import { OnDestroy } from '@angular/core';
import { Observable } from 'rxjs';
import { DbxHelpContextString, DbxHelpContextReference } from './help';
import * as i0 from "@angular/core";
/**
 * Service that tracks all active help context strings in the current context.
 */
export declare class DbxHelpContextService implements OnDestroy {
    private readonly _contextReferences;
    /**
     * Observable of all currently active help context strings.
     */
    readonly activeHelpContextStrings$: Observable<Set<DbxHelpContextString>>;
    readonly activeHelpContextStringsArray$: Observable<string[]>;
    register(reference: DbxHelpContextReference): void;
    unregister(reference: DbxHelpContextReference): void;
    ngOnDestroy(): void;
    static ɵfac: i0.ɵɵFactoryDeclaration<DbxHelpContextService, never>;
    static ɵprov: i0.ɵɵInjectableDeclaration<DbxHelpContextService>;
}
