import { Observable } from 'rxjs';
import { FocusItemDirective } from './focus-item.directive';
export declare class FocusManagerService {
    private changeEvent;
    readonly onChange: Observable<FocusItemDirective[]>;
    /**
     * list of focus items before
     */
    private focus_item_list_old;
    /**
     * list of focus items current
     */
    private focus_item_list_new;
    /**
     * A click will bubble up until it reaches document.
     * This upward trip can pass multiple focus items
     * This property holds the status on whether this bubble-up is happening or not.
     */
    private bubbleUpStarted;
    constructor();
    /**
     * record a focus item into current list of focus items.
     * if bubble-up has just started and bubbleUpStarted is yet to be updated,
     * 1. update bubbleUpStarted to true.
     * 2. move all the current focus item list into the old list
     * 3. create an empty list
     * @param item
     */
    push(item: FocusItemDirective): void;
    private emptyFocusItems;
    private onDocumentClick;
    private filterFocusItemElements;
}