Rolling forward https://codereview.chromium.org/1155683008/ which was

third_party/polymer/v0_8/components-chromium/more-routing/routing-extracted.js

-
-(function(scope) {
-var MoreRouting = scope.MoreRouting = scope.MoreRouting || {};
-
-// Route singletons.
-var routesByPath = {};
-var pathsByName  = {};
-
-// Route Management
-
-/**
- * Retrieves (or builds) the singleton `Route` for the given path expression or
- * route name.
- *
- * Paths begin with `/`; anything else is considered a name.
- *
- * For convenience, `Route` objects can also be passed (and will be returned) -
- * this can be used as a route coercion function.
- *
- * @param {String|MoreRouting.Route} pathOrName
- * @param {MoreRouting.Route} parent
- * @return {MoreRouting.Route}
- */
-MoreRouting.getRoute = function getRoute(pathOrName, parent) {
-  if (typeof pathOrName !== 'string') return pathOrName;
-  if (this.isPath(pathOrName)) {
-    return this.getRouteByPath(pathOrName, parent);
-  } else {
-    return this.getRouteByName(pathOrName);
-  }
-}
-
-/**
- * Retrieves (or builds) the singleton `Route` for the given path expression.
- *
- * @param {String} path
- * @param {MoreRouting.Route} parent
- * @return {MoreRouting.Route}
- */
-MoreRouting.getRouteByPath = function getRouteByPath(path, parent) {
-  var fullPath = (parent ? parent.fullPath : '') + path;
-  if (!routesByPath[fullPath]) {
-    routesByPath[fullPath] = new this.Route(path, parent);
-    this.driver.manageRoute(routesByPath[fullPath]);
-  }
-  return routesByPath[fullPath];
-}
-
-/**
- * Retrieves the route registered via `name`.
- *
- * @param {String} name
- * @return {MoreRouting.Route}
- */
-MoreRouting.getRouteByName = function getRouteByName(name) {
-  var path = pathsByName[name];
-  if (!path) {
-    throw new Error('No route named "' + name + '" has been registered');
-  }
-  return this.getRouteByPath(path);
-}
-
-/**
- * @param {String} path
- * @return {MoreRouting.Route} The newly registered route.
- */
-MoreRouting.registerNamedRoute = function registerNamedRoute(name, path, parent) {
-  if (pathsByName[name]) {
-    console.warn(
-        'Overwriting route named "' + name + '" with path:', path,
-        'previously:', pathsByName[name]);
-  }
-  var route = this.getRouteByPath(path, parent);
-  pathsByName[name] = route.fullPath;
-  return route;
-};
-
-// Route Shortcuts
-MoreRouting.urlFor = function urlFor(pathOrName, params) {
-  return this.getRoute(pathOrName).urlFor(params);
-};
-
-MoreRouting.navigateTo = function navigateTo(pathOrName, params) {
-  return this.getRoute(pathOrName).navigateTo(params);
-};
-
-MoreRouting.isCurrentUrl = function isCurrentUrl(pathOrName, params) {
-  return this.getRoute(pathOrName).isCurrentUrl(params);
-};
-
-// Utility
-
-/**
- *
- */
-MoreRouting.isPath = function isPath(pathOrName) {
-  return this.Route.isPath(pathOrName);
-}
-
-/**
- * @param {...String} paths
- */
-MoreRouting.joinPath = function joinPath(paths) {
-  return this.Route.joinPath.apply(this.Route, arguments);
-}
-
-// Driver Management
-
-var driver;
-Object.defineProperty(MoreRouting, 'driver', {
-  get: function getDriver() {
-    if (!driver) {
-      throw new Error('No routing driver configured. Did you forget <more-routing-config>?');
-    }
-    return driver;
-  },
-  set: function setDriver(newDriver) {
-    if (driver) {
-      console.warn('Changing routing drivers is not supported, ignoring. You should have only one <more-routing-config> on the page!');
-      return;
-    }
-    driver = newDriver;
-  }
-});
-
-})(window);