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- import { Subject } from './Subject';
- import { Subscriber } from './Subscriber';
- import { Subscription } from './Subscription';
- /**
- * A variant of Subject that requires an initial value and emits its current
- * value whenever it is subscribed to.
- */
- export class BehaviorSubject<T> extends Subject<T> {
- constructor(private _value: T) {
- super();
- }
- get value(): T {
- return this.getValue();
- }
- /** @internal */
- protected _subscribe(subscriber: Subscriber<T>): Subscription {
- const subscription = super._subscribe(subscriber);
- !subscription.closed && subscriber.next(this._value);
- return subscription;
- }
- getValue(): T {
- const { hasError, thrownError, _value } = this;
- if (hasError) {
- throw thrownError;
- }
- this._throwIfClosed();
- return _value;
- }
- next(value: T): void {
- super.next((this._value = value));
- }
- }
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