1: <?php
 2: 
 3: namespace React\EventLoop\Tick;
 4: 
 5: use React\EventLoop\LoopInterface;
 6: use SplQueue;
 7: 
 8: class FutureTickQueue
 9: {
10:     private $eventLoop;
11:     private $queue;
12: 
13:     /**
14:      * @param LoopInterface $eventLoop The event loop passed as the first parameter to callbacks.
15:      */
16:     public function __construct(LoopInterface $eventLoop)
17:     {
18:         $this->eventLoop = $eventLoop;
19:         $this->queue = new SplQueue();
20:     }
21: 
22:     /**
23:      * Add a callback to be invoked on a future tick of the event loop.
24:      *
25:      * Callbacks are guaranteed to be executed in the order they are enqueued.
26:      *
27:      * @param callable $listener The callback to invoke.
28:      */
29:     public function add(callable $listener)
30:     {
31:         $this->queue->enqueue($listener);
32:     }
33: 
34:     /**
35:      * Flush the callback queue.
36:      */
37:     public function tick()
38:     {
39:         // Only invoke as many callbacks as were on the queue when tick() was called.
40:         $count = $this->queue->count();
41: 
42:         while ($count--) {
43:             call_user_func(
44:                 $this->queue->dequeue(),
45:                 $this->eventLoop
46:             );
47:         }
48:     }
49: 
50:     /**
51:      * Check if the next tick queue is empty.
52:      *
53:      * @return boolean
54:      */
55:     public function isEmpty()
56:     {
57:         return $this->queue->isEmpty();
58:     }
59: }
60: