text: /*
   * vim:ts=4:sw=4:expandtab
   *
   * i3 - an improved dynamic tiling window manager
   * © 2009 Michael Stapelberg and contributors (see also: LICENSE)
   *
   * regex.c: Interface to libPCRE (perl compatible regular expressions).
   *
   */
  #include "all.h"
  
  /*
   * Creates a new 'regex' struct containing the given pattern and a PCRE
   * compiled regular expression. Also, calls pcre_study because this regex will
   * most likely be used often (like for every new window and on every relevant
   * property change of existing windows).
   *
   * Returns NULL if the pattern could not be compiled into a regular expression
   * (and ELOGs an appropriate error message).
   *
   */
  struct regex *regex_new(const char *pattern) {
      int errorcode;
      PCRE2_SIZE offset;
  
      struct regex *re = scalloc(1, sizeof(struct regex));
      re->pattern = sstrdup(pattern);
      uint32_t options = PCRE2_UTF;
      /* We use PCRE_UCP so that \B, \b, \D, \d, \S, \s, \W, \w and some POSIX
       * character classes play nicely with Unicode */
      options |= PCRE2_UCP;
      if (!(re->regex = pcre2_compile((PCRE2_SPTR)pattern, PCRE2_ZERO_TERMINATED, options, &errorcode, &offset, NULL))) {
          PCRE2_UCHAR buffer[256];
          pcre2_get_error_message(errorcode, buffer, sizeof(buffer));
          ELOG("PCRE regular expression compilation failed at %lu: %s\n",
               offset, buffer);
          regex_free(re);
          return NULL;
      }
      return re;
  }
  
  /*
   * Frees the given regular expression. It must not be used afterwards!
   *
   */
  void regex_free(struct regex *regex) {
      if (!regex)
          return;
      FREE(regex->pattern);
      FREE(regex->regex);
      FREE(regex);
  }
  
  /*
   * Checks if the given regular expression matches the given input and returns
   * true if it does. In either case, it logs the outcome using LOG(), so it will
   * be visible without debug logging.
   *
   */
  bool regex_matches(struct regex *regex, const char *input) {
      pcre2_match_data *match_data;
      int rc;
  
      match_data = pcre2_match_data_create_from_pattern(regex->regex, NULL);
  
      /* We use strlen() because pcre_exec() expects the length of the input
       * string in bytes */
      rc = pcre2_match(regex->regex, (PCRE2_SPTR)input, strlen(input), 0, 0, match_data, NULL);
      pcre2_match_data_free(match_data);
      if (rc > 0) {
          LOG("Regular expression \"%s\" matches \"%s\"\n",
              regex->pattern, input);
          return true;
      }
  
      if (rc == PCRE2_ERROR_NOMATCH) {
          LOG("Regular expression \"%s\" does not match \"%s\"\n",
              regex->pattern, input);
          return false;
      }
  
      ELOG("PCRE error %d while trying to use regular expression \"%s\" on input \"%s\", see pcreapi(3)\n",
           rc, regex->pattern, input);
      return false;
  }
  