115 lines
4.4 KiB
JavaScript
115 lines
4.4 KiB
JavaScript
import { OuterSubscriber } from '../OuterSubscriber';
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import { subscribeToResult } from '../util/subscribeToResult';
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/* tslint:enable:max-line-length */
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/**
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* Projects each source value to the same Observable which is flattened multiple
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* times with {@link switch} in the output Observable.
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*
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* <span class="informal">It's like {@link switchMap}, but maps each value
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* always to the same inner Observable.</span>
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*
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* <img src="./img/switchMapTo.png" width="100%">
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*
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* Maps each source value to the given Observable `innerObservable` regardless
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* of the source value, and then flattens those resulting Observables into one
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* single Observable, which is the output Observable. The output Observables
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* emits values only from the most recently emitted instance of
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* `innerObservable`.
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*
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* @example <caption>Rerun an interval Observable on every click event</caption>
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* var clicks = Rx.Observable.fromEvent(document, 'click');
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* var result = clicks.switchMapTo(Rx.Observable.interval(1000));
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* result.subscribe(x => console.log(x));
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*
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* @see {@link concatMapTo}
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* @see {@link switch}
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* @see {@link switchMap}
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* @see {@link mergeMapTo}
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*
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* @param {ObservableInput} innerObservable An Observable to replace each value from
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* the source Observable.
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* @param {function(outerValue: T, innerValue: I, outerIndex: number, innerIndex: number): any} [resultSelector]
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* A function to produce the value on the output Observable based on the values
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* and the indices of the source (outer) emission and the inner Observable
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* emission. The arguments passed to this function are:
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* - `outerValue`: the value that came from the source
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* - `innerValue`: the value that came from the projected Observable
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* - `outerIndex`: the "index" of the value that came from the source
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* - `innerIndex`: the "index" of the value from the projected Observable
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* @return {Observable} An Observable that emits items from the given
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* `innerObservable` (and optionally transformed through `resultSelector`) every
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* time a value is emitted on the source Observable, and taking only the values
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* from the most recently projected inner Observable.
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* @method switchMapTo
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* @owner Observable
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*/
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export function switchMapTo(innerObservable, resultSelector) {
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return (source) => source.lift(new SwitchMapToOperator(innerObservable, resultSelector));
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}
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class SwitchMapToOperator {
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constructor(observable, resultSelector) {
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this.observable = observable;
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this.resultSelector = resultSelector;
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}
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call(subscriber, source) {
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return source.subscribe(new SwitchMapToSubscriber(subscriber, this.observable, this.resultSelector));
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}
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}
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/**
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* We need this JSDoc comment for affecting ESDoc.
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* @ignore
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* @extends {Ignored}
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*/
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class SwitchMapToSubscriber extends OuterSubscriber {
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constructor(destination, inner, resultSelector) {
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super(destination);
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this.inner = inner;
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this.resultSelector = resultSelector;
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this.index = 0;
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}
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_next(value) {
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const innerSubscription = this.innerSubscription;
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if (innerSubscription) {
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innerSubscription.unsubscribe();
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}
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this.add(this.innerSubscription = subscribeToResult(this, this.inner, value, this.index++));
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}
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_complete() {
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const { innerSubscription } = this;
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if (!innerSubscription || innerSubscription.closed) {
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super._complete();
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}
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}
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/** @deprecated internal use only */ _unsubscribe() {
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this.innerSubscription = null;
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}
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notifyComplete(innerSub) {
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this.remove(innerSub);
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this.innerSubscription = null;
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if (this.isStopped) {
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super._complete();
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}
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}
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notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) {
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const { resultSelector, destination } = this;
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if (resultSelector) {
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this.tryResultSelector(outerValue, innerValue, outerIndex, innerIndex);
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}
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else {
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destination.next(innerValue);
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}
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}
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tryResultSelector(outerValue, innerValue, outerIndex, innerIndex) {
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const { resultSelector, destination } = this;
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let result;
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try {
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result = resultSelector(outerValue, innerValue, outerIndex, innerIndex);
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}
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catch (err) {
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destination.error(err);
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return;
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}
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destination.next(result);
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}
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}
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//# sourceMappingURL=switchMapTo.js.map
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