50 lines
1.2 KiB
TypeScript
Executable file
50 lines
1.2 KiB
TypeScript
Executable file
import { Subject } from './Subject';
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import { Subscriber } from './Subscriber';
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import { Subscription } from './Subscription';
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/**
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* A variant of Subject that only emits a value when it completes. It will emit
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* its latest value to all its observers on completion.
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*
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* @class AsyncSubject<T>
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*/
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export class AsyncSubject<T> extends Subject<T> {
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private value: T = null;
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private hasNext: boolean = false;
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private hasCompleted: boolean = false;
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/** @deprecated This is an internal implementation detail, do not use. */
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_subscribe(subscriber: Subscriber<any>): Subscription {
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if (this.hasError) {
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subscriber.error(this.thrownError);
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return Subscription.EMPTY;
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} else if (this.hasCompleted && this.hasNext) {
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subscriber.next(this.value);
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subscriber.complete();
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return Subscription.EMPTY;
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}
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return super._subscribe(subscriber);
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}
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next(value: T): void {
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if (!this.hasCompleted) {
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this.value = value;
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this.hasNext = true;
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}
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}
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error(error: any): void {
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if (!this.hasCompleted) {
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super.error(error);
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}
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}
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complete(): void {
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this.hasCompleted = true;
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if (this.hasNext) {
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super.next(this.value);
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}
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super.complete();
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}
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}
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