Stream Tokenizr

Easily parse binary data with a convenient accessible fluent interface, and node streams. Tokenzr is a small Transform stream implementation, that pulls binary data in and pushes out whatever tokens you wish.

Tokenizr more or less implements the same API as Substack's Binary where it made sense, although the internals or simplier and (i think) more straight forward, by making use of the newer streams api. Each tokenizr is a Transform stream instance so check here for that api. The ultimate form and content of the parsed data is up to you.

Using the Tokenizr

var Tokenizr = require('stream-tokenizr')
  , stream = getAReadStream();

var tokenizr = stream.pipe(new Tokenizr({ objectMode: true }));

tokenizr
    .readString(5, 'uft8', 'myString')
    .readUInt16LE('myInt')
    .tap(function(state){
        var obj = {
            'message': state.myString,
            'number': state.myInt
        }
        // we can now push the parsed data out to the world
        // see: http://nodejs.org/api/stream.html#stream_readable_push_chunk_encoding
        this.push(obj)
    })

tokenizr.on('data', function(obj){
    console.log('obj')
})

Building parser streams

You can also inherit stream Tokenizr to help create complex stream parsers. Take a look at the various audio file parsers i've written for some real world examples

parser.js

Here we create a new Parser Stream that inherits from Tokenizr

var Tokenizr = require('stream-tokenizr');

module.exports = Parser

require('util').inherits(Parser, Tokenizr);

function Parser(opts){
    Tokenizr.call(this, opts)

    this
        .readString(5, 'uft8', 'myString')
        .readUInt16LE('myInt')
        .tap(function(state){
             var obj = {
                 'message': state.myString,
                 'number': state.myInt
             }
             // we can now push the parsed data out to the world
             // see: http://nodejs.org/api/stream.html#stream_readable_push_chunk_encoding
             this.push(obj)
             this.push(null)
        })
}

main.js

var Parser = require('./parser')
  , source = getAReadStream();

var parser = new Parser();

source
    .pipe(parser)
    .on('data', function(obj){ // you can also use the new read()
        console.log(obj) // => { message: 'hello', myInt: 5 }
    })

API

.readBuffer(Int bytes, Function|String callback)

reads a buffer of a specified size in bytes.

1. if you provide a Function for the callback it will be called with the buffer as the first argument, and the state object as the second.

2. Providing a String as the callback will assign the buffer in the state object under a key of that name

   tokenizr .readBuffer(4, 'first') .readBuffer(5, function(buffer, state){ buffer.length // 5 state.first.length // 4 })