import { Observable } from 'rxjs';
import * as i0 from "@angular/core";
/**
 * Communication service between {@link AriaActiveDescendantDirective} and observer of activeDescendantObservable
 */
export declare class AriaActiveDescendantService {
    private activeDescendantSubject;
    /**
     * Observed by element which owns the section with possible active descendants
     */
    activeDescendantObservable: Observable<string>;
    /**
     * Marks element as active descendant
     * @param id attribute of active descendant element
     */
    selectDescendant(id: string): void;
    static ɵfac: i0.ɵɵFactoryDeclaration<AriaActiveDescendantService, never>;
    static ɵprov: i0.ɵɵInjectableDeclaration<AriaActiveDescendantService>;
}
