ix/asynciterable/merge.mjs

The Interactive Extensions for JavaScript

import { __asyncGenerator, __await } from "tslib";
import { AsyncIterableX } from './asynciterablex.mjs';
import { wrapWithAbort } from './operators/withabort.mjs';
import { throwIfAborted } from '../aborterror.mjs';
import { safeRace } from '../util/safeRace.mjs';
// eslint-disable-next-line @typescript-eslint/no-empty-function
const NEVER_PROMISE = new Promise(() => { });
function wrapPromiseWithIndex(promise, index) {
    return promise
        .then(({ value, done }) => ({ value, done, index }))
        .catch((error) => ({ error, index }));
}
/** @ignore */
export class MergeAsyncIterable extends AsyncIterableX {
    constructor(source) {
        super();
        this._source = source;
    }
    [Symbol.asyncIterator](signal) {
        return __asyncGenerator(this, arguments, function* _a() {
            throwIfAborted(signal);
            const length = this._source.length;
            const iterators = new Array(length);
            const nexts = new Array(length);
            let active = length;
            for (let i = 0; i < length; i++) {
                const iterator = wrapWithAbort(this._source[i], signal)[Symbol.asyncIterator]();
                iterators[i] = iterator;
                nexts[i] = wrapPromiseWithIndex(iterator.next(), i);
            }
            while (active > 0) {
                const next = yield __await(safeRace(nexts));
                if (next.hasOwnProperty('error')) {
                    throw next.error;
                }
                else if (next.done) {
                    nexts[next.index] = NEVER_PROMISE;
                    active--;
                }
                else {
                    const iterator$ = iterators[next.index];
                    nexts[next.index] = wrapPromiseWithIndex(iterator$.next(), next.index);
                    yield yield __await(next.value);
                }
            }
        });
    }
}
export function merge(source, ...args) {
    return new MergeAsyncIterable([source, ...args]);
}

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