AsyncSubject.ts•1.08 kB
import { Subject } from './Subject';
import { Subscriber } from './Subscriber';
/**
* A variant of Subject that only emits a value when it completes. It will emit
* its latest value to all its observers on completion.
*
* @class AsyncSubject<T>
*/
export class AsyncSubject<T> extends Subject<T> {
private _value: T | null = null;
private _hasValue = false;
private _isComplete = false;
/** @internal */
protected _checkFinalizedStatuses(subscriber: Subscriber<T>) {
const { hasError, _hasValue, _value, thrownError, isStopped, _isComplete } = this;
if (hasError) {
subscriber.error(thrownError);
} else if (isStopped || _isComplete) {
_hasValue && subscriber.next(_value!);
subscriber.complete();
}
}
next(value: T): void {
if (!this.isStopped) {
this._value = value;
this._hasValue = true;
}
}
complete(): void {
const { _hasValue, _value, _isComplete } = this;
if (!_isComplete) {
this._isComplete = true;
_hasValue && super.next(_value!);
super.complete();
}
}
}