import { Observer, Observable, Subscription } from 'rxjs';
import { IListener } from './IListener';
/**
 * Provides base functionality for loading data caches (only once) based on an observable boolean value.
 */
export declare abstract class PredicateListener implements IListener, Partial<Observer<boolean>> {
    private readonly predicate$;
    private initialized;
    constructor(predicate$: Observable<boolean>);
    start(): Subscription;
    next(val: boolean): void;
    /**
     * When overriden in a child class, this function is invoked when the predicate publishes a truthy value.
     */
    abstract onNext(): void;
}