binary-parse-stream

binary-parse-stream

Painless streaming binary protocol parsers using generators.

Installation

npm install binary-parse-stream

Synchronous

This module uses the exact same generator interface as binary-parser, which presents a synchronous interface to a generator parser.

Usage

var BinaryParseStream = require('binary-parse-stream')
  , One = BinaryParseStream.One // -1

BinaryParseStream is a TransformStream that consumes buffers and outputs objects on the other end. It expects your subclass to implement a _parse method that is a generator. When your generator yields a number, it'll be fed a buffer of that length from the input. If it yields -1, it'll be given the value of the first byte instead of a single-byte buffer. When your generator returns, the return value will be pushed to the output side.

Example

The following module parses a protocol that consists of a 32-bit unsigned big-endian type parameter, an unsigned 8-bit length parameter, and a buffer of the specified length. It outputs {type, buf} objects.

var BinaryParseStream = require('binary-parse-stream')
  , inherits = require('util').inherits

module.exports = SillyProtocolParseStream
inherits(SillyProtocolParseStream, BinaryParseStream)
function SillyProtocolParseStream(options) {
  BinaryParseStream.call(this, options)
}
SillyProtocolParseStream.prototype._parse = function*() {
  var type = (yield 4).readUInt32BE(0, true)
    , length = yield -1
    , buf = yield length
  return { type: type, buf: buf }
}

There is also a shorter syntax for when you don't want to explicitly subclass: BinaryParseStream.extend(function*()).