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feat(combineLatest): add higher-order lettable version of combineLatest
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,169 @@ | ||
| 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'; | ||
| import { OperatorFunction } from '../interfaces'; | ||
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| const none = {}; | ||
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| /* tslint:disable:max-line-length */ | ||
| export function combineLatest<T, R>(project: (v1: T) => R): OperatorFunction<T, R>; | ||
| export function combineLatest<T, T2, R>(v2: ObservableInput<T2>, project: (v1: T, v2: T2) => R): OperatorFunction<T, R>; | ||
| export function combineLatest<T, T2, T3, R>(v2: ObservableInput<T2>, v3: ObservableInput<T3>, project: (v1: T, v2: T2, v3: T3) => R): OperatorFunction<T, R>; | ||
| export function combineLatest<T, T2, T3, T4, R>(v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, project: (v1: T, v2: T2, v3: T3, v4: T4) => R): OperatorFunction<T, R>; | ||
| export function combineLatest<T, T2, T3, T4, T5, R>(v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, project: (v1: T, v2: T2, v3: T3, v4: T4, v5: T5) => R): OperatorFunction<T, R>; | ||
| export function combineLatest<T, T2, T3, T4, T5, T6, R>(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): OperatorFunction<T, R> ; | ||
| export function combineLatest<T, T2>(v2: ObservableInput<T2>): OperatorFunction<T, [T, T2]>; | ||
| export function combineLatest<T, T2, T3>(v2: ObservableInput<T2>, v3: ObservableInput<T3>): OperatorFunction<T, [T, T2, T3]>; | ||
| export function combineLatest<T, T2, T3, T4>(v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>): OperatorFunction<T, [T, T2, T3, T4]>; | ||
| export function combineLatest<T, T2, T3, T4, T5>(v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>): OperatorFunction<T, [T, T2, T3, T4, T5]>; | ||
| export function combineLatest<T, T2, T3, T4, T5, T6>(v2: ObservableInput<T2>, v3: ObservableInput<T3>, v4: ObservableInput<T4>, v5: ObservableInput<T5>, v6: ObservableInput<T6>): OperatorFunction<T, [T, T2, T3, T4, T5, T6]> ; | ||
| export function combineLatest<T, R>(...observables: Array<ObservableInput<T> | ((...values: Array<T>) => R)>): OperatorFunction<T, R>; | ||
| export function combineLatest<T, R>(array: ObservableInput<T>[]): OperatorFunction<T, Array<T>>; | ||
| export function combineLatest<T, TOther, R>(array: ObservableInput<TOther>[], project: (v1: T, ...values: Array<TOther>) => R): OperatorFunction<T, R>; | ||
| /* tslint:enable:max-line-length */ | ||
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| /** | ||
| * 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>(...observables: Array<ObservableInput<any> | | ||
| Array<ObservableInput<any>> | | ||
| ((...values: Array<any>) => R)>): OperatorFunction<T, R> { | ||
| let project: (...values: Array<any>) => R = null; | ||
| if (typeof observables[observables.length - 1] === 'function') { | ||
| project = <(...values: Array<any>) => R>observables.pop(); | ||
| } | ||
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| // 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(); | ||
| } | ||
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| return (source: Observable<T>) => source.lift.call(new ArrayObservable([source, ...observables]), new CombineLatestOperator(project)); | ||
| } | ||
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| export class CombineLatestOperator<T, R> implements Operator<T, R> { | ||
| constructor(private project?: (...values: Array<any>) => R) { | ||
| } | ||
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| call(subscriber: Subscriber<R>, source: any): any { | ||
| return source.subscribe(new CombineLatestSubscriber(subscriber, this.project)); | ||
| } | ||
| } | ||
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| /** | ||
| * 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; | ||
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| constructor(destination: Subscriber<R>, private project?: (...values: Array<any>) => R) { | ||
| super(destination); | ||
| } | ||
|
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| protected _next(observable: any) { | ||
| this.values.push(none); | ||
| this.observables.push(observable); | ||
| } | ||
|
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| 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)); | ||
| } | ||
| } | ||
| } | ||
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| notifyComplete(unused: Subscriber<R>): void { | ||
| if ((this.active -= 1) === 0) { | ||
| this.destination.complete(); | ||
| } | ||
| } | ||
|
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| 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; | ||
|
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| if (toRespond === 0) { | ||
| if (this.project) { | ||
| this._tryProject(values); | ||
| } else { | ||
| this.destination.next(values.slice()); | ||
| } | ||
| } | ||
| } | ||
|
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| 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); | ||
| } | ||
| } |
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