work.suroh.tk/node_modules/rxjs/_esm2015/observable/merge.js

84 lines
3.6 KiB
JavaScript

import { Observable } from '../Observable';
import { ArrayObservable } from './ArrayObservable';
import { isScheduler } from '../util/isScheduler';
import { mergeAll } from '../operators/mergeAll';
/* tslint:enable:max-line-length */
/**
* Creates an output Observable which concurrently emits all values from every
* given input Observable.
*
* <span class="informal">Flattens multiple Observables together by blending
* their values into one Observable.</span>
*
* <img src="./img/merge.png" width="100%">
*
* `merge` subscribes to each given input Observable (as arguments), and simply
* forwards (without doing any transformation) all the values from all the input
* Observables to the output Observable. The output Observable only completes
* once all input Observables have completed. Any error delivered by an input
* Observable will be immediately emitted on the output Observable.
*
* @example <caption>Merge together two Observables: 1s interval and clicks</caption>
* var clicks = Rx.Observable.fromEvent(document, 'click');
* var timer = Rx.Observable.interval(1000);
* var clicksOrTimer = Rx.Observable.merge(clicks, timer);
* clicksOrTimer.subscribe(x => console.log(x));
*
* // Results in the following:
* // timer will emit ascending values, one every second(1000ms) to console
* // clicks logs MouseEvents to console everytime the "document" is clicked
* // Since the two streams are merged you see these happening
* // as they occur.
*
* @example <caption>Merge together 3 Observables, but only 2 run concurrently</caption>
* var timer1 = Rx.Observable.interval(1000).take(10);
* var timer2 = Rx.Observable.interval(2000).take(6);
* var timer3 = Rx.Observable.interval(500).take(10);
* var concurrent = 2; // the argument
* var merged = Rx.Observable.merge(timer1, timer2, timer3, concurrent);
* merged.subscribe(x => console.log(x));
*
* // Results in the following:
* // - First timer1 and timer2 will run concurrently
* // - timer1 will emit a value every 1000ms for 10 iterations
* // - timer2 will emit a value every 2000ms for 6 iterations
* // - after timer1 hits it's max iteration, timer2 will
* // continue, and timer3 will start to run concurrently with timer2
* // - when timer2 hits it's max iteration it terminates, and
* // timer3 will continue to emit a value every 500ms until it is complete
*
* @see {@link mergeAll}
* @see {@link mergeMap}
* @see {@link mergeMapTo}
* @see {@link mergeScan}
*
* @param {...ObservableInput} observables Input Observables to merge together.
* @param {number} [concurrent=Number.POSITIVE_INFINITY] Maximum number of input
* Observables being subscribed to concurrently.
* @param {Scheduler} [scheduler=null] The IScheduler to use for managing
* concurrency of input Observables.
* @return {Observable} an Observable that emits items that are the result of
* every input Observable.
* @static true
* @name merge
* @owner Observable
*/
export function merge(...observables) {
let concurrent = Number.POSITIVE_INFINITY;
let scheduler = null;
let last = observables[observables.length - 1];
if (isScheduler(last)) {
scheduler = observables.pop();
if (observables.length > 1 && typeof observables[observables.length - 1] === 'number') {
concurrent = observables.pop();
}
}
else if (typeof last === 'number') {
concurrent = observables.pop();
}
if (scheduler === null && observables.length === 1 && observables[0] instanceof Observable) {
return observables[0];
}
return mergeAll(concurrent)(new ArrayObservable(observables, scheduler));
}
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