async-iterator-to-pull-stream

async-iterator-to-pull-stream

Convert a (async) iterator to a pull stream

Install

npm install async-iterator-to-pull-stream

Usage

const pull = require('pull-stream')
const toPull = require('async-iterator-to-pull-stream')

const iterator = async function * () {
  const sourceValues = [1, 2, 3, 4, 5]
  for (let i = 0; i < sourceValues.length; i++) {
    yield await new Promise(resolve => setTimeout(() => resolve(sourceValues[i])))
  }
}

pull(
  toPull(iterator()),
  pull.collect((err, values) => {
    console.log(values) // 1, 2, 3, 4, 5
  })
)

API

toPull(iterator)

Convert an async iterator into a source pull stream. Returns a pull stream that can be used as a source in a pull pipeline.

toPull.through(createIterable)

A "through stream" in async iterator terms is a function that takes an iterable to read from, and returns an iterable that yields (possibly mutated) data.

createIterable is a function that creates a new iterable. It is passed an iterable - the source to read data from, and should return an iterable that yields (possibly mutated data). e.g.

const toPull = require('async-iterator-to-pull-stream')
const pull = require('pull-stream')

// A "pass through stream" that reads from the `source` iterable and returns an
// iterable (a generator in this case) that yields the same data.
const passThrough = source => (async function * () {
  for await (const chunk of source) {
    yield chunk // here we _could_ change the chunk or buffer it or whatever
  }
})()

pull(
  pull.values([1, 2, 3]),
  toPull.through(passThrough),
  pull.collect((err, chunks) => {
    console.log(err, chunks) // logs: undefined, [1, 2, 3]
  })
)

Contribute

Feel free to dive in! Open an issue or submit PRs.

License

MIT © Alan Shaw