Linux manual pages Section 3  

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);
 

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_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_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_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(3) documentation. For details of partial matching, see the pcrepartial(3) page.

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 this matching function, 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(3) page and a description of the POSIX API in the pcreposix(3) page.

COPYRIGHT

This manual page is taken from the PCRE library, which is distributed under the BSD license.