@reactivex/ix-esnext-esm/asynciterable/fromnodestream.js

The Interactive Extensions for JavaScript

import { AsyncIterableX } from './asynciterablex';
const NON_FLOWING = 0;
const READABLE = 1;
const ENDED = 2;
const ERRORED = 3;
export class ReadableStreamAsyncIterable extends AsyncIterableX {
    constructor(stream, size) {
        super();
        this._stream = stream;
        this._defaultSize = size;
        this._state = NON_FLOWING;
        this._error = null;
        this._rejectFns = new Set();
        const onError = (err) => {
            this._state = ERRORED;
            this._error = err;
            for (const rejectFn of this._rejectFns) {
                rejectFn(err);
            }
        };
        const onEnd = () => {
            this._state = ENDED;
        };
        this._stream['once']('error', onError);
        this._stream['once']('end', onEnd);
    }
    [Symbol.asyncIterator]() {
        return this;
    }
    async next(size = this._defaultSize) {
        if (this._state === NON_FLOWING) {
            await Promise.race([this._waitReadable(), this._waitEnd()]);
            return await this.next(size);
        }
        if (this._state === ENDED) {
            return { done: true, value: undefined };
        }
        if (this._state === ERRORED) {
            throw this._error;
        }
        const value = this._stream['read'](size);
        if (value !== null) {
            return { done: false, value };
        }
        else {
            this._state = NON_FLOWING;
            return await this.next(size);
        }
    }
    _waitReadable() {
        return new Promise((resolve, reject) => {
            const onReadable = () => {
                this._state = READABLE;
                this._rejectFns.delete(reject);
                resolve();
            };
            this._rejectFns.add(reject);
            this._stream['once']('readable', onReadable);
        });
    }
    _waitEnd() {
        if (!this._endPromise) {
            this._endPromise = new Promise((resolve, reject) => {
                const onEnd = () => {
                    this._state = ENDED;
                    this._rejectFns.delete(reject);
                    resolve();
                };
                this._rejectFns.add(reject);
                this._stream['once']('end', onEnd);
            });
        }
        return this._endPromise;
    }
}
/**
 * Creates a new async-iterable from a Node.js stream.
 *
 * @export
 * @param {NodeJS.ReadableStream} stream The Node.js stream to convert to an async-iterable.
 * @param {number} [size] The size of the buffers for the stream.
 * @returns {(AsyncIterableX<string | Buffer>)} An async-iterable containing data from the stream either in string or Buffer format.
 */
export function fromNodeStream(stream, size) {
    return new ReadableStreamAsyncIterable(stream, size);
}

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