Introduce a default controller for pages with a _content request attribute.

core/lib/Drupal/Core/CoreBundle.php

@@ -82,6 +82,7 @@ public function build(ContainerBuilder $container) {
     $dispatcher->addSubscriber(new \Drupal\Core\EventSubscriber\FinishResponseSubscriber());
     $dispatcher->addSubscriber(new \Drupal\Core\EventSubscriber\RequestCloseSubscriber());
     $dispatcher->addSubscriber(new \Drupal\Core\EventSubscriber\ConfigGlobalOverrideSubscriber());
+    $dispatcher->addSubscriber(new \Drupal\Core\EventSubscriber\RouteProcessorSubscriber());
     $container->set('content_negotiation', $content_negotation);
     $dispatcher->addSubscriber(\Drupal\Core\ExceptionController::getExceptionListener($container));
 

core/lib/Drupal/Core/EventSubscriber/RouteProcessorSubscriber.php

+<?php
+
+/**
+ * @file
+ * Definition of Drupal\Core\EventSubscriber\RouterListener.
+ */
+
+namespace Drupal\Core\EventSubscriber;
+
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+use Symfony\Component\HttpKernel\HttpKernelInterface;
+use Symfony\Component\HttpKernel\Event\GetResponseEvent;
+use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
+use Symfony\Component\HttpKernel\Exception\MethodNotAllowedHttpException;
+use Symfony\Component\HttpKernel\Log\LoggerInterface;
+use Symfony\Component\HttpKernel\KernelEvents;
+use Symfony\Component\Routing\Matcher\UrlMatcherInterface;
+use Symfony\Component\Routing\Exception\ResourceNotFoundException;
+
+/**
+ * Drupal-specific Router listener.
+ *
+ * This is the bridge from the kernel to the UrlMatcher.
+ */
+class RouteProcessorSubscriber implements EventSubscriberInterface {
+
+  /**
+   * The Matcher object for this listener.
+   *
+   * This property is private in the base class, so we have to hack around it.
+   *
+   * @var Symfony\Component\Router\Matcher\UrlMatcherInterface
+   */
+  protected $urlMatcher;
+
+  /**
+   * The Logging object for this listener.
+   *
+   * This property is private in the base class, so we have to hack around it.
+   *
+   * @var Symfony\Component\HttpKernel\Log\LoggerInterface
+   */
+  protected $logger;
+
+  public function __construct() {
+  }
+
+  /**
+   * Sets a default controller for a route if one was not specified.
+   */
+  public function onRequestSetController(GetResponseEvent $event) {
+    $request = $event->getRequest();
+
+    if (!$request->attributes->has('_controller') && $request->attributes->has('_content')) {
+      $request->attributes->set('_controller', '\Drupal\Core\HtmlPageController::content');
+    }
+
+  }
+
+  /**
+   * Registers the methods in this class that should be listeners.
+   *
+   * @return array
+   *   An array of event listener definitions.
+   */
+  static function getSubscribedEvents() {
+    // The RouterListener has priority 32, and we need to run after that.
+    $events[KernelEvents::REQUEST][] = array('onRequestSetController', 30);
+
+    return $events;
+  }
+}

core/lib/Drupal/Core/HtmlPageController.php

+<?php
+
+namespace Drupal\Core;
+
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+
+class HtmlPageController {
+
+  public function content(Request $request, $_content) {
+
+    $content_controller = $this->getContentController($_content);
+
+    $page_callback_result = call_user_func_array($content_controller, array());
+
+    return new Response(drupal_render_page($page_callback_result));
+  }
+
+  protected function getContentController($controller) {
+    if (is_array($controller) || (is_object($controller) && method_exists($controller, '__invoke'))) {
+      return $controller;
+    }
+
+    if (FALSE === strpos($controller, ':')) {
+      if (method_exists($controller, '__invoke')) {
+        return new $controller;
+      } elseif (function_exists($controller)) {
+        return $controller;
+      }
+    }
+
+    list($controller, $method) = $this->createController($controller);
+
+    if (!method_exists($controller, $method)) {
+      throw new \InvalidArgumentException(sprintf('Method "%s::%s" does not exist.', get_class($controller), $method));
+    }
+
+    return array($controller, $method);
+  }
+
+  protected function createController($controller) {
+    if (false === strpos($controller, '::')) {
+     throw new \InvalidArgumentException(sprintf('Unable to find controller "%s".', $controller));
+    }
+
+    list($class, $method) = explode('::', $controller, 2);
+
+    if (!class_exists($class)) {
+      throw new \InvalidArgumentException(sprintf('Class "%s" does not exist.', $class));
+    }
+
+    return array(new $class(), $method);
+  }
+
+
+}

core/modules/system/lib/Drupal/system/Tests/Routing/RouterTest.php

@@ -25,9 +25,21 @@ public static function getInfo() {
     );
   }
 
+  /**
+   * Confirms that the router can get to a controller.
+   */
   public function testCanRoute() {
     $this->drupalGet('router_test/test1');
     $this->assertRaw('test1', 'The correct string was returned because the route was successful.');
   }
 
+  /**
+   * Confirms that our default controller logic works properly.
+   */
+  public function testDefaultController() {
+    $this->drupalGet('router_test/test2');
+    $this->assertRaw('test2', 'The correct string was returned because the route was successful.');
+    $this->assertRaw('</html>', 'Page markup was found.');
+  }
+
 }

core/modules/system/tests/modules/router_test/lib/Drupal/router_test/TestControllers.php

 <?php
 
+/**
+ * @file
+ * Definition of Drupal\router_test\TestControllers.
+ */
+
 namespace Drupal\router_test;
 
 use Symfony\Component\HttpFoundation\Response;
 
 /**
- * Description of TestControllers
+ * Controller routines for testing the routing system.
  */
 class TestControllers {
 
@@ -13,5 +18,9 @@ public function test1() {
     return new Response('test1');
   }
 
+  public function test2() {
+    return "test2";
+  }
+
 }
 

core/modules/system/tests/modules/router_test/router_test.module

@@ -3,6 +3,9 @@
 use Symfony\Component\Routing\Route;
 use Symfony\Component\Routing\RouteCollection;
 
+/**
+ * Implements hook_router_info().
+ */
 function router_test_route_info() {
   $collection = new RouteCollection();
 
@@ -11,5 +14,10 @@ function router_test_route_info() {
   ));
   $collection->add('router_test_1', $route);
 
+  $route = new Route('router_test/test2', array(
+    '_content' => '\Drupal\router_test\TestControllers::test2'
+  ));
+  $collection->add('router_test_2', $route);
+
   return $collection;
 }