class AccessManager

AccessSubscriber.php in drupal/core/lib/Drupal/Core/EventSubscriber/AccessSubscriber.php

Contains Drupal\Core\EventSubscriber\AccessSubscriber.

class AccessManager extends ContainerAware {

  /**
   * Array of registered access check service ids.
   *
   * @var array
   */
  protected $checkIds;

  /**
   * Array of access check objects keyed by service id.
   *
   * @var array
   */
  protected $checks;

  /**
   * The request object.
   *
   * @var \Symfony\Component\HttpFoundation\Request
   */
  protected $request;

  /**
   * Constructs a new AccessManager.
   *
   * @param \Symfony\Component\HttpFoundation\Request $request
   *   The request object.
   */
  public function __construct(Request $request) {
    $this->request = $request;
  }

  /**
   * Registers a new AccessCheck by service ID.
   *
   * @param string $service_id
   *   The ID of the service in the Container that provides a check.
   */
  public function addCheckService($service_id) {
    $this->checkIds[] = $service_id;
  }

  /**
   * For each route, saves a list of applicable access checks to the route.
   *
   * @param \Symfony\Component\Routing\RouteCollection $routes
   *   A collection of routes to apply checks to.
   */
  public function setChecks(RouteCollection $routes) {
    foreach ($routes as $route) {
      $checks = $this
        ->applies($route);
      if (!empty($checks)) {
        $route
          ->setOption('_access_checks', $checks);
      }
    }
  }

  /**
   * Determine which registered access checks apply to a route.
   *
   * @param \Symfony\Component\Routing\Route $route
   *   The route to get list of access checks for.
   *
   * @return array
   *   An array of service ids for the access checks that apply to passed
   *   route.
   */
  protected function applies(Route $route) {
    $checks = array();
    foreach ($this->checkIds as $service_id) {
      if (empty($this->checks[$service_id])) {
        $this
          ->loadCheck($service_id);
      }
      if ($this->checks[$service_id]
        ->applies($route)) {
        $checks[] = $service_id;
      }
    }
    return $checks;
  }

  /**
   * Checks a route against applicable access check services.
   *
   * Determines whether the route is accessible or not.
   *
   * @param \Symfony\Component\Routing\Route $route
   *   The route to check access to.
   *
   * @throws \Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException
   *   If any access check denies access or none explicitly approve.
   */
  public function check(Route $route) {
    $access = FALSE;
    $checks = $route
      ->getOption('_access_checks') ?: array();

    // No checks == deny by default.
    foreach ($checks as $service_id) {
      if (empty($this->checks[$service_id])) {
        $this
          ->loadCheck($service_id);
      }
      $access = $this->checks[$service_id]
        ->access($route, $this->request);
      if ($access === FALSE) {

        // A check has denied access, no need to continue checking.
        break;
      }
    }

    // Access has been denied or not explicily approved.
    if (!$access) {
      throw new AccessDeniedHttpException();
    }
  }

  /**
   * Lazy-loads access check services.
   *
   * @param string $service_id
   *   The service id of the access check service to load.
   */
  protected function loadCheck($service_id) {
    if (!in_array($service_id, $this->checkIds)) {
      throw new \InvalidArgumentException(sprintf('No check has been registered for %s', $service_id));
    }
    $this->checks[$service_id] = $this->container
      ->get($service_id);
  }

}