class RouteBuilder

class RouteBuilder {

  /**
   * The dumper to which we should send collected routes.
   *
   * @var \Symfony\Component\Routing\Matcher\Dumper\MatcherDumperInterface
   */
  protected $dumper;

  /**
   * The used lock backend instance.
   *
   * @var \Drupal\Core\Lock\LockBackendInterface $lock
   */
  protected $lock;

  /**
   * The event dispatcher to notify of routes.
   *
   * @var \Symfony\Component\EventDispatcher\EventDispatcherInterface
   */
  protected $dispatcher;

  /**
   * Construcs the RouteBuilder using the passed MatcherDumperInterface.
   *
   * @param \Symfony\Component\Routing\Matcher\Dumper\MatcherDumperInterface $dumper
   *   The matcher dumper used to store the route information.
   * @param \Drupal\Core\Lock\LockBackendInterface $lock
   *   The lock backend.
   * @param \Symfony\Component\EventDispatcherEventDispatcherInterface
   *   The event dispatcher to notify of routes.
   */
  public function __construct(MatcherDumperInterface $dumper, LockBackendInterface $lock, EventDispatcherInterface $dispatcher) {
    $this->dumper = $dumper;
    $this->lock = $lock;
    $this->dispatcher = $dispatcher;
  }

  /**
   * Rebuilds the route info and dumps to dumper.
   */
  public function rebuild() {
    if (!$this->lock
      ->acquire('router_rebuild')) {

      // Wait for another request that is already doing this work.
      // We choose to block here since otherwise the routes might not be
      // available, resulting in a 404.
      $this->lock
        ->wait('router_rebuild');
      return;
    }
    $parser = new Parser();

    // We need to manually call each module so that we can know which module
    // a given item came from.
    // @todo Use an injected Extension service rather than module_list():
    //   http://drupal.org/node/1331486.
    foreach (module_list() as $module) {
      $collection = new RouteCollection();
      $routing_file = DRUPAL_ROOT . '/' . drupal_get_path('module', $module) . '/' . $module . '.routing.yml';
      if (file_exists($routing_file)) {
        $routes = $parser
          ->parse(file_get_contents($routing_file));
        if (!empty($routes)) {
          foreach ($routes as $name => $route_info) {
            $defaults = isset($route_info['defaults']) ? $route_info['defaults'] : array();
            $requirements = isset($route_info['requirements']) ? $route_info['requirements'] : array();
            $route = new Route($route_info['pattern'], $defaults, $requirements);
            $collection
              ->add($name, $route);
          }
        }
      }
      $this->dispatcher
        ->dispatch(RoutingEvents::ALTER, new RouteBuildEvent($collection, $module));
      $this->dumper
        ->addRoutes($collection);
      $this->dumper
        ->dump(array(
        'route_set' => $module,
      ));
    }

    // Now allow modules to register additional, dynamic routes.
    $collection = new RouteCollection();
    $this->dispatcher
      ->dispatch(RoutingEvents::DYNAMIC, new RouteBuildEvent($collection, 'dynamic_routes'));
    $this->dispatcher
      ->dispatch(RoutingEvents::ALTER, new RouteBuildEvent($collection, 'dynamic_routes'));
    $this->dumper
      ->addRoutes($collection);
    $this->dumper
      ->dump(array(
      'route_set' => 'dynamic_routes',
    ));
    $this->lock
      ->release('router_rebuild');
  }

}