LoginStatusCheck.php

<?php

/**
 * @file
 * Contains \Drupal\user\Access\LoginStatusCheck.
 */
namespace Drupal\user\Access;

use Drupal\Core\Access\AccessCheckInterface;
use Symfony\Component\Routing\Route;
use Symfony\Component\HttpFoundation\Request;

/**
 * Determines access to routes based on login status of current user.
 */
class LoginStatusCheck implements AccessCheckInterface {

  /**
   * {@inheritdoc}
   */
  public function applies(Route $route) {
    return array_key_exists('_user_is_logged_in', $route
      ->getRequirements());
  }

  /**
   * {@inheritdoc}
   */
  public function access(Route $route, Request $request) {
    return (bool) $GLOBALS['user']->uid;
  }

}