PHP 양방향 대기열 코드

<?php
    class Deque{
        public $queue = array();
        /**
         * 尾部入对
         * @param [type] $value [description]
         */
        public function addLast($value){
            return array_push($this->queue,$value);
        }
        /**
         * 尾部出队
         * @return [type] [description]
         */
        public function removeLast(){
            return array_pop($this->queue);
        }
        /**
         * 头部入队
         * @param [type] $value [description]
         */
        public function addFirst($value){
            return array_unshift($this->queue, $value);
        }
        /**
         * 头部出队
         * @return [type] [description]
         */
        public function removeFirst(){
            return array_shift($this->queue);
        }
        /**
         * 清空队列
         * @return [type] [description]
         */
        public function makeEmpty(){
            unset($this->queue);
        }
        /**
         * 获取列头
         * @return [type] [description]
         */
        public function getFirst(){
            return reset($this->queue);
        }
        /**
         * 获取列尾
         * @return [type] [description]
         */
        public function getLast(){
            return end($this->queue);
        }
        /**
         * 获取长度
         * @return [type] [description]
         */
        public function getLength(){
            return count($this->queue);
        }
    }