/*!
   * express
   * Copyright(c) 2009-2013 TJ Holowaychuk
   * Copyright(c) 2013 Roman Shtylman
   * Copyright(c) 2014-2015 Douglas Christopher Wilson
   * MIT Licensed
   */
  
  'use strict';
  
  /**
   * Module dependencies.
   * @private
   */
  
  var setPrototypeOf = require('setprototypeof')
  
  /**
   * Initialization middleware, exposing the
   * request and response to each other, as well
   * as defaulting the X-Powered-By header field.
   *
   * @param {Function} app
   * @return {Function}
   * @api private
   */
  
  exports.init = function(app){
    return function expressInit(req, res, next){
      if (app.enabled('x-powered-by')) res.setHeader('X-Powered-By', 'Express');
      req.res = res;
      res.req = req;
      req.next = next;
  
      setPrototypeOf(req, app.request)
      setPrototypeOf(res, app.response)
  
      res.locals = res.locals || Object.create(null);
  
      next();
    };
  };