minor #681 Fetch Twig lazily in TemplateListener (nicolas-grekas)

This PR was merged into the 5.5.x-dev branch.

Discussion
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Fetch Twig lazily in TemplateListener

I spotted this when playing with a controller that doesn't use Twig:

`TemplateListener` always instantiate twig. But twig is kinda heavy to create. This makes its instantiation lazy.

Commits
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d10fce5 Fetch Twig lazily in TemplateListener

src/EventListener/TemplateListener.php

@@ -11,6 +11,7 @@
 
 namespace Sensio\Bundle\FrameworkExtraBundle\EventListener;
 
+use Psr\Container\ContainerInterface;
 use Sensio\Bundle\FrameworkExtraBundle\Configuration\Template;
 use Sensio\Bundle\FrameworkExtraBundle\Templating\TemplateGuesser;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
@@ -19,6 +20,7 @@
 use Symfony\Component\HttpFoundation\StreamedResponse;
 use Symfony\Component\HttpKernel\Event\KernelEvent;
 use Symfony\Component\HttpKernel\KernelEvents;
+use Symfony\Contracts\Service\ServiceSubscriberInterface;
 use Twig\Environment;
 
 /**
@@ -28,17 +30,23 @@
  *
  * @author Fabien Potencier <[email protected]>
  */
-class TemplateListener implements EventSubscriberInterface
+class TemplateListener implements EventSubscriberInterface, ServiceSubscriberInterface
 {
     private $templateGuesser;
     private $twig;
+    private $container;
 
     public function __construct(TemplateGuesser $templateGuesser, Environment $twig = null)
     {
         $this->templateGuesser = $templateGuesser;
         $this->twig = $twig;
     }
 
+    public function setContainer(ContainerInterface $container): void
+    {
+        $this->container = $container;
+    }
+
     /**
      * Guesses the template name to render and its variables and adds them to
      * the request object.
@@ -79,7 +87,11 @@ public function onKernelView(KernelEvent $event)
         }
 
         if (null === $this->twig) {
-            throw new \LogicException('You can not use the "@Template" annotation if the Twig Bundle is not available.');
+            if (!$this->container || !$this->container->has('twig')) {
+                throw new \LogicException('You can not use the "@Template" annotation if the Twig Bundle is not available.');
+            }
+
+            $this->twig = $this->container->get('twig');
         }
 
         $parameters = $event->getControllerResult();
@@ -118,6 +130,11 @@ public static function getSubscribedEvents()
         ];
     }
 
+    public static function getSubscribedServices(): array
+    {
+        return ['twig' => '?'.Environment::class];
+    }
+
     private function resolveDefaultParameters(Request $request, Template $template, $controller, $action)
     {
         $parameters = [];

src/Resources/config/view.xml

@@ -11,8 +11,11 @@
 
         <service id="sensio_framework_extra.view.listener" class="Sensio\Bundle\FrameworkExtraBundle\EventListener\TemplateListener">
             <tag name="kernel.event_subscriber" />
+            <tag name="container.service_subscriber" id="twig" />
             <argument type="service" id="sensio_framework_extra.view.guesser" />
-            <argument type="service" id="twig" on-invalid="null" />
+            <call method="setContainer">
+                <argument type="service" id="Psr\Container\ContainerInterface" on-invalid="ignore" />
+            </call>
         </service>
     </services>
 </container>

src/Templating/TemplateGuesser.php

@@ -13,7 +13,6 @@
 
 use Doctrine\Common\Persistence\Proxy;
 use Symfony\Component\HttpFoundation\Request;
-use Symfony\Component\HttpKernel\Bundle\Bundle;
 use Symfony\Component\HttpKernel\KernelInterface;
 
 /**
@@ -59,7 +58,7 @@ public function guessTemplateName($controller, Request $request)
         if (\is_object($controller) && method_exists($controller, '__invoke')) {
             $controller = [$controller, '__invoke'];
         } elseif (!\is_array($controller)) {
-            throw new \InvalidArgumentException(sprintf('First argument of %s must be an array callable or an object defining the magic method __invoke. "%s" given.', __METHOD__, \gettype($controller)));
+            throw new \InvalidArgumentException(sprintf('First argument of "%s" must be an array callable or an object defining the magic method __invoke. "%s" given.', __METHOD__, \gettype($controller)));
         }
 
         $className = $this->getRealClass(\get_class($controller[0]));
@@ -72,7 +71,7 @@ public function guessTemplateName($controller, Request $request)
             }
         }
         if (null === $matchController) {
-            throw new \InvalidArgumentException(sprintf('The "%s" class does not look like a controller class (its FQN must match one of the following regexps: "%s")', \get_class($controller[0]), implode('", "', $this->controllerPatterns)));
+            throw new \InvalidArgumentException(sprintf('The "%s" class does not look like a controller class (its FQN must match one of the following regexps: "%s").', \get_class($controller[0]), implode('", "', $this->controllerPatterns)));
         }
 
         if ('__invoke' === $controller[1]) {