dematerialize.ts
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import { Operator } from '../Operator';
import { Observable } from '../Observable';
import { Subscriber } from '../Subscriber';
import { Notification } from '../Notification';
import { OperatorFunction } from '../types';
/**
* Converts an Observable of {@link Notification} objects into the emissions
* that they represent.
*
* <span class="informal">Unwraps {@link Notification} objects as actual `next`,
* `error` and `complete` emissions. The opposite of {@link materialize}.</span>
*
* 
*
* `dematerialize` is assumed to operate an Observable that only emits
* {@link Notification} objects as `next` emissions, and does not emit any
* `error`. Such Observable is the output of a `materialize` operation. Those
* notifications are then unwrapped using the metadata they contain, and emitted
* as `next`, `error`, and `complete` on the output Observable.
*
* Use this operator in conjunction with {@link materialize}.
*
* ## Example
* Convert an Observable of Notifications to an actual Observable
* ```ts
* import { of, Notification } from 'rxjs';
* import { dematerialize } from 'rxjs/operators';
*
* const notifA = new Notification('N', 'A');
* const notifB = new Notification('N', 'B');
* const notifE = new Notification('E', undefined,
* new TypeError('x.toUpperCase is not a function')
* );
* const materialized = of(notifA, notifB, notifE);
* const upperCase = materialized.pipe(dematerialize());
* upperCase.subscribe(x => console.log(x), e => console.error(e));
*
* // Results in:
* // A
* // B
* // TypeError: x.toUpperCase is not a function
* ```
*
* @see {@link Notification}
* @see {@link materialize}
*
* @return {Observable} An Observable that emits items and notifications
* embedded in Notification objects emitted by the source Observable.
* @method dematerialize
* @owner Observable
*/
export function dematerialize<T>(): OperatorFunction<Notification<T>, T> {
return function dematerializeOperatorFunction(source: Observable<Notification<T>>) {
return source.lift(new DeMaterializeOperator());
};
}
class DeMaterializeOperator<T extends Notification<any>, R> implements Operator<T, R> {
call(subscriber: Subscriber<any>, source: any): any {
return source.subscribe(new DeMaterializeSubscriber(subscriber));
}
}
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
class DeMaterializeSubscriber<T extends Notification<any>> extends Subscriber<T> {
constructor(destination: Subscriber<any>) {
super(destination);
}
protected _next(value: T) {
value.observe(this.destination);
}
}