/**
 * Bridge between a menu widget and the shared {@link MenuKeyboardController}.
 *
 * The controller is intentionally decoupled from any specific menu's internals:
 * it drives navigation purely through this host, so both {@link import('./column-menu').ColumnMenu}
 * (with fly-out submenus) and {@link import('./group-context-menu').GroupContextMenu}
 * (flat) can share one implementation.
 */
export interface MenuKeyboardHost {
    /** The menu's root `[role="menu"]` element, or `null` when the menu is closed. */
    getRootEl(): HTMLElement | null;
    /**
     * The currently-open fly-out submenu (portaled to `document.body`), or `null`.
     * Menus without submenus always return `null`.
     */
    getActiveSubmenuEl(): HTMLElement | null;
    /**
     * Open the submenu owned by `parentItem` (portals + positions it) and return
     * it, or `null` when the item has no submenu.
     */
    openSubmenu(parentItem: HTMLElement): HTMLElement | null;
    /** Close a submenu previously returned by {@link openSubmenu}. */
    closeSubmenu(submenuEl: HTMLElement): void;
    /** Resolve the parent item that owns `submenuEl`, or `null`. */
    getSubmenuParent(submenuEl: HTMLElement): HTMLElement | null;
    /**
     * Close the entire menu. When `restoreFocus` is `true`, focus is returned to
     * the element that opened the menu (the header cell or trigger button).
     */
    closeAll(restoreFocus: boolean): void;
}
/**
 * Reusable keyboard-navigation controller implementing the WAI-ARIA
 * *menu / menubar* pattern for Photon Grid's portaled context menus.
 *
 * ### Behaviour
 * - **ArrowDown / ArrowUp** — move focus between enabled items (skipping
 *   separators and disabled items), wrapping at the ends.
 * - **Home / End** — focus the first / last enabled item.
 * - **ArrowRight / Enter / Space** on a submenu parent — open its fly-out and
 *   focus the first child.
 * - **ArrowLeft** — close the current submenu and return focus to its parent.
 * - **Enter / Space** on a leaf — activate it (dispatches a synthetic click, so
 *   the item's existing handler runs and the menu closes).
 * - **Escape** — close the current submenu, or the whole menu (restoring focus
 *   to the opener) at the root level.
 * - **Printable keys** — type-ahead: focus the first enabled item whose label
 *   starts with the buffered characters.
 *
 * ### Focus model
 * Items are `tabindex="-1"` and moved with `.focus()` (not
 * `aria-activedescendant`). Fly-out submenus are portaled to `document.body`, so
 * the active item is not a DOM descendant of the root menu — `.focus()` crosses
 * that boundary correctly where `aria-activedescendant` would not.
 *
 * ### Lifecycle
 * A single capture-phase `keydown` listener is added in {@link attach} and
 * removed in {@link destroy}; no per-item listeners are created. The type-ahead
 * timer is always cleared on {@link destroy}. Safe to attach/detach on every
 * menu open/close with no listener accumulation.
 */
export declare class MenuKeyboardController {
    private readonly host;
    private readonly boundKeydown;
    private typeaheadBuffer;
    private typeaheadTimer;
    private attached;
    constructor(host: MenuKeyboardHost);
    /**
     * Begin handling keyboard navigation and move focus to the first enabled item
     * of the root menu. Call once, immediately after the menu DOM is shown.
     */
    attach(): void;
    /** Stop handling keyboard navigation and release the type-ahead timer. */
    destroy(): void;
    private onKeydown;
    /** Prevent scrolling / other handlers from also acting on a handled key. */
    private consume;
    /** The menu level (root or open submenu) that currently owns focus. */
    private currentLevel;
    /** Enabled, focusable items within a menu level, in DOM order. */
    private getItems;
    private move;
    private focusEdge;
    private focusFirst;
    private focusAt;
    /** `true` when the focused item opens a submenu. */
    private isParent;
    private openActiveSubmenu;
    private closeCurrentSubmenu;
    private activate;
    private onEscape;
    private isPrintable;
    private typeahead;
    private clearTypeahead;
}
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