| import { OuterSubscriber } from '../OuterSubscriber'; |
| import { subscribeToResult } from '../util/subscribeToResult'; |
| /* tslint:enable:max-line-length */ |
| /** |
| * Projects each source value to an Observable which is merged in the output |
| * Observable, emitting values only from the most recently projected Observable. |
| * |
| * <span class="informal">Maps each value to an Observable, then flattens all of |
| * these inner Observables using {@link switch}.</span> |
| * |
| * <img src="./img/switchMap.png" width="100%"> |
| * |
| * Returns an Observable that emits items based on applying a function that you |
| * supply to each item emitted by the source Observable, where that function |
| * returns an (so-called "inner") Observable. Each time it observes one of these |
| * inner Observables, the output Observable begins emitting the items emitted by |
| * that inner Observable. When a new inner Observable is emitted, `switchMap` |
| * stops emitting items from the earlier-emitted inner Observable and begins |
| * emitting items from the new one. It continues to behave like this for |
| * subsequent inner Observables. |
| * |
| * @example <caption>Rerun an interval Observable on every click event</caption> |
| * var clicks = Rx.Observable.fromEvent(document, 'click'); |
| * var result = clicks.switchMap((ev) => Rx.Observable.interval(1000)); |
| * result.subscribe(x => console.log(x)); |
| * |
| * @see {@link concatMap} |
| * @see {@link exhaustMap} |
| * @see {@link mergeMap} |
| * @see {@link switch} |
| * @see {@link switchMapTo} |
| * |
| * @param {function(value: T, ?index: number): ObservableInput} project A function |
| * that, when applied to an item emitted by the source Observable, returns an |
| * Observable. |
| * @param {function(outerValue: T, innerValue: I, outerIndex: number, innerIndex: number): any} [resultSelector] |
| * A function to produce the value on the output Observable based on the values |
| * and the indices of the source (outer) emission and the inner Observable |
| * emission. The arguments passed to this function are: |
| * - `outerValue`: the value that came from the source |
| * - `innerValue`: the value that came from the projected Observable |
| * - `outerIndex`: the "index" of the value that came from the source |
| * - `innerIndex`: the "index" of the value from the projected Observable |
| * @return {Observable} An Observable that emits the result of applying the |
| * projection function (and the optional `resultSelector`) to each item emitted |
| * by the source Observable and taking only the values from the most recently |
| * projected inner Observable. |
| * @method switchMap |
| * @owner Observable |
| */ |
| export function switchMap(project, resultSelector) { |
| return function switchMapOperatorFunction(source) { |
| return source.lift(new SwitchMapOperator(project, resultSelector)); |
| }; |
| } |
| class SwitchMapOperator { |
| constructor(project, resultSelector) { |
| this.project = project; |
| this.resultSelector = resultSelector; |
| } |
| call(subscriber, source) { |
| return source.subscribe(new SwitchMapSubscriber(subscriber, this.project, this.resultSelector)); |
| } |
| } |
| /** |
| * We need this JSDoc comment for affecting ESDoc. |
| * @ignore |
| * @extends {Ignored} |
| */ |
| class SwitchMapSubscriber extends OuterSubscriber { |
| constructor(destination, project, resultSelector) { |
| super(destination); |
| this.project = project; |
| this.resultSelector = resultSelector; |
| this.index = 0; |
| } |
| _next(value) { |
| let result; |
| const index = this.index++; |
| try { |
| result = this.project(value, index); |
| } |
| catch (error) { |
| this.destination.error(error); |
| return; |
| } |
| this._innerSub(result, value, index); |
| } |
| _innerSub(result, value, index) { |
| const innerSubscription = this.innerSubscription; |
| if (innerSubscription) { |
| innerSubscription.unsubscribe(); |
| } |
| this.add(this.innerSubscription = subscribeToResult(this, result, value, index)); |
| } |
| _complete() { |
| const { innerSubscription } = this; |
| if (!innerSubscription || innerSubscription.closed) { |
| super._complete(); |
| } |
| } |
| _unsubscribe() { |
| this.innerSubscription = null; |
| } |
| notifyComplete(innerSub) { |
| this.remove(innerSub); |
| this.innerSubscription = null; |
| if (this.isStopped) { |
| super._complete(); |
| } |
| } |
| notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) { |
| if (this.resultSelector) { |
| this._tryNotifyNext(outerValue, innerValue, outerIndex, innerIndex); |
| } |
| else { |
| this.destination.next(innerValue); |
| } |
| } |
| _tryNotifyNext(outerValue, innerValue, outerIndex, innerIndex) { |
| let result; |
| try { |
| result = this.resultSelector(outerValue, innerValue, outerIndex, innerIndex); |
| } |
| catch (err) { |
| this.destination.error(err); |
| return; |
| } |
| this.destination.next(result); |
| } |
| } |
| //# sourceMappingURL=switchMap.js.map |