(
    $generateMatcher := function($ch) {
      $match := function($str, $offset) {(
        $before := $substringBefore($str, $ch);
        $start := $length($before) + ($exists($offset) ? $offset : 0);
        $end := $start + $length($ch);
        $before != $str and $length($ch) > 0 ? {
          'match': $ch,
          'start': $start,
          'end': $end,
          'groups': [],
          'next': function() {$match($substringAfter($str, $ch), $end)}
        }
      )}
    };

    $match("abracadabra", $generateMatcher('a'))
)