msgpack.js

"use strict";

var bops = require('bops');

exports.encode = function (value) {
  var size = sizeof(value);
  if (size === 0) return undefined;
  var buffer = bops.create(size);
  encode(value, buffer, 0);
  return buffer;
};

exports.decode = decode;

// http://wiki.msgpack.org/display/MSGPACK/Format+specification
// I've extended the protocol to have two new types that were previously reserved.
//   buffer 16  11011000  0xd8
//   buffer 32  11011001  0xd9
// These work just like raw16 and raw32 except they are node buffers instead of strings.
//
// Also I've added a type for `undefined`
//   undefined  11000100  0xc4

function Decoder(buffer, offset) {
  this.offset = offset || 0;
  this.buffer = buffer;
}
Decoder.prototype.map = function (length) {
  var value = {};
  for (var i = 0; i < length; i++) {
    var key = this.parse();
    value[key] = this.parse();
  }
  return value;
};
Decoder.prototype.buf = function (length) {
  var value = bops.subarray(this.buffer, this.offset, this.offset + length);
  this.offset += length;
  return value;
};
Decoder.prototype.raw = function (length) {
  var value = bops.to(bops.subarray(this.buffer, this.offset, this.offset + length), "hex");
  this.offset += length;
  return value;
};
Decoder.prototype.array = function (length) {
  var value = new Array(length);
  for (var i = 0; i < length; i++) {
    value[i] = this.parse();
  }
  return value;
};
Decoder.prototype.parse = function () {
  var type = this.buffer[this.offset];
  var value, length;
  // FixRaw
  if ((type & 0xe0) === 0xa0) {
    length = type & 0x1f;
    this.offset++;
    return this.raw(length);
  }
  // FixMap
  if ((type & 0xf0) === 0x80) {
    length = type & 0x0f;
    this.offset++;
    return this.map(length);
  }
  // FixArray
  if ((type & 0xf0) === 0x90) {
    length = type & 0x0f;
    this.offset++;
    return this.array(length);
  }
  // Positive FixNum
  if ((type & 0x80) === 0x00) {
    this.offset++;
    return type;
  }
  // Negative Fixnum
  if ((type & 0xe0) === 0xe0) {
    value = bops.readInt8(this.buffer, this.offset);
    this.offset++;
    return value;
  }
  switch (type) {
  // raw 16
  case 0xda:
    length = bops.readUInt16BE(this.buffer, this.offset + 1);
    this.offset += 3;
    return this.raw(length);
  // raw 32
  case 0xdb:
    length = bops.readUInt32BE(this.buffer, this.offset + 1);
    this.offset += 5;
    return this.raw(length);
  // nil
  case 0xc0:
    this.offset++;
    return null;
  // false
  case 0xc2:
    this.offset++;
    return false;
  // true
  case 0xc3:
    this.offset++;
    return true;
  // undefined
  case 0xc4:
    this.offset++;
    return undefined;
  // uint8
  case 0xcc:
    value = this.buffer[this.offset + 1];
    this.offset += 2;
    return value;
  // uint 16
  case 0xcd:
    value = bops.readUInt16BE(this.buffer, this.offset + 1);
    this.offset += 3;
    return value;
  // uint 32
  case 0xce:
    value = bops.readUInt32BE(this.buffer, this.offset + 1);
    this.offset += 5;
    return value;
  // uint64
  case 0xcf:
    value = bops.readUInt64BE(this.buffer, this.offset + 1);
    this.offset += 9;
    return value;
  // int 8
  case 0xd0:
    value = bops.readInt8(this.buffer, this.offset + 1);
    this.offset += 2;
    return value;
  // int 16
  case 0xd1:
    value = bops.readInt16BE(this.buffer, this.offset + 1);
    this.offset += 3;
    return value;
  // int 32
  case 0xd2:
    value = bops.readInt32BE(this.buffer, this.offset + 1);
    this.offset += 5;
    return value;
  // int 64
  case 0xd3:
    value = bops.readInt64BE(this.buffer, this.offset + 1);
    this.offset += 9;
    return value;
  // map 16
  case 0xde:
    length = bops.readUInt16BE(this.buffer, this.offset + 1);
    this.offset += 3;
    return this.map(length);
  // map 32
  case 0xdf:
    length = bops.readUInt32BE(this.buffer, this.offset + 1);
    this.offset += 5;
    return this.map(length);
  // array 16
  case 0xdc:
    length = bops.readUInt16BE(this.buffer, this.offset + 1);
    this.offset += 3;
    return this.array(length);
  // array 32
  case 0xdd:
    length = bops.readUInt32BE(this.buffer, this.offset + 1);
    this.offset += 5;
    return this.array(length);
  // buffer 16
  case 0xd8:
    length = bops.readUInt16BE(this.buffer, this.offset + 1);
    this.offset += 3;
    return this.buf(length);
  // buffer 32
  case 0xd9:
    length = bops.readUInt32BE(this.buffer, this.offset + 1);
    this.offset += 5;
    return this.buf(length);
  // float
  case 0xca:
    value = bops.readFloatBE(this.buffer, this.offset + 1);
    this.offset += 5;
    return value;
  // double
  case 0xcb:
    value = bops.readDoubleBE(this.buffer, this.offset + 1);
    this.offset += 9;
    return value;
  }
  throw new Error("Unknown type 0x" + type.toString(16));
};
function decode(buffer) {
  var decoder = new Decoder(buffer);
  var value = decoder.parse();
  if (decoder.offset !== buffer.length) throw new Error((buffer.length - decoder.offset) + " trailing bytes");
  return value;
}

function encodeableKeys (value) {
  return Object.keys(value).filter(function (e) {
    return typeof value[e] !== 'function' || value[e].toJSON;
  });
}

function encode(value, buffer, offset) {
  var type = typeof value;
  var length, size;

  // Strings Bytes
  if (type === "string") {
    value = bops.from(value, "hex");
    length = value.length;
    // fix raw
    if (length < 0x20) {
      buffer[offset] = length | 0xa0;
      bops.copy(value, buffer, offset + 1);
      return 1 + length;
    }
    // raw 16
    if (length < 0x10000) {
      buffer[offset] = 0xda;
      bops.writeUInt16BE(buffer, length, offset + 1);
      bops.copy(value, buffer, offset + 3);
      return 3 + length;
    }
    // raw 32
    if (length < 0x100000000) {
      buffer[offset] = 0xdb;
      bops.writeUInt32BE(buffer, length, offset + 1);
      bops.copy(value, buffer, offset + 5);
      return 5 + length;
    }
  }

  if (bops.is(value)) {
    length = value.length;
    // buffer 16
    if (length < 0x10000) {
      buffer[offset] = 0xd8;
      bops.writeUInt16BE(buffer, length, offset + 1);
      bops.copy(value, buffer, offset + 3);
      return 3 + length;
    }
    // buffer 32
    if (length < 0x100000000) {
      buffer[offset] = 0xd9;
      bops.writeUInt32BE(buffer, length, offset + 1);
      bops.copy(value, buffer, offset + 5);
      return 5 + length;
    }
  }

  if (type === "number") {
    // Floating Point
    if ((value << 0) !== value) {
      buffer[offset] =  0xcb;
      bops.writeDoubleBE(buffer, value, offset + 1);
      return 9;
    }

    // Integers
    if (value >=0) {
      // positive fixnum
      if (value < 0x80) {
        buffer[offset] = value;
        return 1;
      }
      // uint 8
      if (value < 0x100) {
        buffer[offset] = 0xcc;
        buffer[offset + 1] = value;
        return 2;
      }
      // uint 16
      if (value < 0x10000) {
        buffer[offset] = 0xcd;
        bops.writeUInt16BE(buffer, value, offset + 1);
        return 3;
      }
      // uint 32
      if (value < 0x100000000) {
        buffer[offset] = 0xce;
        bops.writeUInt32BE(buffer, value, offset + 1);
        return 5;
      }
      // uint 64
      if (value < 0x10000000000000000) {
        buffer[offset] = 0xcf;
        bops.writeUInt64BE(buffer, value, offset + 1);
        return 9;
      }
      throw new Error("Number too big 0x" + value.toString(16));
    }
    // negative fixnum
    if (value >= -0x20) {
      bops.writeInt8(buffer, value, offset);
      return 1;
    }
    // int 8
    if (value >= -0x80) {
      buffer[offset] = 0xd0;
      bops.writeInt8(buffer, value, offset + 1);
      return 2;
    }
    // int 16
    if (value >= -0x8000) {
      buffer[offset] = 0xd1;
      bops.writeInt16BE(buffer, value, offset + 1);
      return 3;
    }
    // int 32
    if (value >= -0x80000000) {
      buffer[offset] = 0xd2;
      bops.writeInt32BE(buffer, value, offset + 1);
      return 5;
    }
    // int 64
    if (value >= -0x8000000000000000) {
      buffer[offset] = 0xd3;
      bops.writeInt64BE(buffer, value, offset + 1);
      return 9;
    }
    throw new Error("Number too small -0x" + value.toString(16).substr(1));
  }

  // undefined
  if (type === "undefined") {
    buffer[offset] = 0xc4;
    return 1;
  }

  // null
  if (value === null) {
    buffer[offset] = 0xc0;
    return 1;
  }

  // Boolean
  if (type === "boolean") {
    buffer[offset] = value ? 0xc3 : 0xc2;
    return 1;
  }

  // Custom toJSON function.
  if (typeof value.toJSON === 'function') {
    return encode(value.toJSON(), buffer, offset);
  }

  // Container Types
  if (type === "object") {

    size = 0;
    var isArray = Array.isArray(value);

    if (isArray) {
      length = value.length;
    }
    else {
      var keys = encodeableKeys(value);
      length = keys.length;
    }

    if (length < 0x10) {
      buffer[offset] = length | (isArray ? 0x90 : 0x80);
      size = 1;
    }
    else if (length < 0x10000) {
      buffer[offset] = isArray ? 0xdc : 0xde;
      bops.writeUInt16BE(buffer, length, offset + 1);
      size = 3;
    }
    else if (length < 0x100000000) {
      buffer[offset] = isArray ? 0xdd : 0xdf;
      bops.writeUInt32BE(buffer, length, offset + 1);
      size = 5;
    }

    if (isArray) {
      for (var i = 0; i < length; i++) {
        size += encode(value[i], buffer, offset + size);
      }
    }
    else {
      for (var i = 0; i < length; i++) {
        var key = keys[i];
        size += encode(key, buffer, offset + size);
        size += encode(value[key], buffer, offset + size);
      }
    }

    return size;
  }
  if (type === "function") return undefined;
  throw new Error("Unknown type " + type);
}

function sizeof(value) {
  var type = typeof value;
  var length, size;

  // Raw Bytes
  if (type === "string") {
    // TODO: this creates a throw-away buffer which is probably expensive on browsers.
    length = bops.from(value).length;
    if (length < 0x20) {
      return 1 + length;
    }
    if (length < 0x10000) {
      return 3 + length;
    }
    if (length < 0x100000000) {
      return 5 + length;
    }
  }

  if (bops.is(value)) {
    length = value.length;
    if (length < 0x10000) {
      return 3 + length;
    }
    if (length < 0x100000000) {
      return 5 + length;
    }
  }

  if (type === "number") {
    // Floating Point
    // double
    if (value << 0 !== value) return 9;

    // Integers
    if (value >=0) {
      // positive fixnum
      if (value < 0x80) return 1;
      // uint 8
      if (value < 0x100) return 2;
      // uint 16
      if (value < 0x10000) return 3;
      // uint 32
      if (value < 0x100000000) return 5;
      // uint 64
      if (value < 0x10000000000000000) return 9;
      throw new Error("Number too big 0x" + value.toString(16));
    }
    // negative fixnum
    if (value >= -0x20) return 1;
    // int 8
    if (value >= -0x80) return 2;
    // int 16
    if (value >= -0x8000) return 3;
    // int 32
    if (value >= -0x80000000) return 5;
    // int 64
    if (value >= -0x8000000000000000) return 9;
    throw new Error("Number too small -0x" + value.toString(16).substr(1));
  }

  // Boolean, null, undefined
  if (type === "boolean" || type === "undefined" || value === null) return 1;

  if (typeof value.toJSON === 'function') {
    return sizeof(value.toJSON());
  }

  // Container Types
  if (type === "object") {
    if ('function' === typeof value.toJSON) {
      value = value.toJSON();
    }

    size = 0;
    if (Array.isArray(value)) {
      length = value.length;
      for (var i = 0; i < length; i++) {
        size += sizeof(value[i]);
      }
    }
    else {
      var keys = encodeableKeys(value);
      length = keys.length;
      for (var i = 0; i < length; i++) {
        var key = keys[i];
        size += sizeof(key) + sizeof(value[key]);
      }
    }
    if (length < 0x10) {
      return 1 + size;
    }
    if (length < 0x10000) {
      return 3 + size;
    }
    if (length < 0x100000000) {
      return 5 + size;
    }
    throw new Error("Array or object too long 0x" + length.toString(16));
  }
  if (type === "function") {
    return 0;
  }
  throw new Error("Unknown type " + type);
}