biobulkbende.org/node_modules/rxjs/_esm2015/operators/windowWhen.js
2020-09-16 14:23:28 +02:00

118 lines
4.1 KiB
JavaScript

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