PCRE2_SUBSTITUTE(3)

NAME
PCRE2 - Perl-compatible regular expressions (revised API)

SYNOPSIS

#include <pcre2.h>

int pcre2_substitute(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, PCRE2_SPTR replacement,
  PCRE2_SIZE rlength, PCRE2_UCHAR *outputbuffer,
  PCRE2_SIZE *outlengthptr);

DESCRIPTION

This function matches a compiled regular expression against a given subject string, using a matching algorithm that is similar to Perl's. It then makes a copy of the subject, substituting a replacement string for what was matched. Its arguments 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, or is NULL
  mcontext Points to a match context, or is NULL
  replacement Points to the replacement string
  rlength Length of the replacement string
  outputbuffer Points to the output buffer
  outlengthptr Points to the length of the output buffer

A match data block is needed only if you want to inspect the data from the final match that is returned in that block or if PCRE2_SUBSTITUTE_MATCHED is set. A match context is needed only if you want to:

  Set up a callout function
  Set a matching offset limit
  Change the backtracking match limit
  Change the backtracking depth limit
  Set custom memory management in the match context

The length, startoffset and rlength values are code units, not characters, as is the contents of the variable pointed at by outlengthptr. This variable must contain the length of the output buffer when the function is called. If the function is successful, the value is changed to the length of the new string, excluding the trailing zero that is automatically added.

The subject and replacement lengths can be given as PCRE2_ZERO_TERMINATED for zero-terminated strings. The options are:

  PCRE2_ANCHORED Match only at the first position
  PCRE2_ENDANCHORED 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_JIT Do not use JIT matching
  PCRE2_NO_UTF_CHECK Do not check for UTF validity in
                        the subject or replacement
                        (only relevant if PCRE2_UTF was
                        set at compile time)
  PCRE2_SUBSTITUTE_EXTENDED Do extended replacement processing
  PCRE2_SUBSTITUTE_GLOBAL Replace all occurrences in the
                        subject
  PCRE2_SUBSTITUTE_LITERAL The replacement string is literal
  PCRE2_SUBSTITUTE_MATCHED Use pre-existing match data for
                        first match
  PCRE2_SUBSTITUTE_OVERFLOW_LENGTH If overflow, compute needed length
  PCRE2_SUBSTITUTE_REPLACEMENT_ONLY Return only replacement string(s)
  PCRE2_SUBSTITUTE_UNKNOWN_UNSET Treat unknown group as unset
  PCRE2_SUBSTITUTE_UNSET_EMPTY Simple unset insert = empty string

If PCRE2_SUBSTITUTE_LITERAL is set, PCRE2_SUBSTITUTE_EXTENDED, PCRE2_SUBSTITUTE_UNKNOWN_UNSET, and PCRE2_SUBSTITUTE_UNSET_EMPTY are ignored.

If PCRE2_SUBSTITUTE_MATCHED is set, match_data must be non-NULL; its contents must be the result of a call to pcre2_match() using the same pattern and subject.

The function returns the number of substitutions, which may be zero if there are no matches. The result may be greater than one only when PCRE2_SUBSTITUTE_GLOBAL is set. In the event of an error, a negative error code is returned.

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.