| import { OuterSubscriber } from '../OuterSubscriber'; |
| import { subscribeToResult } from '../util/subscribeToResult'; |
| /* tslint:enable:max-line-length */ |
| /** |
| * Combines the source Observable with other Observables to create an Observable |
| * whose values are calculated from the latest values of each, only when the |
| * source emits. |
| * |
| * <span class="informal">Whenever the source Observable emits a value, it |
| * computes a formula using that value plus the latest values from other input |
| * Observables, then emits the output of that formula.</span> |
| * |
| * <img src="./img/withLatestFrom.png" width="100%"> |
| * |
| * `withLatestFrom` combines each value from the source Observable (the |
| * instance) with the latest values from the other input Observables only when |
| * the source emits a value, optionally using a `project` function to determine |
| * the value to be emitted on the output Observable. All input Observables must |
| * emit at least one value before the output Observable will emit a value. |
| * |
| * @example <caption>On every click event, emit an array with the latest timer event plus the click event</caption> |
| * var clicks = Rx.Observable.fromEvent(document, 'click'); |
| * var timer = Rx.Observable.interval(1000); |
| * var result = clicks.withLatestFrom(timer); |
| * result.subscribe(x => console.log(x)); |
| * |
| * @see {@link combineLatest} |
| * |
| * @param {ObservableInput} other An input Observable to combine with the source |
| * Observable. More than one input Observables may be given as argument. |
| * @param {Function} [project] Projection function for combining values |
| * together. Receives all values in order of the Observables passed, where the |
| * first parameter is a value from the source Observable. (e.g. |
| * `a.withLatestFrom(b, c, (a1, b1, c1) => a1 + b1 + c1)`). If this is not |
| * passed, arrays will be emitted on the output Observable. |
| * @return {Observable} An Observable of projected values from the most recent |
| * values from each input Observable, or an array of the most recent values from |
| * each input Observable. |
| * @method withLatestFrom |
| * @owner Observable |
| */ |
| export function withLatestFrom(...args) { |
| return (source) => { |
| let project; |
| if (typeof args[args.length - 1] === 'function') { |
| project = args.pop(); |
| } |
| const observables = args; |
| return source.lift(new WithLatestFromOperator(observables, project)); |
| }; |
| } |
| class WithLatestFromOperator { |
| constructor(observables, project) { |
| this.observables = observables; |
| this.project = project; |
| } |
| call(subscriber, source) { |
| return source.subscribe(new WithLatestFromSubscriber(subscriber, this.observables, this.project)); |
| } |
| } |
| /** |
| * We need this JSDoc comment for affecting ESDoc. |
| * @ignore |
| * @extends {Ignored} |
| */ |
| class WithLatestFromSubscriber extends OuterSubscriber { |
| constructor(destination, observables, project) { |
| super(destination); |
| this.observables = observables; |
| this.project = project; |
| this.toRespond = []; |
| const len = observables.length; |
| this.values = new Array(len); |
| for (let i = 0; i < len; i++) { |
| this.toRespond.push(i); |
| } |
| for (let i = 0; i < len; i++) { |
| let observable = observables[i]; |
| this.add(subscribeToResult(this, observable, observable, i)); |
| } |
| } |
| notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) { |
| this.values[outerIndex] = innerValue; |
| const toRespond = this.toRespond; |
| if (toRespond.length > 0) { |
| const found = toRespond.indexOf(outerIndex); |
| if (found !== -1) { |
| toRespond.splice(found, 1); |
| } |
| } |
| } |
| notifyComplete() { |
| // noop |
| } |
| _next(value) { |
| if (this.toRespond.length === 0) { |
| const args = [value, ...this.values]; |
| if (this.project) { |
| this._tryProject(args); |
| } |
| else { |
| this.destination.next(args); |
| } |
| } |
| } |
| _tryProject(args) { |
| let result; |
| try { |
| result = this.project.apply(this, args); |
| } |
| catch (err) { |
| this.destination.error(err); |
| return; |
| } |
| this.destination.next(result); |
| } |
| } |
| //# sourceMappingURL=withLatestFrom.js.map |