pcre2_dfa_match specification

# pcre2_dfa_match man page

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## SYNOPSIS

#include <pcre2.h>

int pcre2_dfa_match(const pcre2_code *code, PCRE2_SPTR subject, PCRE2_SIZE length, PCRE2_SIZE startoffset, uint32_t options, pcre2_match_data *match_data, pcre2_match_context *mcontext, int *workspace, PCRE2_SIZE 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 (except when processing lookaround assertions). This function is not Perl-compatible (the Perl-compatible matching function is pcre2_match()). The arguments for this function are:

      code         Points to the compiled pattern
      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
      match_data   Points to a match data block, for results
      mcontext     Points to a match context, or is NULL
      workspace    Points to a vector of ints used as working space
      wscount      Number of elements in the vector

The size of output vector needed to contain all the results depends on the number of simultaneous matches, not on the number of parentheses in the pattern. Using pcre2_match_data_create_from_pattern() to create the match data block is therefore not advisable when using this function.

A match context is needed only if you want to set up a callout function or specify the heap limit or the match or the recursion depth limits. The length and startoffset values are code units, not characters. The options are:

      PCRE2_ANCHORED          Match only at the first position
      PCRE2_COPY_MATCHED_SUBJECT
                              On success, make a private subject copy
      PCRE2_ENDANCHORED       Pattern can match only at end of subject
      PCRE2_NOTBOL            Subject is not the beginning of a line
      PCRE2_NOTEOL            Subject is not the end of a line
      PCRE2_NOTEMPTY          An empty string is not a valid match
      PCRE2_NOTEMPTY_ATSTART  An empty string at the start of the subject is not a valid match
      PCRE2_NO_UTF_CHECK      Do not check the subject for UTF validity (only relevant if PCRE2_UTF
                               was set at compile time)
      PCRE2_PARTIAL_HARD      Return PCRE2_ERROR_PARTIAL for a partial match even if there is a full match
      PCRE2_PARTIAL_SOFT      Return PCRE2_ERROR_PARTIAL for a partial match if no full matches are found
      PCRE2_DFA_RESTART       Restart after a partial match
      PCRE2_DFA_SHORTEST      Return only the shortest match

There are restrictions on what may appear in a pattern when using this matching function. Details are given in the pcre2matching documentation. For details of partial matching, see the pcre2partial page. There is a complete description of the PCRE2 native API in the pcre2api page and a description of the POSIX API in the pcre2posix page.

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