import { Observable } from '../Observable'; /** * Converts a higher-order Observable into a first-order Observable by dropping * inner Observables while the previous inner Observable has not yet completed. * * Flattens an Observable-of-Observables by dropping the * next inner Observables while the current inner is still executing. * * * * `exhaust` subscribes to an Observable that emits Observables, also known as a * higher-order Observable. Each time it observes one of these emitted inner * Observables, the output Observable begins emitting the items emitted by that * inner Observable. So far, it behaves like {@link mergeAll}. However, * `exhaust` ignores every new inner Observable if the previous Observable has * not yet completed. Once that one completes, it will accept and flatten the * next inner Observable and repeat this process. * * @example Run a finite timer for each click, only if there is no currently active timer * var clicks = Rx.Observable.fromEvent(document, 'click'); * var higherOrder = clicks.map((ev) => Rx.Observable.interval(1000).take(5)); * var result = higherOrder.exhaust(); * result.subscribe(x => console.log(x)); * * @see {@link combineAll} * @see {@link concatAll} * @see {@link switch} * @see {@link mergeAll} * @see {@link exhaustMap} * @see {@link zipAll} * * @return {Observable} An Observable that takes a source of Observables and propagates the first observable * exclusively until it completes before subscribing to the next. * @method exhaust * @owner Observable */ export declare function exhaust(this: Observable): Observable;