PHP双向队列

<?php
    # 双向队列
    class Deque {
        public $queue = array();
        
        public function frontAdd($obj) {
            array_unshift($this->queue, $obj);
        }
        
        public function frontRemove() {
            return array_shift($this->queue);
        }
        
        public function rearAdd($obj) {
            array_push($this->queue, $obj);
        }
        
        public function rearRemove() {
            return array_pop($this->queue);
        }
        
        public function size() {
            return count($queue);
        }
    }
    
    $deque = new Deque();
    $deque->rearAdd(2);
    $deque->rearAdd(2);
    $deque->frontAdd(1);
    $deque->frontAdd(1);
    $deque->rearAdd(2);
    $deque->rearAdd(2);
    print_r($deque);
    $deque->frontRemove();
    $deque->rearRemove();
    print_r($deque);
?>

Deque Object ( [queue] => Array ( [0] => 1 [1] => 1 [2] => 2 [3] => 2 [4] => 2 [5] => 2 ) ) Deque Object ( [queue] => Array ( [0] => 1 [1] => 2 [2] => 2 [3] => 2 ) )