40 lines
1.0 KiB
Plaintext
40 lines
1.0 KiB
Plaintext
import { Subject } from './Subject';
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import { Subscriber } from './Subscriber';
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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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export class AsyncSubject<T> extends Subject<T> {
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private _value: T | null = null;
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private _hasValue = false;
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private _isComplete = false;
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/** @internal */
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protected _checkFinalizedStatuses(subscriber: Subscriber<T>) {
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const { hasError, _hasValue, _value, thrownError, isStopped, _isComplete } = this;
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if (hasError) {
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subscriber.error(thrownError);
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} else if (isStopped || _isComplete) {
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_hasValue && subscriber.next(_value!);
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subscriber.complete();
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}
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}
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next(value: T): void {
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if (!this.isStopped) {
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this._value = value;
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this._hasValue = true;
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}
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}
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complete(): void {
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const { _hasValue, _value, _isComplete } = this;
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if (!_isComplete) {
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this._isComplete = true;
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_hasValue && super.next(_value!);
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super.complete();
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}
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}
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}
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