| 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. |
| * |
| * <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(...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 |