parse-binary-stream

Parse n-byte chunks from a binary stream.

Call read(n, callback) and your callback will be call when n bytes of data are available from the stream. Reads can be nested to read a series of values in order.

Example

This example parses a binary message where the first two bytes represent the length of the data in the following bytes.

For example, 04 16 a1 means that there are 4 bytes of data and the data is 16 a1.

var parse = require("parse-binary-stream");

var stream = parse(function(read) {
  // Parse the length value
  read(1, function(data) {
    var length = data.readUInt8(0);
    // Parse the data of size length
    read(length, function(data) {
      console.log(data);
    });
  });
});

stream.end(new Buffer([0, 4, 1, 6, 10, 1]));
// -> logs <Buffer 16 a1>

Looping Example

Sometimes you want to continuously parse messages from an indefinite stream of data. This example parses the same protocol as above, but will parse out as many messages possible until the stream ends.

var through = require("through2");
var parse = require("parse-binary-stream");

var stream = parse(function(read) {
  (function next() {
    parseMessage(function(data) {
      console.log(data);
      next();
    });
  })();

  function parseMessage(callback) {
    // Parse the length value
    read(1, function(data) {
      var length = data.readUInt8(0);
      // Parse the data of size length
      read(length, function(data) {
        callback(data);
      });
    });
  }
});

stream.write(new Buffer([0, 2]));
stream.write(new Buffer([5]));
// logs <Buffer 05>
stream.end(new Buffer([0, 4, 1, 6, 10, 1]));
// logs <Buffer 16 a1>

API

var parse = require("parse-binary-stream");

parse(callback)

Creates a stream that will parse n-length chunks from the binary data written to it.

The callback is called with a read function that is used to parse chunks.

read(n, callback)

Calls the callback with n bytes of data when the data is available. The callback may never be called if enough data never becomes available.

Installation

npm install parse-binary-stream