# pull-length-prefixed

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> Streaming length prefixed buffers with pull-streams

## Table of Contents

- [Installation](#installation)
- [Usage](#usage)
- [Contribute](#contribute)
- [License](#license)

## Installation

```bash
$ npm install --save pull-length-prefixed
```

## Usage

```js
var pull = require('pull-stream')
var lp = require('pull-length-prefixed')

// encode
pull(
  pull.values([Buffer.from('hello world')]),
  lp.encode(),
  pull.collect(function (err, encoded) {
    if (err) throw err
    console.log(encoded)
    // => [Buffer <0b 68 65 6c 6c 6f 20 77 6f 72 6c 64>]
  })
)

// decode
pull(
  pull.values(encoded), // e.g. from above
  lp.decode(),
  pull.collect(function (err, decoded) {
    if (err) throw err
    console.log(decoded)
    // => [Buffer <68 65 6c 6c 6f 20 77 6f 72 6c 64>]
  })
)
```

## API

### `encode([opts])`

- `opts: Object`, optional
  - `fixed: false`: If true uses a fixed 4 byte Int32BE prefix instead of varint

By default all messages will be prefixed with a varint. If you want to use a fixed length prefix you can specify this through the `opts`.

Returns a pull-stream through.

### `decode([opts])`

- `opts: Object`, optional
  - `fixed: false`: If true uses a fixed 4 byte Int32BE prefix instead of varint
  - `maxLength`: If provided, will not decode messages longer than the size specified, if omitted will use the current default of 4MB.

By default all messages will be prefixed with a varint. If you want to use a fixed length prefix you can specify this through the `opts`.


Returns a pull-stream through.

### `decodeFromReader(reader, [opts], cb)`

- `reader: [pull-reader](https://github.com/dominictarr/pull-reader)`
- `opts: Object`, optional. Same as for `decode`.
- `cb: Function`: Callback called with `(err, message)`.

This uses a [pull-reader](https://github.com/dominictarr/pull-reader) instance to reade and decode a single message. Useful when using [pull-handshake](https://github.com/pull-stream/pull-handshake) with length prefixed messages.


## Contribute

PRs and issues gladly accepted! Check out the [issues](//github.com/dignifiedquire/pull-length-prefixed/issues).

## License

MIT © 2016 Friedel Ziegelmayer