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

114 lines
3.8 KiB
JavaScript

import { Subscription } from '../Subscription';
import { tryCatch } from '../util/tryCatch';
import { errorObject } from '../util/errorObject';
import { OuterSubscriber } from '../OuterSubscriber';
import { subscribeToResult } from '../util/subscribeToResult';
/**
* Buffers the source Observable values, using a factory function of closing
* Observables to determine when to close, emit, and reset the buffer.
*
* <span class="informal">Collects values from the past as an array. When it
* starts collecting values, it calls a function that returns an Observable that
* tells when to close the buffer and restart collecting.</span>
*
* <img src="./img/bufferWhen.png" width="100%">
*
* Opens a buffer immediately, then closes the buffer when the observable
* returned by calling `closingSelector` function emits a value. When it closes
* the buffer, it immediately opens a new buffer and repeats the process.
*
* @example <caption>Emit an array of the last clicks every [1-5] random seconds</caption>
* var clicks = Rx.Observable.fromEvent(document, 'click');
* var buffered = clicks.bufferWhen(() =>
* Rx.Observable.interval(1000 + Math.random() * 4000)
* );
* buffered.subscribe(x => console.log(x));
*
* @see {@link buffer}
* @see {@link bufferCount}
* @see {@link bufferTime}
* @see {@link bufferToggle}
* @see {@link windowWhen}
*
* @param {function(): Observable} closingSelector A function that takes no
* arguments and returns an Observable that signals buffer closure.
* @return {Observable<T[]>} An observable of arrays of buffered values.
* @method bufferWhen
* @owner Observable
*/
export function bufferWhen(closingSelector) {
return function (source) {
return source.lift(new BufferWhenOperator(closingSelector));
};
}
class BufferWhenOperator {
constructor(closingSelector) {
this.closingSelector = closingSelector;
}
call(subscriber, source) {
return source.subscribe(new BufferWhenSubscriber(subscriber, this.closingSelector));
}
}
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
class BufferWhenSubscriber extends OuterSubscriber {
constructor(destination, closingSelector) {
super(destination);
this.closingSelector = closingSelector;
this.subscribing = false;
this.openBuffer();
}
_next(value) {
this.buffer.push(value);
}
_complete() {
const buffer = this.buffer;
if (buffer) {
this.destination.next(buffer);
}
super._complete();
}
/** @deprecated internal use only */ _unsubscribe() {
this.buffer = null;
this.subscribing = false;
}
notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) {
this.openBuffer();
}
notifyComplete() {
if (this.subscribing) {
this.complete();
}
else {
this.openBuffer();
}
}
openBuffer() {
let { closingSubscription } = this;
if (closingSubscription) {
this.remove(closingSubscription);
closingSubscription.unsubscribe();
}
const buffer = this.buffer;
if (this.buffer) {
this.destination.next(buffer);
}
this.buffer = [];
const closingNotifier = tryCatch(this.closingSelector)();
if (closingNotifier === errorObject) {
this.error(errorObject.e);
}
else {
closingSubscription = new Subscription();
this.closingSubscription = closingSubscription;
this.add(closingSubscription);
this.subscribing = true;
closingSubscription.add(subscribeToResult(this, closingNotifier));
this.subscribing = false;
}
}
}
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