinfo()</b>, to obtain the length of the compiled pattern: |
| <pre> |
| int rc; |
| size_t length; |
| rc = pcre_fullinfo( |
| re, /* result of pcre_compile() */ |
| sd, /* result of pcre_study(), or NULL */ |
| PCRE_INFO_SIZE, /* what is required */ |
| &length); /* where to put the data */ |
| </pre> |
| The possible values for the third argument are defined in <b>pcre.h</b>, and are |
| as follows: |
| <pre> |
| PCRE_INFO_BACKREFMAX |
| </pre> |
| Return the number of the highest back reference in the pattern. The fourth |
| argument should point to an <b>int</b> variable. Zero is returned if there are |
| no back references. |
| <pre> |
| PCRE_INFO_CAPTURECOUNT |
| </pre> |
| Return the number of capturing subpatterns in the pattern. The fourth argument |
| should point to an <b>int</b> variable. |
| <pre> |
| PCRE_INFO_DEFAULT_TABLES |
| </pre> |
| Return a pointer to the internal default character tables within PCRE. The |
| fourth argument should point to an <b>unsigned char *</b> variable. This |
| information call is provided for internal use by the <b>pcre_study()</b> |
| function. External callers can cause PCRE to use its internal tables by passing |
| a NULL table pointer. |
| <pre> |
| PCRE_INFO_FIRSTBYTE |
| </pre> |
| Return information about the first byte of any matched string, for a |
| non-anchored pattern. The fourth argument should point to an <b>int</b> |
| variable. (This option used to be called PCRE_INFO_FIRSTCHAR; the old name is |
| still recognized for backwards compatibility.) |
| </P> |
| <P> |
| If there is a fixed first byte, for example, from a pattern such as |
| (cat|cow|coyote), its value is returned. Otherwise, if either |
| <br> |
| <br> |
| (a) the pattern was compiled with the PCRE_MULTILINE option, and every branch |
| starts with "^", or |
| <br> |
| <br> |
| (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set |
| (if it were set, the pattern would be anchored), |
| <br> |
| <br> |
| -1 is returned, indicating that the pattern matches only at the start of a |
| subject string or after any newline within the string. Otherwise -2 is |
| returned. For anchored patterns, -2 is returned. |
| <pre> |
| PCRE_INFO_FIRSTTABLE |
| </pre> |
| 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 <b>unsigned char *</b> variable. |
| <pre> |
| PCRE_INFO_HASCRORLF |
| </pre> |
| Return 1 if the pattern contains any explicit matches for CR or LF characters, |
| otherwise 0. The fourth argument should point to an <b>int</b> variable. An |
| explicit match is either a literal CR or LF character, or \r or \n. |
| <pre> |
| PCRE_INFO_JCHANGED |
| </pre> |
| Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise |
| 0. The fourth argument should point to an <b>int</b> variable. (?J) and |
| (?-J) set and unset the local PCRE_DUPNAMES option, respectively. |
| <pre> |
| PCRE_INFO_JIT |
| </pre> |
| Return 1 if the pattern was studied with the PCRE_STUDY_JIT_COMPILE option, and |
| just-in-time compiling was successful. The fourth argument should point to an |
| <b>int</b> variable. A return value of 0 means that JIT support is not available |
| in this version of PCRE, or that the pattern was not studied with the |
| PCRE_STUDY_JIT_COMPILE option, or that the JIT compiler could not handle this |
| particular pattern. See the |
| <a href="pcrejit.html"><b>pcrejit</b></a> |
| documentation for details of what can and cannot be handled. |
| <pre> |
| PCRE_INFO_JITSIZE |
| </pre> |
| If the pattern was successfully studied with the PCRE_STUDY_JIT_COMPILE option, |
| return the size of the JIT compiled code, otherwise return zero. The fourth |
| argument should point to a <b>size_t</b> variable. |
| <pre> |
| PCRE_INFO_LASTLITERAL |
| </pre> |
| Return the value of the rightmost literal 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 <b>int</b> 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 example, for the pattern |
| /^a\d+z\d+/ the returned value is "z", but for /^a\dz\d/ the returned value |
| is -1. |
| <pre> |
| PCRE_INFO_MINLENGTH |
| </pre> |
| If the pattern was studied and a minimum length for matching subject strings |
| was computed, its value is returned. Otherwise the returned value is -1. The |
| value is a number of characters, not bytes (this may be relevant in UTF-8 |
| mode). The fourth argument should point to an <b>int</b> variable. A |
| non-negative value is a lower bound to the length of any matching string. There |
| may not be any strings of that length that do actually match, but every string |
| that does match is at least that long. |
| <pre> |
| PCRE_INFO_NAMECOUNT |
| PCRE_INFO_NAMEENTRYSIZE |
| PCRE_INFO_NAMETABLE |
| </pre> |
| PCRE supports the use of named as well as numbered capturing parentheses. The |
| names are just an additional way of identifying the parentheses, which still |
| acquire numbers. Several convenience functions such as |
| <b>pcre_get_named_substring()</b> are provided for extracting captured |
| substrings by name. It is also possible to extract the data directly, by first |
| converting the name to a number in order to access the correct pointers in the |
| output vector (described with <b>pcre_exec()</b> below). To do the conversion, |
| you need to use the name-to-number map, which is described by these three |
| values. |
| </P> |
| <P> |
| The map consists of a number of fixed-size entries. PCRE_INFO_NAMECOUNT gives |
| the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size of each |
| entry; both of these return an <b>int</b> value. The entry size depends on the |
| length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first |
| entry of the table (a pointer to <b>char</b>). The first two bytes of each entry |
| are the number of the capturing parenthesis, most significant byte first. The |
| rest of the entry is the corresponding name, zero terminated. |
| </P> |
| <P> |
| 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 |
| <a href="pcrepattern.html#dupsubpatternnumber">section on duplicate subpattern numbers</a> |
| in the |
| <a href="pcrepattern.html"><b>pcrepattern</b></a> |
| 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 pattern. In the absence of |
| (?| this is the order of increasing number; when (?| is used this is not |
| necessarily the case because later subpatterns may have lower numbers. |
| </P> |
| <P> |
| As a simple example of the name/number table, consider the following pattern |
| (assume PCRE_EXTENDED is set, so white space - including newlines - is |
| ignored): |
| <pre> |
| (?<date> (?<year>(\d\d)?\d\d) - (?<month>\d\d) - (?<day>\d\d) ) |
| </pre> |
| There are four named subpatterns, so the table has four entries, and each entry |
| in the table is eight bytes long. The table is as follows, with non-printing |
| bytes shows in hexadecimal, and undefined bytes shown as ??: |
| <pre> |
| 00 01 d a t e 00 ?? |
| 00 05 d a y 00 ?? ?? |
| 00 04 m o n t h 00 |
| 00 02 y e a r 00 ?? |
| </pre> |
| When writing code to extract data from named subpatterns using the |
| name-to-number map, remember that the length of the entries is likely to be |
| different for each compiled pattern. |
| <pre> |
| PCRE_INFO_OKPARTIAL |
| </pre> |
| Return 1 if the pattern can be used for partial matching with |
| <b>pcre_exec()</b>, otherwise 0. The fourth argument should point to an |
| <b>int</b> variable. From release 8.00, this always returns 1, because the |
| restrictions that previously applied to partial matching have been lifted. The |
| <a href="pcrepartial.html"><b>pcrepartial</b></a> |
| documentation gives details of partial matching. |
| <pre> |
| PCRE_INFO_OPTIONS |
| </pre> |
| Return a copy of the options with which the pattern was compiled. The fourth |
| argument should point to an <b>unsigned long int</b> variable. These option bits |
| are those specified in the call to <b>pcre_compile()</b>, modified by any |
| top-level option settings at the start of the pattern itself. In other words, |
| they are the options that will be in force when matching starts. For example, |
| if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the |
| result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED. |
| </P> |
| <P> |
| A pattern is automatically anchored by PCRE if all of its top-level |
| alternatives begin with one of the following: |
| <pre> |
| ^ unless PCRE_MULTILINE is set |
| \A always |
| \G always |
| .* if PCRE_DOTALL is set and there are no back references to the subpattern in which .* appears |
| </pre> |
| For such patterns, the PCRE_ANCHORED bit is set in the options returned by |
| <b>pcre_fullinfo()</b>. |
| <pre> |
| PCRE_INFO_SIZE |
| </pre> |
| Return the size of the compiled pattern. The fourth argument should point to a |
| <b>size_t</b> variable. This value does not include the size of the <b>pcre</b> |
| structure that is returned by <b>pcre_compile()</b>. The value that is passed as |
| the argument to <b>pcre_malloc()</b> when <b>pcre_compile()</b> is getting memory |
| in which to place the compiled data is the value returned by this option plus |
| the size of the <b>pcre</b> structure. Studying a compiled pattern, with or |
| without JIT, does not alter the value returned by this option. |
| <pre> |
| PCRE_INFO_STUDYSIZE |
| </pre> |
| Return the size of the data block pointed to by the <i>study_data</i> field in a |
| <b>pcre_extra</b> block. If <b>pcre_extra</b> is NULL, or there is no study data, |
| zero is returned. The fourth argument should point to a <b>size_t</b> variable. |
| The <i>study_data</i> field is set by <b>pcre_study()</b> to record information |
| that will speed up matching (see the section entitled |
| <a href="#studyingapattern">"Studying a pattern"</a> |
| above). The format of the <i>study_data</i> block is private, but its length |
| is made available via this option so that it can be saved and restored (see the |
| <a href="pcreprecompile.html"><b>pcreprecompile</b></a> |
| documentation for details). |
| </P> |
| <br><a name="SEC14" href="#TOC1">OBSOLETE INFO FUNCTION</a><br> |
| <P> |
| <b>int pcre_info(const pcre *<i>code</i>, int *<i>optptr</i>, int</b> |
| <b>*<i>firstcharptr</i>);</b> |
| </P> |
| <P> |
| The <b>pcre_info()</b> function is now obsolete because its interface is too |
| restrictive to return all the available data about a compiled pattern. New |
| programs should use <b>pcre_fullinfo()</b> instead. The yield of |
| <b>pcre_info()</b> is the number of capturing subpatterns, or one of the |
| following negative numbers: |
| <pre> |
| PCRE_ERROR_NULL the argument <i>code</i> was NULL |
| PCRE_ERROR_BADMAGIC the "magic number" was not found |
| </pre> |
| If the <i>optptr</i> 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). |
| </P> |
| <P> |
| If the pattern is not anchored and the <i>firstcharptr</i> argument is not NULL, |
| it is used to pass back information about the first character of any matched |
| string (see PCRE_INFO_FIRSTBYTE above). |
| </P> |
| <br><a name="SEC15" href="#TOC1">REFERENCE COUNTS</a><br> |
| <P> |
| <b>int pcre_refcount(pcre *<i>code</i>, int <i>adjust</i>);</b> |
| </P> |
| <P> |
| The <b>pcre_refcount()</b> function is used to maintain a reference count in the |
| data block that contains a compiled pattern. It is provided for the benefit of |
| applications that operate in an object-oriented manner, where different parts |
| of the application may be using the same compiled pattern, but you want to free |
| the block when they are all done. |
| </P> |
| <P> |
| When a pattern is compiled, the reference count field is initialized to zero. |
| It is changed only by calling this function, whose action is to add the |
| <i>adjust</i> value (which may be positive or negative) to it. The yield of the |
| function is the new value. However, the value of the count is constrained to |
| lie between 0 and 65535, inclusive. If the new value is outside these limits, |
| it is forced to the appropriate limit value. |
| </P> |
| <P> |
| Except when it is zero, the reference count is not correctly preserved if a |
| pattern is compiled on one host and then transferred to a host whose byte-order |
| is different. (This seems a highly unlikely scenario.) |
| </P> |
| <br><a name="SEC16" href="#TOC1">MATCHING A PATTERN: THE TRADITIONAL FUNCTION</a><br> |
| <P> |
| <b>int pcre_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b> |
| <b>const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b> |
| <b>int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>);</b> |
| </P> |
| <P> |
| The function <b>pcre_exec()</b> is called to match a subject string against a |
| compiled pattern, which is passed in the <i>code</i> argument. If the |
| pattern was studied, the result of the study should be passed in the |
| <i>extra</i> argument. You can call <b>pcre_exec()</b> with the same <i>code</i> |
| and <i>extra</i> arguments as many times as you like, in order to match |
| different subject strings with the same pattern. |
| </P> |
| <P> |
| This function is the main matching facility of the library, and it operates in |
| a Perl-like manner. For specialist use there is also an alternative matching |
| function, which is described |
| <a href="#dfamatch">below</a> |
| in the section about the <b>pcre_dfa_exec()</b> function. |
| </P> |
| <P> |
| In most applications, the pattern will have been compiled (and optionally |
| studied) in the same process that calls <b>pcre_exec()</b>. However, it is |
| possible to save compiled patterns and study data, and then use them later |
| in different processes, possibly even on different hosts. For a discussion |
| about this, see the |
| <a href="pcreprecompile.html"><b>pcreprecompile</b></a> |
| documentation. |
| </P> |
| <P> |
| Here is an example of a simple call to <b>pcre_exec()</b>: |
| <pre> |
| int rc; |
| int ovector[30]; |
| rc = pcre_exec( |
| re, /* result of pcre_compile() */ |
| NULL, /* we didn't study the pattern */ |
| "some string", /* the subject string */ |
| 11, /* the length of the subject string */ |
| 0, /* start at offset 0 in the subject */ |
| 0, /* default options */ |
| ovector, /* vector of integers for substring information */ |
| 30); /* number of elements (NOT size in bytes) */ |
| <a name="extradata"></a></PRE> |
| </P> |
| <br><b> |
| Extra data for <b>pcre_exec()</b> |
| </b><br> |
| <P> |
| If the <i>extra</i> argument is not NULL, it must point to a <b>pcre_extra</b> |
| data block. The <b>pcre_study()</b> function returns such a block (when it |
| doesn't return NULL), but you can also create one for yourself, and pass |
| additional information in it. The <b>pcre_extra</b> block contains the following |
| fields (not necessarily in this order): |
| <pre> |
| unsigned long int <i>flags</i>; |
| void *<i>study_data</i>; |
| void *<i>executable_jit</i>; |
| unsigned long int <i>match_limit</i>; |
| unsigned long int <i>match_limit_recursion</i>; |
| void *<i>callout_data</i>; |
| const unsigned char *<i>tables</i>; |
| unsigned char **<i>mark</i>; |
| </pre> |
| The <i>flags</i> field is a bitmap that specifies which of the other fields |
| are set. The flag bits are: |
| <pre> |
| 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 |
| </pre> |
| Other flag bits should be set to zero. The <i>study_data</i> field and sometimes |
| the <i>executable_jit</i> field are set in the <b>pcre_extra</b> block that is |
| returned by <b>pcre_study()</b>, together with the appropriate flag bits. You |
| should not set these yourself, but you may add to the block by setting the |
| other fields and their corresponding flag bits. |
| </P> |
| <P> |
| The <i>match_limit</i> field provides a means of preventing PCRE from using up a |
| vast amount of resources when running patterns that are not going to match, |
| but which have a very large number of possibilities in their search trees. The |
| classic example is a pattern that uses nested unlimited repeats. |
| </P> |
| <P> |
| Internally, <b>pcre_exec()</b> uses a function called <b>match()</b>, which it |
| calls repeatedly (sometimes recursively). The limit set by <i>match_limit</i> is |
| imposed on the number of times this function is called during a match, which |
| has the effect of limiting the amount of backtracking that can take place. For |
| patterns that are not anchored, the count restarts from zero for each position |
| in the subject string. |
| </P> |
| <P> |
| When <b>pcre_exec()</b> is called with a pattern that was successfully studied |
| with 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 <i>match_limit</i> value |
| is also used in this case (but in a different way) to limit how long the |
| matching can continue. |
| </P> |
| <P> |
| The default value for the limit can be set when PCRE is built; the default |
| default is 10 million, which handles all but the most extreme cases. You can |
| override the default by suppling <b>pcre_exec()</b> with a <b>pcre_extra</b> |
| block in which <i>match_limit</i> is set, and PCRE_EXTRA_MATCH_LIMIT is set in |
| the <i>flags</i> field. If the limit is exceeded, <b>pcre_exec()</b> returns |
| PCRE_ERROR_MATCHLIMIT. |
| </P> |
| <P> |
| The <i>match_limit_recursion</i> field is similar to <i>match_limit</i>, but |
| instead of limiting the total number of times that <b>match()</b> is called, it |
| limits the depth of recursion. The recursion depth is a smaller number than the |
| total number of calls, because not all calls to <b>match()</b> are recursive. |
| This limit is of use only if it is set smaller than <i>match_limit</i>. |
| </P> |
| <P> |
| Limiting the recursion depth limits the amount of machine stack that can be |
| used, or, when PCRE has been compiled to use memory on the heap instead of the |
| stack, the amount of heap memory that can be used. This limit is not relevant, |
| and is ignored, if the pattern was successfully studied with |
| PCRE_STUDY_JIT_COMPILE. |
| </P> |
| <P> |
| The default value for <i>match_limit_recursion</i> can be set when PCRE is |
| built; the default default is the same value as the default for |
| <i>match_limit</i>. You can override the default by suppling <b>pcre_exec()</b> |
| with a <b>pcre_extra</b> block in which <i>match_limit_recursion</i> is set, and |
| PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the <i>flags</i> field. If the limit |
| is exceeded, <b>pcre_exec()</b> returns PCRE_ERROR_RECURSIONLIMIT. |
| </P> |
| <P> |
| The <i>callout_data</i> field is used in conjunction with the "callout" feature, |
| and is described in the |
| <a href="pcrecallout.html"><b>pcrecallout</b></a> |
| documentation. |
| </P> |
| <P> |
| The <i>tables</i> field is used to pass a character tables pointer to |
| <b>pcre_exec()</b>; this overrides the value that is stored with the compiled |
| pattern. A non-NULL value is stored with the compiled pattern only if custom |
| tables were supplied to <b>pcre_compile()</b> via its <i>tableptr</i> argument. |
| If NULL is passed to <b>pcre_exec()</b> using this mechanism, it forces PCRE's |
| internal tables to be used. This facility is helpful when re-using patterns |
| that have been saved after compiling with an external set of tables, because |
| the external tables might be at a different address when <b>pcre_exec()</b> is |
| called. See the |
| <a href="pcreprecompile.html"><b>pcreprecompile</b></a> |
| documentation for a discussion of saving compiled patterns for later use. |
| </P> |
| <P> |
| If PCRE_EXTRA_MARK is set in the <i>flags</i> field, the <i>mark</i> field must |
| be set to point to a <b>char *</b> variable. If the pattern contains any |
| backtracking control verbs such as (*MARK:NAME), and the execution ends up with |
| a name to pass back, a pointer to the name string (zero terminated) is placed |
| in the variable pointed to by the <i>mark</i> field. The names are within the |
| compiled pattern; if you wish to retain such a name you must copy it before |
| freeing the memory of a compiled pattern. If there is no name to pass back, the |
| variable pointed to by the <i>mark</i> field set to NULL. For details of the |
| backtracking control verbs, see the section entitled |
| <a href="pcrepattern#backtrackcontrol">"Backtracking control"</a> |
| in the |
| <a href="pcrepattern.html"><b>pcrepattern</b></a> |
| documentation. |
| <a name="execoptions"></a></P> |
| <br><b> |
| Option bits for <b>pcre_exec()</b> |
| </b><br> |
| <P> |
| The unused bits of the <i>options</i> argument for <b>pcre_exec()</b> must be |
| zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>, |
| PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART, |
| PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and |
| PCRE_PARTIAL_HARD. |
| </P> |
| <P> |
| 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 |
| <b>pcre_exec()</b> is run. |
| <pre> |
| PCRE_ANCHORED |
| </pre> |
| The PCRE_ANCHORED option limits <b>pcre_exec()</b> to matching at the first |
| matching position. If a pattern was compiled with PCRE_ANCHORED, or turned out |
| to be anchored by virtue of its contents, it cannot be made unachored at |
| matching time. |
| <pre> |
| PCRE_BSR_ANYCRLF |
| PCRE_BSR_UNICODE |
| </pre> |
| These options (which are mutually exclusive) control what the \R escape |
| sequence matches. The choice is either to match only CR, LF, or CRLF, or to |
| match any Unicode newline sequence. These options override the choice that was |
| made or defaulted when the pattern was compiled. |
| <pre> |
| PCRE_NEWLINE_CR |
| PCRE_NEWLINE_LF |
| PCRE_NEWLINE_CRLF |
| PCRE_NEWLINE_ANYCRLF |
| PCRE_NEWLINE_ANY |
| </pre> |
| These options override the newline definition that was chosen or defaulted when |
| the pattern was compiled. For details, see the description of |
| <b>pcre_compile()</b> above. During matching, the newline choice affects the |
| behaviour of the dot, circumflex, and dollar metacharacters. It may also alter |
| the way the match position is advanced after a match failure for an unanchored |
| pattern. |
| </P> |
| <P> |
| When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a |
| match attempt for an unanchored pattern fails when the current position is at a |
| CRLF sequence, and the pattern contains no explicit matches for CR or LF |
| characters, the match position is advanced by two characters instead of one, in |
| other words, to after the CRLF. |
| </P> |
| <P> |
| The above rule is a compromise that makes the most common cases work as |
| expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not |
| set), it does not match the string "\r\nA" because, after failing at the |
| start, it skips both the CR and the LF before retrying. However, the pattern |
| [\r\n]A does match that string, because it contains an explicit CR or LF |
| reference, and so advances only by one character after the first failure. |
| </P> |
| <P> |
| An explicit match for CR of LF is either a literal appearance of one of those |
| characters, or one of the \r or \n escape sequences. Implicit matches such as |
| [^X] do not count, nor does \s (which includes CR and LF in the characters |
| that it matches). |
| </P> |
| <P> |
| Notwithstanding the above, anomalous effects may still occur when CRLF is a |
| valid newline sequence and explicit \r or \n escapes appear in the pattern. |
| <pre> |
| PCRE_NOTBOL |
| </pre> |
| This option specifies that first character of the subject string is not the |
| beginning of a line, so the circumflex metacharacter should not match before |
| it. Setting this without PCRE_MULTILINE (at compile time) causes circumflex |
| never to match. This option affects only the behaviour of the circumflex |
| metacharacter. It does not affect \A. |
| <pre> |
| PCRE_NOTEOL |
| </pre> |
| This option specifies that the end of the subject string is not the end of a |
| line, so the dollar metacharacter should not match it nor (except in multiline |
| mode) a newline immediately before it. Setting this without PCRE_MULTILINE (at |
| compile time) causes dollar never to match. This option affects only the |
| behaviour of the dollar metacharacter. It does not affect \Z or \z. |
| <pre> |
| PCRE_NOTEMPTY |
| </pre> |
| An empty string is not considered to be a valid match if this option is set. If |
| there are alternatives in the pattern, they are tried. If all the alternatives |
| match the empty string, the entire match fails. For example, if the pattern |
| <pre> |
| a?b? |
| </pre> |
| is applied to a string not beginning with "a" or "b", it matches an empty |
| string at the start of the subject. With PCRE_NOTEMPTY set, this match is not |
| valid, so PCRE searches further into the string for occurrences of "a" or "b". |
| <pre> |
| PCRE_NOTEMPTY_ATSTART |
| </pre> |
| This is like PCRE_NOTEMPTY, except that an empty string match that is not at |
| the start of the subject is permitted. If the pattern is anchored, such a match |
| can occur only if the pattern contains \K. |
| </P> |
| <P> |
| Perl has no direct equivalent of PCRE_NOTEMPTY or PCRE_NOTEMPTY_ATSTART, but it |
| does make a special case of a pattern match of the empty string within its |
| <b>split()</b> function, and when using the /g modifier. It is possible to |
| emulate Perl's behaviour after matching a null string by first trying the match |
| again at the same offset with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then |
| if that fails, by advancing the starting offset (see below) and trying an |
| ordinary match again. There is some code that demonstrates how to do this in |
| the |
| <a href="pcredemo.html"><b>pcredemo</b></a> |
| sample program. In the most general case, you have to check to see if the |
| newline convention recognizes CRLF as a newline, and if so, and the current |
| character is CR followed by LF, advance the starting offset by two characters |
| instead of one. |
| <pre> |
| PCRE_NO_START_OPTIMIZE |
| </pre> |
| There are a number of optimizations that <b>pcre_exec()</b> uses at the start of |
| a match, in order to speed up the process. For example, if it is known that an |
| unanchored match must start with a specific character, it searches the subject |
| for that character, and fails immediately if it cannot find it, without |
| actually running the main matching function. This means that a special item |
| such as (*COMMIT) at the start of a pattern is not considered until after a |
| suitable starting point for the match has been found. When callouts or (*MARK) |
| items are in use, these "start-up" optimizations can cause them to be skipped |
| if the pattern is never actually used. The start-up optimizations are in effect |
| a pre-scan of the subject that takes place before the pattern is run. |
| </P> |
| <P> |
| The PCRE_NO_START_OPTIMIZE option disables the start-up optimizations, possibly |
| causing performance to suffer, but ensuring that in cases where the result is |
| "no match", the callouts do occur, and that items such as (*COMMIT) and (*MARK) |
| are considered at every possible starting position in the subject string. If |
| PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching |
| time. |
| </P> |
| <P> |
| Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation. |
| Consider the pattern |
| <pre> |
| (*COMMIT)ABC |
| </pre> |
| When this is compiled, PCRE records the fact that a match must start with the |
| character "A". Suppose the subject string is "DEFABC". The start-up |
| optimization scans along the subject, finds "A" and runs the first match |
| attempt from there. The (*COMMIT) item means that the pattern must match the |
| current starting position, which in this case, it does. However, if the same |
| match is run with PCRE_NO_START_OPTIMIZE set, the initial scan along the |
| subject string does not happen. The first match attempt is run starting from |
| "D" and when this fails, (*COMMIT) prevents any further matches being tried, so |
| the overall result is "no match". If the pattern is studied, more start-up |
| optimizations may be used. For example, a minimum length for the subject may be |
| recorded. Consider the pattern |
| <pre> |
| (*MARK:A)(X|Y) |
| </pre> |
| The minimum length for a match is one character. If the subject is "ABC", there |
| will be attempts to match "ABC", "BC", "C", and then finally an empty string. |
| If the pattern is studied, the final attempt does not take place, because PCRE |
| knows that the subject is too short, and so the (*MARK) is never encountered. |
| In this case, studying the pattern does not affect the overall match result, |
| which is still "no match", but it does affect the auxiliary information that is |
| returned. |
| <pre> |
| PCRE_NO_UTF8_CHECK |
| </pre> |
| When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8 |
| string is automatically checked when <b>pcre_exec()</b> is subsequently called. |
| The value of <i>startoffset</i> is also checked to ensure that it points to the |
| start of a UTF-8 character. There is a discussion about the validity of UTF-8 |
| strings in the |
| <a href="pcre.html#utf8strings">section on UTF-8 support</a> |
| in the main |
| <a href="pcre.html"><b>pcre</b></a> |
| page. If an invalid UTF-8 sequence of bytes is found, <b>pcre_exec()</b> returns |
| the error PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is |
| a truncated 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 \fIError |
| return values from\fP <b>pcre_exec()</b> |
| <a href="#errorlist">below).</a> |
| If <i>startoffset</i> contains a value that does not point to the start of a |
| UTF-8 character (or to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is |
| returned. |
| </P> |
| <P> |
| If you already know that your subject is valid, and you want to skip these |
| checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when |
| calling <b>pcre_exec()</b>. You might want to do this for the second and |
| subsequent calls to <b>pcre_exec()</b> if you are making repeated calls to find |
| all the matches in a single subject string. However, you should be sure that |
| the value of <i>startoffset</i> points to the start of a 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 <i>startoffset</i> is |
| undefined. Your program may crash. |
| <pre> |
| PCRE_PARTIAL_HARD |
| PCRE_PARTIAL_SOFT |
| </pre> |
| These options turn on the partial matching feature. For backwards |
| compatibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. A partial match |
| occurs if the end of the subject string is reached successfully, but there are |
| not enough subject characters to complete the match. If this happens when |
| PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set, matching continues by |
| testing any remaining alternatives. Only if no complete match can be found is |
| PCRE_ERROR_PARTIAL returned instead of PCRE_ERROR_NOMATCH. In other words, |
| PCRE_PARTIAL_SOFT says that the caller is prepared to handle a partial match, |
| but only if no complete match can be found. |
| </P> |
| <P> |
| If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this case, if a |
| partial match is found, <b>pcre_exec()</b> immediately returns |
| PCRE_ERROR_PARTIAL, without considering any other alternatives. In other words, |
| when PCRE_PARTIAL_HARD is set, a partial match is considered to be more |
| important that an alternative complete match. |
| </P> |
| <P> |
| In both cases, the portion of the string that was inspected when the partial |
| match was found is set as the first matching string. There is a more detailed |
| discussion of partial and multi-segment matching, with examples, in the |
| <a href="pcrepartial.html"><b>pcrepartial</b></a> |
| documentation. |
| </P> |
| <br><b> |
| The string to be matched by <b>pcre_exec()</b> |
| </b><br> |
| <P> |
| The subject string is passed to <b>pcre_exec()</b> as a pointer in |
| <i>subject</i>, a length (in bytes) in <i>length</i>, and a starting byte offset |
| in <i>startoffset</i>. If this is negative or greater than the length of the |
| subject, <b>pcre_exec()</b> returns PCRE_ERROR_BADOFFSET. When the starting |
| offset is zero, the search for a match starts at the beginning of the subject, |
| and this is by far the most common case. In UTF-8 mode, the byte offset must |
| point to the start of a UTF-8 character (or the end of the subject). Unlike the |
| pattern string, the subject may contain binary zero bytes. |
| </P> |
| <P> |
| A non-zero starting offset is useful when searching for another match in the |
| same subject by calling <b>pcre_exec()</b> again after a previous success. |
| Setting <i>startoffset</i> differs from just passing over a shortened string and |
| setting PCRE_NOTBOL in the case of a pattern that begins with any kind of |
| lookbehind. For example, consider the pattern |
| <pre> |
| \Biss\B |
| </pre> |
| which finds occurrences of "iss" in the middle of words. (\B matches only if |
| the current position in the subject is not a word boundary.) When applied to |
| the string "Mississipi" the first call to <b>pcre_exec()</b> finds the first |
| occurrence. If <b>pcre_exec()</b> is called again with just the remainder of the |
| subject, namely "issipi", it does not match, because \B is always false at the |
| start of the subject, which is deemed to be a word boundary. However, if |
| <b>pcre_exec()</b> is passed the entire string again, but with <i>startoffset</i> |
| set to 4, it finds the second occurrence of "iss" because it is able to look |
| behind the starting point to discover that it is preceded by a letter. |
| </P> |
| <P> |
| Finding all the matches in a subject is tricky when the pattern can match an |
| empty string. It is possible to emulate Perl's /g behaviour by first trying the |
| match again at the same offset, with the PCRE_NOTEMPTY_ATSTART and |
| PCRE_ANCHORED options, and then if that fails, advancing the starting offset |
| and trying an ordinary match again. There is some code that demonstrates how to |
| do this in the |
| <a href="pcredemo.html"><b>pcredemo</b></a> |
| sample program. In the most general case, you have to check to see if the |
| newline convention recognizes CRLF as a newline, and if so, and the current |
| character is CR followed by LF, advance the starting offset by two characters |
| instead of one. |
| </P> |
| <P> |
| If a non-zero starting offset is passed when the pattern is anchored, one |
| attempt to match at the given offset is made. This can only succeed if the |
| pattern does not require the match to be at the start of the subject. |
| </P> |
| <br><b> |
| How <b>pcre_exec()</b> returns captured substrings |
| </b><br> |
| <P> |
| In general, a pattern matches a certain portion of the subject, and in |
| addition, further substrings from the subject may be picked out by parts of the |
| pattern. Following the usage in Jeffrey Friedl's book, this is called |
| "capturing" in what follows, and the phrase "capturing subpattern" is used for |
| a fragment of a pattern that picks out a substring. PCRE supports several other |
| kinds of parenthesized subpattern that do not cause substrings to be captured. |
| </P> |
| <P> |
| Captured substrings are returned to the caller via a vector of integers whose |
| address is passed in <i>ovector</i>. The number of elements in the vector is |
| passed in <i>ovecsize</i>, which must be a non-negative number. <b>Note</b>: this |
| argument is NOT the size of <i>ovector</i> in bytes. |
| </P> |
| <P> |
| The first two-thirds of the vector is used to pass back captured substrings, |
| each substring using a pair of integers. The remaining third of the vector is |
| used as workspace by <b>pcre_exec()</b> while matching capturing subpatterns, |
| and is not available for passing back information. The number passed in |
| <i>ovecsize</i> should always be a multiple of three. If it is not, it is |
| rounded down. |
| </P> |
| <P> |
| When a match is successful, information about captured substrings is returned |
| in pairs of integers, starting at the beginning of <i>ovector</i>, and |
| continuing up to two-thirds of its length at the most. The first element of |
| each pair is set to the 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. <b>Note</b>: these values are always byte offsets, even in UTF-8 |
| mode. They are not character counts. |
| </P> |
| <P> |
| The first pair of integers, <i>ovector[0]</i> and <i>ovector[1]</i>, identify the |
| portion of the subject string matched by the entire pattern. The next pair is |
| used for the first capturing subpattern, and so on. The value returned by |
| <b>pcre_exec()</b> is one more than the highest numbered pair that has been set. |
| For example, if two substrings have been captured, the returned value is 3. If |
| there are no capturing subpatterns, the return value from a successful match is |
| 1, indicating that just the first pair of offsets has been set. |
| </P> |
| <P> |
| If a capturing subpattern is matched repeatedly, it is the last portion of the |
| string that it matched that is returned. |
| </P> |
| <P> |
| If the vector is too small to hold all the captured substring offsets, it is |
| used as far as possible (up to two-thirds of its length), and the function |
| returns a value of zero. If neither the actual string matched not any captured |
| substrings are of interest, <b>pcre_exec()</b> may be called with <i>ovector</i> |
| passed as NULL and <i>ovecsize</i> as zero. However, if the pattern contains |
| back references and the <i>ovector</i> is not big enough to remember the related |
| substrings, PCRE has to get additional memory for use during matching. Thus it |
| is usually advisable to supply an <i>ovector</i> of reasonable size. |
| </P> |
| <P> |
| There are some cases where zero is returned (indicating vector overflow) when |
| in fact the vector is exactly the right size for the final match. For example, |
| consider the pattern |
| <pre> |
| (a)(?:(b)c|bd) |
| </pre> |
| If a vector of 6 elements (allowing for only 1 captured substring) is given |
| with subject string "abd", <b>pcre_exec()</b> will try to set the second |
| captured string, thereby recording a vector overflow, before failing to match |
| "c" and backing up to try the second alternative. The zero return, however, |
| does correctly indicate that the maximum number of slots (namely 2) have been |
| filled. In similar cases where there is temporary overflow, but the final |
| number of used slots is actually less than the maximum, a non-zero value is |
| returned. |
| </P> |
| <P> |
| The <b>pcre_fullinfo()</b> function can be used to find out how many capturing |
| subpatterns there are in a compiled pattern. The smallest size for |
| <i>ovector</i> that will allow for <i>n</i> captured substrings, in addition to |
| the offsets of the substring matched by the whole pattern, is (<i>n</i>+1)*3. |
| </P> |
| <P> |
| It is possible for capturing subpattern number <i>n+1</i> to match some part of |
| the subject when subpattern <i>n</i> has not been used at all. For example, if |
| the string "abc" is matched against the pattern (a|(z))(bc) the return from the |
| function is 4, and subpatterns 1 and 3 are matched, but 2 is not. When this |
| happens, both values in the offset pairs corresponding to unused subpatterns |
| are set to -1. |
| </P> |
| <P> |
| Offset values that correspond to unused subpatterns at the end of the |
| expression are also set to -1. For example, if the string "abc" is matched |
| against the pattern (abc)(x(yz)?)? subpatterns 2 and 3 are not matched. The |
| return from the function is 2, because the highest used capturing subpattern |
| number is 1, and the offsets for for the second and third capturing subpatterns |
| (assuming the vector is large enough, of course) are set to -1. |
| </P> |
| <P> |
| <b>Note</b>: Elements in the first two-thirds of <i>ovector</i> that do not |
| correspond to capturing parentheses in the pattern are never changed. That is, |
| if a pattern contains <i>n</i> capturing parentheses, no more than |
| <i>ovector[0]</i> to <i>ovector[2n+1]</i> are set by <b>pcre_exec()</b>. The other |
| elements (in the first two-thirds) retain whatever values they previously had. |
| </P> |
| <P> |
| Some convenience functions are provided for extracting the captured substrings |
| as separate strings. These are described below. |
| <a name="errorlist"></a></P> |
| <br><b> |
| Error return values from <b>pcre_exec()</b> |
| </b><br> |
| <P> |
| If <b>pcre_exec()</b> fails, it returns a negative number. The following are |
| defined in the header file: |
| <pre> |
| PCRE_ERROR_NOMATCH (-1) |
| </pre> |
| The subject string did not match the pattern. |
| <pre> |
| PCRE_ERROR_NULL (-2) |
| </pre> |
| Either <i>code</i> or <i>subject</i> was passed as NULL, or <i>ovector</i> was |
| NULL and <i>ovecsize</i> was not zero. |
| <pre> |
| PCRE_ERROR_BADOPTION (-3) |
| </pre> |
| An unrecognized bit was set in the <i>options</i> argument. |
| <pre> |
| PCRE_ERROR_BADMAGIC (-4) |
| </pre> |
| PCRE stores a 4-byte "magic number" at the start of the compiled code, to catch |
| the case when it is passed a junk pointer and to detect when a pattern that was |
| compiled in an environment of one endianness is run in an environment with the |
| other endianness. This is the error that PCRE gives when the magic number is |
| not present. |
| <pre> |
| PCRE_ERROR_UNKNOWN_OPCODE (-5) |
| </pre> |
| While running the pattern match, an unknown item was encountered in the |
| compiled pattern. This error could be caused by a bug in PCRE or by overwriting |
| of the compiled pattern. |
| <pre> |
| PCRE_ERROR_NOMEMORY (-6) |
| </pre> |
| If a pattern contains back references, but the <i>ovector</i> that is passed to |
| <b>pcre_exec()</b> is not big enough to remember the referenced substrings, PCRE |
| gets a block of memory at the start of matching to use for this purpose. If the |
| call via <b>pcre_malloc()</b> fails, this error is given. The memory is |
| automatically freed at the end of matching. |
| </P> |
| <P> |
| This error is also given if <b>pcre_stack_malloc()</b> fails in |
| <b>pcre_exec()</b>. This can happen only when PCRE has been compiled with |
| <b>--disable-stack-for-recursion</b>. |
| <pre> |
| PCRE_ERROR_NOSUBSTRING (-7) |
| </pre> |
| This error is used by the <b>pcre_copy_substring()</b>, |
| <b>pcre_get_substring()</b>, and <b>pcre_get_substring_list()</b> functions (see |
| below). It is never returned by <b>pcre_exec()</b>. |
| <pre> |
| PCRE_ERROR_MATCHLIMIT (-8) |
| </pre> |
| The backtracking limit, as specified by the <i>match_limit</i> field in a |
| <b>pcre_extra</b> structure (or defaulted) was reached. See the description |
| above. |
| <pre> |
| PCRE_ERROR_CALLOUT (-9) |
| </pre> |
| This error is never generated by <b>pcre_exec()</b> itself. It is provided for |
| use by callout functions that want to yield a distinctive error code. See the |
| <a href="pcrecallout.html"><b>pcrecallout</b></a> |
| documentation for details. |
| <pre> |
| PCRE_ERROR_BADUTF8 (-10) |
| </pre> |
| A string that contains an invalid UTF-8 byte sequence was passed as a subject, |
| and the PCRE_NO_UTF8_CHECK option was not set. If the size of the output vector |
| (<i>ovecsize</i>) is at least 2, the byte offset to the start of the the invalid |
| UTF-8 character is placed in the first element, and a reason code is placed in |
| the second element. The reason codes are listed in the |
| <a href="#badutf8reasons">following section.</a> |
| For backward compatibility, if PCRE_PARTIAL_HARD is set and the problem is a |
| truncated UTF-8 character at the end of the subject (reason codes 1 to 5), |
| PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8. |
| <pre> |
| PCRE_ERROR_BADUTF8_OFFSET (-11) |
| </pre> |
| The UTF-8 byte sequence that was passed as a subject was checked and found to |
| be valid (the PCRE_NO_UTF8_CHECK option was not set), but the value of |
| <i>startoffset</i> did not point to the beginning of a UTF-8 character or the |
| end of the subject. |
| <pre> |
| PCRE_ERROR_PARTIAL (-12) |
| </pre> |
| The subject string did not match, but it did match partially. See the |
| <a href="pcrepartial.html"><b>pcrepartial</b></a> |
| documentation for details of partial matching. |
| <pre> |
| PCRE_ERROR_BADPARTIAL (-13) |
| </pre> |
| This code is no longer in use. It was formerly returned when the PCRE_PARTIAL |
| option was used with a compiled pattern containing items that were not |
| supported for partial matching. From release 8.00 onwards, there are no |
| restrictions on partial matching. |
| <pre> |
| PCRE_ERROR_INTERNAL (-14) |
| </pre> |
| An unexpected internal error has occurred. This error could be caused by a bug |
| in PCRE or by overwriting of the compiled pattern. |
| <pre> |
| PCRE_ERROR_BADCOUNT (-15) |
| </pre> |
| This error is given if the value of the <i>ovecsize</i> argument is negative. |
| <pre> |
| PCRE_ERROR_RECURSIONLIMIT (-21) |
| </pre> |
| The internal recursion limit, as specified by the <i>match_limit_recursion</i> |
| field in a <b>pcre_extra</b> structure (or defaulted) was reached. See the |
| description above. |
| <pre> |
| PCRE_ERROR_BADNEWLINE (-23) |
| </pre> |
| An invalid combination of PCRE_NEWLINE_<i>xxx</i> options was given. |
| <pre> |
| PCRE_ERROR_BADOFFSET (-24) |
| </pre> |
| The value of <i>startoffset</i> was negative or greater than the length of the |
| subject, that is, the value in <i>length</i>. |
| <pre> |
| PCRE_ERROR_SHORTUTF8 (-25) |
| </pre> |
| This error is returned instead of PCRE_ERROR_BADUTF8 when the subject string |
| ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD option is set. |
| Information about the failure is returned as for PCRE_ERROR_BADUTF8. It is in |
| fact sufficient to detect this case, but this special error code for |
| PCRE_PARTIAL_HARD precedes the implementation of returned information; it is |
| retained for backwards compatibility. |
| <pre> |
| PCRE_ERROR_RECURSELOOP (-26) |
| </pre> |
| This error is returned when <b>pcre_exec()</b> detects a recursion loop within |
| the pattern. Specifically, it means that either the whole pattern or a |
| subpattern has been called recursively for the second time at the same position |
| in the subject string. Some simple patterns that might do this are detected and |
| faulted at compile time, but more complicated cases, in particular mutual |
| recursions between two different subpatterns, cannot be detected until run |
| time. |
| <pre> |
| PCRE_ERROR_JIT_STACKLIMIT (-27) |
| </pre> |
| This error is returned when a pattern that was successfully studied using the |
| PCRE_STUDY_JIT_COMPILE option is being matched, but the memory available for |
| the just-in-time processing stack is not large enough. See the |
| <a href="pcrejit.html"><b>pcrejit</b></a> |
| documentation for more details. |
| </P> |
| <P> |
| Error numbers -16 to -20 and -22 are not used by <b>pcre_exec()</b>. |
| <a name="badutf8reasons"></a></P> |
| <br><b> |
| Reason codes for invalid UTF-8 strings |
| </b><br> |
| <P> |
| When <b>pcre_exec()</b> returns either PCRE_ERROR_BADUTF8 or |
| PCRE_ERROR_SHORTUTF8, and the size of the output vector (<i>ovecsize</i>) is at |
| least 2, the offset of the start of the invalid UTF-8 character is placed in |
| the first output vector element (<i>ovector[0]</i>) and a reason code is placed |
| in the second element (<i>ovector[1]</i>). The reason codes are given names in |
| the <b>pcre.h</b> header file: |
| <pre> |
| PCRE_UTF8_ERR1 |
| PCRE_UTF8_ERR2 |
| PCRE_UTF8_ERR3 |
| PCRE_UTF8_ERR4 |
| PCRE_UTF8_ERR5 |
| </pre> |
| The string ends with a truncated UTF-8 character; the code specifies how many |
| bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8 characters to be |
| no longer than 4 bytes, the encoding scheme (originally defined by RFC 2279) |
| allows for up to 6 bytes, and this is checked first; hence the possibility of |
| 4 or 5 missing bytes. |
| <pre> |
| PCRE_UTF8_ERR6 |
| PCRE_UTF8_ERR7 |
| PCRE_UTF8_ERR8 |
| PCRE_UTF8_ERR9 |
| PCRE_UTF8_ERR10 |
| </pre> |
| The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of the |
| character do not have the binary value 0b10 (that is, either the most |
| significant bit is 0, or the next bit is 1). |
| <pre> |
| PCRE_UTF8_ERR11 |
| PCRE_UTF8_ERR12 |
| </pre> |
| A character that is valid by the RFC 2279 rules is either 5 or 6 bytes long; |
| these code points are excluded by RFC 3629. |
| <pre> |
| PCRE_UTF8_ERR13 |
| </pre> |
| A 4-byte character has a value greater than 0x10fff; these code points are |
| excluded by RFC 3629. |
| <pre> |
| PCRE_UTF8_ERR14 |
| </pre> |
| A 3-byte character has a value in the range 0xd800 to 0xdfff; this range of |
| code points are reserved by RFC 3629 for use with UTF-16, and so are excluded |
| from UTF-8. |
| <pre> |
| PCRE_UTF8_ERR15 |
| PCRE_UTF8_ERR16 |
| PCRE_UTF8_ERR17 |
| PCRE_UTF8_ERR18 |
| PCRE_UTF8_ERR19 |
| </pre> |
| A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes for a |
| value that can be represented by fewer bytes, which is invalid. For example, |
| the two bytes 0xc0, 0xae give the value 0x2e, whose correct coding uses just |
| one byte. |
| <pre> |
| PCRE_UTF8_ERR20 |
| </pre> |
| The two most significant bits of the first byte of a character have the binary |
| value 0b10 (that is, the most significant bit is 1 and the second is 0). Such a |
| byte can only validly occur as the second or subsequent byte of a multi-byte |
| character. |
| <pre> |
| PCRE_UTF8_ERR21 |
| </pre> |
| The first byte of a character has the value 0xfe or 0xff. These values can |
| never occur in a valid UTF-8 string. |
| </P> |
| <br><a name="SEC17" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NUMBER</a><br> |
| <P> |
| <b>int pcre_copy_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b> |
| <b>int <i>stringcount</i>, int <i>stringnumber</i>, char *<i>buffer</i>,</b> |
| <b>int <i>buffersize</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_get_substring(const char *<i>subject</i>, int *<i>ovector</i>,</b> |
| <b>int <i>stringcount</i>, int <i>stringnumber</i>,</b> |
| <b>const char **<i>stringptr</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_get_substring_list(const char *<i>subject</i>,</b> |
| <b>int *<i>ovector</i>, int <i>stringcount</i>, const char ***<i>listptr</i>);</b> |
| </P> |
| <P> |
| Captured substrings can be accessed directly by using the offsets returned by |
| <b>pcre_exec()</b> in <i>ovector</i>. For convenience, the functions |
| <b>pcre_copy_substring()</b>, <b>pcre_get_substring()</b>, and |
| <b>pcre_get_substring_list()</b> are provided for extracting captured substrings |
| as new, separate, zero-terminated strings. These functions identify substrings |
| by number. The next section describes functions for extracting named |
| substrings. |
| </P> |
| <P> |
| A substring that contains a binary zero is correctly extracted and has a |
| further zero added on the end, but the result is not, of course, a C string. |
| However, you can process such a string by referring to the length that is |
| returned by <b>pcre_copy_substring()</b> and <b>pcre_get_substring()</b>. |
| Unfortunately, the interface to <b>pcre_get_substring_list()</b> is not adequate |
| for handling strings containing binary zeros, because the end of the final |
| string is not independently indicated. |
| </P> |
| <P> |
| The first three arguments are the same for all three of these functions: |
| <i>subject</i> is the subject string that has just been successfully matched, |
| <i>ovector</i> is a pointer to the vector of integer offsets that was passed to |
| <b>pcre_exec()</b>, and <i>stringcount</i> is the number of substrings that were |
| captured by the match, including the substring that matched the entire regular |
| expression. This is the value returned by <b>pcre_exec()</b> if it is greater |
| than zero. If <b>pcre_exec()</b> returned zero, indicating that it ran out of |
| space in <i>ovector</i>, the value passed as <i>stringcount</i> should be the |
| number of elements in the vector divided by three. |
| </P> |
| <P> |
| The functions <b>pcre_copy_substring()</b> and <b>pcre_get_substring()</b> |
| extract a single substring, whose number is given as <i>stringnumber</i>. A |
| value of zero extracts the substring that matched the entire pattern, whereas |
| higher values extract the captured substrings. For <b>pcre_copy_substring()</b>, |
| the string is placed in <i>buffer</i>, whose length is given by |
| <i>buffersize</i>, while for <b>pcre_get_substring()</b> a new block of memory is |
| obtained via <b>pcre_malloc</b>, and its address is returned via |
| <i>stringptr</i>. The yield of the function is the length of the string, not |
| including the terminating zero, or one of these error codes: |
| <pre> |
| PCRE_ERROR_NOMEMORY (-6) |
| </pre> |
| The buffer was too small for <b>pcre_copy_substring()</b>, or the attempt to get |
| memory failed for <b>pcre_get_substring()</b>. |
| <pre> |
| PCRE_ERROR_NOSUBSTRING (-7) |
| </pre> |
| There is no substring whose number is <i>stringnumber</i>. |
| </P> |
| <P> |
| The <b>pcre_get_substring_list()</b> function extracts all available substrings |
| and builds a list of pointers to them. All this is done in a single block of |
| memory that is obtained via <b>pcre_malloc</b>. The address of the memory block |
| is returned via <i>listptr</i>, which is also the start of the list of string |
| pointers. The end of the list is marked by a NULL pointer. The yield of the |
| function is zero if all went well, or the error code |
| <pre> |
| PCRE_ERROR_NOMEMORY (-6) |
| </pre> |
| if the attempt to get the memory block failed. |
| </P> |
| <P> |
| When any of these functions encounter a substring that is unset, which can |
| happen when capturing subpattern number <i>n+1</i> matches some part of the |
| subject, but subpattern <i>n</i> has not been used at all, they return an empty |
| string. This can be distinguished from a genuine zero-length substring by |
| inspecting the appropriate offset in <i>ovector</i>, which is negative for unset |
| substrings. |
| </P> |
| <P> |
| The two convenience functions <b>pcre_free_substring()</b> and |
| <b>pcre_free_substring_list()</b> can be used to free the memory returned by |
| a previous call of <b>pcre_get_substring()</b> or |
| <b>pcre_get_substring_list()</b>, respectively. They do nothing more than call |
| the function pointed to by <b>pcre_free</b>, which of course could be called |
| directly from a C program. However, PCRE is used in some situations where it is |
| linked via a special interface to another programming language that cannot use |
| <b>pcre_free</b> directly; it is for these cases that the functions are |
| provided. |
| </P> |
| <br><a name="SEC18" href="#TOC1">EXTRACTING CAPTURED SUBSTRINGS BY NAME</a><br> |
| <P> |
| <b>int pcre_get_stringnumber(const pcre *<i>code</i>,</b> |
| <b>const char *<i>name</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_copy_named_substring(const pcre *<i>code</i>,</b> |
| <b>const char *<i>subject</i>, int *<i>ovector</i>,</b> |
| <b>int <i>stringcount</i>, const char *<i>stringname</i>,</b> |
| <b>char *<i>buffer</i>, int <i>buffersize</i>);</b> |
| </P> |
| <P> |
| <b>int pcre_get_named_substring(const pcre *<i>code</i>,</b> |
| <b>const char *<i>subject</i>, int *<i>ovector</i>,</b> |
| <b>int <i>stringcount</i>, const char *<i>stringname</i>,</b> |
| <b>const char **<i>stringptr</i>);</b> |
| </P> |
| <P> |
| To extract a substring by name, you first have to find associated number. |
| For example, for this pattern |
| <pre> |
| (a+)b(?<xxx>\d+)... |
| </pre> |
| the number of the subpattern called "xxx" is 2. If the name is known to be |
| unique (PCRE_DUPNAMES was not set), you can find the number from the name by |
| calling <b>pcre_get_stringnumber()</b>. The first argument is the compiled |
| pattern, and the second is the name. The yield of the function is the |
| subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no subpattern of |
| that name. |
| </P> |
| <P> |
| Given the number, you can extract the substring directly, or use one of the |
| functions described in the previous section. For convenience, there are also |
| two functions that do the whole job. |
| </P> |
| <P> |
| Most of the arguments of <b>pcre_copy_named_substring()</b> and |
| <b>pcre_get_named_substring()</b> are the same as those for the similarly named |
| functions that extract by number. As these are described in the previous |
| section, they are not re-described here. There are just two differences: |
| </P> |
| <P> |
| First, instead of a substring number, a substring name is given. Second, there |
| is an extra argument, given at the start, which is a pointer to the compiled |
| pattern. This is needed in order to gain access to the name-to-number |
| translation table. |
| </P> |
| <P> |
| These functions call <b>pcre_get_stringnumber()</b>, and if it succeeds, they |
| then call <b>pcre_copy_substring()</b> or <b>pcre_get_substring()</b>, as |
| appropriate. <b>NOTE:</b> If PCRE_DUPNAMES is set and there are duplicate names, |
| the behaviour may not be what you want (see the next section). |
| </P> |
| <P> |
| <b>Warning:</b> If the pattern uses the (?| feature to set up multiple |
| subpatterns with the same number, as described in the |
| <a href="pcrepattern.html#dupsubpatternnumber">section on duplicate subpattern numbers</a> |
| in the |
| <a href="pcrepattern.html"><b>pcrepattern</b></a> |
| page, you cannot use names to distinguish the different subpatterns, because |
| names are not included in the compiled code. The matching process uses only |
| numbers. For this reason, the use of different names for subpatterns of the |
| same number causes an error at compile time. |
| </P> |
| <br><a name="SEC19" href="#TOC1">DUPLICATE SUBPATTERN NAMES</a><br> |
| <P> |
| <b>int pcre_get_stringtable_entries(const pcre *<i>code</i>,</b> |
| <b>const char *<i>name</i>, char **<i>first</i>, char **<i>last</i>);</b> |
| </P> |
| <P> |
| When a pattern is compiled with the PCRE_DUPNAMES option, names for subpatterns |
| are not required to be unique. (Duplicate names are always allowed for |
| subpatterns with the same number, created by using the (?| feature. Indeed, if |
| such subpatterns are named, they are required to use the same names.) |
| </P> |
| <P> |
| Normally, patterns with duplicate names are such that in any one match, only |
| one of the named subpatterns participates. An example is shown in the |
| <a href="pcrepattern.html"><b>pcrepattern</b></a> |
| documentation. |
| </P> |
| <P> |
| When duplicates are present, <b>pcre_copy_named_substring()</b> and |
| <b>pcre_get_named_substring()</b> return the first substring corresponding to |
| the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING (-7) is |
| returned; no data is returned. The <b>pcre_get_stringnumber()</b> function |
| returns one of the numbers that are associated with the name, but it is not |
| defined which it is. |
| </P> |
| <P> |
| If you want to get full details of all captured substrings for a given name, |
| you must use the <b>pcre_get_stringtable_entries()</b> function. The first |
| argument is the compiled pattern, and the second is the name. The third and |
| fourth are pointers to variables which are updated by the function. After it |
| has run, they point to the first and last entries in the name-to-number table |
| for the given name. The function itself returns the length of each entry, or |
| PCRE_ERROR_NOSUBSTRING (-7) if there are none. The format of the table is |
| described above in the section entitled <i>Information about a pattern</i> |
| <a href="#infoaboutpattern">above.</a> |
| Given all the relevant entries for the name, you can extract each of their |
| numbers, and hence the captured data, if any. |
| </P> |
| <br><a name="SEC20" href="#TOC1">FINDING ALL POSSIBLE MATCHES</a><br> |
| <P> |
| The traditional matching function uses a similar algorithm to Perl, which stops |
| when it finds the first match, starting at a given point in the subject. If you |
| want to find all possible matches, or the longest possible match, consider |
| using the alternative matching function (see below) instead. If you cannot use |
| the alternative function, but still need to find all possible matches, you |
| can kludge it up by making use of the callout facility, which is described in |
| the |
| <a href="pcrecallout.html"><b>pcrecallout</b></a> |
| documentation. |
| </P> |
| <P> |
| What you have to do is to insert a callout right at the end of the pattern. |
| When your callout function is called, extract and save the current matched |
| substring. Then return 1, which forces <b>pcre_exec()</b> to backtrack and try |
| other alternatives. Ultimately, when it runs out of matches, <b>pcre_exec()</b> |
| will yield PCRE_ERROR_NOMATCH. |
| <a name="dfamatch"></a></P> |
| <br><a name="SEC21" href="#TOC1">MATCHING A PATTERN: THE ALTERNATIVE FUNCTION</a><br> |
| <P> |
| <b>int pcre_dfa_exec(const pcre *<i>code</i>, const pcre_extra *<i>extra</i>,</b> |
| <b>const char *<i>subject</i>, int <i>length</i>, int <i>startoffset</i>,</b> |
| <b>int <i>options</i>, int *<i>ovector</i>, int <i>ovecsize</i>,</b> |
| <b>int *<i>workspace</i>, int <i>wscount</i>);</b> |
| </P> |
| <P> |
| The function <b>pcre_dfa_exec()</b> is called to match a subject string against |
| a compiled pattern, using a matching algorithm that scans the subject string |
| just once, and does not backtrack. This has different characteristics to the |
| normal algorithm, and is not compatible with Perl. Some of the features of PCRE |
| patterns are not supported. Nevertheless, there are times when this kind of |
| matching can be useful. For a discussion of the two matching algorithms, and a |
| list of features that <b>pcre_dfa_exec()</b> does not support, see the |
| <a href="pcrematching.html"><b>pcrematching</b></a> |
| documentation. |
| </P> |
| <P> |
| The arguments for the <b>pcre_dfa_exec()</b> function are the same as for |
| <b>pcre_exec()</b>, plus two extras. The <i>ovector</i> argument is used in a |
| different way, and this is described below. The other common arguments are used |
| in the same way as for <b>pcre_exec()</b>, so their description is not repeated |
| here. |
| </P> |
| <P> |
| The two additional arguments provide workspace for the function. The workspace |
| vector should contain at least 20 elements. It is used for keeping track of |
| multiple paths through the pattern tree. More workspace will be needed for |
| patterns and subjects where there are a lot of potential matches. |
| </P> |
| <P> |
| Here is an example of a simple call to <b>pcre_dfa_exec()</b>: |
| <pre> |
| int rc; |
| int ovector[10]; |
| int wspace[20]; |
| rc = pcre_dfa_exec( |
| re, /* result of pcre_compile() */ |
| NULL, /* we didn't study the pattern */ |
| "some string", /* the subject string */ |
| 11, /* the length of the subject string */ |
| 0, /* start at offset 0 in the subject */ |
| 0, /* default options */ |
| ovector, /* vector of integers for substring information */ |
| 10, /* number of elements (NOT size in bytes) */ |
| wspace, /* working space vector */ |
| 20); /* number of elements (NOT size in bytes) */ |
| </PRE> |
| </P> |
| <br><b> |
| Option bits for <b>pcre_dfa_exec()</b> |
| </b><br> |
| <P> |
| The unused bits of the <i>options</i> argument for <b>pcre_dfa_exec()</b> must be |
| zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>, |
| PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART, |
| PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF, PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE, |
| PCRE_PARTIAL_HARD, PCRE_PARTIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. |
| All but the last four of these are exactly the same as for <b>pcre_exec()</b>, |
| so their description is not repeated here. |
| <pre> |
| PCRE_PARTIAL_HARD |
| PCRE_PARTIAL_SOFT |
| </pre> |
| These have the same general effect as they do for <b>pcre_exec()</b>, but the |
| details are slightly different. When PCRE_PARTIAL_HARD is set for |
| <b>pcre_dfa_exec()</b>, it returns PCRE_ERROR_PARTIAL if the end of the subject |
| is reached and there is still at least one matching possibility that requires |
| additional characters. This happens even if some complete matches have also |
| been found. When PCRE_PARTIAL_SOFT is set, the return code PCRE_ERROR_NOMATCH |
| is converted into PCRE_ERROR_PARTIAL if the end of the subject is reached, |
| there have been no complete matches, but there is still at least one matching |
| possibility. The portion of the string that was inspected when the longest |
| partial match was found is set as the first matching string in both cases. |
| There is a more detailed discussion of partial and multi-segment matching, with |
| examples, in the |
| <a href="pcrepartial.html"><b>pcrepartial</b></a> |
| documentation. |
| <pre> |
| PCRE_DFA_SHORTEST |
| </pre> |
| Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to stop as |
| soon as it has found one match. Because of the way the alternative algorithm |
| works, this is necessarily the shortest possible match at the first possible |
| matching point in the subject string. |
| <pre> |
| PCRE_DFA_RESTART |
| </pre> |
| When <b>pcre_dfa_exec()</b> returns a partial match, it is possible to call it |
| again, with additional subject characters, and have it continue with the same |
| match. The PCRE_DFA_RESTART option requests this action; when it is set, the |
| <i>workspace</i> and <i>wscount</i> options must reference the same vector as |
| before because data about the match so far is left in them after a partial |
| match. There is more discussion of this facility in the |
| <a href="pcrepartial.html"><b>pcrepartial</b></a> |
| documentation. |
| </P> |
| <br><b> |
| Successful returns from <b>pcre_dfa_exec()</b> |
| </b><br> |
| <P> |
| When <b>pcre_dfa_exec()</b> succeeds, it may have matched more than one |
| substring in the subject. Note, however, that all the matches from one run of |
| the function start at the same point in the subject. The shorter matches are |
| all initial substrings of the longer matches. For example, if the pattern |
| <pre> |
| <.*> |
| </pre> |
| is matched against the string |
| <pre> |
| This is <something> <something else> <something further> no more |
| </pre> |
| the three matched strings are |
| <pre> |
| <something> |
| <something> <something else> |
| <something> <something else> <something further> |
| </pre> |
| On success, the yield of the function is a number greater than zero, which is |
| the number of matched substrings. The substrings themselves are returned in |
| <i>ovector</i>. Each string uses two elements; the first is the offset to the |
| start, and the second is the offset to the end. In fact, all the strings have |
| the same start offset. (Space could have been saved by giving this only once, |
| but it was decided to retain some compatibility with the way <b>pcre_exec()</b> |
| returns data, even though the meaning of the strings is different.) |
| </P> |
| <P> |
| The strings are returned in reverse order of length; that is, the longest |
| matching string is given first. If there were too many matches to fit into |
| <i>ovector</i>, the yield of the function is zero, and the vector is filled with |
| the longest matches. Unlike <b>pcre_exec()</b>, <b>pcre_dfa_exec()</b> can use |
| the entire <i>ovector</i> for returning matched strings. |
| </P> |
| <br><b> |
| Error returns from <b>pcre_dfa_exec()</b> |
| </b><br> |
| <P> |
| The <b>pcre_dfa_exec()</b> function returns a negative number when it fails. |
| Many of the errors are the same as for <b>pcre_exec()</b>, and these are |
| described |
| <a href="#errorlist">above.</a> |
| There are in addition the following errors that are specific to |
| <b>pcre_dfa_exec()</b>: |
| <pre> |
| PCRE_ERROR_DFA_UITEM (-16) |
| </pre> |
| This return is given if <b>pcre_dfa_exec()</b> encounters an item in the pattern |
| that it does not support, for instance, the use of \C or a back reference. |
| <pre> |
| PCRE_ERROR_DFA_UCOND (-17) |
| </pre> |
| This return is given if <b>pcre_dfa_exec()</b> encounters a condition item that |
| uses a back reference for the condition, or a test for recursion in a specific |
| group. These are not supported. |
| <pre> |
| PCRE_ERROR_DFA_UMLIMIT (-18) |
| </pre> |
| This return is given if <b>pcre_dfa_exec()</b> is called with an <i>extra</i> |
| block that contains a setting of the <i>match_limit</i> or |
| <i>match_limit_recursion</i> fields. This is not supported (these fields are |
| meaningless for DFA matching). |
| <pre> |
| PCRE_ERROR_DFA_WSSIZE (-19) |
| </pre> |
| This return is given if <b>pcre_dfa_exec()</b> runs out of space in the |
| <i>workspace</i> vector. |
| <pre> |
| PCRE_ERROR_DFA_RECURSE (-20) |
| </pre> |
| When a recursive subpattern is processed, the matching function calls itself |
| recursively, using private vectors for <i>ovector</i> and <i>workspace</i>. This |
| error is given if the output vector is not large enough. This should be |
| extremely rare, as a vector of size 1000 is used. |
| </P> |
| <br><a name="SEC22" href="#TOC1">SEE ALSO</a><br> |
| <P> |
| <b>pcrebuild</b>(3), <b>pcrecallout</b>(3), <b>pcrecpp(3)</b>(3), |
| <b>pcrematching</b>(3), <b>pcrepartial</b>(3), <b>pcreposix</b>(3), |
| <b>pcreprecompile</b>(3), <b>pcresample</b>(3), <b>pcrestack</b>(3). |
| </P> |
| <br><a name="SEC23" href="#TOC1">AUTHOR</a><br> |
| <P> |
| Philip Hazel |
| <br> |
| University Computing Service |
| <br> |
| Cambridge CB2 3QH, England. |
| <br> |
| </P> |
| <br><a name="SEC24" href="#TOC1">REVISION</a><br> |
| <P> |
| Last updated: 02 December 2011 |
| <br> |
| Copyright © 1997-2011 University of Cambridge. |
| <br> |
| <p> |
| Return to the <a href="index.html">PCRE index page</a>. |
| </p> |