import { Observable } from '../Observable';
import { MonoTypeOperatorFunction } from '../types';
/**
 * Emits the values emitted by the source Observable until a `notifier`
 * Observable emits a value.
 *
 * <span class="informal">Lets values pass until a second Observable,
 * `notifier`, emits a value. Then, it completes.</span>
 *
 * ![](takeUntil.png)
 *
 * `takeUntil` subscribes and begins mirroring the source Observable. It also
 * monitors a second Observable, `notifier` that you provide. If the `notifier`
 * emits a value, the output Observable stops mirroring the source Observable
 * and completes. If the `notifier` doesn't emit any value and completes
 * then `takeUntil` will pass all values.
 *
 * ## Example
 * Tick every second until the first click happens
 * ```javascript
 * const interval = interval(1000);
 * const clicks = fromEvent(document, 'click');
 * const result = interval.pipe(takeUntil(clicks));
 * result.subscribe(x => console.log(x));
 * ```
 *
 * @see {@link take}
 * @see {@link takeLast}
 * @see {@link takeWhile}
 * @see {@link skip}
 *
 * @param {Observable} notifier The Observable whose first emitted value will
 * cause the output Observable of `takeUntil` to stop emitting values from the
 * source Observable.
 * @return {Observable<T>} An Observable that emits the values from the source
 * Observable until such time as `notifier` emits its first value.
 * @method takeUntil
 * @owner Observable
 */
export declare function takeUntil<T>(notifier: Observable<any>): MonoTypeOperatorFunction<T>;