Class Menu

src/aria/menu/menu.ts:81–215

  providers: [{provide: MENU_COMPONENT, useExisting: Menu}],
})
export class Menu<V> implements OnDestroy {
  /** The DeferredContentAware host directive. */
  private readonly _deferredContentAware = inject(DeferredContentAware, {optional: true});

  /** The collection of menu items. */
  readonly _collection = new SortedCollection<MenuItem<V>>();

  /** The menu items that are direct children of this menu. */
  readonly _items: Signal<MenuItem<V>[]> = computed(() =>
    this._collection.orderedItems().filter(i => i.parent === this),
  );

  /** A reference to the host element. */
  private readonly _elementRef = inject(ElementRef);

  /** A reference to the host element. */
  readonly element = this._elementRef.nativeElement as HTMLElement;

  /** The directionality (LTR / RTL) context for the application (or a subtree of it). */
  readonly textDirection = inject(Directionality).valueSignal;

  /** The unique ID of the menu. */
  readonly id = input(inject(_IdGenerator).getId('ng-menu-', true));

  /** Whether the menu should wrap its items. */
  readonly wrap = input(true, {transform: booleanAttribute});

  /** The delay in milliseconds before the typeahead buffer is cleared. */
  readonly typeaheadDelay = input<number>(500); // Picked arbitrarily.

  /** Whether the menu is disabled. */
  readonly disabled = input(false, {transform: booleanAttribute});

  /** A reference to the parent menu item or menu trigger. */
  readonly parent = signal<MenuTrigger<V> | MenuItem<V> | undefined>(undefined);

  /** Whether the menu is soft disabled. */
  readonly softDisabled = input(true, {transform: booleanAttribute});

  /** The menu ui pattern instance. */
  readonly _pattern: MenuPattern<V>;

  /**
   * The menu item patterns for the menu items that are direct children of this menu, passed
   * to the menu pattern.
   *
   * Note: contentChildren has an issue where it will return a successively smaller list
   * each time that the menu is open and closed, eventually resulting in an empty list.
   * The workaround is to trigger a recomputation of this signal whenever the menu is opened
   * or closed, by calling this._pattern.visible() in the signal body. Otherwise, computed could
   * not be used and would have to rebuild the list each time this method is called.
   */
  private readonly _itemPatterns = computed(() => {
    // Only needed to force a recompute.
    this._pattern.visible();

    return this._items().map(i => i._pattern);
  });