interface MenuLinkTreeInterface in Drupal 8

Defines an interface for loading, transforming and rendering menu link trees.

The main purposes of this interface are:

• Load a list of menu links, given a menu name, using MenuLinkTreeInterface::load(). Loaded menu links are returned as a tree by looking at the links' tree meta-data.
• Which links are loaded can be specified in the menu link tree parameters that are passed to the load() method. You can build your own set of parameters, or you can start from typical defaults by calling the MenuLinkTreeInterface::getCurrentRouteMenuTreeParameters() method. See \Drupal\Core\Menu\MenuTreeParameters for more on menu tree parameters.
• Transform a menu link tree, by calling MenuLinkTreeInterface::transform(). Examples include access checking, adding custom classes, extracting a subtree depending on the active trail, etc. Note that translation is not a tree transformation, because menu links themselves are responsible for translation. Transformations are performed by "menu link tree manipulators", which are functions or methods; see \Drupal\Core\Menu\DefaultMenuLinkTreeManipulators for examples.
• Create a render array using MenuLinkTreeInterface::build().

Hierarchy

• interface \Drupal\Core\Menu\MenuLinkTreeInterface

4 files declare their use of MenuLinkTreeInterface

MenuForm.php in core/modules/menu_ui/src/MenuForm.php

SystemController.php in core/modules/system/src/Controller/SystemController.php

SystemManager.php in core/modules/system/src/SystemManager.php

SystemMenuBlock.php in core/modules/system/src/Plugin/Block/SystemMenuBlock.php

File

core/lib/Drupal/Core/Menu/MenuLinkTreeInterface.php, line 26

Namespace

Drupal\Core\Menu

interface MenuLinkTreeInterface {

  /**
   * Gets the link tree parameters for rendering a specific menu.
   *
   * Builds menu link tree parameters that:
   * - Expand all links in the active trail based on route being viewed.
   * - Expand the descendants of the links in the active trail whose
   *   'expanded' flag is enabled.
   *
   * This only sets the (relatively complex) parameters to achieve the two above
   * goals, but you can still further customize these parameters.
   *
   * @param string $menu_name
   *   The menu name, needed for retrieving the active trail and links with the
   *   'expanded' flag enabled.
   *
   * @return \Drupal\Core\Menu\MenuTreeParameters
   *   The parameters to determine which menu links to be loaded into a tree.
   *
   * @see \Drupal\Core\Menu\MenuTreeParameters
   */
  public function getCurrentRouteMenuTreeParameters($menu_name);

  /**
   * Loads a menu tree with a menu link plugin instance at each element.
   *
   * @param string $menu_name
   *   The name of the menu.
   * @param \Drupal\Core\Menu\MenuTreeParameters $parameters
   *   The parameters to determine which menu links to be loaded into a tree.
   *
   * @return \Drupal\Core\Menu\MenuLinkTreeElement[]
   *   A menu link tree.
   */
  public function load($menu_name, MenuTreeParameters $parameters);

  /**
   * Applies menu link tree manipulators to transform the given tree.
   *
   * @param \Drupal\Core\Menu\MenuLinkTreeElement[] $tree
   *   The menu tree to manipulate.
   * @param array $manipulators
   *   The menu link tree manipulators to apply. Each is an array with keys:
   *   - callable: a callable or a string that can be resolved to a callable
   *     by \Drupal\Core\Controller\ControllerResolverInterface::getControllerFromDefinition()
   *   - args: optional array of arguments to pass to the callable after $tree.
   *
   * @return \Drupal\Core\Menu\MenuLinkTreeElement[]
   *   The manipulated menu link tree.
   */
  public function transform(array $tree, array $manipulators);

  /**
   * Builds a renderable array from a menu tree.
   *
   * The menu item's LI element is given one of the following classes:
   * - expanded: The menu item is showing its submenu.
   * - collapsed: The menu item has a submenu that is not shown.
   * - leaf: The menu item has no submenu.
   *
   * @param \Drupal\Core\Menu\MenuLinkTreeElement[] $tree
   *   A data structure representing the tree, as returned from
   *   MenuLinkTreeInterface::load().
   *
   * @return array
   *   A renderable array.
   */
  public function build(array $tree);

  /**
   * Returns the maximum depth of tree that is supported.
   *
   * @return int
   *   The maximum depth.
   */
  public function maxDepth();

  /**
   * Finds the height of a subtree rooted by of the given ID.
   *
   * @param string $id
   *   The ID of an item in the storage.
   *
   * @return int
   *   Returns the height of the subtree. This will be at least 1 if the ID
   *   exists, or 0 if the ID does not exist in the storage.
   */
  public function getSubtreeHeight($id);

  /**
   * Finds expanded links in a menu given a set of possible parents.
   *
   * @param string $menu_name
   *   The menu name.
   * @param array $parents
   *   One or more parent IDs to match.
   *
   * @return array
   *   The menu link IDs that are flagged as expanded in this menu.
   */
  public function getExpanded($menu_name, array $parents);

}

Members

Name	Modifiers	Type	Description	Overrides
MenuLinkTreeInterface::build	public	function	Builds a renderable array from a menu tree.	1
MenuLinkTreeInterface::getCurrentRouteMenuTreeParameters	public	function	Gets the link tree parameters for rendering a specific menu.	1
MenuLinkTreeInterface::getExpanded	public	function	Finds expanded links in a menu given a set of possible parents.	1
MenuLinkTreeInterface::getSubtreeHeight	public	function	Finds the height of a subtree rooted by of the given ID.	1
MenuLinkTreeInterface::load	public	function	Loads a menu tree with a menu link plugin instance at each element.	1
MenuLinkTreeInterface::maxDepth	public	function	Returns the maximum depth of tree that is supported.	1
MenuLinkTreeInterface::transform	public	function	Applies menu link tree manipulators to transform the given tree.	1