@wwa/socket.io-stream/socket.io-stream.js

stream for socket.io

(function(f){if(typeof exports==="object"&&typeof module!=="undefined"){module.exports=f()}else if(typeof define==="function"&&define.amd){define([],f)}else{var g;if(typeof window!=="undefined"){g=window}else if(typeof global!=="undefined"){g=global}else if(typeof self!=="undefined"){g=self}else{g=this}g.ss = f()}})(function(){var define,module,exports;return (function(){function r(e,n,t){function o(i,f){if(!n[i]){if(!e[i]){var c="function"==typeof require&&require;if(!f&&c)return c(i,!0);if(u)return u(i,!0);var a=new Error("Cannot find module '"+i+"'");throw a.code="MODULE_NOT_FOUND",a}var p=n[i]={exports:{}};e[i][0].call(p.exports,function(r){var n=e[i][1][r];return o(n||r)},p,p.exports,r,e,n,t)}return n[i].exports}for(var u="function"==typeof require&&require,i=0;i<t.length;i++)o(t[i]);return o}return r})()({1:[function(require,module,exports){

module.exports = require('./lib');


},{"./lib":3}],2:[function(require,module,exports){
(function (Buffer){(function (){
const { Readable } = require('stream');

/**
 * Readable stream for Blob and File on browser.
 */
class BlobReadStream extends Readable {
  /**
   * @param {Blob} blob - Blob or File object
   * @param {Object} [options] - Stream options
   * @param {boolean} [options.synchronous] - Use synchronous FileReader
   * @api private
   */
  constructor(blob, options = {}) {
    // Extract stream-specific options from options object
    const { synchronous, ...streamOptions } = options;
    super(streamOptions);

    this.blob = blob;
    this.start = 0;
    this.sync = synchronous || false;

    // Initialize FileReader based on sync preference
    if (this.sync && typeof window !== 'undefined' && 'FileReaderSync' in window && window.FileReaderSync) {
      // @ts-expect-error - TypeScript does not recognize FileReaderSync as a valid property of the window object
      this.fileReader = new window.FileReaderSync();
    } else {
      this.fileReader = new FileReader();
      this.sync = false; // Force async if sync not available

      this.fileReader.addEventListener('load', this._onload);
      this.fileReader.addEventListener('error', this._onerror);
    }
  }

  /**
   * Read implementation for Readable stream
   *
   * @param {number} size - Size to read
   * @api private
   */
  _read(size) {
    const start = this.start;
    const end = this.start = this.start + size;
    const chunk = this.blob.slice(start, end);

    if (chunk.size) {
      if (this.sync) {
        const result = this.fileReader.readAsArrayBuffer(chunk);
        const bufferChunk = Buffer.from(new Uint8Array(result));
        this.push(bufferChunk);
      } else {
        this.fileReader.readAsArrayBuffer(chunk);
      }
    } else {
      this.push(null);
    }
  }

  /**
   * Handle FileReader load event
   *
   * @param {ProgressEvent<FileReader>} e - Load event
   * @api private
   */
  _onload = (e) => {
    if (e.target?.result instanceof ArrayBuffer) {
      const chunk = Buffer.from(new Uint8Array(e.target.result));
      this.push(chunk);
    }
  };

  /**
   * Handle FileReader error event
   *
   * @param {ProgressEvent<FileReader>} e - Error event
   * @api private
   */
  _onerror = (e) => {
    if (e.target?.error) {
      this.emit('error', e.target.error);
    }
  }
}

module.exports = BlobReadStream;

}).call(this)}).call(this,require("buffer").Buffer)
},{"buffer":10,"stream":18}],3:[function(require,module,exports){
(function (Buffer){(function (){
const Socket = require('./socket');
const IOStream = require('./iostream');
const BlobReadStream = require('./blob-read-stream');

/**
 * Look up an existing Socket.
 *
 * @param {Object} sio - socket.io instance
 * @param {Object} [options]
 * @return {Socket} Socket instance
 * @api public
 */
function lookup(sio, options) {
  options = options || {};
  if (null == options.forceBase64) {
    options.forceBase64 = exports.forceBase64;
  }

  if (!sio._streamSocket) {
    sio._streamSocket = new Socket(sio, options);
  }
  return sio._streamSocket;
}

exports = module.exports = lookup;

/**
 * Expose Node Buffer for browser.
 *
 * @api public
 */
exports.Buffer = Buffer;

/**
 * Expose Socket constructor.
 *
 * @api public
 */
exports.Socket = Socket;

/**
 * Expose IOStream constructor.
 *
 * @api public
 */
exports.IOStream = IOStream;

/**
 * Forces base 64 encoding when emitting. Must be set to true for Socket.IO v0.9 or lower.
 *
 * @api public
 * @type {boolean}
 */
exports.forceBase64 = false;

/**
 * Creates a new duplex stream.
 *
 * @param {Object} [options]
 * @return {IOStream} duplex stream
 * @api public
 */
exports.createStream = (options) => new IOStream(options);

/**
 * Creates a new readable stream for Blob/File on browser.
 *
 * @param {Blob} blob
 * @param {Object} options
 * @return {BlobReadStream} stream
 * @api public
 */
exports.createBlobReadStream = (blob, options) => new BlobReadStream(blob, options);

}).call(this)}).call(this,require("buffer").Buffer)
},{"./blob-read-stream":2,"./iostream":4,"./socket":6,"buffer":10}],4:[function(require,module,exports){
const { Duplex } = require('stream');
const uuid = require('./uuid');
const debug = require('debug')('socket.io-stream:iostream');

/**
 * Duplex stream for socket.io-stream
 */
class IOStream extends Duplex {
  /**
   * @param {Object} [options] - Stream options
   * @api private
   */
  constructor(options) {
    super(options);

    this.options = options;
    this.id = uuid();
    this.socket = null;

    // Buffers
    this.pushBuffer = [];
    this.writeBuffer = [];

    // Op states
    this._readable = false;
    this._writable = false;

    // default to *not* allowing half open sockets
    this.allowHalfOpen = options?.allowHalfOpen || false;

    this.on('finish', this._onfinish);
    this.on('end', this._onend);
    this.on('error', this._onerror);
  }

  /**
   * Ensures that no more I/O activity happens on this stream.
   * Not necessary in the usual case.
   *
   * @api public
   */
  destroy() {
    debug('destroy');

    if (this.destroyed) {
      debug('already destroyed');
      return this;
    }

    super.destroy();

    if (this.socket) {
      debug('clean up');
      this.socket.cleanup(this.id);
      this.socket = null;
    }

    return this;
  }

  /**
   * Local read
   *
   * @api private
   */
  _read(size) {
    // We cannot read from the socket if it's destroyed obviously ...
    if (this.destroyed) return;

    if (this.pushBuffer.length) {
      // flush buffer and end if it exists.
      let push;
      while ((push = this.pushBuffer.shift())) {
        if (!push()) break;
      }
      return;
    }

    this._readable = true;

    // Go get data from remote stream
    // Calls ._onread remotely then ._onwrite locally
    this.socket._read(this.id, size);
  }

  /**
   * Read from remote stream
   *
   * @api private
   */
  _onread(size) {
    const write = this.writeBuffer.shift();
    if (write) return write();

    this._writable = true;
  }

  /**
   * Write local data to remote stream
   * Calls remote ._onwrite
   *
   * @api private
   */
  _write(chunk, encoding, callback) {
    const write = () => {
      // We cannot write to the socket if it's destroyed obviously ...
      if (this.destroyed) return;

      this._writable = false;
      this.socket._write(this.id, chunk, encoding, callback);
    };

    if (this._writable) {
      write();
    } else {
      this.writeBuffer.push(write);
    }
  }

  /**
   * Write the data fetched remotely
   * so that we can now read locally
   *
   * @api private
   */
  _onwrite(chunk, encoding, callback) {
    const push = () => {
      this._readable = false;
      const ret = this.push(chunk || '', encoding);
      callback();
      return ret;
    };

    if (this._readable) {
      push();
    } else {
      this.pushBuffer.push(push);
    }
  }

  /**
   * When ending send 'end' event to remote stream
   *
   * @api private
   */
  _end() {
    if (this.pushBuffer.length) {
      // end after flushing buffer.
      this.pushBuffer.push(() => this._done());
    } else {
      this._done();
    }
  }

  /**
   * Remote stream just ended
   *
   * @api private
   */
  _done() {
    this._readable = false;
    // signal the end of the data.
    return this.push(null);
  }

  /**
   * the user has called .end(), and all the bytes have been
   * sent out to the other side.
   * If allowHalfOpen is false, or if the readable side has
   * ended already, then destroy.
   * If allowHalfOpen is true, then we need to set writable false,
   * so that only the writable side will be cleaned up.
   *
   * @api private
   */
  _onfinish() {
    debug('_onfinish');
    // Local socket just finished
    // send 'end' event to remote
    this.socket?._end(this.id);

    if (!this.writableEnded) {
      this.end();
    }

    if (!this.readable || this._readableState.ended) {
      debug('_onfinish: ended, destroy %s', this._readableState);
      return this.destroy();
    }

    debug('_onfinish: not ended');

    if (!this.allowHalfOpen) {
      this.push(null);

      // just in case we're waiting for an EOF.
      if (this.readable && !this.readableEnded) {
        this.read(0);
      }
    }
  }

  /**
   * the EOF has been received, and no more bytes are coming.
   * if the writable side has ended already, then clean everything
   * up.
   *
   * @api private
   */
  _onend() {
    debug('_onend');
    if (!this.readableEnded) {
      this.push(null);
    }

    if (!this.writable || this.writableFinished) {
      debug('_onend: %s', this.writableFinished);
      return this.destroy();
    }

    debug('_onend: not finished');

    if (!this.allowHalfOpen) {
      this.end();
    }
  }

  /**
   * When error in local stream
   * notify remote
   * if err.remote = true
   * then error happened on remote stream
   *
   * @api private
   */
  _onerror(err) {
    // check if the error came from remote stream.
    if (!err.remote && this.socket) {
      // notify the error to the corresponding remote stream.
      this.socket._error(this.id, err);
    }

    this.destroy();
  }
}

module.exports = IOStream;

},{"./uuid":7,"debug":11,"stream":18}],5:[function(require,module,exports){
const { EventEmitter } = require('events');
const IOStream = require('./iostream');

class Encoder extends EventEmitter {
  encode(v) {
    if (v instanceof IOStream) {
      return this.encodeStream(v);
    }

    if (Array.isArray(v)) {
      return this.encodeArray(v);
    }

    if (v && 'object' == typeof v) {
      return this.encodeObject(v);
    }

    return v;
  }

  /**
   * @param {IOStream} stream
   */
  encodeStream(stream) {
    this.emit('stream', stream);

    // represent a stream in an object.
    const v = { $stream: stream.id };
    if (stream.options) {
      v.options = stream.options;
    }

    return v;
  }

  /**
   * @param {Array} arr
   * @return {Array}
   */
  encodeArray(arr) {
    return arr.map(item => this.encode(item));
  }

  /**
   * @param {Object} obj
   * @return {Object}
   */
  encodeObject(obj) {
    const v = {};
    for (const k in obj) {
      if (Object.hasOwn(obj, k)) {
        v[k] = this.encode(obj[k]);
      }
    }

    return v;
  }
}

class Decoder extends EventEmitter {
  /**
   * @param {unknown} v
   */
  decode(v) {
    if (v && 'object' === typeof v && '$stream' in v && v.$stream) {
      return this.decodeStream(v);
    }

    if (Array.isArray(v)) {
      return this.decodeArray(v);
    }

    if (v && 'object' == typeof v) {
      return this.decodeObject(v);
    }

    return v;
  }

  /**
   * @param {Object} obj
   * @return {IOStream}
   */
  decodeStream(obj) {
    const stream = new IOStream(obj.options);
    stream.id = obj.$stream;
    this.emit('stream', stream);
    return stream;
  }

  /**
   * @param {Array} arr
   * @return {Array}
   */
  decodeArray(arr) {
    return arr.map(item => this.decode(item));
  }

  /**
   * @param {Object} obj
   * @return {Object}
   */
  decodeObject(obj) {
    const v = {};
    for (const k in obj) {
      if (Object.hasOwn(obj, k)) {
        v[k] = this.decode(obj[k]);
      }
    }

    return v;
  }
}

exports.Encoder = Encoder;
exports.Decoder = Decoder;

},{"./iostream":4,"events":13}],6:[function(require,module,exports){
(function (global,Buffer){(function (){
const { EventEmitter } = require('events');
const parser = require('./parser');
const debug = require('debug')('socket.io-stream:socket');

/**
 * Base event name for messaging.
 *
 * @api public
 */
const EVENT_NAME = '$stream';

const RESERVED_EVENTS = [
  'error',
  'newListener',
  'removeListener'
];

/**
 * Bidirectional stream socket which wraps Socket.IO.
 */
class Socket extends EventEmitter {
  /**
   * @param {import('socket.io').Socket} sio - Socket.IO socket instance
   * @param {Object} [options] - Configuration options
   * @param {boolean} [options.forceBase64] - Force base64 encoding
   */
  constructor(sio, options = {}) {
    super();

    this.sio = sio;
    this.forceBase64 = Boolean(options.forceBase64);
    this.streams = {};
    this.encoder = new parser.Encoder();
    this.decoder = new parser.Decoder();

    // Bind Socket.IO events
    sio.on(EVENT_NAME, (...args) => super.emit(...args));
    sio.on(`${EVENT_NAME}-read`, this._onread);
    sio.on(`${EVENT_NAME}-write`, this._onwrite);
    sio.on(`${EVENT_NAME}-end`, this._onend);
    sio.on(`${EVENT_NAME}-error`, this._onerror);
    sio.on('error', (err) => super.emit('error', err));
    sio.on('disconnect', this._ondisconnect);

    // Bind parser events
    this.encoder.on('stream', this._onencode);
    this.decoder.on('stream', this._ondecode);
  }

  $emit(type, ...args) {
    return super.emit(type, ...args);
  }

  /**
   * Emits streams to this corresponding server/client.
   * Overrides EventEmitter.emit to handle stream events specially.
   *
   * @param {string} type - Event type
   * @param {...any} args - Arguments to emit
   * @return {this} self for chaining
   * @api public
   */
  emit(type, ...args) {
    if (RESERVED_EVENTS.includes(type)) {
      super.emit(type, ...args);
      return this;
    }
    this._stream(type, ...args);
    return this;
  }

  /**
   * Add event listener with stream support.
   *
   * @param {string} type - Event type
   * @param {(...args: any[]) => void} listener - Event listener
   * @return {this} self
   */
  on(type, listener) {
    if (RESERVED_EVENTS.includes(type)) {
      return super.on(type, listener);
    }

    this._onstream(type, listener);
    return this;
  }

  /**
   * Sends a new stream request.
   *
   * @param {string} type - Event type
   * @param {...any} args - Arguments including streams
   * @api private
   */
  _stream(type, ...args) {
    debug('sending new streams');

    const ack = args[args.length - 1];
    if (typeof ack === 'function') {
      args[args.length - 1] = (...ackArgs) => {
        const decodedArgs = this.decoder.decode(ackArgs);
        ack.apply(this, decodedArgs);
      };
    }

    const encodedArgs = this.encoder.encode(args);
    this.sio.emit(EVENT_NAME, type, ...encodedArgs);
  }

  /**
   * Notifies the read event.
   *
   * @param {string} id - Stream ID
   * @param {number} size - Read size
   * @api private
   */
  _read(id, size) {
    this.sio.emit(`${EVENT_NAME}-read`, id, size);
  }

  /**
   * Requests to write a chunk.
   *
   * @param {string} id - Stream ID
   * @param {Buffer|string|ArrayBuffer} chunk - Data chunk
   * @param {string} encoding - Encoding type
   * @param {Function} callback - Callback function
   * @api private
   */
  _write(id, chunk, encoding, callback) {
    if (Buffer.isBuffer(chunk)) {
      if (this.forceBase64) {
        encoding = 'base64';
        chunk = chunk.toString('base64');
      } else if (!global.Buffer) {
        // socket.io can't handle Buffer when using browserify.
        if ('toArrayBuffer' in chunk && typeof chunk.toArrayBuffer === 'function') {
          chunk = chunk.toArrayBuffer();
        } else {
          chunk = chunk.buffer;
        }
      }
    }
    this.sio.emit(`${EVENT_NAME}-write`, id, chunk, encoding, callback);
  }

  /**
   * Sends end event to remote stream.
   *
   * @param {string} id - Stream ID
   * @api private
   */
  _end(id) {
    this.sio.emit(`${EVENT_NAME}-end`, id);
  }

  /**
   * Sends error event to remote stream.
   *
   * @param {string} id - Stream ID
   * @param {Error|string} err - Error object or message
   * @api private
   */
  _error(id, err) {
    const message = typeof err === 'string' ? err : err.message || String(err);
    this.sio.emit(`${EVENT_NAME}-error`, id, message);
  }

  /**
   * Handles a new stream request.
   *
   * @param {string} type - Event type
   * @param {(...args: any[]) => void} listener - Event listener
   * @api private
   */
  _onstream(type, listener) {
    if (typeof listener !== 'function') {
      throw new TypeError('listener must be a function');
    }

    const onstream = (...args) => {
      debug('new streams');

      const ack = args[args.length - 1];
      if (typeof ack === 'function') {
        args[args.length - 1] = (...ackArgs) => {
          const encodedArgs = this.encoder.encode(ackArgs);
          ack.apply(this, encodedArgs);
        };
      }

      const decodedArgs = this.decoder.decode(args);
      listener.apply(this, decodedArgs);
    };

    // Store original listener for removeListener
    onstream.listener = listener;

    super.on(type, onstream);
  }

  /**
   * Handles read request from remote stream.
   *
   * @param {string} id - Stream ID
   * @param {number} size - Read size
   * @api private
   */
  _onread = (id, size) => {
    debug('read: "%s"', id);

    const stream = this.streams[id];
    if (stream) {
      stream._onread(size);
    } else {
      debug('ignore invalid stream id');
    }
  };

  /**
   * Handles write request from remote stream.
   *
   * @param {string} id - Stream ID
   * @param {any} chunk - Data chunk
   * @param {string} encoding - Encoding type
   * @param {Function} callback - Callback function
   * @api private
   */
  _onwrite = (id, chunk, encoding, callback) => {
    debug('write: "%s"', id);

    const stream = this.streams[id];
    if (!stream) {
      callback(`invalid stream id: ${id}`);
      return;
    }

    if (global.ArrayBuffer && chunk instanceof ArrayBuffer) {
      // Make sure that chunk is a buffer for stream
      chunk = Buffer.from(new Uint8Array(chunk));
    }
    stream._onwrite(chunk, encoding, callback);
  };

  /**
   * Handles end event from remote stream.
   *
   * @param {string} id - Stream ID
   * @api private
   */
  _onend = (id) => {
    debug('end: "%s"', id);

    const stream = this.streams[id];
    if (!stream) {
      debug('ignore non-existent stream id: "%s"', id);
      return;
    }

    stream._end();
  };

  /**
   * Handles error event from remote stream.
   *
   * @param {string} id - Stream ID
   * @param {string} message - Error message
   * @api private
   */
  _onerror = (id, message) => {
    debug('error: "%s", "%s"', id, message);

    const stream = this.streams[id];
    if (!stream) {
      debug('invalid stream id: "%s"', id);
      return;
    }

    const err = new Error(message);
    // @ts-ignore - Adding custom property for error source tracking
    err.remote = true;
    stream.emit('error', err);
  };

  /**
   * Handles disconnect event from socket.io.
   * Destroys all active streams.
   *
   * @api private
   */
  _ondisconnect = () => {
    for (const id in this.streams) {
      const stream = this.streams[id];
      stream.destroy();

      // Close streams when the underlying
      // socket.io connection is closed (regardless why)
      stream.emit('close');
      stream.emit('error', new Error('Connection aborted'));
    }
  };

  /**
   * Handles encoded stream from encoder.
   *
   * @param {import('./iostream')} stream - Stream instance
   * @api private
   */
  _onencode = (stream) => {
    if (stream.socket || stream.destroyed) {
      throw new Error('stream has already been sent.');
    }

    const { id } = stream;
    if (this.streams[id]) {
      throw new Error(`Encoded stream already exists: ${id}`);
    }

    this.streams[id] = stream;
    stream.socket = this;
  }

  /**
   * Handles decoded stream from decoder.
   *
   * @param {import('./iostream')} stream - Stream instance
   * @api private
   */
  _ondecode = (stream) => {
    const { id } = stream;
    if (this.streams[id]) {
      this._error(id, new Error(`Decoded stream already exists: ${id}`));
      return;
    }

    this.streams[id] = stream;
    stream.socket = this;
  }

  /**
   * Cleans up stream reference.
   *
   * @param {string} id - Stream ID
   * @api public
   */
  cleanup(id) {
    delete this.streams[id];
  }
}

// Export the Socket class and constants
module.exports = Socket;
module.exports.event = EVENT_NAME;
module.exports.events = RESERVED_EVENTS;

}).call(this)}).call(this,typeof global !== "undefined" ? global : typeof self !== "undefined" ? self : typeof window !== "undefined" ? window : {},require("buffer").Buffer)
},{"./parser":5,"buffer":10,"debug":11,"events":13}],7:[function(require,module,exports){
// UUID function from https://gist.github.com/jed/982883
// More lightweight than node-uuid

/**
 * Generate a UUID v4 string
 * @param {*} [a] - placeholder for recursion
 * @returns {string} UUID string
 */
function generateUUID(a) {
  return a           // if the placeholder was passed, return
    ? (              // a random number from 0 to 15
      a ^            // unless b is 8,
      Math.random()  // in which case
      * 16           // a random number from
      >> a/4         // 8 to 11
      ).toString(16) // in hexadecimal
    : '10000000-1000-4000-80000000-100000000000'.replace(/[018]/g, generateUUID);
}

module.exports = generateUUID;

},{}],8:[function(require,module,exports){
'use strict'

exports.byteLength = byteLength
exports.toByteArray = toByteArray
exports.fromByteArray = fromByteArray

var lookup = []
var revLookup = []
var Arr = typeof Uint8Array !== 'undefined' ? Uint8Array : Array

var code = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
for (var i = 0, len = code.length; i < len; ++i) {
  lookup[i] = code[i]
  revLookup[code.charCodeAt(i)] = i
}

// Support decoding URL-safe base64 strings, as Node.js does.
// See: https://en.wikipedia.org/wiki/Base64#URL_applications
revLookup['-'.charCodeAt(0)] = 62
revLookup['_'.charCodeAt(0)] = 63

function getLens (b64) {
  var len = b64.length

  if (len % 4 > 0) {
    throw new Error('Invalid string. Length must be a multiple of 4')
  }

  // Trim off extra bytes after placeholder bytes are found
  // See: https://github.com/beatgammit/base64-js/issues/42
  var validLen = b64.indexOf('=')
  if (validLen === -1) validLen = len

  var placeHoldersLen = validLen === len
    ? 0
    : 4 - (validLen % 4)

  return [validLen, placeHoldersLen]
}

// base64 is 4/3 + up to two characters of the original data
function byteLength (b64) {
  var lens = getLens(b64)
  var validLen = lens[0]
  var placeHoldersLen = lens[1]
  return ((validLen + placeHoldersLen) * 3 / 4) - placeHoldersLen
}

function _byteLength (b64, validLen, placeHoldersLen) {
  return ((validLen + placeHoldersLen) * 3 / 4) - placeHoldersLen
}

function toByteArray (b64) {
  var tmp
  var lens = getLens(b64)
  var validLen = lens[0]
  var placeHoldersLen = lens[1]

  var arr = new Arr(_byteLength(b64, validLen, placeHoldersLen))

  var curByte = 0

  // if there are placeholders, only get up to the last complete 4 chars
  var len = placeHoldersLen > 0
    ? validLen - 4
    : validLen

  var i
  for (i = 0; i < len; i += 4) {
    tmp =
      (revLookup[b64.charCodeAt(i)] << 18) |
      (revLookup[b64.charCodeAt(i + 1)] << 12) |
      (revLookup[b64.charCodeAt(i + 2)] << 6) |
      revLookup[b64.charCodeAt(i + 3)]
    arr[curByte++] = (tmp >> 16) & 0xFF
    arr[curByte++] = (tmp >> 8) & 0xFF
    arr[curByte++] = tmp & 0xFF
  }

  if (placeHoldersLen === 2) {
    tmp =
      (revLookup[b64.charCodeAt(i)] << 2) |
      (revLookup[b64.charCodeAt(i + 1)] >> 4)
    arr[curByte++] = tmp & 0xFF
  }

  if (placeHoldersLen === 1) {
    tmp =
      (revLookup[b64.charCodeAt(i)] << 10) |
      (revLookup[b64.charCodeAt(i + 1)] << 4) |
      (revLookup[b64.charCodeAt(i + 2)] >> 2)
    arr[curByte++] = (tmp >> 8) & 0xFF
    arr[curByte++] = tmp & 0xFF
  }

  return arr
}

function tripletToBase64 (num) {
  return lookup[num >> 18 & 0x3F] +
    lookup[num >> 12 & 0x3F] +
    lookup[num >> 6 & 0x3F] +
    lookup[num & 0x3F]
}

function encodeChunk (uint8, start, end) {
  var tmp
  var output = []
  for (var i = start; i < end; i += 3) {
    tmp =
      ((uint8[i] << 16) & 0xFF0000) +
      ((uint8[i + 1] << 8) & 0xFF00) +
      (uint8[i + 2] & 0xFF)
    output.push(tripletToBase64(tmp))
  }
  return output.join('')
}

function fromByteArray (uint8) {
  var tmp
  var len = uint8.length
  var extraBytes = len % 3 // if we have 1 byte left, pad 2 bytes
  var parts = []
  var maxChunkLength = 16383 // must be multiple of 3

  // go through the array every three bytes, we'll deal with trailing stuff later
  for (var i = 0, len2 = len - extraBytes; i < len2; i += maxChunkLength) {
    parts.push(encodeChunk(uint8, i, (i + maxChunkLength) > len2 ? len2 : (i + maxChunkLength)))
  }

  // pad the end with zeros, but make sure to not forget the extra bytes
  if (extraBytes === 1) {
    tmp = uint8[len - 1]
    parts.push(
      lookup[tmp >> 2] +
      lookup[(tmp << 4) & 0x3F] +
      '=='
    )
  } else if (extraBytes === 2) {
    tmp = (uint8[len - 2] << 8) + uint8[len - 1]
    parts.push(
      lookup[tmp >> 10] +
      lookup[(tmp >> 4) & 0x3F] +
      lookup[(tmp << 2) & 0x3F] +
      '='
    )
  }

  return parts.join('')
}

},{}],9:[function(require,module,exports){

},{}],10:[function(require,module,exports){
(function (Buffer){(function (){
/*!
 * The buffer module from node.js, for the browser.
 *
 * @author   Feross Aboukhadijeh <https://feross.org>
 * @license  MIT
 */
/* eslint-disable no-proto */

'use strict'

var base64 = require('base64-js')
var ieee754 = require('ieee754')

exports.Buffer = Buffer
exports.SlowBuffer = SlowBuffer
exports.INSPECT_MAX_BYTES = 50

var K_MAX_LENGTH = 0x7fffffff
exports.kMaxLength = K_MAX_LENGTH

/**
 * If `Buffer.TYPED_ARRAY_SUPPORT`:
 *   === true    Use Uint8Array implementation (fastest)
 *   === false   Print warning and recommend using `buffer` v4.x which has an Object
 *               implementation (most compatible, even IE6)
 *
 * Browsers that support typed arrays are IE 10+, Firefox 4+, Chrome 7+, Safari 5.1+,
 * Opera 11.6+, iOS 4.2+.
 *
 * We report that the browser does not support typed arrays if the are not subclassable
 * using __proto__. Firefox 4-29 lacks support for adding new properties to `Uint8Array`
 * (See: https://bugzilla.mozilla.org/show_bug.cgi?id=695438). IE 10 lacks support
 * for __proto__ and has a buggy typed array implementation.
 */
Buffer.TYPED_ARRAY_SUPPORT = typedArraySupport()

if (!Buffer.TYPED_ARRAY_SUPPORT && typeof console !== 'undefined' &&
    typeof console.error === 'function') {
  console.error(
    'This browser lacks typed array (Uint8Array) support which is required by ' +
    '`buffer` v5.x. Use `buffer` v4.x if you require old browser support.'
  )
}

function typedArraySupport () {
  // Can typed array instances can be augmented?
  try {
    var arr = new Uint8Array(1)
    arr.__proto__ = { __proto__: Uint8Array.prototype, foo: function () { return 42 } }
    return arr.foo() === 42
  } catch (e) {
    return false
  }
}

Object.defineProperty(Buffer.prototype, 'parent', {
  enumerable: true,
  get: function () {
    if (!Buffer.isBuffer(this)) return undefined
    return this.buffer
  }
})

Object.defineProperty(Buffer.prototype, 'offset', {
  enumerable: true,
  get: function () {
    if (!Buffer.isBuffer(this)) return undefined
    return this.byteOffset
  }
})

function createBuffer (length) {
  if (length > K_MAX_LENGTH) {
    throw new RangeError('The value "' + length + '" is invalid for option "size"')
  }
  // Return an augmented `Uint8Array` instance
  var buf = new Uint8Array(length)
  buf.__proto__ = Buffer.prototype
  return buf
}

/**
 * The Buffer constructor returns instances of `Uint8Array` that have their
 * prototype changed to `Buffer.prototype`. Furthermore, `Buffer` is a subclass of
 * `Uint8Array`, so the returned instances will have all the node `Buffer` methods
 * and the `Uint8Array` methods. Square bracket notation works as expected -- it
 * returns a single octet.
 *
 * The `Uint8Array` prototype remains unmodified.
 */

function Buffer (arg, encodingOrOffset, length) {
  // Common case.
  if (typeof arg === 'number') {
    if (typeof encodingOrOffset === 'string') {
      throw new TypeError(
        'The "string" argument must be of type string. Received type number'
      )
    }
    return allocUnsafe(arg)
  }
  return from(arg, encodingOrOffset, length)
}

// Fix subarray() in ES2016. See: https://github.com/feross/buffer/pull/97
if (typeof Symbol !== 'undefined' && Symbol.species != null &&
    Buffer[Symbol.species] === Buffer) {
  Object.defineProperty(Buffer, Symbol.species, {
    value: null,
    configurable: true,
    enumerable: false,
    writable: false
  })
}

Buffer.poolSize = 8192 // not used by this implementation

function from (value, encodingOrOffset, length) {
  if (typeof value === 'string') {
    return fromString(value, encodingOrOffset)
  }

  if (ArrayBuffer.isView(value)) {
    return fromArrayLike(value)
  }

  if (value == null) {
    throw TypeError(
      'The first argument must be one of type string, Buffer, ArrayBuffer, Array, ' +
      'or Array-like Object. Received type ' + (typeof value)
    )
  }

  if (isInstance(value, ArrayBuffer) ||
      (value && isInstance(value.buffer, ArrayBuffer))) {
    return fromArrayBuffer(value, encodingOrOffset, length)
  }

  if (typeof value === 'number') {
    throw new TypeError(
      'The "value" argument must not be of type number. Received type number'
    )
  }

  var valueOf = value.valueOf && value.valueOf()
  if (valueOf != null && valueOf !== value) {
    return Buffer.from(valueOf, encodingOrOffset, length)
  }

  var b = fromObject(value)
  if (b) return b

  if (typeof Symbol !== 'undefined' && Symbol.toPrimitive != null &&
      typeof value[Symbol.toPrimitive] === 'function') {
    return Buffer.from(
      value[Symbol.toPrimitive]('string'), encodingOrOffset, length
    )
  }

  throw new TypeError(
    'The first argument must be one of type string, Buffer, ArrayBuffer, Array, ' +
    'or Array-like Object. Received type ' + (typeof value)
  )
}

/**
 * Functionally equivalent to Buffer(arg, encoding) but throws a TypeError
 * if value is a number.
 * Buffer.from(str[, encoding])
 * Buffer.from(array)
 * Buffer.from(buffer)
 * Buffer.from(arrayBuffer[, byteOffset[, length]])
 **/
Buffer.from = function (value, encodingOrOffset, length) {
  return from(value, encodingOrOffset, length)
}

// Note: Change prototype *after* Buffer.from is defined to workaround Chrome bug:
// https://github.com/feross/buffer/pull/148
Buffer.prototype.__proto__ = Uint8Array.prototype
Buffer.__proto__ = Uint8Array

function assertSize (size) {
  if (typeof size !== 'number') {
    throw new TypeError('"size" argument must be of type number')
  } else if (size < 0) {
    throw new RangeError('The value "' + size + '" is invalid for option "size"')
  }
}

function alloc (size, fill, encoding) {
  assertSize(size)
  if (size <= 0) {
    return createBuffer(size)
  }
  if (fill !== undefined) {
    // Only pay attention to encoding if it's a string. This
    // prevents accidentally sending in a number that would
    // be interpretted as a start offset.
    return typeof encoding === 'string'
      ? createBuffer(size).fill(fill, encoding)
      : createBuffer(size).fill(fill)
  }
  return createBuffer(size)
}

/**
 * Creates a new filled Buffer instance.
 * alloc(size[, fill[, encoding]])
 **/
Buffer.alloc = function (size, fill, encoding) {
  return alloc(size, fill, encoding)
}

function allocUnsafe (size) {
  assertSize(size)
  return createBuffer(size < 0 ? 0 : checked(size) | 0)
}

/**
 * Equivalent to Buffer(num), by default creates a non-zero-filled Buffer instance.
 * */
Buffer.allocUnsafe = function (size) {
  return allocUnsafe(size)
}
/**
 * Equivalent to SlowBuffer(num), by default creates a non-zero-filled Buffer instance.
 */
Buffer.allocUnsafeSlow = function (size) {
  return allocUnsafe(size)
}

function fromString (string, encoding) {
  if (typeof encoding !== 'string' || encoding === '') {
    encoding = 'utf8'
  }

  if (!Buffer.isEncoding(encoding)) {
    throw new TypeError('Unknown encoding: ' + encoding)
  }

  var length = byteLength(string, encoding) | 0
  var buf = createBuffer(length)

  var actual = buf.write(string, encoding)

  if (actual !== length) {
    // Writing a hex string, for example, that contains invalid characters will
    // cause everything after the first invalid character to be ignored. (e.g.
    // 'abxxcd' will be treated as 'ab')
    buf = buf.slice(0, actual)
  }

  return buf
}

function fromArrayLike (array) {
  var length = array.length < 0 ? 0 : checked(array.length) | 0
  var buf = createBuffer(length)
  for (var i = 0; i < length; i += 1) {
    buf[i] = array[i] & 255
  }
  return buf
}

function fromArrayBuffer (array, byteOffset, length) {
  if (byteOffset < 0 || array.byteLength < byteOffset) {
    throw new RangeError('"offset" is outside of buffer bounds')
  }

  if (array.byteLength < byteOffset + (length || 0)) {
    throw new RangeError('"length" is outside of buffer bounds')
  }

  var buf
  if (byteOffset === undefined && length === undefined) {
    buf = new Uint8Array(array)
  } else if (length === undefined) {
    buf = new Uint8Array(array, byteOffset)
  } else {
    buf = new Uint8Array(array, byteOffset, length)
  }

  // Return an augmented `Uint8Array` instance
  buf.__proto__ = Buffer.prototype
  return buf
}

function fromObject (obj) {
  if (Buffer.isBuffer(obj)) {
    var len = checked(obj.length) | 0
    var buf = createBuffer(len)

    if (buf.length === 0) {
      return buf
    }

    obj.copy(buf, 0, 0, len)
    return buf
  }

  if (obj.length !== undefined) {
    if (typeof obj.length !== 'number' || numberIsNaN(obj.length)) {
      return createBuffer(0)
    }
    return fromArrayLike(obj)
  }

  if (obj.type === 'Buffer' && Array.isArray(obj.data)) {
    return fromArrayLike(obj.data)
  }
}

function checked (length) {
  // Note: cannot use `length < K_MAX_LENGTH` here because that fails when
  // length is NaN (which is otherwise coerced to zero.)
  if (length >= K_MAX_LENGTH) {
    throw new RangeError('Attempt to allocate Buffer larger than maximum ' +
                         'size: 0x' + K_MAX_LENGTH.toString(16) + ' bytes')
  }
  return length | 0
}

function SlowBuffer (length) {
  if (+length != length) { // eslint-disable-line eqeqeq
    length = 0
  }
  return Buffer.alloc(+length)
}

Buffer.isBuffer = function isBuffer (b) {
  return b != null && b._isBuffer === true &&
    b !== Buffer.prototype // so Buffer.isBuffer(Buffer.prototype) will be false
}

Buffer.compare = function compare (a, b) {
  if (isInstance(a, Uint8Array)) a = Buffer.from(a, a.offset, a.byteLength)
  if (isInstance(b, Uint8Array)) b = Buffer.from(b, b.offset, b.byteLength)
  if (!Buffer.isBuffer(a) || !Buffer.isBuffer(b)) {
    throw new TypeError(
      'The "buf1", "buf2" arguments must be one of type Buffer or Uint8Array'
    )
  }

  if (a === b) return 0

  var x = a.length
  var y = b.length

  for (var i = 0, len = Math.min(x, y); i < len; ++i) {
    if (a[i] !== b[i]) {
      x = a[i]
      y = b[i]
      break
    }
  }

  if (x < y) return -1
  if (y < x) return 1
  return 0
}

Buffer.isEncoding = function isEncoding (encoding) {
  switch (String(encoding).toLowerCase()) {
    case 'hex':
    case 'utf8':
    case 'utf-8':
    case 'ascii':
    case 'latin1':
    case 'binary':
    case 'base64':
    case 'ucs2':
    case 'ucs-2':
    case 'utf16le':
    case 'utf-16le':
      return true
    default:
      return false
  }
}

Buffer.concat = function concat (list, length) {
  if (!Array.isArray(list)) {
    throw new TypeError('"list" argument must be an Array of Buffers')
  }

  if (list.length === 0) {
    return Buffer.alloc(0)
  }

  var i
  if (length === undefined) {
    length = 0
    for (i = 0; i < list.length; ++i) {
      length += list[i].length
    }
  }

  var buffer = Buffer.allocUnsafe(length)
  var pos = 0
  for (i = 0; i < list.length; ++i) {
    var buf = list[i]
    if (isInstance(buf, Uint8Array)) {
      buf = Buffer.from(buf)
    }
    if (!Buffer.isBuffer(buf)) {
      throw new TypeError('"list" argument must be an Array of Buffers')
    }
    buf.copy(buffer, pos)
    pos += buf.length
  }
  return buffer
}

function byteLength (string, encoding) {
  if (Buffer.isBuffer(string)) {
    return string.length
  }
  if (ArrayBuffer.isView(string) || isInstance(string, ArrayBuffer)) {
    return string.byteLength
  }
  if (typeof string !== 'string') {
    throw new TypeError(
      'The "string" argument must be one of type string, Buffer, or ArrayBuffer. ' +
      'Received type ' + typeof string
    )
  }

  var len = string.length
  var mustMatch = (arguments.length > 2 && arguments[2] === true)
  if (!mustMatch && len === 0) return 0

  // Use a for loop to avoid recursion
  var loweredCase = false
  for (;;) {
    switch (encoding) {
      case 'ascii':
      case 'latin1':
      case 'binary':
        return len
      case 'utf8':
      case 'utf-8':
        return utf8ToBytes(string).length
      case 'ucs2':
      case 'ucs-2':
      case 'utf16le':
      case 'utf-16le':
        return len * 2
      case 'hex':
        return len >>> 1
      case 'base64':
        return base64ToBytes(string).length
      default:
        if (loweredCase) {
          return mustMatch ? -1 : utf8ToBytes(string).length // assume utf8
        }
        encoding = ('' + encoding).toLowerCase()
        loweredCase = true
    }
  }
}
Buffer.byteLength = byteLength

function slowToString (encoding, start, end) {
  var loweredCase = false

  // No need to verify that "this.length <= MAX_UINT32" since it's a read-only
  // property of a typed array.

  // This behaves neither like String nor Uint8Array in that we set start/end
  // to their upper/lower bounds if the value passed is out of range.
  // undefined is handled specially as per ECMA-262 6th Edition,
  // Section 13.3.3.7 Runtime Semantics: KeyedBindingInitialization.
  if (start === undefined || start < 0) {
    start = 0
  }
  // Return early if start > this.length. Done here to prevent potential uint32
  // coercion fail below.
  if (start > this.length) {
    return ''
  }

  if (end === undefined || end > this.length) {
    end = this.length
  }

  if (end <= 0) {
    return ''
  }

  // Force coersion to uint32. This will also coerce falsey/NaN values to 0.
  end >>>= 0
  start >>>= 0

  if (end <= start) {
    return ''
  }

  if (!encoding) encoding = 'utf8'

  while (true) {
    switch (encoding) {
      case 'hex':
        return hexSlice(this, start, end)

      case 'utf8':
      case 'utf-8':
        return utf8Slice(this, start, end)

      case 'ascii':
        return asciiSlice(this, start, end)

      case 'latin1':
      case 'binary':
        return latin1Slice(this, start, end)

      case 'base64':
        return base64Slice(this, start, end)

      case 'ucs2':
      case 'ucs-2':
      case 'utf16le':
      case 'utf-16le':
        return utf16leSlice(this, start, end)

      default:
        if (loweredCase) throw new TypeError('Unknown encoding: ' + encoding)
        encoding = (encoding + '').toLowerCase()
        loweredCase = true
    }
  }
}

// This property is used by `Buffer.isBuffer` (and the `is-buffer` npm package)
// to detect a Buffer instance. It's not possible to use `instanceof Buffer`
// reliably in a browserify context because there could be multiple different
// copies of the 'buffer' package in use. This method works even for Buffer
// instances that were created from another copy of the `buffer` package.
// See: https://github.com/feross/buffer/issues/154
Buffer.prototype._isBuffer = true

function swap (b, n, m) {
  var i = b[n]
  b[n] = b[m]
  b[m] = i
}

Buffer.prototype.swap16 = function swap16 () {
  var len = this.length
  if (len % 2 !== 0) {
    throw new RangeError('Buffer size must be a multiple of 16-bits')
  }
  for (var i = 0; i < len; i += 2) {
    swap(this, i, i + 1)
  }
  return this
}

Buffer.prototype.swap32 = function swap32 () {
  var len = this.length
  if (len % 4 !== 0) {
    throw new RangeError('Buffer size must be a multiple of 32-bits')
  }
  for (var i = 0; i < len; i += 4) {
    swap(this, i, i + 3)
    swap(this, i + 1, i + 2)
  }
  return this
}

Buffer.prototype.swap64 = function swap64 () {
  var len = this.length
  if (len % 8 !== 0) {
    throw new RangeError('Buffer size must be a multiple of 64-bits')
  }
  for (var i = 0; i < len; i += 8) {
    swap(this, i, i + 7)
    swap(this, i + 1, i + 6)
    swap(this, i + 2, i + 5)
    swap(this, i + 3, i + 4)
  }
  return this
}

Buffer.prototype.toString = function toString () {
  var length = this.length
  if (length === 0) return ''
  if (arguments.length === 0) return utf8Slice(this, 0, length)
  return slowToString.apply(this, arguments)
}

Buffer.prototype.toLocaleString = Buffer.prototype.toString

Buffer.prototype.equals = function equals (b) {
  if (!Buffer.isBuffer(b)) throw new TypeError('Argument must be a Buffer')
  if (this === b) return true
  return Buffer.compare(this, b) === 0
}

Buffer.prototype.inspect = function inspect () {
  var str = ''
  var max = exports.INSPECT_MAX_BYTES
  str = this.toString('hex', 0, max).replace(/(.{2})/g, '$1 ').trim()
  if (this.length > max) str += ' ... '
  return '<Buffer ' + str + '>'
}

Buffer.prototype.compare = function compare (target, start, end, thisStart, thisEnd) {
  if (isInstance(target, Uint8Array)) {
    target = Buffer.from(target, target.offset, target.byteLength)
  }
  if (!Buffer.isBuffer(target)) {
    throw new TypeError(
      'The "target" argument must be one of type Buffer or Uint8Array. ' +
      'Received type ' + (typeof target)
    )
  }

  if (start === undefined) {
    start = 0
  }
  if (end === undefined) {
    end = target ? target.length : 0
  }
  if (thisStart === undefined) {
    thisStart = 0
  }
  if (thisEnd === undefined) {
    thisEnd = this.length
  }

  if (start < 0 || end > target.length || thisStart < 0 || thisEnd > this.length) {
    throw new RangeError('out of range index')
  }

  if (thisStart >= thisEnd && start >= end) {
    return 0
  }
  if (thisStart >= thisEnd) {
    return -1
  }
  if (start >= end) {
    return 1
  }

  start >>>= 0
  end >>>= 0
  thisStart >>>= 0
  thisEnd >>>= 0

  if (this === target) return 0

  var x = thisEnd - thisStart
  var y = end - start
  var len = Math.min(x, y)

  var thisCopy = this.slice(thisStart, thisEnd)
  var targetCopy = target.slice(start, end)

  for (var i = 0; i < len; ++i) {
    if (thisCopy[i] !== targetCopy[i]) {
      x = thisCopy[i]
      y = targetCopy[i]
      break
    }
  }

  if (x < y) return -1
  if (y < x) return 1
  return 0
}

// Finds either the first index of `val` in `buffer` at offset >= `byteOffset`,
// OR the last index of `val` in `buffer` at offset <= `byteOffset`.
//
// Arguments:
// - buffer - a Buffer to search
// - val - a string, Buffer, or number
// - byteOffset - an index into `buffer`; will be clamped to an int32
// - encoding - an optional encoding, relevant is val is a string
// - dir - true for indexOf, false for lastIndexOf
function bidirectionalIndexOf (buffer, val, byteOffset, encoding, dir) {
  // Empty buffer means no match
  if (buffer.length === 0) return -1

  // Normalize byteOffset
  if (typeof byteOffset === 'string') {
    encoding = byteOffset
    byteOffset = 0
  } else if (byteOffset > 0x7fffffff) {
    byteOffset = 0x7fffffff
  } else if (byteOffset < -0x80000000) {
    byteOffset = -0x80000000
  }
  byteOffset = +byteOffset // Coerce to Number.
  if (numberIsNaN(byteOffset)) {
    // byteOffset: it it's undefined, null, NaN, "foo", etc, search whole buffer
    byteOffset = dir ? 0 : (buffer.length - 1)
  }

  // Normalize byteOffset: negative offsets start from the end of the buffer
  if (byteOffset < 0) byteOffset = buffer.length + byteOffset
  if (byteOffset >= buffer.length) {
    if (dir) return -1
    else byteOffset = buffer.length - 1
  } else if (byteOffset < 0) {
    if (dir) byteOffset = 0
    else return -1
  }

  // Normalize val
  if (typeof val === 'string') {
    val = Buffer.from(val, encoding)
  }

  // Finally, search either indexOf (if dir is true) or lastIndexOf
  if (Buffer.isBuffer(val)) {
    // Special case: looking for empty string/buffer always fails
    if (val.length === 0) {
      return -1
    }
    return arrayIndexOf(buffer, val, byteOffset, encoding, dir)
  } else if (typeof val === 'number') {
    val = val & 0xFF // Search for a byte value [0-255]
    if (typeof Uint8Array.prototype.indexOf === 'function') {
      if (dir) {
        return Uint8Array.prototype.indexOf.call(buffer, val, byteOffset)
      } else {
        return Uint8Array.prototype.lastIndexOf.call(buffer, val, byteOffset)
      }
    }
    return arrayIndexOf(buffer, [ val ], byteOffset, encoding, dir)
  }

  throw new TypeError('val must be string, number or Buffer')
}

function arrayIndexOf (arr, val, byteOffset, encoding, dir) {
  var indexSize = 1
  var arrLength = arr.length
  var valLength = val.length

  if (encoding !== undefined) {
    encoding = String(encoding).toLowerCase()
    if (encoding === 'ucs2' || encoding === 'ucs-2' ||
        encoding === 'utf16le' || encoding === 'utf-16le') {
      if (arr.length < 2 || val.length < 2) {
        return -1
      }
      indexSize = 2
      arrLength /= 2
      valLength /= 2
      byteOffset /= 2
    }
  }

  function read (buf, i) {
    if (indexSize === 1) {
      return buf[i]
    } else {
      return buf.readUInt16BE(i * indexSize)
    }
  }

  var i
  if (dir) {
    var foundIndex = -1
    for (i = byteOffset; i < arrLength; i++) {
      if (read(arr, i) === read(val, foundIndex === -1 ? 0 : i - foundIndex)) {
        if (foundIndex === -1) foundIndex = i
        if (i - foundIndex + 1 === valLength) return foundIndex * indexSize
      } else {
        if (foundIndex !== -1) i -= i - foundIndex
        foundIndex = -1
      }
    }
  } else {
    if (byteOffset + valLength > arrLength) byteOffset = arrLength - valLength
    for (i = byteOffset; i >= 0; i--) {
      var found = true
      for (var j = 0; j < valLength; j++) {
        if (read(arr, i + j) !== read(val, j)) {
          found = false
          break
        }
      }
      if (found) return i
    }
  }

  return -1
}

Buffer.prototype.includes = function includes (val, byteOffset, encoding) {
  return this.indexOf(val, byteOffset, encoding) !== -1
}

Buffer.prototype.indexOf = function indexOf (val, byteOffset, encoding) {
  return bidirectionalIndexOf(this, val, byteOffset, encoding, true)
}

Buffer.prototype.lastIndexOf = function lastIndexOf (val, byteOffset, encoding) {
  return bidirectionalIndexOf(this, val, byteOffset, encoding, false)
}

function hexWrite (buf, string, offset, length) {
  offset = Number(offset) || 0
  var remaining = buf.length - offset
  if (!length) {
    length = remaining
  } else {
    length = Number(length)
    if (length > remaining) {
      length = remaining
    }
  }

  var strLen = string.length

  if (length > strLen / 2) {
    length = strLen / 2
  }
  for (var i = 0; i < length; ++i) {
    var parsed = parseInt(string.substr(i * 2, 2), 16)
    if (numberIsNaN(parsed)) return i
    buf[offset + i] = parsed
  }
  return i
}

function utf8Write (buf, string, offset, length) {
  return blitBuffer(utf8ToBytes(string, buf.length - offset), buf, offset, length)
}

function asciiWrite (buf, string, offset, length) {
  return blitBuffer(asciiToBytes(string), buf, offset, length)
}

function latin1Write (buf, string, offset, length) {
  return asciiWrite(buf, string, offset, length)
}

function base64Write (buf, string, offset, length) {
  return blitBuffer(base64ToBytes(string), buf, offset, length)
}

function ucs2Write (buf, string, offset, length) {
  return blitBuffer(utf16leToBytes(string, buf.length - offset), buf, offset, length)
}

Buffer.prototype.write = function write (string, offset, length, encoding) {
  // Buffer#write(string)
  if (offset === undefined) {
    encoding = 'utf8'
    length = this.length
    offset = 0
  // Buffer#write(string, encoding)
  } else if (length === undefined && typeof offset === 'string') {
    encoding = offset
    length = this.length
    offset = 0
  // Buffer#write(string, offset[, length][, encoding])
  } else if (isFinite(offset)) {
    offset = offset >>> 0
    if (isFinite(length)) {
      length = length >>> 0
      if (encoding === undefined) encoding = 'utf8'
    } else {
      encoding = length
      length = undefined
    }
  } else {
    throw new Error(
      'Buffer.write(string, encoding, offset[, length]) is no longer supported'
    )
  }

  var remaining = this.length - offset
  if (length === undefined || length > remaining) length = remaining

  if ((string.length > 0 && (length < 0 || offset < 0)) || offset > this.length) {
    throw new RangeError('Attempt to write outside buffer bounds')
  }

  if (!encoding) encoding = 'utf8'

  var loweredCase = false
  for (;;) {
    switch (encoding) {
      case 'hex':
        return hexWrite(this, string, offset, length)

      case 'utf8':