/** * Adds a visitor. * * @param Twig_NodeVisitorInterface $visitor A Twig_NodeVisitorInterface instance */ public function addVisitor(Twig_NodeVisitorInterface $visitor) { if (!isset($this->visitors[$visitor->getPriority()])) { $this->visitors[$visitor->getPriority()] = array(); } $this->visitors[$visitor->getPriority()][] = $visitor; }