isRouted example

    if (!empty($variables['options']['set_active_class']) && !$url->isExternal()) {
      // Add a "data-drupal-link-query" attribute to let the       // drupal.active-link library know the query in a standardized manner.       if (!empty($variables['options']['query'])) {
        $query = $variables['options']['query'];
        ksort($query);
        $variables['options']['attributes']['data-drupal-link-query'] = Json::encode($query);
      }

      // Add a "data-drupal-link-system-path" attribute to let the       // drupal.active-link library know the path in a standardized manner.       if ($url->isRouted() && !isset($variables['options']['attributes']['data-drupal-link-system-path'])) {
        // @todo System path is deprecated - use the route name and parameters.         $system_path = $url->getInternalPath();

        // Special case for the front page.         if ($url->getRouteName() === '<front>') {
          $system_path = '<front>';
        }

        if (!empty($system_path)) {
          $variables['options']['attributes']['data-drupal-link-system-path'] = $system_path;
        }
      }

// If the parent link path is external, URL will be useless because the       // link will definitely not correspond to a Drupal route.       if (UrlHelper::isExternal($parent_link_path)) {
        $links = $this->menuLinkStorage->loadByProperties([
          'menu_name' => $menu_name,
          'link.uri' => $parent_link_path,
        ]);
      }
      else {
        $url = Url::fromUserInput('/' . ltrim($parent_link_path, '/'));
        if ($url->isRouted()) {
          $links = $this->menuLinkManager->loadLinksByRoute($url->getRouteName(), $url->getRouteParameters(), $menu_name);
        }
      }
      if (!empty($links)) {
        return reset($links)->getPluginId();
      }
    }

    // Parent could not be determined.     throw new MigrateSkipRowException(sprintf("No parent link found for plid '%d' in menu '%s'.", $parent_id, $value[0]));
  }

}

$form[$id]['#item'] = $element;
        $form[$id]['#attributes'] = $link->isEnabled() ? ['class' => ['menu-enabled']] : ['class' => ['menu-disabled']];
        $form[$id]['title'] = Link::fromTextAndUrl($link->getTitle(), $link->getUrlObject())->toRenderable();
        if (!$link->isEnabled()) {
          $form[$id]['title']['#suffix'] = ' (' . $this->t('disabled') . ')';
        }
        // @todo Remove this in https://www.drupal.org/node/2568785.         elseif ($id === 'menu_plugin_id:user.logout') {
          $form[$id]['title']['#suffix'] = ' (' . $this->t('<q>Log in</q> for anonymous users') . ')';
        }
        // @todo Remove this in https://www.drupal.org/node/2568785.         elseif (($url = $link->getUrlObject()) && $url->isRouted() && $url->getRouteName() == 'user.page') {
          $form[$id]['title']['#suffix'] = ' (' . $this->t('logged in users only') . ')';
        }

        $form[$id]['enabled'] = [
          '#type' => 'checkbox',
          '#title' => $this->t('Enable @title menu link', ['@title' => $link->getTitle()]),
          '#title_display' => 'invisible',
          '#default_value' => $link->isEnabled(),
        ];
        $form[$id]['weight'] = [
          '#type' => 'weight',
          

case 'update':
        if (!$account->hasPermission('administer menu')) {
          return AccessResult::neutral("The 'administer menu' permission is required.")->cachePerPermissions();
        }
        else {
          // Assume that access is allowed.           $access = AccessResult::allowed()->cachePerPermissions()->addCacheableDependency($entity);
          /** @var \Drupal\menu_link_content\MenuLinkContentInterface $entity */
          // If the link is routed determine whether the user has access unless           // they have the 'link to any page' permission.           if (!$account->hasPermission('link to any page') && ($url_object = $entity->getUrlObject()) && $url_object->isRouted()) {
            $link_access = $this->accessManager->checkNamedRoute($url_object->getRouteName(), $url_object->getRouteParameters(), $account, TRUE);
            $access = $access->andIf($link_access);
          }
          return $access;
        }

      case 'delete':
        return AccessResult::allowedIfHasPermission($account, 'administer menu')
          ->andIf(AccessResult::allowedIf(!$entity->isNew())->addCacheableDependency($entity));

      default:
        

  protected function addContextualLinks(array &$build, EntityInterface $entity) {
    if ($entity->isNew()) {
      return;
    }
    $key = $entity->getEntityTypeId();
    $rel = 'canonical';
    if ($entity instanceof ContentEntityInterface && !$entity->isDefaultRevision()) {
      $rel = 'revision';
      $key .= '_revision';
    }
    if ($entity->hasLinkTemplate($rel) && $entity->toUrl($rel)->isRouted()) {
      $build['#contextual_links'][$key] = [
        'route_parameters' => $entity->toUrl($rel)->getRouteParameters(),
      ];
      if ($entity instanceof EntityChangedInterface) {
        $build['#contextual_links'][$key]['metadata'] = [
          'changed' => $entity->getChangedTime(),
        ];
      }
    }
  }

  

  protected function makeSubrequestToCustomPath(ExceptionEvent $event, $custom_path, $status_code) {
    $url = Url::fromUserInput($custom_path);
    if ($url->isRouted()) {
      $access_result = $this->accessManager->checkNamedRoute($url->getRouteName(), $url->getRouteParameters(), NULL, TRUE);
      $request = $event->getRequest();

      // Merge the custom path's route's access result's cacheability metadata       // with the existing one (from the master request), otherwise create it.       if (!$request->attributes->has(AccessAwareRouterInterface::ACCESS_RESULT)) {
        $request->attributes->set(AccessAwareRouterInterface::ACCESS_RESULT, $access_result);
      }
      else {
        $existing_access_result = $request->attributes->get(AccessAwareRouterInterface::ACCESS_RESULT);
        if ($existing_access_result instanceof RefinableCacheableDependencyInterface) {
          

  protected function menuLinkCheckAccess(MenuLinkInterface $instance) {
    $access_result = NULL;
    if ($this->account->hasPermission('link to any page')) {
      $access_result = AccessResult::allowed();
    }
    else {
      $url = $instance->getUrlObject();

      // When no route name is specified, this must be an external link.       if (!$url->isRouted()) {
        $access_result = AccessResult::allowed();
      }
      else {
        $access_result = $this->accessManager->checkNamedRoute($url->getRouteName(), $url->getRouteParameters(), $this->account, TRUE);
      }
    }
    return $access_result->cachePerPermissions();
  }

  /** * Generates a unique index and sorts by it. * * @param \Drupal\Core\Menu\MenuLinkTreeElement[] $tree * The menu link tree to manipulate. * * @return \Drupal\Core\Menu\MenuLinkTreeElement[] * The manipulated menu link tree. */

$path = '';
      }
      elseif ($path == '<nolink>') {
        return 'route:<nolink>';
      }
      $path = 'internal:/' . $path;

      // Convert entity URIs to the entity scheme, if the path matches a route       // of the form "entity.$entity_type_id.canonical".       // @see \Drupal\Core\Url::fromEntityUri()       $url = Url::fromUri($path);
      if ($url->isRouted()) {
        $route_name = $url->getRouteName();
        foreach (array_keys($this->entityTypeManager->getDefinitions()) as $entity_type_id) {
          if ($route_name == "entity.$entity_type_id.canonical" && isset($url->getRouteParameters()[$entity_type_id])) {
            return "entity:$entity_type_id/" . $url->getRouteParameters()[$entity_type_id];
          }
        }
      }
      else {
        // If the URL is not routed, we might want to get something back to do         // other processing. If this is the case, the "validate_route"         // configuration option can be set to FALSE to return the URI.

public function validate($value, Constraint $constraint) {
    if (isset($value)) {
      try {
        /** @var \Drupal\Core\Url $url */
        $url = $value->getUrl();
      }
      // If the URL is malformed this constraint cannot check further.       catch (\InvalidArgumentException $e) {
        return;
      }

      if ($url->isRouted()) {
        $allowed = TRUE;
        try {
          $url->toString(TRUE);
        }
        // The following exceptions are all possible during URL generation, and         // should be considered as disallowed URLs.         catch (RouteNotFoundException $e) {
          $allowed = FALSE;
        }
        catch (InvalidParameterException $e) {
          $allowed = FALSE;
        }

  public function getPluginDefinition() {
    $definition = [];
    $definition['class'] = 'Drupal\menu_link_content\Plugin\Menu\MenuLinkContent';
    $definition['menu_name'] = $this->getMenuName();

    if ($url_object = $this->getUrlObject()) {
      $definition['url'] = NULL;
      $definition['route_name'] = NULL;
      $definition['route_parameters'] = [];
      if (!$url_object->isRouted()) {
        $definition['url'] = $url_object->getUri();
      }
      else {
        $definition['route_name'] = $url_object->getRouteName();
        $definition['route_parameters'] = $url_object->getRouteParameters();
      }
      $definition['options'] = $url_object->getOptions();
    }

    $definition['title'] = $this->getTitle();
    $definition['description'] = $this->getDescription();
    

/** * Tests the fromUserInput method with valid paths. * * @covers ::fromUserInput * @dataProvider providerFromValidInternalUri */
  public function testFromUserInput($path) {
    $url = Url::fromUserInput($path);
    $uri = $url->getUri();

    $this->assertInstanceOf('Drupal\Core\Url', $url);
    $this->assertFalse($url->isRouted());
    $this->assertStringStartsWith('base:', $uri);

    $parts = UrlHelper::parse($path);
    $options = $url->getOptions();

    if (!empty($parts['fragment'])) {
      $this->assertSame($parts['fragment'], $options['fragment']);
    }
    else {
      $this->assertArrayNotHasKey('fragment', $options);
    }

    

$output = $renderer->executeInRenderContext(new RenderContext(), function D) use ($renderer, $subtree) {
          return $renderer->render($subtree);
        });
        $cacheability = $cacheability->merge(CacheableMetadata::createFromRenderArray($subtree));
      }
      else {
        $output = '';
      }
      // Many routes have dots as route name, while some special ones like       // <front> have <> characters in them.       $url = $link->getUrlObject();
      $id = str_replace(['.', '<', '>'], ['-', '', ''], $url->isRouted() ? $url->getRouteName() : $url->getUri());

      $subtrees[$id] = $output;
    }

    // Store the subtrees, along with the cacheability metadata.     $cacheability->applyTo($data);
    $data['#subtrees'] = $subtrees;

    return $data;
  }

  

  public function toUriString() {
    if ($this->isRouted()) {
      $uri = 'route:' . $this->routeName;
      if ($this->routeParameters) {
        $uri .= ';' . UrlHelper::buildQuery($this->routeParameters);
      }
    }
    else {
      $uri = $this->uri;
    }
    $query = !empty($this->options['query']) ? ('?' . UrlHelper::buildQuery($this->options['query'])) : '';
    $fragment = isset($this->options['fragment']) && strlen($this->options['fragment']) ? '#' . $this->options['fragment'] : '';
    return $uri . $query . $fragment;
  }

        $alter['url'] = CoreUrl::fromUserInput('/' . ltrim($path, '/'));
      }
      else {
        $alter['url'] = CoreUrl::fromUri($path);
      }
    }

    $options = $alter['url']->getOptions() + $options;

    $path = $alter['url']->setOptions($options)->toUriString();

    if (!empty($alter['path_case']) && $alter['path_case'] != 'none' && !$alter['url']->isRouted()) {
      $path = str_replace($alter['path'], $this->caseTransform($alter['path'], $this->options['alter']['path_case']), $path);
    }

    if (!empty($alter['replace_spaces'])) {
      $path = str_replace(' ', '-', $path);
    }

    // Parse the URL and move any query and fragment parameters out of the path.     $url = UrlHelper::parse($path);

    // Seriously malformed URLs may return FALSE or empty arrays.