protected function moveWatch($fromLiteral, $toLiteral, $node)
    {
        if (!isset($this->watchChains[$toLiteral])) {
            $this->watchChains[$toLiteral] = new RuleWatchChain;
        }

        $node->moveWatch($fromLiteral, $toLiteral);
        $this->watchChains[$fromLiteral]->remove();
        $this->watchChains[$toLiteral]->unshift($node);
    }