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node_modules/select-hose/lib/hose.js 2.2 KB
aaac7fed   liuqimichale   add
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  'use strict';
  
  var util = require('util');
  var EventEmitter = require('events').EventEmitter;
  
  function Hose(socket, options, filter) {
    EventEmitter.call(this);
  
    if (typeof options === 'function') {
      filter = options;
      options = {};
    }
  
    this.socket = socket;
    this.options = options;
    this.filter = filter;
  
    this.buffer = null;
  
    var self = this;
    this.listeners = {
      error: function(err) {
        return self.onError(err);
      },
      data: function(chunk) {
        return self.onData(chunk);
      },
      end: function() {
        return self.onEnd();
      }
    };
  
    this.socket.on('error', this.listeners.error);
    this.socket.on('data', this.listeners.data);
    this.socket.on('end', this.listeners.end);
  }
  util.inherits(Hose, EventEmitter);
  module.exports = Hose;
  
  Hose.create = function create(socket, options, filter) {
    return new Hose(socket, options, filter);
  };
  
  Hose.prototype.detach = function detach() {
    // Stop the flow
    this.socket.pause();
  
    this.socket.removeListener('error', this.listeners.error);
    this.socket.removeListener('data', this.listeners.data);
    this.socket.removeListener('end', this.listeners.end);
  };
  
  Hose.prototype.reemit = function reemit() {
    var buffer = this.buffer;
    this.buffer = null;
  
    // Modern age
    if (this.socket.unshift) {
      this.socket.unshift(buffer);
      if (this.socket.listeners('data').length > 0)
        this.socket.resume();
      return;
    }
  
    // Rusty node v0.8
    if (this.socket.ondata)
      this.socket.ondata(buffer, 0, buffer.length);
    this.socket.emit('data', buffer);
    this.socket.resume();
  };
  
  Hose.prototype.onError = function onError(err) {
    this.detach();
    this.emit('error', err);
  };
  
  Hose.prototype.onData = function onData(chunk) {
    if (this.buffer)
      this.buffer = Buffer.concat([ this.buffer, chunk ]);
    else
      this.buffer = chunk;
  
    var self = this;
    this.filter(this.buffer, function(err, protocol) {
      if (err)
        return self.onError(err);
  
      // No protocol selected yet
      if (!protocol)
        return;
  
      self.detach();
      self.emit('select', protocol, self.socket);
      self.reemit();
    });
  };
  
  Hose.prototype.onEnd = function onEnd() {
    this.detach();
    this.emit('error', new Error('Not enough data to recognize protocol'));
  };