text: /**
  Provides URL-based routing using HTML5 `pushState()` or the location hash.
  
  @module app
  @submodule router
  @since 3.4.0
  **/
  
  var HistoryHash = Y.HistoryHash,
      QS          = Y.QueryString,
      YArray      = Y.Array,
  
      win = Y.config.win,
  
      // Holds all the active router instances. This supports the static
      // `dispatch()` method which causes all routers to dispatch.
      instances = [],
  
      // We have to queue up pushState calls to avoid race conditions, since the
      // popstate event doesn't actually provide any info on what URL it's
      // associated with.
      saveQueue = [],
  
      /**
      Fired when the router is ready to begin dispatching to route handlers.
  
      You shouldn't need to wait for this event unless you plan to implement some
      kind of custom dispatching logic. It's used internally in order to avoid
      dispatching to an initial route if a browser history change occurs first.
  
      @event ready
      @param {Boolean} dispatched `true` if routes have already been dispatched
        (most likely due to a history change).
      @fireOnce
      **/
      EVT_READY = 'ready';
  
  /**
  Provides URL-based routing using HTML5 `pushState()` or the location hash.
  
  This makes it easy to wire up route handlers for different application states
  while providing full back/forward navigation support and bookmarkable, shareable
  URLs.
  
  @class Router
  @param {Object} [config] Config properties.
      @param {Boolean} [config.html5] Overrides the default capability detection
          and forces this router to use (`true`) or not use (`false`) HTML5
          history.
      @param {String} [config.root=''] Root path from which all routes should be
          evaluated.
      @param {Array} [config.routes=[]] Array of route definition objects.
  @constructor
  @extends Base
  @since 3.4.0
  **/
  function Router() {
      Router.superclass.constructor.apply(this, arguments);
  }
  
  Y.Router = Y.extend(Router, Y.Base, {
      // -- Protected Properties -------------------------------------------------
  
      /**
      Whether or not `_dispatch()` has been called since this router was
      instantiated.
  
      @property _dispatched
      @type Boolean
      @default undefined
      @protected
      **/
  
      /**
      Whether or not we're currently in the process of dispatching to routes.
  
      @property _dispatching
      @type Boolean
      @default undefined
      @protected
      **/
  
      /**
      History event handle for the `history:change` or `hashchange` event
      subscription.
  
      @property _historyEvents
      @type EventHandle
      @protected
      **/
  
      /**
      Cached copy of the `html5` attribute for internal use.
  
      @property _html5
      @type Boolean
      @protected
      **/
  
      /**
      Whether or not the `ready` event has fired yet.
  
      @property _ready
      @type Boolean
      @default undefined
      @protected
      **/
  
      /**
      Regex used to match parameter placeholders in route paths.
  
      Subpattern captures:
  
        1. Parameter prefix character. Either a `:` for subpath parameters that
           should only match a single level of a path, or `*` for splat parameters
           that should match any number of path levels.
  
        2. Parameter name, if specified, otherwise it is a wildcard match.
  
      @property _regexPathParam
      @type RegExp
      @protected
      **/
      _regexPathParam: /([:*])([\w\-]+)?/g,
  
      /**
      Regex that matches and captures the query portion of a URL, minus the
      preceding `?` character, and discarding the hash portion of the URL if any.
  
      @property _regexUrlQuery
      @type RegExp
      @protected
      **/
      _regexUrlQuery: /\?([^#]*).*$/,
  
      /**
      Regex that matches everything before the path portion of a URL (the origin).
      This will be used to strip this part of the URL from a string when we
      only want the path.
  
      @property _regexUrlOrigin
      @type RegExp
      @protected
      **/
      _regexUrlOrigin: /^(?:[^\/#?:]+:\/\/|\/\/)[^\/]*/,
  
      // -- Lifecycle Methods ----------------------------------------------------
      initializer: function (config) {
          var self = this;
  
          self._html5  = self.get('html5');
          self._routes = [];
          self._url    = self._getURL();
  
          // Necessary because setters don't run on init.
          self._setRoutes(config && config.routes ? config.routes :
                  self.get('routes'));
  
          // Set up a history instance or hashchange listener.
          if (self._html5) {
              self._history       = new Y.HistoryHTML5({force: true});
              self._historyEvents =
                      Y.after('history:change', self._afterHistoryChange, self);
          } else {
              self._historyEvents =
                      Y.on('hashchange', self._afterHistoryChange, win, self);
          }
  
          // Fire a `ready` event once we're ready to route. We wait first for all
          // subclass initializers to finish, then for window.onload, and then an
          // additional 20ms to allow the browser to fire a useless initial
          // `popstate` event if it wants to (and Chrome always wants to).
          self.publish(EVT_READY, {
              defaultFn  : self._defReadyFn,
              fireOnce   : true,
              preventable: false
          });
  
          self.once('initializedChange', function () {
              Y.once('load', function () {
                  setTimeout(function () {
                      self.fire(EVT_READY, {dispatched: !!self._dispatched});
                  }, 20);
              });
          });
  
          // Store this router in the collection of all active router instances.
          instances.push(this);
      },
  
      destructor: function () {
          var instanceIndex = YArray.indexOf(instances, this);
  
          // Remove this router from the collection of active router instances.
          if (instanceIndex > -1) {
              instances.splice(instanceIndex, 1);
          }
  
          if (this._historyEvents) {
              this._historyEvents.detach();
          }
      },
  
      // -- Public Methods -------------------------------------------------------
  
      /**
      Dispatches to the first route handler that matches the current URL, if any.
  
      If `dispatch()` is called before the `ready` event has fired, it will
      automatically wait for the `ready` event before dispatching. Otherwise it
      will dispatch immediately.
  
      @method dispatch
      @chainable
      **/
      dispatch: function () {
          this.once(EVT_READY, function () {
              this._ready = true;
  
              if (!this.upgrade()) {
                  this._dispatch(this._getPath(), this._getURL());
              }
          });
  
          return this;
      },
  
      /**
      Gets the current route path, relative to the `root` (if any).
  
      @method getPath
      @return {String} Current route path.
      **/
      getPath: function () {
          return this._getPath();
      },
  
      /**
      Returns `true` if this router has at least one route that matches the
      specified URL, `false` otherwise.
  
      This method enforces the same-origin security constraint on the specified
      `url`; any URL which is not from the same origin as the current URL will
      always return `false`.
  
      @method hasRoute
      @param {String} url URL to match.
      @return {Boolean} `true` if there's at least one matching route, `false`
        otherwise.
      **/
      hasRoute: function (url) {
          var path;
  
          if (!this._hasSameOrigin(url)) {
              return false;
          }
  
          if (!this._html5) {
              url = this._upgradeURL(url);
          }
  
          path = this.removeQuery(this.removeRoot(url));
  
          return !!this.match(path).length;
      },
  
      /**
      Returns an array of route objects that match the specified URL path.
  
      This method is called internally to determine which routes match the current
      path whenever the URL changes. You may override it if you want to customize
      the route matching logic, although this usually shouldn't be necessary.
  
      Each returned route object has the following properties:
  
        * `callback`: A function or a string representing the name of a function
          this router that should be executed when the route is triggered.
  
        * `keys`: An array of strings representing the named parameters defined in
          the route's path specification, if any.
  
        * `path`: The route's path specification, which may be either a string or
          a regex.
  
        * `regex`: A regular expression version of the route's path specification.
          This regex is used to determine whether the route matches a given path.
  
      @example
          router.route('/foo', function () {});
          router.match('/foo');
          // => [{callback: ..., keys: [], path: '/foo', regex: ...}]
  
      @method match
      @param {String} path URL path to match.
      @return {Object[]} Array of route objects that match the specified path.
      **/
      match: function (path) {
          return YArray.filter(this._routes, function (route) {
              return path.search(route.regex) > -1;
          });
      },
  
      /**
      Removes the `root` URL from the front of _url_ (if it's there) and returns
      the result. The returned path will always have a leading `/`.
  
      @method removeRoot
      @param {String} url URL.
      @return {String} Rootless path.
      **/
      removeRoot: function (url) {
          var root = this.get('root');
  
          // Strip out the non-path part of the URL, if any (e.g.
          // "http://foo.com"), so that we're left with just the path.
          url = url.replace(this._regexUrlOrigin, '');
  
          if (root && url.indexOf(root) === 0) {
              url = url.substring(root.length);
          }
  
          return url.charAt(0) === '/' ? url : '/' + url;
      },
  
      /**
      Removes a query string from the end of the _url_ (if one exists) and returns
      the result.
  
      @method removeQuery
      @param {String} url URL.
      @return {String} Queryless path.
      **/
      removeQuery: function (url) {
          return url.replace(/\?.*$/, '');
      },
  
      /**
      Replaces the current browser history entry with a new one, and dispatches to
      the first matching route handler, if any.
  
      Behind the scenes, this method uses HTML5 `pushState()` in browsers that
      support it (or the location hash in older browsers and IE) to change the
      URL.
  
      The specified URL must share the same origin (i.e., protocol, host, and
      port) as the current page, or an error will occur.
  
      @example
          // Starting URL: http://example.com/
  
          router.replace('/path/');
          // New URL: http://example.com/path/
  
          router.replace('/path?foo=bar');
          // New URL: http://example.com/path?foo=bar
  
          router.replace('/');
          // New URL: http://example.com/
  
      @method replace
      @param {String} [url] URL to set. This URL needs to be of the same origin as
        the current URL. This can be a URL relative to the router's `root`
        attribute. If no URL is specified, the page's current URL will be used.
      @chainable
      @see save()
      **/
      replace: function (url) {
          return this._queue(url, true);
      },
  
      /**
      Adds a route handler for the specified URL _path_.
  
      The _path_ parameter may be either a string or a regular expression. If it's
      a string, it may contain named parameters: `:param` will match any single
      part of a URL path (not including `/` characters), and `*param` will match
      any number of parts of a URL path (including `/` characters). These named
      parameters will be made available as keys on the `req.params` object that's
      passed to route handlers.
  
      If the _path_ parameter is a regex, all pattern matches will be made
      available as numbered keys on `req.params`, starting with `0` for the full
      match, then `1` for the first subpattern match, and so on.
  
      Here's a set of sample routes along with URL paths that they match:
  
        * Route: `/photos/:tag/:page`
          * URL: `/photos/kittens/1`, params: `{tag: 'kittens', page: '1'}`
          * URL: `/photos/puppies/2`, params: `{tag: 'puppies', page: '2'}`
  
        * Route: `/file/*path`
          * URL: `/file/foo/bar/baz.txt`, params: `{path: 'foo/bar/baz.txt'}`
          * URL: `/file/foo`, params: `{path: 'foo'}`
  
      **Middleware**: Routes also support an arbitrary number of callback
      functions. This allows you to easily reuse parts of your route-handling code
      with different route. This method is liberal in how it processes the
      specified `callbacks`, you can specify them as separate arguments, or as
      arrays, or both.
  
      If multiple route match a given URL, they will be executed in the order they
      were added. The first route that was added will be the first to be executed.
  
      **Passing Control**: Invoking the `next()` function within a route callback
      will pass control to the next callback function (if any) or route handler
      (if any). If a value is passed to `next()`, it's assumed to be an error,
      therefore stopping the dispatch chain, unless that value is: `"route"`,
      which is special case and dispatching will skip to the next route handler.
      This allows middleware to skip any remaining middleware for a particular
      route.
  
      @example
          router.route('/photos/:tag/:page', function (req, res, next) {
            Y.log('Current tag: ' + req.params.tag);
            Y.log('Current page number: ' + req.params.page);
          });
  
          // Using middleware.
  
          router.findUser = function (req, res, next) {
              req.user = this.get('users').findById(req.params.user);
              next();
          };
  
          router.route('/users/:user', 'findUser', function (req, res, next) {
              // The `findUser` middleware puts the `user` object on the `req`.
              Y.log('Current user:' req.user.get('name'));
          });
  
      @method route
      @param {String|RegExp} path Path to match. May be a string or a regular
        expression.
      @param {Array|Function|String} callbacks* Callback functions to call
          whenever this route is triggered. These can be specified as separate
          arguments, or in arrays, or both. If a callback is specified as a
          string, the named function will be called on this router instance.
  
        @param {Object} callbacks.req Request object containing information about
            the request. It contains the following properties.
  
          @param {Array|Object} callbacks.req.params Captured parameters matched by
            the route path specification. If a string path was used and contained
            named parameters, then this will be a key/value hash mapping parameter
            names to their matched values. If a regex path was used, this will be
            an array of subpattern matches starting at index 0 for the full match,
            then 1 for the first subpattern match, and so on.
          @param {String} callbacks.req.path The current URL path.
          @param {Number} callbacks.req.pendingCallbacks Number of remaining
            callbacks the route handler has after this one in the dispatch chain.
          @param {Number} callbacks.req.pendingRoutes Number of matching routes
            after this one in the dispatch chain.
          @param {Object} callbacks.req.query Query hash representing the URL
            query string, if any. Parameter names are keys, and are mapped to
            parameter values.
          @param {String} callbacks.req.url The full URL.
          @param {String} callbacks.req.src What initiated the dispatch. In an
            HTML5 browser, when the back/forward buttons are used, this property
            will have a value of "popstate".
  
        @param {Object} callbacks.res Response object containing methods and
            information that relate to responding to a request. It contains the
            following properties.
          @param {Object} callbacks.res.req Reference to the request object.
  
        @param {Function} callbacks.next Function to pass control to the next
            callback or the next matching route if no more callbacks (middleware)
            exist for the current route handler. If you don't call this function,
            then no further callbacks or route handlers will be executed, even if
            there are more that match. If you do call this function, then the next
            callback (if any) or matching route handler (if any) will be called.
            All of these functions will receive the same `req` and `res` objects
            that were passed to this route (so you can use these objects to pass
            data along to subsequent callbacks and routes).
          @param {String} [callbacks.next.err] Optional error which will stop the
            dispatch chaining for this `req`, unless the value is `"route"`, which
            is special cased to jump skip past any callbacks for the current route
            and pass control the next route handler.
      @chainable
      **/
      route: function (path, callbacks) {
          callbacks = YArray.flatten(YArray(arguments, 1, true));
  
          var keys = [];
  
          this._routes.push({
              callbacks: callbacks,
              keys     : keys,
              path     : path,
              regex    : this._getRegex(path, keys),
  
              // For back-compat.
              callback: callbacks[0]
          });
  
          return this;
      },
  
      /**
      Saves a new browser history entry and dispatches to the first matching route
      handler, if any.
  
      Behind the scenes, this method uses HTML5 `pushState()` in browsers that
      support it (or the location hash in older browsers and IE) to change the
      URL and create a history entry.
  
      The specified URL must share the same origin (i.e., protocol, host, and
      port) as the current page, or an error will occur.
  
      @example
          // Starting URL: http://example.com/
  
          router.save('/path/');
          // New URL: http://example.com/path/
  
          router.save('/path?foo=bar');
          // New URL: http://example.com/path?foo=bar
  
          router.save('/');
          // New URL: http://example.com/
  
      @method save
      @param {String} [url] URL to set. This URL needs to be of the same origin as
        the current URL. This can be a URL relative to the router's `root`
        attribute. If no URL is specified, the page's current URL will be used.
      @chainable
      @see replace()
      **/
      save: function (url) {
          return this._queue(url);
      },
  
      /**
      Upgrades a hash-based URL to an HTML5 URL if necessary. In non-HTML5
      browsers, this method is a noop.
  
      @method upgrade
      @return {Boolean} `true` if the URL was upgraded, `false` otherwise.
      **/
      upgrade: function () {
          if (!this._html5) {
              return false;
          }
  
          // Get the resolve hash path.
          var hashPath = this._getHashPath();
  
          if (hashPath) {
              // This is an HTML5 browser and we have a hash-based path in the
              // URL, so we need to upgrade the URL to a non-hash URL. This
              // will trigger a `history:change` event, which will in turn
              // trigger a dispatch.
              this.once(EVT_READY, function () {
                  this.replace(hashPath);
              });
  
              return true;
          }
  
          return false;
      },
  
      // -- Protected Methods ----------------------------------------------------
  
      /**
      Wrapper around `decodeURIComponent` that also converts `+` chars into
      spaces.
  
      @method _decode
      @param {String} string String to decode.
      @return {String} Decoded string.
      @protected
      **/
      _decode: function (string) {
          return decodeURIComponent(string.replace(/\+/g, ' '));
      },
  
      /**
      Shifts the topmost `_save()` call off the queue and executes it. Does
      nothing if the queue is empty.
  
      @method _dequeue
      @chainable
      @see _queue
      @protected
      **/
      _dequeue: function () {
          var self = this,
              fn;
  
          // If window.onload hasn't yet fired, wait until it has before
          // dequeueing. This will ensure that we don't call pushState() before an
          // initial popstate event has fired.
          if (!YUI.Env.windowLoaded) {
              Y.once('load', function () {
                  self._dequeue();
              });
  
              return this;
          }
  
          fn = saveQueue.shift();
          return fn ? fn() : this;
      },
  
      /**
      Dispatches to the first route handler that matches the specified _path_.
  
      If called before the `ready` event has fired, the dispatch will be aborted.
      This ensures normalized behavior between Chrome (which fires a `popstate`
      event on every pageview) and other browsers (which do not).
  
      @method _dispatch
      @param {String} path URL path.
      @param {String} url Full URL.
      @param {String} src What initiated the dispatch.
      @chainable
      @protected
      **/
      _dispatch: function (path, url, src) {
          var self      = this,
              decode    = self._decode,
              routes    = self.match(path),
              callbacks = [],
              matches, req, res;
  
          self._dispatching = self._dispatched = true;
  
          if (!routes || !routes.length) {
              self._dispatching = false;
              return self;
          }
  
          req = self._getRequest(path, url, src);
          res = self._getResponse(req);
  
          req.next = function (err) {
              var callback, name, route;
  
              if (err) {
                  // Special case "route" to skip to the next route handler
                  // avoiding any additional callbacks for the current route.
                  if (err === 'route') {
                      callbacks = [];
                      req.next();
                  } else {
                      Y.error(err);
                  }
  
              } else if ((callback = callbacks.shift())) {
                  if (typeof callback === 'string') {
                      name     = callback;
                      callback = self[name];
  
                      if (!callback) {
                          Y.error('Router: Callback not found: ' + name, null, 'router');
                      }
                  }
  
                  // Allow access to the number of remaining callbacks for the
                  // route.
                  req.pendingCallbacks = callbacks.length;
  
                  callback.call(self, req, res, req.next);
  
              } else if ((route = routes.shift())) {
                  // Make a copy of this route's `callbacks` so the original array
                  // is preserved.
                  callbacks = route.callbacks.concat();
  
                  // Decode each of the path matches so that the any URL-encoded
                  // path segments are decoded in the `req.params` object.
                  matches = YArray.map(route.regex.exec(path) || [], decode);
  
                  // Use named keys for parameter names if the route path contains
                  // named keys. Otherwise, use numerical match indices.
                  if (matches.length === route.keys.length + 1) {
                      req.params = YArray.hash(route.keys, matches.slice(1));
                  } else {
                      req.params = matches.concat();
                  }
  
                  // Allow access to the number of remaining routes for this
                  // request.
                  req.pendingRoutes = routes.length;
  
                  // Execute this route's `callbacks`.
                  req.next();
              }
          };
  
          req.next();
  
          self._dispatching = false;
          return self._dequeue();
      },
  
      /**
      Returns the resolved path from the hash fragment, or an empty string if the
      hash is not path-like.
  
      @method _getHashPath
      @param {String} [hash] Hash fragment to resolve into a path. By default this
          will be the hash from the current URL.
      @return {String} Current hash path, or an empty string if the hash is empty.
      @protected
      **/
      _getHashPath: function (hash) {
          hash || (hash = HistoryHash.getHash());
  
          // Make sure the `hash` is path-like.
          if (hash && hash.charAt(0) === '/') {
              return this._joinURL(hash);
          }
  
          return '';
      },
  
      /**
      Gets the location origin (i.e., protocol, host, and port) as a URL.
  
      @example
          http://example.com
  
      @method _getOrigin
      @return {String} Location origin (i.e., protocol, host, and port).
      @protected
      **/
      _getOrigin: function () {
          var location = Y.getLocation();
          return location.origin || (location.protocol + '//' + location.host);
      },
  
      /**
      Gets the current route path, relative to the `root` (if any).
  
      @method _getPath
      @return {String} Current route path.
      @protected
      **/
      _getPath: function () {
          var path = (!this._html5 && this._getHashPath()) ||
                  Y.getLocation().pathname;
  
          return this.removeQuery(this.removeRoot(path));
      },
  
      /**
      Returns the current path root after popping off the last path segment,
      making it useful for resolving other URL paths against.
  
      The path root will always begin and end with a '/'.
  
      @method _getPathRoot
      @return {String} The URL's path root.
      @protected
      @since 3.5.0
      **/
      _getPathRoot: function () {
          var slash = '/',
              path  = Y.getLocation().pathname,
              segments;
  
          if (path.charAt(path.length - 1) === slash) {
              return path;
          }
  
          segments = path.split(slash);
          segments.pop();
  
          return segments.join(slash) + slash;
      },
  
      /**
      Gets the current route query string.
  
      @method _getQuery
      @return {String} Current route query string.
      @protected
      **/
      _getQuery: function () {
          var location = Y.getLocation(),
              hash, matches;
  
          if (this._html5) {
              return location.search.substring(1);
          }
  
          hash    = HistoryHash.getHash();
          matches = hash.match(this._regexUrlQuery);
  
          return hash && matches ? matches[1] : location.search.substring(1);
      },
  
      /**
      Creates a regular expression from the given route specification. If _path_
      is already a regex, it will be returned unmodified.
  
      @method _getRegex
      @param {String|RegExp} path Route path specification.
      @param {Array} keys Array reference to which route parameter names will be
        added.
      @return {RegExp} Route regex.
      @protected
      **/
      _getRegex: function (path, keys) {
          if (path instanceof RegExp) {
              return path;
          }
  
          // Special case for catchall paths.
          if (path === '*') {
              return (/.*/);
          }
  
          path = path.replace(this._regexPathParam, function (match, operator, key) {
              // Only `*` operators are supported for key-less matches to allowing
              // in-path wildcards like: '/foo/*'.
              if (!key) {
                  return operator === '*' ? '.*' : match;
              }
  
              keys.push(key);
              return operator === '*' ? '(.*?)' : '([^/#?]*)';
          });
  
          return new RegExp('^' + path + '$');
      },
  
      /**
      Gets a request object that can be passed to a route handler.
  
      @method _getRequest
      @param {String} path Current path being dispatched.
      @param {String} url Current full URL being dispatched.
      @param {String} src What initiated the dispatch.
      @return {Object} Request object.
      @protected
      **/
      _getRequest: function (path, url, src) {
          return {
              path : path,
              query: this._parseQuery(this._getQuery()),
              url  : url,
              src  : src
          };
      },
  
      /**
      Gets a response object that can be passed to a route handler.
  
      @method _getResponse
      @param {Object} req Request object.
      @return {Object} Response Object.
      @protected
      **/
      _getResponse: function (req) {
          // For backwards compatibility, the response object is a function that
          // calls `next()` on the request object and returns the result.
          var res = function () {
              return req.next.apply(this, arguments);
          };
  
          res.req = req;
          return res;
      },
  
      /**
      Getter for the `routes` attribute.
  
      @method _getRoutes
      @return {Object[]} Array of route objects.
      @protected
      **/
      _getRoutes: function () {
          return this._routes.concat();
      },
  
      /**
      Gets the current full URL.
  
      @method _getURL
      @return {String} URL.
      @protected
      **/
      _getURL: function () {
          var url = Y.getLocation().toString();
  
          if (!this._html5) {
              url = this._upgradeURL(url);
          }
  
          return url;
      },
  
      /**
      Returns `true` when the specified `url` is from the same origin as the
      current URL; i.e., the protocol, host, and port of the URLs are the same.
  
      All host or path relative URLs are of the same origin. A scheme-relative URL
      is first prefixed with the current scheme before being evaluated.
  
      @method _hasSameOrigin
      @param {String} url URL to compare origin with the current URL.
      @return {Boolean} Whether the URL has the same origin of the current URL.
      @protected
      **/
      _hasSameOrigin: function (url) {
          var origin = ((url && url.match(this._regexUrlOrigin)) || [])[0];
  
          // Prepend current scheme to scheme-relative URLs.
          if (origin && origin.indexOf('//') === 0) {
              origin = Y.getLocation().protocol + origin;
          }
  
          return !origin || origin === this._getOrigin();
      },
  
      /**
      Joins the `root` URL to the specified _url_, normalizing leading/trailing
      `/` characters.
  
      @example
          router.set('root', '/foo');
          router._joinURL('bar');  // => '/foo/bar'
          router._joinURL('/bar'); // => '/foo/bar'
  
          router.set('root', '/foo/');
          router._joinURL('bar');  // => '/foo/bar'
          router._joinURL('/bar'); // => '/foo/bar'
  
      @method _joinURL
      @param {String} url URL to append to the `root` URL.
      @return {String} Joined URL.
      @protected
      **/
      _joinURL: function (url) {
          var root = this.get('root');
  
          // Causes `url` to _always_ begin with a "/".
          url = this.removeRoot(url);
  
          if (url.charAt(0) === '/') {
              url = url.substring(1);
          }
  
          return root && root.charAt(root.length - 1) === '/' ?
                  root + url :
                  root + '/' + url;
      },
  
      /**
      Returns a normalized path, ridding it of any '..' segments and properly
      handling leading and trailing slashes.
  
      @method _normalizePath
      @param {String} path URL path to normalize.
      @return {String} Normalized path.
      @protected
      @since 3.5.0
      **/
      _normalizePath: function (path) {
          var dots  = '..',
              slash = '/',
              i, len, normalized, segments, segment, stack;
  
          if (!path || path === slash) {
              return slash;
          }
  
          segments = path.split(slash);
          stack    = [];
  
          for (i = 0, len = segments.length; i < len; ++i) {
              segment = segments[i];
  
              if (segment === dots) {
                  stack.pop();
              } else if (segment) {
                  stack.push(segment);
              }
          }
  
          normalized = slash + stack.join(slash);
  
          // Append trailing slash if necessary.
          if (normalized !== slash && path.charAt(path.length - 1) === slash) {
              normalized += slash;
          }
  
          return normalized;
      },
  
      /**
      Parses a URL query string into a key/value hash. If `Y.QueryString.parse` is
      available, this method will be an alias to that.
  
      @method _parseQuery
      @param {String} query Query string to parse.
      @return {Object} Hash of key/value pairs for query parameters.
      @protected
      **/
      _parseQuery: QS && QS.parse ? QS.parse : function (query) {
          var decode = this._decode,
              params = query.split('&'),
              i      = 0,
              len    = params.length,
              result = {},
              param;
  
          for (; i < len; ++i) {
              param = params[i].split('=');
  
              if (param[0]) {
                  result[decode(param[0])] = decode(param[1] || '');
              }
          }
  
          return result;
      },
  
      /**
      Queues up a `_save()` call to run after all previously-queued calls have
      finished.
  
      This is necessary because if we make multiple `_save()` calls before the
      first call gets dispatched, then both calls will dispatch to the last call's
      URL.
  
      All arguments passed to `_queue()` will be passed on to `_save()` when the
      queued function is executed.
  
      @method _queue
      @chainable
      @see _dequeue
      @protected
      **/
      _queue: function () {
          var args = arguments,
              self = this;
  
          saveQueue.push(function () {
              if (self._html5) {
                  if (Y.UA.ios && Y.UA.ios < 5) {
                      // iOS <5 has buggy HTML5 history support, and needs to be
                      // synchronous.
                      self._save.apply(self, args);
                  } else {
                      // Wrapped in a timeout to ensure that _save() calls are
                      // always processed asynchronously. This ensures consistency
                      // between HTML5- and hash-based history.
                      setTimeout(function () {
                          self._save.apply(self, args);
                      }, 1);
                  }
              } else {
                  self._dispatching = true; // otherwise we'll dequeue too quickly
                  self._save.apply(self, args);
              }
  
              return self;
          });
  
          return !this._dispatching ? this._dequeue() : this;
      },
  
      /**
      Returns the normalized result of resolving the `path` against the current
      path. Falsy values for `path` will return just the current path.
  
      @method _resolvePath
      @param {String} path URL path to resolve.
      @return {String} Resolved path.
      @protected
      @since 3.5.0
      **/
      _resolvePath: function (path) {
          if (!path) {
              return Y.getLocation().pathname;
          }
  
          if (path.charAt(0) !== '/') {
              path = this._getPathRoot() + path;
          }
  
          return this._normalizePath(path);
      },
  
      /**
      Resolves the specified URL against the current URL.
  
      This method resolves URLs like a browser does and will always return an
      absolute URL. When the specified URL is already absolute, it is assumed to
      be fully resolved and is simply returned as is. Scheme-relative URLs are
      prefixed with the current protocol. Relative URLs are giving the current
      URL's origin and are resolved and normalized against the current path root.
  
      @method _resolveURL
      @param {String} url URL to resolve.
      @return {String} Resolved URL.
      @protected
      @since 3.5.0
      **/
      _resolveURL: function (url) {
          var parts    = url && url.match(this._regexURL),
              origin, path, query, hash, resolved;
  
          if (!parts) {
              return Y.getLocation().toString();
          }
  
          origin = parts[1];
          path   = parts[2];
          query  = parts[3];
          hash   = parts[4];
  
          // Absolute and scheme-relative URLs are assumed to be fully-resolved.
          if (origin) {
              // Prepend the current scheme for scheme-relative URLs.
              if (origin.indexOf('//') === 0) {
                  origin = Y.getLocation().protocol + origin;
              }
  
              return origin + (path || '/') + (query || '') + (hash || '');
          }
  
          // Will default to the current origin and current path.
          resolved = this._getOrigin() + this._resolvePath(path);
  
          // A path or query for the specified URL trumps the current URL's.
          if (path || query) {
              return resolved + (query || '') + (hash || '');
          }
  
          query = this._getQuery();
  
          return resolved + (query ? ('?' + query) : '') + (hash || '');
      },
  
      /**
      Saves a history entry using either `pushState()` or the location hash.
  
      This method enforces the same-origin security constraint; attempting to save
      a `url` that is not from the same origin as the current URL will result in
      an error.
  
      @method _save
      @param {String} [url] URL for the history entry.
      @param {Boolean} [replace=false] If `true`, the current history entry will
        be replaced instead of a new one being added.
      @chainable
      @protected
      **/
      _save: function (url, replace) {
          var urlIsString = typeof url === 'string',
              currentPath, root, hash;
  
          // Perform same-origin check on the specified URL.
          if (urlIsString && !this._hasSameOrigin(url)) {
              Y.error('Security error: The new URL must be of the same origin as the current URL.');
              return this;
          }
  
          // Joins the `url` with the `root`.
          if (urlIsString) {
              url = this._joinURL(url);
          }
  
          // Force _ready to true to ensure that the history change is handled
          // even if _save is called before the `ready` event fires.
          this._ready = true;
  
          if (this._html5) {
              this._history[replace ? 'replace' : 'add'](null, {url: url});
          } else {
              currentPath = Y.getLocation().pathname;
              root        = this.get('root');
              hash        = HistoryHash.getHash();
  
              if (!urlIsString) {
                  url = hash;
              }
  
              // Determine if the `root` already exists in the current location's
              // `pathname`, and if it does then we can exclude it from the
              // hash-based path. No need to duplicate the info in the URL.
              if (root === currentPath || root === this._getPathRoot()) {
                  url = this.removeRoot(url);
              }
  
              // The `hashchange` event only fires when the new hash is actually
              // different. This makes sure we'll always dequeue and dispatch
              // _all_ router instances, mimicking the HTML5 behavior.
              if (url === hash) {
                  Y.Router.dispatch();
              } else {
                  HistoryHash[replace ? 'replaceHash' : 'setHash'](url);
              }
          }
  
          return this;
      },
  
      /**
      Setter for the `routes` attribute.
  
      @method _setRoutes
      @param {Object[]} routes Array of route objects.
      @return {Object[]} Array of route objects.
      @protected
      **/
      _setRoutes: function (routes) {
          this._routes = [];
  
          YArray.each(routes, function (route) {
              // Makes sure to check `callback` for back-compat.
              var callbacks = route.callbacks || route.callback;
  
              this.route(route.path, callbacks);
          }, this);
  
          return this._routes.concat();
      },
  
      /**
      Upgrades a hash-based URL to a full-path URL, if necessary.
  
      The specified `url` will be upgraded if its of the same origin as the
      current URL and has a path-like hash. URLs that don't need upgrading will be
      returned as-is.
  
      @example
          app._upgradeURL('http://example.com/#/foo/'); // => 'http://example.com/foo/';
  
      @method _upgradeURL
      @param {String} url The URL to upgrade from hash-based to full-path.
      @return {String} The upgraded URL, or the specified URL untouched.
      @protected
      @since 3.5.0
      **/
      _upgradeURL: function (url) {
          // We should not try to upgrade paths for external URLs.
          if (!this._hasSameOrigin(url)) {
              return url;
          }
  
          var hash       = (url.match(/#(.*)$/) || [])[1] || '',
              hashPrefix = Y.HistoryHash.hashPrefix,
              hashPath;
  
          // Strip any hash prefix, like hash-bangs.
          if (hashPrefix && hash.indexOf(hashPrefix) === 0) {
              hash = hash.replace(hashPrefix, '');
          }
  
          // If the hash looks like a URL path, assume it is, and upgrade it!
          if (hash) {
              hashPath = this._getHashPath(hash);
  
              if (hashPath) {
                  return this._resolveURL(hashPath);
              }
          }
  
          return url;
      },
  
      // -- Protected Event Handlers ---------------------------------------------
  
      /**
      Handles `history:change` and `hashchange` events.
  
      @method _afterHistoryChange
      @param {EventFacade} e
      @protected
      **/
      _afterHistoryChange: function (e) {
          var self       = this,
              src        = e.src,
              prevURL    = self._url,
              currentURL = self._getURL();
  
          self._url = currentURL;
  
          // Handles the awkwardness that is the `popstate` event. HTML5 browsers
          // fire `popstate` right before they fire `hashchange`, and Chrome fires
          // `popstate` on page load. If this router is not ready or the previous
          // and current URLs only differ by their hash, then we want to ignore
          // this `popstate` event.
          if (src === 'popstate' &&
                  (!self._ready || prevURL.replace(/#.*$/, '') === currentURL.replace(/#.*$/, ''))) {
  
              return;
          }
  
          self._dispatch(self._getPath(), currentURL, src);
      },
  
      // -- Default Event Handlers -----------------------------------------------
  
      /**
      Default handler for the `ready` event.
  
      @method _defReadyFn
      @param {EventFacade} e
      @protected
      **/
      _defReadyFn: function (e) {
          this._ready = true;
      }
  }, {
      // -- Static Properties ----------------------------------------------------
      NAME: 'router',
  
      ATTRS: {
          /**
          Whether or not this browser is capable of using HTML5 history.
  
          Setting this to `false` will force the use of hash-based history even on
          HTML5 browsers, but please don't do this unless you understand the
          consequences.
  
          @attribute html5
          @type Boolean
          @initOnly
          **/
          html5: {
              // Android versions lower than 3.0 are buggy and don't update
              // window.location after a pushState() call, so we fall back to
              // hash-based history for them.
              //
              // See http://code.google.com/p/android/issues/detail?id=17471
              valueFn: function () { return Y.Router.html5; },
              writeOnce: 'initOnly'
          },
  
          /**
          Absolute root path from which all routes should be evaluated.
  
          For example, if your router is running on a page at
          `http://example.com/myapp/` and you add a route with the path `/`, your
          route will never execute, because the path will always be preceded by
          `/myapp`. Setting `root` to `/myapp` would cause all routes to be
          evaluated relative to that root URL, so the `/` route would then execute
          when the user browses to `http://example.com/myapp/`.
  
          @attribute root
          @type String
          @default `''`
          **/
          root: {
              value: ''
          },
  
          /**
          Array of route objects.
  
          Each item in the array must be an object with the following properties:
  
            * `path`: String or regex representing the path to match. See the docs
              for the `route()` method for more details.
  
            * `callbacks`: Function or a string representing the name of a
              function on this router instance that should be called when the
              route is triggered. An array of functions and/or strings may also be
              provided. See the docs for the `route()` method for more details.
  
          This attribute is intended to be used to set routes at init time, or to
          completely reset all routes after init. To add routes after init without
          resetting all existing routes, use the `route()` method.
  
          @attribute routes
          @type Object[]
          @default `[]`
          @see route
          **/
          routes: {
              value : [],
              getter: '_getRoutes',
              setter: '_setRoutes'
          }
      },
  
      // Used as the default value for the `html5` attribute, and for testing.
      html5: Y.HistoryBase.html5 && (!Y.UA.android || Y.UA.android >= 3),
  
      // To make this testable.
      _instances: instances,
  
      /**
      Dispatches to the first route handler that matches the specified `path` for
      all active router instances.
  
      This provides a mechanism to cause all active router instances to dispatch
      to their route handlers without needing to change the URL or fire the
      `history:change` or `hashchange` event.
  
      @method dispatch
      @static
      @since 3.6.0
      **/
      dispatch: function () {
          var i, len, router;
  
          for (i = 0, len = instances.length; i < len; i += 1) {
              router = instances[i];
  
              if (router) {
                  router._dispatch(router._getPath(), router._getURL());
              }
          }
      }
  });
  
  /**
  The `Controller` class was deprecated in YUI 3.5.0 and is now an alias for the
  `Router` class. Use that class instead. This alias will be removed in a future
  version of YUI.
  
  @class Controller
  @constructor
  @extends Base
  @deprecated Use `Router` instead.
  @see Router
  **/
  Y.Controller = Y.Router;
  