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import { AsyncIterableX } from '../asynciterable'; | |
// tslint:disable-next-line:no-empty | |
const NEVER_PROMISE = new Promise(() => { }); | |
class MergeAsyncIterable<T> extends AsyncIterableX<T> { | |
private _source: AsyncIterable<T>[]; | |
constructor(source: AsyncIterable<T>[]) { | |
super(); | |
this._source = source; | |
} | |
async *[Symbol.asyncIterator](): AsyncIterator<T> { | |
const length = this._source.length; | |
const iterators = new Array<AsyncIterator<T>>(length); | |
const nexts = new Array<Promise<{value: IteratorResult<T>, i: number}>>(length); | |
let active = length; | |
for (let i = 0; i < length; i++) { | |
const iterator = this._source[i][Symbol.asyncIterator](); | |
iterators[i] = iterator; | |
nexts[i] = iterator.next().then(value => { return { value, i }; }); | |
} | |
while (active > 0) { | |
const { value, i } = await Promise.race(nexts); | |
if (value.done) { | |
nexts[i] = <Promise<{value: IteratorResult<T>, i: number}>>(NEVER_PROMISE); | |
active--; | |
} else { | |
const iterator$ = iterators[i]; | |
nexts[i] = iterator$.next().then(value => { return { value, i }; }); | |
yield value.value; | |
} | |
} | |
} | |
} | |
export function _mergeAll<TSource>(source: AsyncIterable<TSource>[]): AsyncIterableX<TSource> { | |
return new MergeAsyncIterable<TSource>(source); | |
} | |
export function merge<T>(source: AsyncIterable<T>, ...args: AsyncIterable<T>[]): AsyncIterableX<T> { | |
return new MergeAsyncIterable<T>([source, ...args]); | |
} | |
export function mergeStatic<T>(...args: AsyncIterable<T>[]): AsyncIterableX<T> { | |
return new MergeAsyncIterable<T>(args); | |
} |
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