separate-stream

Separates the chunks of one writable stream into multiple readable streams.

Usage

The package exports the SeparateStream class. It can be imported like this:

``javascript
const SeparateStream = require('separate-stream')
`

$3

Creates a new instance of SeparateStream that implements a Writable stream interface.
All chunks written to the Writable interface are forwarded to a Readable stream that is given as an argument to the change callback function.
Every chunk after the first chunk is handed over to the split function that must return a boolean value which must be true if a new stream should be started.
The map callback allows translating incoming chunks before they are forwarded.

The following options are supported:

- async change(stream, chunk): A callback function that is called whenever a new stream is started.
It will be called at least once for the first chunk.
Stream processing will wait until the function returned.
(default: () => {})
- split(chunk): A callback function that controls when to change to the next output stream.
A new output stream is started if the function returns true.
(default: () => false)
- map(chunk): A callback function that translates incoming chunks.
(default: v => v)

$3

This example splits the incoming stream whenever there is an o in the chunk.
The chunks are translated to upper case.

`javascript
const { promisify } = require('util')
const { finished, Readable } = require('readable-stream')
const SeparateStream = require('..')

async function main () {
const input = new Readable({ objectMode: true, read: () => {} })
const separateStream = new SeparateStream({
change: stream => {
console.log('new stream!')
stream.on('data', chunk => console.log(chunk))
},
split: chunk => {
return chunk.includes('o')
},
map: v => v.toUpperCase()
})

input.push('this')
input.push('stream')
input.push('is')
input.push('separated')
input.push('to')
input.push('multiple')
input.push('output')
input.push('streams')
input.push(null)

input.pipe(separateStream)

await promisify(finished)(separateStream)
}

main()
``