PHP实现数据队列

/** * Class Queue * * 参考地址：https://www.jianshu.com/p/ca1bb95ada76 */class Queue {    /**     * 队列list     *     * @var array     */    protected $items = [];    /**     * 创建队列元素     *     * @param $element     * @param $priority     * @return array     */    public function queueElement($element, $priority) {        return [            'element' => $element,            'priority' => $priority        ];    }    /**     * 将数据加入队列     *     * @param $element     * @param null $priority     * @return array     */    public function enqueue($element, $priority = NULL) {        $queueElement = $this->queueElement($element, $priority);        if ($this->isEmpty() || $priority === NULL) {            array_push($this->items, $queueElement);        } else {            $add = false;            foreach ($this->items as $key => $value) {                if ( $priority < $value['priority'] ) {                    array_splice($this->items, $key, 0, [$queueElement]);                    $add = true;                    break;                }            }            if (! $add) {                array_push($this->items, $queueElement);            }        }        return $queueElement;    }    /**     * 队列消费     *     * @return mixed     */    public function dequeue() {        return array_shift($this->items);    }    /**     * 队列的第一个元素     *     * @return mixed     */    public function front() {        return $this->items[0];    }    /**     * 队列是否为空     *     * @return bool     */    public function isEmpty() {        return !!! count($this->items);    }    /**     * 队列items大小     *     * @return int     */    public function size() {        return count($this->items);    }}$queue = new Queue();$queue->enqueue("abc", 10);$queue->enqueue("def", 5);$queue->enqueue("hig", 12);$queue->enqueue("ijk", 3);$size = $queue->size();for ($i = 0; $i < $size; $i++) {    $item = $queue->dequeue();    print_r($item);}