Synopsis

#include <pcre2.h>

int pcre2_dfa_match(const pcre2_code *code, PCRE2_SPTR subject,
                    PCRE2_SIZE length, PCRE2_SIZE start_offset,
                    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

start_offset

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 start_offset 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.