named routes in angular (directive and filter)

namedRoutes.js

'use strict';

(function (angular) {
  function tokenToRegExp(token) {
    return new RegExp(':(' + token + ')(?:\\(([^\\(]+)\\))?');
  }

  angular.module('fdNamedRoutes', [])

    .provider('namedRouteProvider', ['$locationProvider', function namedRouteProvider($locationProvider) {
      this.$get = ['$route', function ($route) {
        var prefix = !$locationProvider.html5Mode() ? '#' + $locationProvider.hashPrefix() : '';
        var namedRoutes = Object.keys($route.routes).reduce(function (obj, key) {
          var route = $route.routes[key];

          if (route.name) {
            if (obj[route.name]) throw new Error('A route named "' + route.name + '" exists');
            obj[route.name] = route;
          }

          return obj;
        }, {});

        function generate(routeName, routeParams) {
          var route = namedRoutes[routeName],
              tokens = routeParams ? Object.keys(routeParams) : null;

          if (!route) throw new Error('Route "' + name + '" not found');

          var url = !tokens ? route.originalPath : tokens.reduce(function (route, token) {
            return route.replace(tokenToRegExp(token), routeParams[token]);
          }, route.originalPath);

          return prefix + url;
        }

        return generate;
      }];

      return this;
    }])

    .filter('url', ['namedRouteProvider', function urlFilter(namedRouteProvider) {
      function filter(routeParams, routeName) {
        return namedRouteProvider(routeName, routeParams);
      }

      return filter;
    }])

    .directive('link', ['namedRouteProvider', function linkDirective(namedRouteProvider) {
      return {
        link: function ($scope, ele, attr) {
          var routeName = attr.link,
              routeParams = {};

          for (var key in attr) {
            if (attr.hasOwnProperty(key) && /link\w+$/.test(key)) {
              routeParams[key.slice(4).toLowerCase()] = attr[key];
            }
          }

          ele.attr('href', namedRouteProvider(routeName, routeParams));
        }
      };
    }]);
})(window.angular);