PHP two-way queue implementation code

1. What is a two-way queue

Deque, the full name is double-ended queue, is a data structure with the properties of queue and stack. Elements in a double-ended queue can be popped from both ends, and insertion and deletion operations are limited to both ends of the table. A deque (double-ended queue) is like a queue, but elements can be added or removed from either end.

Reference: http://zh.wikipedia.org/zh-cn/%E5%8F%8C%E7%AB%AF%E9%98%9F%E5%88%97

2, PHP code to implement two-way queue

class DoubleQueue
{
 public $queue = array();

 /**(Tail)Enter the queue**/
 public function addLast($value)
 {
 return array_push($this->queue,$value);
 }
 /**(Tail) Dequeue**/
 public function removeLast()
 {
 return array_pop($this->queue);
 }
 /* *(head) join the team**/
 public function addFirst($value)
 {
 return array_unshift($this->queue,$value);
 }
 /**(head) dequeue**/
 public function removeFirst()
 {
 return array_shift($this->queue);
 }
 /**Clear queue**/
 public function makeEmpty()
 {
 unset($this->queue);
 }

 /**Get column header**/
 public function getFirst()
 {
 return reset($this->queue);
 }
 /**Get column tail **/
 public function getLast()
 {
 return end($this->queue);
 }
 /**Get length **/
 public function getLength()
 {
 return count($this-> ;queue);
 }

}