| import { tryCatch } from '../util/tryCatch'; |
| import { errorObject } from '../util/errorObject'; |
| import { OuterSubscriber } from '../OuterSubscriber'; |
| import { subscribeToResult } from '../util/subscribeToResult'; |
| /* tslint:enable:max-line-length */ |
| /** |
| * Recursively projects each source value to an Observable which is merged in |
| * the output Observable. |
| * |
| * <span class="informal">It's similar to {@link mergeMap}, but applies the |
| * projection function to every source value as well as every output value. |
| * It's recursive.</span> |
| * |
| * <img src="./img/expand.png" width="100%"> |
| * |
| * Returns an Observable that emits items based on applying a function that you |
| * supply to each item emitted by the source Observable, where that function |
| * returns an Observable, and then merging those resulting Observables and |
| * emitting the results of this merger. *Expand* will re-emit on the output |
| * Observable every source value. Then, each output value is given to the |
| * `project` function which returns an inner Observable to be merged on the |
| * output Observable. Those output values resulting from the projection are also |
| * given to the `project` function to produce new output values. This is how |
| * *expand* behaves recursively. |
| * |
| * @example <caption>Start emitting the powers of two on every click, at most 10 of them</caption> |
| * var clicks = Rx.Observable.fromEvent(document, 'click'); |
| * var powersOfTwo = clicks |
| * .mapTo(1) |
| * .expand(x => Rx.Observable.of(2 * x).delay(1000)) |
| * .take(10); |
| * powersOfTwo.subscribe(x => console.log(x)); |
| * |
| * @see {@link mergeMap} |
| * @see {@link mergeScan} |
| * |
| * @param {function(value: T, index: number) => Observable} project A function |
| * that, when applied to an item emitted by the source or the output Observable, |
| * returns an Observable. |
| * @param {number} [concurrent=Number.POSITIVE_INFINITY] Maximum number of input |
| * Observables being subscribed to concurrently. |
| * @param {Scheduler} [scheduler=null] The IScheduler to use for subscribing to |
| * each projected inner Observable. |
| * @return {Observable} An Observable that emits the source values and also |
| * result of applying the projection function to each value emitted on the |
| * output Observable and and merging the results of the Observables obtained |
| * from this transformation. |
| * @method expand |
| * @owner Observable |
| */ |
| export function expand(project, concurrent = Number.POSITIVE_INFINITY, scheduler = undefined) { |
| concurrent = (concurrent || 0) < 1 ? Number.POSITIVE_INFINITY : concurrent; |
| return (source) => source.lift(new ExpandOperator(project, concurrent, scheduler)); |
| } |
| export class ExpandOperator { |
| constructor(project, concurrent, scheduler) { |
| this.project = project; |
| this.concurrent = concurrent; |
| this.scheduler = scheduler; |
| } |
| call(subscriber, source) { |
| return source.subscribe(new ExpandSubscriber(subscriber, this.project, this.concurrent, this.scheduler)); |
| } |
| } |
| /** |
| * We need this JSDoc comment for affecting ESDoc. |
| * @ignore |
| * @extends {Ignored} |
| */ |
| export class ExpandSubscriber extends OuterSubscriber { |
| constructor(destination, project, concurrent, scheduler) { |
| super(destination); |
| this.project = project; |
| this.concurrent = concurrent; |
| this.scheduler = scheduler; |
| this.index = 0; |
| this.active = 0; |
| this.hasCompleted = false; |
| if (concurrent < Number.POSITIVE_INFINITY) { |
| this.buffer = []; |
| } |
| } |
| static dispatch(arg) { |
| const { subscriber, result, value, index } = arg; |
| subscriber.subscribeToProjection(result, value, index); |
| } |
| _next(value) { |
| const destination = this.destination; |
| if (destination.closed) { |
| this._complete(); |
| return; |
| } |
| const index = this.index++; |
| if (this.active < this.concurrent) { |
| destination.next(value); |
| let result = tryCatch(this.project)(value, index); |
| if (result === errorObject) { |
| destination.error(errorObject.e); |
| } |
| else if (!this.scheduler) { |
| this.subscribeToProjection(result, value, index); |
| } |
| else { |
| const state = { subscriber: this, result, value, index }; |
| this.add(this.scheduler.schedule(ExpandSubscriber.dispatch, 0, state)); |
| } |
| } |
| else { |
| this.buffer.push(value); |
| } |
| } |
| subscribeToProjection(result, value, index) { |
| this.active++; |
| this.add(subscribeToResult(this, result, value, index)); |
| } |
| _complete() { |
| this.hasCompleted = true; |
| if (this.hasCompleted && this.active === 0) { |
| this.destination.complete(); |
| } |
| } |
| notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) { |
| this._next(innerValue); |
| } |
| notifyComplete(innerSub) { |
| const buffer = this.buffer; |
| this.remove(innerSub); |
| this.active--; |
| if (buffer && buffer.length > 0) { |
| this._next(buffer.shift()); |
| } |
| if (this.hasCompleted && this.active === 0) { |
| this.destination.complete(); |
| } |
| } |
| } |
| //# sourceMappingURL=expand.js.map |