import { Observable, ObservableInput } from '../Observable'; import { ArrayObservable } from '../observable/ArrayObservable'; import { isArray } from '../util/isArray'; import { Operator } from '../Operator'; import { Subscriber } from '../Subscriber'; import { OuterSubscriber } from '../OuterSubscriber'; import { InnerSubscriber } from '../InnerSubscriber'; import { subscribeToResult } from '../util/subscribeToResult'; const none = {}; /* tslint:disable:max-line-length */ export function combineLatest<T, R>(this: Observable<T>, project: (v1: T) => R): Observable<R>; export function combineLatest<T, T2, R>(this: Observable<T>, v2: ObservableInput<T2>, project: (v1: T, v2: T2) => R): Observable<R>; export function combineLatest<T, T2, T3, R>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, project: (v1: T, v2: T2, v3: T3) => R): Observable<R>; export function combineLatest<T, T2, T3, T4, R>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, project: (v1: T, v2: T2, v3: T3, v4: T4) => R): Observable<R>; export function combineLatest<T, T2, T3, T4, T5, R>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, project: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5) => R): Observable<R>; export function combineLatest<T, T2, T3, T4, T5, T6, R>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, v6: ObservableInput<T6>, project: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5, v6: T6) => R): Observable<R> ; export function combineLatest<T, T2>(this: Observable<T>, v2: ObservableInput<T2>): Observable<[T, T2]>; export function combineLatest<T, T2, T3>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>): Observable<[T, T2, T3]>; export function combineLatest<T, T2, T3, T4>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>): Observable<[T, T2, T3, T4]>; export function combineLatest<T, T2, T3, T4, T5>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>): Observable<[T, T2, T3, T4, T5]>; export function combineLatest<T, T2, T3, T4, T5, T6>(this: Observable<T>, v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, v6: ObservableInput<T6>): Observable<[T, T2, T3, T4, T5, T6]> ; export function combineLatest<T, R>(this: Observable<T>, ...observables: Array<ObservableInput<T> | ((...values: Array<T>) => R)>): Observable<R>; export function combineLatest<T, R>(this: Observable<T>, array: ObservableInput<T>[]): Observable<Array<T>>; export function combineLatest<T, TOther, R>(this: Observable<T>, array: ObservableInput<TOther>[], project: (v1: T, ...values: Array<TOther>) => R): Observable<R>; /* 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. * * <span class="informal">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.</span> * * <img src="./img/combineLatest.png" width="100%"> * * `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 <caption>Dynamically calculate the Body-Mass Index from an Observable of weight and one for height</caption> * 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<T, R>(this: Observable<T>, ...observables: Array<ObservableInput<any> | Array<ObservableInput<any>> | ((...values: Array<any>) => R)>): Observable<R> { let project: (...values: Array<any>) => R = null; if (typeof observables[observables.length - 1] === 'function') { project = <(...values: Array<any>) => R>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 = (<any>observables[0]).slice(); } observables.unshift(this); return this.lift.call(new ArrayObservable(observables), new CombineLatestOperator(project)); } export class CombineLatestOperator<T, R> implements Operator<T, R> { constructor(private project?: (...values: Array<any>) => R) { } call(subscriber: Subscriber<R>, source: any): any { return source.subscribe(new CombineLatestSubscriber(subscriber, this.project)); } } /** * We need this JSDoc comment for affecting ESDoc. * @ignore * @extends {Ignored} */ export class CombineLatestSubscriber<T, R> extends OuterSubscriber<T, R> { private active: number = 0; private values: any[] = []; private observables: any[] = []; private toRespond: number; constructor(destination: Subscriber<R>, private project?: (...values: Array<any>) => R) { super(destination); } protected _next(observable: any) { this.values.push(none); this.observables.push(observable); } protected _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: Subscriber<R>): void { if ((this.active -= 1) === 0) { this.destination.complete(); } } notifyNext(outerValue: T, innerValue: R, outerIndex: number, innerIndex: number, innerSub: InnerSubscriber<T, R>): void { 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()); } } } private _tryProject(values: any[]) { let result: any; try { result = this.project.apply(this, values); } catch (err) { this.destination.error(err); return; } this.destination.next(result); } }