import { SingleSubject } from '../types/signal';
import { BalFocusInfo, BalFocusObserver } from './focus.interfaces';
export declare class BalFocusSubject extends SingleSubject<BalFocusObserver, BalFocusInfo> {
    private listener;
    constructor();
    attach(observer: BalFocusObserver): void;
    detach(): void;
}