40 lines
912 B
Plaintext
40 lines
912 B
Plaintext
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 requires an initial value and emits its current
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* value whenever it is subscribed to.
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*
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* @class BehaviorSubject<T>
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*/
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export class BehaviorSubject<T> extends Subject<T> {
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constructor(private _value: T) {
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super();
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}
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get value(): T {
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return this.getValue();
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}
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/** @internal */
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protected _subscribe(subscriber: Subscriber<T>): Subscription {
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const subscription = super._subscribe(subscriber);
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!subscription.closed && subscriber.next(this._value);
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return subscription;
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}
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getValue(): T {
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const { hasError, thrownError, _value } = this;
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if (hasError) {
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throw thrownError;
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}
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this._throwIfClosed();
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return _value;
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}
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next(value: T): void {
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super.next((this._value = value));
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}
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}
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