140 lines
5.3 KiB
JavaScript
140 lines
5.3 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 merged multiple
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* times in the output Observable.
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*
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* <span class="informal">It's like {@link mergeMap}, but maps each value always
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* to the same inner Observable.</span>
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*
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* <img src="./img/mergeMapTo.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 merges those resulting Observables into one
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* single Observable, which is the output Observable.
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*
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* @example <caption>For each click event, start an interval Observable ticking every 1 second</caption>
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* var clicks = Rx.Observable.fromEvent(document, 'click');
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* var result = clicks.mergeMapTo(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 merge}
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* @see {@link mergeAll}
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* @see {@link mergeMap}
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* @see {@link mergeScan}
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* @see {@link switchMapTo}
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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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* @param {number} [concurrent=Number.POSITIVE_INFINITY] Maximum number of input
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* Observables being subscribed to concurrently.
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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.
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* @method mergeMapTo
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* @owner Observable
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*/
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export function mergeMapTo(innerObservable, resultSelector, concurrent = Number.POSITIVE_INFINITY) {
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if (typeof resultSelector === 'number') {
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concurrent = resultSelector;
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resultSelector = null;
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}
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return (source) => source.lift(new MergeMapToOperator(innerObservable, resultSelector, concurrent));
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}
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// TODO: Figure out correct signature here: an Operator<Observable<T>, R>
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// needs to implement call(observer: Subscriber<R>): Subscriber<Observable<T>>
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export class MergeMapToOperator {
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constructor(ish, resultSelector, concurrent = Number.POSITIVE_INFINITY) {
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this.ish = ish;
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this.resultSelector = resultSelector;
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this.concurrent = concurrent;
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}
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call(observer, source) {
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return source.subscribe(new MergeMapToSubscriber(observer, this.ish, this.resultSelector, this.concurrent));
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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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export class MergeMapToSubscriber extends OuterSubscriber {
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constructor(destination, ish, resultSelector, concurrent = Number.POSITIVE_INFINITY) {
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super(destination);
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this.ish = ish;
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this.resultSelector = resultSelector;
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this.concurrent = concurrent;
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this.hasCompleted = false;
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this.buffer = [];
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this.active = 0;
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this.index = 0;
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}
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_next(value) {
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if (this.active < this.concurrent) {
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const resultSelector = this.resultSelector;
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const index = this.index++;
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const ish = this.ish;
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const destination = this.destination;
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this.active++;
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this._innerSub(ish, destination, resultSelector, value, index);
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}
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else {
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this.buffer.push(value);
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}
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}
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_innerSub(ish, destination, resultSelector, value, index) {
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this.add(subscribeToResult(this, ish, value, index));
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}
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_complete() {
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this.hasCompleted = true;
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if (this.active === 0 && this.buffer.length === 0) {
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this.destination.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.trySelectResult(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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trySelectResult(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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notifyError(err) {
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this.destination.error(err);
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}
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notifyComplete(innerSub) {
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const buffer = this.buffer;
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this.remove(innerSub);
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this.active--;
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if (buffer.length > 0) {
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this._next(buffer.shift());
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}
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else if (this.active === 0 && this.hasCompleted) {
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this.destination.complete();
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}
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}
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}
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//# sourceMappingURL=mergeMapTo.js.map
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