BufferWriter for Cloud Code Buffer

gistfile1.js

/**
 * Lets you fill a Buffer without having to know its size beforehand.
 */
var BufferWriter = function() {
  this._size = 0;
  this._buffer = new Buffer(100);
};

_.extend(BufferWriter.prototype, {
  buffer: function() {
    return this._buffer.slice(0, this._size);
  },

  writeUInt8: function(value) {
    this._reserve(this._size + 1);
    this._buffer.writeUInt8(value, this._size);
    this._size = this._size + 1;
  },

  writeInt16LE: function(value) {
    this._reserve(this._size + 2);
    this._buffer.writeInt16LE(value, this._size);
    this._size = this._size + 2;
  },

  writeUInt16LE: function(value) {
    this._reserve(this._size + 2);
    this._buffer.writeUInt16LE(value, this._size);
    this._size = this._size + 2;
  },

  writeUInt32LE: function(value) {
    this._reserve(this._size + 4);
    this._buffer.writeUInt32LE(value, this._size);
    this._size = this._size + 4;
  },

  writeUTF8: function(str) {
    this._reserve(this._size + str.length * 6);
    this._size = this._size + this._buffer.write(str, this._size);
  },

  /**
   * Resizes the backing buffer to ensure it can hold at least size bytes.
   */
  _reserve: function(size) {
    var current = this._buffer.length;
    while (size >= current) {
      this._buffer = Buffer.concat([this._buffer, new Buffer(current)],
                                   current * 2);
      current = this._buffer.length;
    }
  }
});