72 lines
2.4 KiB
JavaScript
72 lines
2.4 KiB
JavaScript
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import { Observable } from '../Observable';
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/**
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* We need this JSDoc comment for affecting ESDoc.
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* @extends {Ignored}
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* @hide true
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*/
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export class EmptyObservable extends Observable {
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constructor(scheduler) {
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super();
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this.scheduler = scheduler;
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}
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/**
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* Creates an Observable that emits no items to the Observer and immediately
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* emits a complete notification.
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*
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* <span class="informal">Just emits 'complete', and nothing else.
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* </span>
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*
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* <img src="./img/empty.png" width="100%">
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*
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* This static operator is useful for creating a simple Observable that only
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* emits the complete notification. It can be used for composing with other
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* Observables, such as in a {@link mergeMap}.
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*
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* @example <caption>Emit the number 7, then complete.</caption>
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* var result = Rx.Observable.empty().startWith(7);
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* result.subscribe(x => console.log(x));
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*
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* @example <caption>Map and flatten only odd numbers to the sequence 'a', 'b', 'c'</caption>
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* var interval = Rx.Observable.interval(1000);
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* var result = interval.mergeMap(x =>
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* x % 2 === 1 ? Rx.Observable.of('a', 'b', 'c') : Rx.Observable.empty()
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* );
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* result.subscribe(x => console.log(x));
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*
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* // Results in the following to the console:
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* // x is equal to the count on the interval eg(0,1,2,3,...)
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* // x will occur every 1000ms
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* // if x % 2 is equal to 1 print abc
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* // if x % 2 is not equal to 1 nothing will be output
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*
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* @see {@link create}
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* @see {@link never}
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* @see {@link of}
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* @see {@link throw}
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*
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* @param {Scheduler} [scheduler] A {@link IScheduler} to use for scheduling
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* the emission of the complete notification.
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* @return {Observable} An "empty" Observable: emits only the complete
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* notification.
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* @static true
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* @name empty
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* @owner Observable
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*/
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static create(scheduler) {
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return new EmptyObservable(scheduler);
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}
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static dispatch(arg) {
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const { subscriber } = arg;
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subscriber.complete();
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}
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/** @deprecated internal use only */ _subscribe(subscriber) {
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const scheduler = this.scheduler;
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if (scheduler) {
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return scheduler.schedule(EmptyObservable.dispatch, 0, { subscriber });
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}
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else {
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subscriber.complete();
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}
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}
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}
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//# sourceMappingURL=EmptyObservable.js.map
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