118 lines
4.1 KiB
JavaScript
118 lines
4.1 KiB
JavaScript
import { Subject } from '../Subject';
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import { tryCatch } from '../util/tryCatch';
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import { errorObject } from '../util/errorObject';
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import { OuterSubscriber } from '../OuterSubscriber';
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import { subscribeToResult } from '../util/subscribeToResult';
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/**
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* Branch out the source Observable values as a nested Observable using a
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* factory function of closing Observables to determine when to start a new
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* window.
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*
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* <span class="informal">It's like {@link bufferWhen}, but emits a nested
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* Observable instead of an array.</span>
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*
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* <img src="./img/windowWhen.png" width="100%">
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*
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* Returns an Observable that emits windows of items it collects from the source
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* Observable. The output Observable emits connected, non-overlapping windows.
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* It emits the current window and opens a new one whenever the Observable
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* produced by the specified `closingSelector` function emits an item. The first
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* window is opened immediately when subscribing to the output Observable.
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*
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* @example <caption>Emit only the first two clicks events in every window of [1-5] random seconds</caption>
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* var clicks = Rx.Observable.fromEvent(document, 'click');
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* var result = clicks
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* .windowWhen(() => Rx.Observable.interval(1000 + Math.random() * 4000))
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* .map(win => win.take(2)) // each window has at most 2 emissions
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* .mergeAll(); // flatten the Observable-of-Observables
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* result.subscribe(x => console.log(x));
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*
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* @see {@link window}
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* @see {@link windowCount}
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* @see {@link windowTime}
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* @see {@link windowToggle}
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* @see {@link bufferWhen}
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*
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* @param {function(): Observable} closingSelector A function that takes no
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* arguments and returns an Observable that signals (on either `next` or
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* `complete`) when to close the previous window and start a new one.
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* @return {Observable<Observable<T>>} An observable of windows, which in turn
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* are Observables.
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* @method windowWhen
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* @owner Observable
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*/
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export function windowWhen(closingSelector) {
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return function windowWhenOperatorFunction(source) {
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return source.lift(new WindowOperator(closingSelector));
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};
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}
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class WindowOperator {
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constructor(closingSelector) {
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this.closingSelector = closingSelector;
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}
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call(subscriber, source) {
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return source.subscribe(new WindowSubscriber(subscriber, this.closingSelector));
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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 WindowSubscriber extends OuterSubscriber {
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constructor(destination, closingSelector) {
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super(destination);
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this.destination = destination;
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this.closingSelector = closingSelector;
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this.openWindow();
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}
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notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) {
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this.openWindow(innerSub);
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}
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notifyError(error, innerSub) {
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this._error(error);
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}
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notifyComplete(innerSub) {
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this.openWindow(innerSub);
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}
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_next(value) {
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this.window.next(value);
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}
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_error(err) {
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this.window.error(err);
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this.destination.error(err);
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this.unsubscribeClosingNotification();
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}
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_complete() {
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this.window.complete();
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this.destination.complete();
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this.unsubscribeClosingNotification();
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}
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unsubscribeClosingNotification() {
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if (this.closingNotification) {
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this.closingNotification.unsubscribe();
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}
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}
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openWindow(innerSub = null) {
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if (innerSub) {
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this.remove(innerSub);
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innerSub.unsubscribe();
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}
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const prevWindow = this.window;
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if (prevWindow) {
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prevWindow.complete();
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}
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const window = this.window = new Subject();
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this.destination.next(window);
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const closingNotifier = tryCatch(this.closingSelector)();
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if (closingNotifier === errorObject) {
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const err = errorObject.e;
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this.destination.error(err);
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this.window.error(err);
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}
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else {
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this.add(this.closingNotification = subscribeToResult(this, closingNotifier));
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}
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}
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}
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//# sourceMappingURL=windowWhen.js.map
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