pcre2_callout_enumerate - Man Page

#include <pcre2.h>

int pcre2_callout_enumerate(const pcre2_code *code,
  int (*callback)(pcre2_callout_enumerate_block *, void *),
  void *callout_data);

This function scans a compiled regular expression and calls the callback() function for each callout within the pattern. The yield of the function is zero for success and non-zero otherwise. The arguments are:

 code           Points to the compiled pattern
 callback       The callback function
 callout_data   User data that is passed to the callback

The callback() function is passed a pointer to a data block containing the following fields (not necessarily in this order):

 uint32_t   version                Block version number
 uint32_t   callout_number         Number for numbered callouts
 PCRE2_SIZE pattern_position       Offset to next item in pattern
 PCRE2_SIZE next_item_length       Length of next item in pattern
 PCRE2_SIZE callout_string_offset  Offset to string within pattern
 PCRE2_SIZE callout_string_length  Length of callout string
 PCRE2_SPTR callout_string         Points to callout string or is NULL

The second argument passed to the callback() function is the callout data that was passed to pcre2_callout_enumerate(). The callback() function must return zero for success. Any other value causes the pattern scan to stop, with the value being passed back as the result of pcre2_callout_enumerate().

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.