import { ArrayObservable } from '../observable/ArrayObservable'; import { isArray } from '../util/isArray'; import { OuterSubscriber } from '../OuterSubscriber'; import { subscribeToResult } from '../util/subscribeToResult'; const none = {}; /* tslint:enable:max-line-length */ /** * Combines multiple Observables to create an Observable whose values are * calculated from the latest values of each of its input Observables. * * Whenever any input Observable emits a value, it * computes a formula using the latest values from all the inputs, then emits * the output of that formula. * * * * `combineLatest` combines the values from this Observable with values from * Observables passed as arguments. This is done by subscribing to each * Observable, in order, and collecting an array of each of the most recent * values any time any of the input Observables emits, then either taking that * array and passing it as arguments to an optional `project` function and * emitting the return value of that, or just emitting the array of recent * values directly if there is no `project` function. * * @example Dynamically calculate the Body-Mass Index from an Observable of weight and one for height * var weight = Rx.Observable.of(70, 72, 76, 79, 75); * var height = Rx.Observable.of(1.76, 1.77, 1.78); * var bmi = weight.combineLatest(height, (w, h) => w / (h * h)); * bmi.subscribe(x => console.log('BMI is ' + x)); * * // With output to console: * // BMI is 24.212293388429753 * // BMI is 23.93948099205209 * // BMI is 23.671253629592222 * * @see {@link combineAll} * @see {@link merge} * @see {@link withLatestFrom} * * @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] An optional function to project the values from * the combined latest values into a new value 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 combineLatest * @owner Observable */ export function combineLatest(...observables) { let project = null; if (typeof observables[observables.length - 1] === 'function') { project = observables.pop(); } // if the first and only other argument besides the resultSelector is an array // assume it's been called with `combineLatest([obs1, obs2, obs3], project)` if (observables.length === 1 && isArray(observables[0])) { observables = observables[0].slice(); } return (source) => source.lift.call(new ArrayObservable([source, ...observables]), new CombineLatestOperator(project)); } export class CombineLatestOperator { constructor(project) { this.project = project; } call(subscriber, source) { return source.subscribe(new CombineLatestSubscriber(subscriber, this.project)); } } /** * We need this JSDoc comment for affecting ESDoc. * @ignore * @extends {Ignored} */ export class CombineLatestSubscriber extends OuterSubscriber { constructor(destination, project) { super(destination); this.project = project; this.active = 0; this.values = []; this.observables = []; } _next(observable) { this.values.push(none); this.observables.push(observable); } _complete() { const observables = this.observables; const len = observables.length; if (len === 0) { this.destination.complete(); } else { this.active = len; this.toRespond = len; for (let i = 0; i < len; i++) { const observable = observables[i]; this.add(subscribeToResult(this, observable, observable, i)); } } } notifyComplete(unused) { if ((this.active -= 1) === 0) { this.destination.complete(); } } notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) { const values = this.values; const oldVal = values[outerIndex]; const toRespond = !this.toRespond ? 0 : oldVal === none ? --this.toRespond : this.toRespond; values[outerIndex] = innerValue; if (toRespond === 0) { if (this.project) { this._tryProject(values); } else { this.destination.next(values.slice()); } } } _tryProject(values) { let result; try { result = this.project.apply(this, values); } catch (err) { this.destination.error(err); return; } this.destination.next(result); } } //# sourceMappingURL=combineLatest.js.map