work.suroh.tk/node_modules/rxjs/_esm2015/operators/mergeScan.js

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2019-12-02 12:22:45 +00:00
import { tryCatch } from '../util/tryCatch';
import { errorObject } from '../util/errorObject';
import { subscribeToResult } from '../util/subscribeToResult';
import { OuterSubscriber } from '../OuterSubscriber';
/**
* Applies an accumulator function over the source Observable where the
* accumulator function itself returns an Observable, then each intermediate
* Observable returned is merged into the output Observable.
*
* <span class="informal">It's like {@link scan}, but the Observables returned
* by the accumulator are merged into the outer Observable.</span>
*
* @example <caption>Count the number of click events</caption>
* const click$ = Rx.Observable.fromEvent(document, 'click');
* const one$ = click$.mapTo(1);
* const seed = 0;
* const count$ = one$.mergeScan((acc, one) => Rx.Observable.of(acc + one), seed);
* count$.subscribe(x => console.log(x));
*
* // Results:
* 1
* 2
* 3
* 4
* // ...and so on for each click
*
* @param {function(acc: R, value: T): Observable<R>} accumulator
* The accumulator function called on each source value.
* @param seed The initial accumulation value.
* @param {number} [concurrent=Number.POSITIVE_INFINITY] Maximum number of
* input Observables being subscribed to concurrently.
* @return {Observable<R>} An observable of the accumulated values.
* @method mergeScan
* @owner Observable
*/
export function mergeScan(accumulator, seed, concurrent = Number.POSITIVE_INFINITY) {
return (source) => source.lift(new MergeScanOperator(accumulator, seed, concurrent));
}
export class MergeScanOperator {
constructor(accumulator, seed, concurrent) {
this.accumulator = accumulator;
this.seed = seed;
this.concurrent = concurrent;
}
call(subscriber, source) {
return source.subscribe(new MergeScanSubscriber(subscriber, this.accumulator, this.seed, this.concurrent));
}
}
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
export class MergeScanSubscriber extends OuterSubscriber {
constructor(destination, accumulator, acc, concurrent) {
super(destination);
this.accumulator = accumulator;
this.acc = acc;
this.concurrent = concurrent;
this.hasValue = false;
this.hasCompleted = false;
this.buffer = [];
this.active = 0;
this.index = 0;
}
_next(value) {
if (this.active < this.concurrent) {
const index = this.index++;
const ish = tryCatch(this.accumulator)(this.acc, value);
const destination = this.destination;
if (ish === errorObject) {
destination.error(errorObject.e);
}
else {
this.active++;
this._innerSub(ish, value, index);
}
}
else {
this.buffer.push(value);
}
}
_innerSub(ish, value, index) {
this.add(subscribeToResult(this, ish, value, index));
}
_complete() {
this.hasCompleted = true;
if (this.active === 0 && this.buffer.length === 0) {
if (this.hasValue === false) {
this.destination.next(this.acc);
}
this.destination.complete();
}
}
notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) {
const { destination } = this;
this.acc = innerValue;
this.hasValue = true;
destination.next(innerValue);
}
notifyComplete(innerSub) {
const buffer = this.buffer;
this.remove(innerSub);
this.active--;
if (buffer.length > 0) {
this._next(buffer.shift());
}
else if (this.active === 0 && this.hasCompleted) {
if (this.hasValue === false) {
this.destination.next(this.acc);
}
this.destination.complete();
}
}
}
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