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import { Operator } from '../Operator';
import { Observable } from '../Observable';
import { Subscriber } from '../Subscriber';
import { OuterSubscriber } from '../OuterSubscriber';
import { InnerSubscriber } from '../InnerSubscriber';
import { subscribeToResult } from '../util/subscribeToResult';
import { MonoTypeOperatorFunction, TeardownLogic } from '../types';
/**
* Emits the most recently emitted value from the source Observable whenever
* another Observable, the `notifier`, emits.
*
* <span class="informal">It's like {@link sampleTime}, but samples whenever
* the `notifier` Observable emits something.</span>
*
* 
*
* Whenever the `notifier` Observable emits a value or completes, `sample`
* looks at the source Observable and emits whichever value it has most recently
* emitted since the previous sampling, unless the source has not emitted
* anything since the previous sampling. The `notifier` is subscribed to as soon
* as the output Observable is subscribed.
*
* ## Example
* On every click, sample the most recent "seconds" timer
* ```javascript
* import { fromEvent, interval } from 'rxjs';
* import { sample } from 'rxjs/operators';
*
* const seconds = interval(1000);
* const clicks = fromEvent(document, 'click');
* const result = seconds.pipe(sample(clicks));
* result.subscribe(x => console.log(x));
* ```
*
* @see {@link audit}
* @see {@link debounce}
* @see {@link sampleTime}
* @see {@link throttle}
*
* @param {Observable<any>} notifier The Observable to use for sampling the
* source Observable.
* @return {Observable<T>} An Observable that emits the results of sampling the
* values emitted by the source Observable whenever the notifier Observable
* emits value or completes.
* @method sample
* @owner Observable
*/
export function sample<T>(notifier: Observable<any>): MonoTypeOperatorFunction<T> {
return (source: Observable<T>) => source.lift(new SampleOperator(notifier));
}
class SampleOperator<T> implements Operator<T, T> {
constructor(private notifier: Observable<any>) {
}
call(subscriber: Subscriber<T>, source: any): TeardownLogic {
const sampleSubscriber = new SampleSubscriber(subscriber);
const subscription = source.subscribe(sampleSubscriber);
subscription.add(subscribeToResult(sampleSubscriber, this.notifier));
return subscription;
}
}
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
class SampleSubscriber<T, R> extends OuterSubscriber<T, R> {
private value: T;
private hasValue: boolean = false;
protected _next(value: T) {
this.value = value;
this.hasValue = true;
}
notifyNext(outerValue: T, innerValue: R,
outerIndex: number, innerIndex: number,
innerSub: InnerSubscriber<T, R>): void {
this.emitValue();
}
notifyComplete(): void {
this.emitValue();
}
emitValue() {
if (this.hasValue) {
this.hasValue = false;
this.destination.next(this.value);
}
}
}
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