Add ContainerRuntimeLoader

composer.json

@@ -31,7 +31,8 @@
     },
     "require-dev": {
         "symfony/phpunit-bridge": "~3.2",
-        "symfony/debug": "~2.7"
+        "symfony/debug": "~2.7",
+        "psr/container": "^1.0"
     },
     "autoload": {
         "psr-0" : {

lib/Twig/ContainerRuntimeLoader.php

@@ -0,0 +1,37 @@
+<?php
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) Fabien Potencier
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+use Psr\Container\ContainerInterface;
+
+/**
+ * Lazily loads Twig runtime implementations from a PSR-11 container.
+ *
+ * The runtime services must use their class name as identifier in the container.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ * @author Robin Chalas <robin.chalas@gmail.com>
+ */
+class Twig_ContainerRuntimeLoader implements Twig_RuntimeLoaderInterface
+{
+    private $container;
+
+    public function __construct(ContainerInterface $container)
+    {
+        $this->container = $container;
+    }
+
+    public function load($class)
+    {
+        if ($this->container->has($class)) {
+            return $this->container->get($class);
+        }
+    }
+}

test/Twig/Tests/ContainerRuntimeLoaderTest.php

@@ -0,0 +1,35 @@
+<?php
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) Fabien Potencier
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+use Psr\Container\ContainerInterface;
+
+class Twig_Tests_ContainerRuntimeLoaderTest extends PHPUnit_Framework_TestCase
+{
+    public function testLoad()
+    {
+        $container = $this->getMockBuilder(ContainerInterface::class)->getMock();
+        $container->expects($this->once())->method('has')->with('stdClass')->willReturn(true);
+        $container->expects($this->once())->method('get')->with('stdClass')->willReturn(new \Stdclass());
+
+        $loader = new Twig_ContainerRuntimeLoader($container);
+
+        $this->assertInstanceOf('stdClass', $loader->load('stdClass'));
+    }
+
+    public function testLoadUnknownRuntimeReturnsNull()
+    {
+        $container = $this->getMockBuilder(ContainerInterface::class)->getMock();
+        $container->expects($this->once())->method('has')->with('Foo');
+        $container->expects($this->never())->method('get');
+
+        $this->assertNull((new Twig_ContainerRuntimeLoader($container))->load('Foo'));
+    }
+}