code: public function hasReference(
          /*# string */ $subject,
          array &$matched
      )/*# : bool */ {
          if (is_string($subject) &&
              false !== strpos($subject, $this->ref_start) &&
              preg_match($this->ref_pattern, $subject, $matched)
          ) {
              return true;
          }
          return false;
      }
docs: {@inheritDoc}