pcre_dfa_exec specification

# pcre_dfa_exec man page

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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 documentation. For details of partial matching, see the pcrepartial 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 page and a description of the POSIX API in the pcreposix page.

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