Twig_Environment::getNodeVisitors PHP Method

    public function getNodeVisitors()
    {
        if (null === $this->visitors) {
            $this->visitors = array();
            foreach ($this->getExtensions() as $extension) {
                $this->visitors = array_merge($this->visitors, $extension->getNodeVisitors());
            }
        }

        return $this->visitors;
    }

 public function setEnvironment(Twig_Environment $env)
 {
     $this->env = $env;
     $this->handlers = array();
     $this->visitors = array();
     // tag handlers
     foreach ($this->env->getTokenParsers() as $handler) {
         $handler->setParser($this);
         $this->handlers[$handler->getTag()] = $handler;
     }
     // node visitors
     $this->visitors = $env->getNodeVisitors();
 }