promise-piping

This module allows to convert stacked streams into one Promise object.

The piping object can be open-ended PromiseReadable object or PromiseWritable object or close-ended.

The piping object can be build from streams: standard objects or promisified versions or another piping objects.

Requirements

This module requires Node >= 4. For Node < 6 --harmony flag is required.

Installation

npm install promise-piping

Usage

const {
  PromiseReadablePiping,
  PromiseWritablePiping,
  PromisePiping
} = require('promise-piping')

or:

const PromisePiping = require('promise-piping')

Typescript:

import {
  PromiseReadablePiping,
  PromiseWritablePiping,
  PromisePiping
} from 'promise-piping'

or:

import PromisePiping from 'promise-piping'

constructor

const readablePiping = new PromiseReadablePiping(readable, duplex...)
const writablePiping = new PromiseWritablePiping(duplex..., writable)
const piping = new PromisePiping(readable, duplex..., writable)

Example:

const fs = require('fs')
const zlib = require('zlib')

const filein = fs.createReadStream('/etc/hosts')
const fileout = fs.createWriteStream('/tmp/hosts.gz')
const gzip = zlib.createGzip()
const gunzip = zlib.createGunzip()

const readablePiping = new PromiseReadablePiping(filein, gzip, gunzip)
const writablePiping = new PromiseWritablePiping(gzip, fileout)
const piping = new PromisePiping(filein, gzip, fileout)

once

const result = await piping.once(event)

This method returns Promise which is fulfilled when last stream (first stream for end event) emits event. The result of this event is returned or undefined value if stream is already ended.

The promise will reject on error. Errors in piping are propagated from intermediate streams to the first stream and the last stream. It means that operation on piping will be rejected if an error occurs in any of its streams.

Example:

await piping.once('finish')

destroy

piping.destroy()

This method calls destroy method on stream and cleans up all own handlers.

See also

PromiseReadable, PromiseWritable, PromiseDuplex, PromiseSocket.

License

Copyright (c) 2017-2018 Piotr Roszatycki mailto:piotr.roszatycki@gmail.com

MIT