Manual Reference Pages  - PCRE_DFA_EXEC (3)


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,     int options, int *ovector, int ovecsize,     int *workspace, int wscount);


This function matches a compiled regular expression against a given subject string, using a DFA matching algorithm (not Perl-compatible). Note that the main, Perl-compatible, matching function is pcre_exec(). The arguments for this function are:

code Points to the compiled pattern
extra Points to an associated pcre_extra structure,
or is NULL
subject Points to the subject string
length Length of the subject string, in bytes
startoffset Offset in bytes 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 options are:

PCRE_ANCHORED Match only at the first position
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_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 match
PCRE_DFA_SHORTEST Return only the shortest match
PCRE_DFA_RESTART This is a restart after a partial match

There are restrictions on what may appear in a pattern when matching using the DFA algorithm is requested. Details are given in the pcrematching documentation.

A pcre_extra structure contains the following fields:

flags Bits indicating which fields are set
study_data Opaque data from pcre_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

The flag bits are PCRE_EXTRA_STUDY_DATA, PCRE_EXTRA_MATCH_LIMIT, PCRE_EXTRA_MATCH_LIMIT_RECURSION, PCRE_EXTRA_CALLOUT_DATA, and PCRE_EXTRA_TABLES. For DFA matching, the match_limit and match_limit_recursion fields are not used, and must not be set.

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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