NAME

PCRE - Perl-compatible regular expressions

SYNOPSIS

#include <pcre.h>

int pcre_dfa_exec(const pcre *code, const pcre_extra *extra,
     const char *subject, int length, int startoffset,
     int options, int *ovector, int ovecsize,
     int *workspace, int wscount);

int pcre16_dfa_exec(const pcre16 *code, const pcre16_extra *extra,
     PCRE_SPTR16 subject, int length, int startoffset,
     int options, int *ovector, int ovecsize,
     int *workspace, int wscount);

int pcre32_dfa_exec(const pcre32 *code, const pcre32_extra *extra,
     PCRE_SPTR32 subject, int length, int startoffset,
     int options, int *ovector, int ovecsize,
     int *workspace, int wscount);

DESCRIPTION

This function matches a compiled regular expression against a given subject string, using an alternative matching algorithm that scans the subject string just once (not Perl-compatible). Note that the main, Perl-compatible, matching function is pcre[16|32]_exec(). The arguments for this function are:

code Points to the compiled pattern
extra Points to an associated pcre[16|32]_extra structure,
or is NULL
subject Points to the subject string
length Length of the subject string
startoffset Offset in the subject at which to start matching
options Option bits
ovector Points to a vector of ints for result offsets
ovecsize Number of elements in the vector
workspace Points to a vector of ints used as working space
wscount Number of elements in the vector

The units for length and startoffset are bytes for pcre_exec(), 16-bit data items for pcre16_exec(), and 32-bit items for pcre32_exec(). The options are:

PCRE_ANCHORED Match only at the first position
PCRE_BSR_ANYCRLF \R matches only CR, LF, or CRLF
PCRE_BSR_UNICODE \R matches all Unicode line endings
PCRE_NEWLINE_ANY Recognize any Unicode newline sequence
PCRE_NEWLINE_ANYCRLF Recognize CR, LF, & CRLF as newline sequences
PCRE_NEWLINE_CR Recognize CR as the only newline sequence
PCRE_NEWLINE_CRLF Recognize CRLF as the only newline sequence
PCRE_NEWLINE_LF Recognize LF as the only newline sequence
PCRE_NOTBOL Subject is not the beginning of a line
PCRE_NOTEOL Subject is not the end of a line
PCRE_NOTEMPTY An empty string is not a valid match
PCRE_NOTEMPTY_ATSTART An empty string at the start of the subject
is not a valid match
PCRE_NO_START_OPTIMIZE Do not do "start-match" optimizations
PCRE_NO_UTF16_CHECK Do not check the subject for UTF-16
validity (only relevant if PCRE_UTF16
was set at compile time)
PCRE_NO_UTF32_CHECK Do not check the subject for UTF-32
validity (only relevant if PCRE_UTF32
was set at compile time)
PCRE_NO_UTF8_CHECK Do not check the subject for UTF-8
validity (only relevant if PCRE_UTF8
was set at compile time)
PCRE_PARTIAL ) Return PCRE_ERROR_PARTIAL for a partial
PCRE_PARTIAL_SOFT ) match if no full matches are found
PCRE_PARTIAL_HARD Return PCRE_ERROR_PARTIAL for a partial match
even if there is a full match as well
PCRE_DFA_SHORTEST Return only the shortest match
PCRE_DFA_RESTART Restart after a partial match

There are restrictions on what may appear in a pattern when using this matching function. Details are given in the pcrematching documentation. For details of partial matching, see the pcrepartial page.

A pcre[16|32]_extra structure contains the following fields:

flags Bits indicating which fields are set
study_data Opaque data from pcre[16|32]_study()
match_limit Limit on internal resource use
match_limit_recursion Limit on internal recursion depth
callout_data Opaque data passed back to callouts
tables Points to character tables or is NULL
mark For passing back a *MARK pointer
executable_jit Opaque data from JIT compilation

The flag bits are PCRE_EXTRA_STUDY_DATA, PCRE_EXTRA_MATCH_LIMIT, PCRE_EXTRA_MATCH_LIMIT_RECURSION, PCRE_EXTRA_CALLOUT_DATA, PCRE_EXTRA_TABLES, PCRE_EXTRA_MARK and PCRE_EXTRA_EXECUTABLE_JIT. For this matching function, the match_limit and match_limit_recursion fields are not used, and must not be set. The PCRE_EXTRA_EXECUTABLE_JIT flag and the corresponding variable are ignored.

There is a complete description of the PCRE native API in the pcreapi page and a description of the POSIX API in the pcreposix page.