fix(router): redirect should not add unnecessary brackets

modules/@angular/router/index.ts

@@ -12,6 +12,9 @@ import {RouterOutlet} from './src/directives/router_outlet';
 
 export {ExtraOptions} from './src/common_router_providers';
 export {Data, ResolveData, Route, RouterConfig} from './src/config';
+export {RouterLink, RouterLinkWithHref} from './src/directives/router_link';
+export {RouterLinkActive} from './src/directives/router_link_active';
+export {RouterOutlet} from './src/directives/router_outlet';
 export {CanActivate, CanDeactivate, Resolve} from './src/interfaces';
 export {Event, NavigationCancel, NavigationEnd, NavigationError, NavigationStart, Router, RoutesRecognized} from './src/router';
 export {RouterOutletMap} from './src/router_outlet_map';
@@ -19,9 +22,7 @@ export {provideRouter} from './src/router_providers';
 export {ActivatedRoute, ActivatedRouteSnapshot, RouterState, RouterStateSnapshot} from './src/router_state';
 export {PRIMARY_OUTLET, Params} from './src/shared';
 export {DefaultUrlSerializer, UrlPathWithParams, UrlSerializer, UrlTree} from './src/url_tree';
-export {RouterLink, RouterLinkWithHref} from './src/directives/router_link';
-export {RouterLinkActive} from './src/directives/router_link_active';
-export {RouterOutlet} from './src/directives/router_outlet';
+
 
 
 /**

modules/@angular/router/src/apply_redirects.ts

@@ -235,19 +235,28 @@ function split(
     const s = new UrlSegment(
         consumedPaths,
         createChildrenForEmptyPaths(config, new UrlSegment(slicedPath, segment.children)));
-    return {segment: s, slicedPath: []};
+    return {segment: mergeTrivialChildren(s), slicedPath: []};
 
   } else if (slicedPath.length === 0 && containsEmptyPathRedirects(segment, slicedPath, config)) {
     const s = new UrlSegment(
         segment.pathsWithParams,
         addEmptyPathsToChildrenIfNeeded(segment, slicedPath, config, segment.children));
-    return {segment: s, slicedPath};
+    return {segment: mergeTrivialChildren(s), slicedPath};
 
   } else {
     return {segment, slicedPath};
   }
 }
 
+function mergeTrivialChildren(s: UrlSegment): UrlSegment {
+  if (s.numberOfChildren === 1 && s.children[PRIMARY_OUTLET]) {
+    const c = s.children[PRIMARY_OUTLET];
+    return new UrlSegment(s.pathsWithParams.concat(c.pathsWithParams), c.children);
+  } else {
+    return s;
+  }
+}
+
 function addEmptyPathsToChildrenIfNeeded(
     segment: UrlSegment, slicedPath: UrlPathWithParams[], routes: Route[],
     children: {[name: string]: UrlSegment}): {[name: string]: UrlSegment} {

modules/@angular/router/src/url_tree.ts

@@ -96,7 +96,15 @@ export class UrlSegment {
     forEach(children, (v: any, k: any) => v.parent = this);
   }
 
-  hasChildren(): boolean { return Object.keys(this.children).length > 0; }
+  /**
+   * Return true if the segment has child segments
+   */
+  hasChildren(): boolean { return this.numberOfChildren > 0; }
+
+  /**
+   * Returns the number of child sements.
+   */
+  get numberOfChildren(): number { return Object.keys(this.children).length; }
 
   toString(): string { return serializePaths(this); }
 }

modules/@angular/router/test/apply_redirects.spec.ts

@@ -187,7 +187,7 @@ describe('applyRedirects', () => {
             },
             {path: '', redirectTo: 'a'}
           ],
-          '', (t: UrlTree) => { compareTrees(t, tree('a/(b)')); });
+          '', (t: UrlTree) => { compareTrees(t, tree('a/b')); });
     });
 
     it('redirect to an empty path should work', () => {