work.suroh.tk/node_modules/rxjs/_esm2015/operators/materialize.js

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2019-12-02 12:22:45 +00:00
import { Subscriber } from '../Subscriber';
import { Notification } from '../Notification';
/**
* Represents all of the notifications from the source Observable as `next`
* emissions marked with their original types within {@link Notification}
* objects.
*
* <span class="informal">Wraps `next`, `error` and `complete` emissions in
* {@link Notification} objects, emitted as `next` on the output Observable.
* </span>
*
* <img src="./img/materialize.png" width="100%">
*
* `materialize` returns an Observable that emits a `next` notification for each
* `next`, `error`, or `complete` emission of the source Observable. When the
* source Observable emits `complete`, the output Observable will emit `next` as
* a Notification of type "complete", and then it will emit `complete` as well.
* When the source Observable emits `error`, the output will emit `next` as a
* Notification of type "error", and then `complete`.
*
* This operator is useful for producing metadata of the source Observable, to
* be consumed as `next` emissions. Use it in conjunction with
* {@link dematerialize}.
*
* @example <caption>Convert a faulty Observable to an Observable of Notifications</caption>
* var letters = Rx.Observable.of('a', 'b', 13, 'd');
* var upperCase = letters.map(x => x.toUpperCase());
* var materialized = upperCase.materialize();
* materialized.subscribe(x => console.log(x));
*
* // Results in the following:
* // - Notification {kind: "N", value: "A", error: undefined, hasValue: true}
* // - Notification {kind: "N", value: "B", error: undefined, hasValue: true}
* // - Notification {kind: "E", value: undefined, error: TypeError:
* // x.toUpperCase is not a function at MapSubscriber.letters.map.x
* // [as project] (http://1…, hasValue: false}
*
* @see {@link Notification}
* @see {@link dematerialize}
*
* @return {Observable<Notification<T>>} An Observable that emits
* {@link Notification} objects that wrap the original emissions from the source
* Observable with metadata.
* @method materialize
* @owner Observable
*/
export function materialize() {
return function materializeOperatorFunction(source) {
return source.lift(new MaterializeOperator());
};
}
class MaterializeOperator {
call(subscriber, source) {
return source.subscribe(new MaterializeSubscriber(subscriber));
}
}
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
class MaterializeSubscriber extends Subscriber {
constructor(destination) {
super(destination);
}
_next(value) {
this.destination.next(Notification.createNext(value));
}
_error(err) {
const destination = this.destination;
destination.next(Notification.createError(err));
destination.complete();
}
_complete() {
const destination = this.destination;
destination.next(Notification.createComplete());
destination.complete();
}
}
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