# Source: src/ol/source/mapquestsource.js

    goog.provide('ol.source.MapQuest');

    goog.require('goog.asserts');
    goog.require('ol');
    goog.require('ol.Attribution');
    goog.require('ol.source.OSM');
    goog.require('ol.source.XYZ');

    /**
     * @classdesc
     * Layer source for the MapQuest tile server.
     *
     * @constructor
     * @extends {ol.source.XYZ}
     * @param {olx.source.MapQuestOptions=} opt_options MapQuest options.
     * @todo api
     */
    ol.source.MapQuest = function(opt_options) {

      var options = goog.isDef(opt_options) ? opt_options : {};
      goog.asserts.assert(options.layer in ol.source.MapQuestConfig);

      var layerConfig = ol.source.MapQuestConfig[options.layer];

      var protocol = ol.IS_HTTPS ? 'https:' : 'http:';
      var url = protocol + '//otile{1-4}-s.mqcdn.com/tiles/1.0.0/' +
          options.layer + '/{z}/{x}/{y}.jpg';

      goog.base(this, {
        attributions: layerConfig.attributions,
        crossOrigin: 'anonymous',
        logo: '//developer.mapquest.com/content/osm/mq_logo.png',
        maxZoom: layerConfig.maxZoom,
        opaque: true,
        tileLoadFunction: options.tileLoadFunction,
        url: url
      });

    };
    goog.inherits(ol.source.MapQuest, ol.source.XYZ);

    /**
     * @const
     * @type {ol.Attribution}
     */
    ol.source.MapQuest.TILE_ATTRIBUTION = new ol.Attribution({
      html: 'Tiles Courtesy of ' +
          '<a href="http://www.mapquest.com/" target="_blank">MapQuest</a>'
    });

    /**
     * @type {Object.<string, {maxZoom: number, attributions: (Array.<ol.Attribution>)}>}
     */
    ol.source.MapQuestConfig = {
      'osm': {
        maxZoom: 28,
        attributions: [
          ol.source.MapQuest.TILE_ATTRIBUTION,
          ol.source.OSM.DATA_ATTRIBUTION
        ]
      },
      'sat': {
        maxZoom: 18,
        attributions: [
          ol.source.MapQuest.TILE_ATTRIBUTION,
          new ol.Attribution({
            html: 'Portions Courtesy NASA/JPL-Caltech and ' +
                'U.S. Depart. of Agriculture, Farm Service Agency'
          })
        ]
      },
      'hyb': {
        maxZoom: 18,
        attributions: [
          ol.source.MapQuest.TILE_ATTRIBUTION,
          ol.source.OSM.DATA_ATTRIBUTION
        ]
      }
    };