Linux manual pages Section 3: Subroutines  

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