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node_modules/negotiator/index.js 3.27 KB
f7563de62   Palak Handa   first commit
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  /*!
   * negotiator
   * Copyright(c) 2012 Federico Romero
   * Copyright(c) 2012-2014 Isaac Z. Schlueter
   * Copyright(c) 2015 Douglas Christopher Wilson
   * MIT Licensed
   */
  
  'use strict';
  
  /**
   * Cached loaded submodules.
   * @private
   */
  
  var modules = Object.create(null);
  
  /**
   * Module exports.
   * @public
   */
  
  module.exports = Negotiator;
  module.exports.Negotiator = Negotiator;
  
  /**
   * Create a Negotiator instance from a request.
   * @param {object} request
   * @public
   */
  
  function Negotiator(request) {
    if (!(this instanceof Negotiator)) {
      return new Negotiator(request);
    }
  
    this.request = request;
  }
  
  Negotiator.prototype.charset = function charset(available) {
    var set = this.charsets(available);
    return set && set[0];
  };
  
  Negotiator.prototype.charsets = function charsets(available) {
    var preferredCharsets = loadModule('charset').preferredCharsets;
    return preferredCharsets(this.request.headers['accept-charset'], available);
  };
  
  Negotiator.prototype.encoding = function encoding(available) {
    var set = this.encodings(available);
    return set && set[0];
  };
  
  Negotiator.prototype.encodings = function encodings(available) {
    var preferredEncodings = loadModule('encoding').preferredEncodings;
    return preferredEncodings(this.request.headers['accept-encoding'], available);
  };
  
  Negotiator.prototype.language = function language(available) {
    var set = this.languages(available);
    return set && set[0];
  };
  
  Negotiator.prototype.languages = function languages(available) {
    var preferredLanguages = loadModule('language').preferredLanguages;
    return preferredLanguages(this.request.headers['accept-language'], available);
  };
  
  Negotiator.prototype.mediaType = function mediaType(available) {
    var set = this.mediaTypes(available);
    return set && set[0];
  };
  
  Negotiator.prototype.mediaTypes = function mediaTypes(available) {
    var preferredMediaTypes = loadModule('mediaType').preferredMediaTypes;
    return preferredMediaTypes(this.request.headers.accept, available);
  };
  
  // Backwards compatibility
  Negotiator.prototype.preferredCharset = Negotiator.prototype.charset;
  Negotiator.prototype.preferredCharsets = Negotiator.prototype.charsets;
  Negotiator.prototype.preferredEncoding = Negotiator.prototype.encoding;
  Negotiator.prototype.preferredEncodings = Negotiator.prototype.encodings;
  Negotiator.prototype.preferredLanguage = Negotiator.prototype.language;
  Negotiator.prototype.preferredLanguages = Negotiator.prototype.languages;
  Negotiator.prototype.preferredMediaType = Negotiator.prototype.mediaType;
  Negotiator.prototype.preferredMediaTypes = Negotiator.prototype.mediaTypes;
  
  /**
   * Load the given module.
   * @private
   */
  
  function loadModule(moduleName) {
    var module = modules[moduleName];
  
    if (module !== undefined) {
      return module;
    }
  
    // This uses a switch for static require analysis
    switch (moduleName) {
      case 'charset':
        module = require('./lib/charset');
        break;
      case 'encoding':
        module = require('./lib/encoding');
        break;
      case 'language':
        module = require('./lib/language');
        break;
      case 'mediaType':
        module = require('./lib/mediaType');
        break;
      default:
        throw new Error('Cannot find module \'' + moduleName + '\'');
    }
  
    // Store to prevent invoking require()
    modules[moduleName] = module;
  
    return module;
  }