feature #25275 [DI] Allow for invokable event listeners (ro0NL)

This PR was merged into the 4.1-dev branch.

Discussion
----------

[DI] Allow for invokable event listeners

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #... <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!--highly recommended for new features-->

Inspired by #24637 / #25259. This adds invokable support for event listeners :)

```yaml
Some\Foo:
    tags: [{ name: kernel.event_listener, event: kernel.request }]
```

```php
class Foo {
    public function __invoke(GetResponseEvent $event) { }
}
```

Commits
-------

fa5b7eb [DI] Allow for invokable event listeners

Author: fabpot

src/Symfony/Component/EventDispatcher/CHANGELOG.md

@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+4.1.0
+-----
+
+ * added support for invokable event listeners tagged with `kernel.event_listener` by default 
+
 4.0.0
 -----
 

src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php

@@ -68,6 +68,10 @@ public function process(ContainerBuilder $container)
                         '/[^a-z0-9]/i',
                     ), function ($matches) { return strtoupper($matches[0]); }, $event['event']);
                     $event['method'] = preg_replace('/[^a-z0-9]/i', '', $event['method']);
+
+                    if (null !== ($class = $container->getDefinition($id)->getClass()) && ($r = $container->getReflectionClass($class, false)) && !$r->hasMethod($event['method']) && $r->hasMethod('__invoke')) {
+                        $event['method'] = '__invoke';
+                    }
                 }
 
                 $definition->addMethodCall('addListener', array($event['event'], array(new ServiceClosureArgument(new Reference($id)), $event['method']), $priority));

src/Symfony/Component/EventDispatcher/Tests/DependencyInjection/RegisterListenersPassTest.php

@@ -166,6 +166,47 @@ public function testEventSubscriberUnresolvableClassName()
         $registerListenersPass = new RegisterListenersPass();
         $registerListenersPass->process($container);
     }
+
+    public function testInvokableEventListener()
+    {
+        $container = new ContainerBuilder();
+        $container->register('foo', \stdClass::class)->addTag('kernel.event_listener', array('event' => 'foo.bar'));
+        $container->register('bar', InvokableListenerService::class)->addTag('kernel.event_listener', array('event' => 'foo.bar'));
+        $container->register('baz', InvokableListenerService::class)->addTag('kernel.event_listener', array('event' => 'event'));
+        $container->register('event_dispatcher', \stdClass::class);
+
+        $registerListenersPass = new RegisterListenersPass();
+        $registerListenersPass->process($container);
+
+        $definition = $container->getDefinition('event_dispatcher');
+        $expectedCalls = array(
+            array(
+                'addListener',
+                array(
+                    'foo.bar',
+                    array(new ServiceClosureArgument(new Reference('foo')), 'onFooBar'),
+                    0,
+                ),
+            ),
+            array(
+                'addListener',
+                array(
+                    'foo.bar',
+                    array(new ServiceClosureArgument(new Reference('bar')), '__invoke'),
+                    0,
+                ),
+            ),
+            array(
+                'addListener',
+                array(
+                    'event',
+                    array(new ServiceClosureArgument(new Reference('baz')), 'onEvent'),
+                    0,
+                ),
+            ),
+        );
+        $this->assertEquals($expectedCalls, $definition->getMethodCalls());
+    }
 }
 
 class SubscriberService implements \Symfony\Component\EventDispatcher\EventSubscriberInterface
@@ -177,3 +218,14 @@ public static function getSubscribedEvents()
         );
     }
 }
+
+class InvokableListenerService
+{
+    public function __invoke()
+    {
+    }
+
+    public function onEvent()
+    {
+    }
+}