code: protected function invokeParser($content, $is_match)
      {
          if (($content === '') || ($content === false)) {
              return true;
          }
          $handler = $this->mode_handlers[$this->mode->getCurrent()];
  
          return $this->parser->$handler($content, $is_match);
      }
docs: Calls the parser method named after the current mode.
  Empty content will be ignored.
  The lexer has a parser handler for each mode in the lexer.
  
  @param string $content        Text parsed.
  @param bool $is_match      Token is recognised rather than unparsed data.