PCRE - Perl-compatible regular expressions


#include <pcre.h>

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

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

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


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
Points to an associated pcre[16|32]_extra structure,
or is NULL
Points to the subject string
Length of the subject string
Offset in the subject at which to start matching
Option bits
Points to a vector of ints for result offsets
Number of elements in the vector
Points to a vector of ints used as working space
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_SOFT ) match if no full matches are found
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
Opaque data from pcre[16|32]_study()
Limit on internal resource use
Limit on internal recursion depth
Opaque data passed back to callouts
Points to character tables or is NULL
For passing back a *MARK pointer
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.


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