116 lines
3.9 KiB
JavaScript
Executable File
116 lines
3.9 KiB
JavaScript
Executable File
import { tryCatch } from '../util/tryCatch';
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import { errorObject } from '../util/errorObject';
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import { subscribeToResult } from '../util/subscribeToResult';
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import { OuterSubscriber } from '../OuterSubscriber';
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/**
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* Applies an accumulator function over the source Observable where the
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* accumulator function itself returns an Observable, then each intermediate
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* Observable returned is merged into the output Observable.
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*
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* <span class="informal">It's like {@link scan}, but the Observables returned
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* by the accumulator are merged into the outer Observable.</span>
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*
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* @example <caption>Count the number of click events</caption>
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* const click$ = Rx.Observable.fromEvent(document, 'click');
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* const one$ = click$.mapTo(1);
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* const seed = 0;
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* const count$ = one$.mergeScan((acc, one) => Rx.Observable.of(acc + one), seed);
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* count$.subscribe(x => console.log(x));
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*
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* // Results:
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* 1
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* 2
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* 3
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* 4
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* // ...and so on for each click
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*
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* @param {function(acc: R, value: T): Observable<R>} accumulator
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* The accumulator function called on each source value.
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* @param seed The initial accumulation value.
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* @param {number} [concurrent=Number.POSITIVE_INFINITY] Maximum number of
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* input Observables being subscribed to concurrently.
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* @return {Observable<R>} An observable of the accumulated values.
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* @method mergeScan
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* @owner Observable
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*/
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export function mergeScan(accumulator, seed, concurrent = Number.POSITIVE_INFINITY) {
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return (source) => source.lift(new MergeScanOperator(accumulator, seed, concurrent));
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}
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export class MergeScanOperator {
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constructor(accumulator, seed, concurrent) {
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this.accumulator = accumulator;
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this.seed = seed;
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this.concurrent = concurrent;
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}
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call(subscriber, source) {
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return source.subscribe(new MergeScanSubscriber(subscriber, this.accumulator, this.seed, 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 MergeScanSubscriber extends OuterSubscriber {
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constructor(destination, accumulator, acc, concurrent) {
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super(destination);
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this.accumulator = accumulator;
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this.acc = acc;
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this.concurrent = concurrent;
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this.hasValue = false;
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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 index = this.index++;
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const ish = tryCatch(this.accumulator)(this.acc, value);
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const destination = this.destination;
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if (ish === errorObject) {
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destination.error(errorObject.e);
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}
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else {
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this.active++;
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this._innerSub(ish, value, index);
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}
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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, 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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if (this.hasValue === false) {
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this.destination.next(this.acc);
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}
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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 { destination } = this;
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this.acc = innerValue;
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this.hasValue = true;
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destination.next(innerValue);
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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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if (this.hasValue === false) {
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this.destination.next(this.acc);
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}
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this.destination.complete();
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}
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}
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}
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//# sourceMappingURL=mergeScan.js.map
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