Make Queue internal

src/FulfilledPromise.php

@@ -22,7 +22,7 @@ public function then(callable $onFulfilled = null, callable $onRejected = null)
         }
 
         return new Promise(function (callable $resolve, callable $reject) use ($onFulfilled) {
-            Queue::enqueue(function () use ($resolve, $reject, $onFulfilled) {
+            enqueue(function () use ($resolve, $reject, $onFulfilled) {
                 try {
                     $resolve($onFulfilled($this->value));
                 } catch (\Throwable $exception) {
@@ -40,7 +40,7 @@ public function done(callable $onFulfilled = null, callable $onRejected = null)
             return;
         }
 
-        Queue::enqueue(function () use ($onFulfilled) {
+        enqueue(function () use ($onFulfilled) {
             $result = $onFulfilled($this->value);
 
             if ($result instanceof PromiseInterface) {

src/Queue/SynchronousDriver.php → src/Internal/Queue.php

@@ -1,8 +1,11 @@
 <?php
 
-namespace React\Promise\Queue;
+namespace React\Promise\Internal;
 
-final class SynchronousDriver implements DriverInterface
+/**
+ * @internal
+ */
+final class Queue
 {
     private $queue = [];
 

src/RejectedPromise.php

@@ -22,7 +22,7 @@ public function then(callable $onFulfilled = null, callable $onRejected = null)
         }
 
         return new Promise(function (callable $resolve, callable $reject) use ($onRejected) {
-            Queue::enqueue(function () use ($resolve, $reject, $onRejected) {
+            enqueue(function () use ($resolve, $reject, $onRejected) {
                 try {
                     $resolve($onRejected($this->reason));
                 } catch (\Throwable $exception) {
@@ -36,7 +36,7 @@ public function then(callable $onFulfilled = null, callable $onRejected = null)
 
     public function done(callable $onFulfilled = null, callable $onRejected = null)
     {
-        Queue::enqueue(function () use ($onRejected) {
+        enqueue(function () use ($onRejected) {
             if (null === $onRejected) {
                 throw UnhandledRejectionException::resolve($this->reason);
             }

src/functions.php

@@ -189,6 +189,20 @@ function reduce(array $promisesOrValues, callable $reduceFunc, $initialValue = n
     }, $cancellationQueue);
 }
 
+/**
+ * @internal
+ */
+function enqueue(callable $task)
+{
+    static $queue;
+
+    if (!$queue) {
+        $queue = new Internal\Queue();
+    }
+
+    $queue->enqueue($task);
+}
+
 /**
  * @internal
  */

tests/Internal/QueueTest.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace React\Promise\Internal;
+
+use React\Promise\TestCase;
+
+class QueueTest extends TestCase
+{
+    /** @test */
+    public function excutesTasks()
+    {
+        $queue = new Queue();
+
+        $queue->enqueue($this->expectCallableOnce());
+        $queue->enqueue($this->expectCallableOnce());
+    }
+
+    /** @test */
+    public function excutesNestedEnqueuedTasks()
+    {
+        $queue = new Queue();
+
+        $nested = $this->expectCallableOnce();
+
+        $task = function() use ($queue, $nested) {
+            $queue->enqueue($nested);
+        };
+
+        $queue->enqueue($task);
+    }
+
+    /** @test */
+    public function rethrowsExceptionsThrownFromTasks()
+    {
+        $this->setExpectedException('\Exception', 'test');
+
+        $mock = $this->createCallableMock();
+        $mock
+            ->expects($this->once())
+            ->method('__invoke')
+            ->will($this->throwException(new \Exception('test')));
+
+        $queue = new Queue();
+        $queue->enqueue($mock);
+    }
+}