fix(router): allow router-link to link to redirects

Closes #3335

Closes #3624

modules/angular2/src/router/path_recognizer.ts

@@ -216,17 +216,17 @@ export class PathRecognizer {
     var captured = [];
 
     for (var i = 0; i < this._segments.length; i += 1) {
-      if (isBlank(nextSegment)) {
-        return null;
-      }
-      currentSegment = nextSegment;
-
       var segment = this._segments[i];
 
+      currentSegment = nextSegment;
       if (segment instanceof ContinuationSegment) {
         break;
       }
 
+      if (isBlank(currentSegment)) {
+        return null;
+      }
+
       captured.push(currentSegment.path);
 
       // the star segment consumes all of the remaining URL, including matrix params
@@ -251,18 +251,26 @@ export class PathRecognizer {
 
     var urlPath = captured.join('/');
 
-    // If this is the root component, read query params. Otherwise, read matrix params.
-    var paramsSegment = beginningSegment instanceof RootUrl ? beginningSegment : currentSegment;
+    var auxiliary;
+    var instruction: ComponentInstruction;
+    if (isPresent(currentSegment)) {
+      // If this is the root component, read query params. Otherwise, read matrix params.
+      var paramsSegment = beginningSegment instanceof RootUrl ? beginningSegment : currentSegment;
 
+      var allParams = isPresent(paramsSegment.params) ?
+                          StringMapWrapper.merge(paramsSegment.params, positionalParams) :
+                          positionalParams;
 
-    var allParams = isPresent(paramsSegment.params) ?
-                        StringMapWrapper.merge(paramsSegment.params, positionalParams) :
-                        positionalParams;
-    var urlParams = serializeParams(paramsSegment.params);
+      var urlParams = serializeParams(paramsSegment.params);
 
-    var instruction = new ComponentInstruction(urlPath, urlParams, this, allParams);
+      instruction = new ComponentInstruction(urlPath, urlParams, this, allParams);
 
-    return new PathMatch(instruction, nextSegment, currentSegment.auxiliary);
+      auxiliary = currentSegment.auxiliary;
+    } else {
+      instruction = new ComponentInstruction(urlPath, [], this, positionalParams);
+      auxiliary = [];
+    }
+    return new PathMatch(instruction, nextSegment, auxiliary);
   }
 
 

modules/angular2/src/router/route_registry.ts

@@ -33,7 +33,7 @@ import {
 import {reflector} from 'angular2/src/reflection/reflection';
 import {Injectable} from 'angular2/di';
 import {normalizeRouteConfig} from './route_config_nomalizer';
-import {parser, Url} from './url_parser';
+import {parser, Url, pathSegmentsToUrl} from './url_parser';
 
 var _resolveToNull = PromiseWrapper.resolve(null);
 
@@ -236,7 +236,8 @@ export class RouteRegistry {
       componentCursor = response.componentType;
     }
 
-    var instruction = null;
+    var instruction: Instruction = this._generateRedirects(componentCursor);
+
 
     while (segments.length > 0) {
       instruction = new Instruction(segments.pop(), instruction, {});
@@ -244,6 +245,38 @@ export class RouteRegistry {
 
     return instruction;
   }
+
+  // if the child includes a redirect like : "/" -> "/something",
+  // we want to honor that redirection when creating the link
+  private _generateRedirects(componentCursor: Type): Instruction {
+    if (isBlank(componentCursor)) {
+      return null;
+    }
+    var componentRecognizer = this._rules.get(componentCursor);
+    if (isBlank(componentRecognizer)) {
+      return null;
+    }
+
+    for (let i = 0; i < componentRecognizer.redirects.length; i += 1) {
+      let redirect = componentRecognizer.redirects[i];
+
+      // we only handle redirecting from an empty segment
+      if (redirect.segments.length == 1 && redirect.segments[0] == '') {
+        var toSegments = pathSegmentsToUrl(redirect.toSegments);
+        var matches = componentRecognizer.recognize(toSegments);
+        var primaryInstruction =
+            ListWrapper.maximum(matches, (match: PathMatch) => match.instruction.specificity);
+
+        if (isPresent(primaryInstruction)) {
+          var child = this._generateRedirects(primaryInstruction.instruction.componentType);
+          return new Instruction(primaryInstruction.instruction, child, {});
+        }
+        return null;
+      }
+    }
+
+    return null;
+  }
 }
 
 
@@ -251,20 +284,8 @@ export class RouteRegistry {
  * Given a list of instructions, returns the most specific instruction
  */
 function mostSpecific(instructions: List<PrimaryInstruction>): PrimaryInstruction {
-  if (instructions.length == 0) {
-    return null;
-  }
-  var mostSpecificSolution = instructions[0];
-  for (var solutionIndex = 1; solutionIndex < instructions.length; solutionIndex++) {
-    var solution: PrimaryInstruction = instructions[solutionIndex];
-    if (isBlank(solution)) {
-      continue;
-    }
-    if (solution.component.specificity > mostSpecificSolution.component.specificity) {
-      mostSpecificSolution = solution;
-    }
-  }
-  return mostSpecificSolution;
+  return ListWrapper.maximum(
+      instructions, (instruction: PrimaryInstruction) => instruction.component.specificity);
 }
 
 function assertTerminalComponent(component, path) {

modules/angular2/src/router/url_parser.ts

@@ -57,6 +57,14 @@ export class RootUrl extends Url {
   }
 }
 
+export function pathSegmentsToUrl(pathSegments: List<string>): Url {
+  var url = new Url(pathSegments[pathSegments.length - 1]);
+  for (var i = pathSegments.length - 2; i >= 0; i -= 1) {
+    url = new Url(pathSegments[i], url);
+  }
+  return url;
+}
+
 var SEGMENT_RE = RegExpWrapper.create('^[^\\/\\(\\)\\?;=&]+');
 function matchUrlSegment(str: string): string {
   var match = RegExpWrapper.firstMatch(SEGMENT_RE, str);

modules/angular2/test/router/route_registry_spec.ts

@@ -14,7 +14,13 @@ import {Promise, PromiseWrapper} from 'angular2/src/facade/async';
 import {Type} from 'angular2/src/facade/lang';
 
 import {RouteRegistry} from 'angular2/src/router/route_registry';
-import {RouteConfig, Route, AuxRoute, AsyncRoute} from 'angular2/src/router/route_config_decorator';
+import {
+  RouteConfig,
+  Route,
+  Redirect,
+  AuxRoute,
+  AsyncRoute
+} from 'angular2/src/router/route_config_decorator';
 import {stringifyInstruction} from 'angular2/src/router/instruction';
 import {IS_DART} from '../platform';
 
@@ -45,6 +51,24 @@ export function main() {
           .toEqual('second');
     });
 
+    it('should generate URLs that account for redirects', () => {
+      registry.config(
+          RootHostCmp,
+          new Route({path: '/first/...', component: DummyParentRedirectCmp, as: 'firstCmp'}));
+
+      expect(stringifyInstruction(registry.generate(['firstCmp'], RootHostCmp)))
+          .toEqual('first/second');
+    });
+
+    it('should generate URLs in a hierarchy of redirects', () => {
+      registry.config(
+          RootHostCmp,
+          new Route({path: '/first/...', component: DummyMultipleRedirectCmp, as: 'firstCmp'}));
+
+      expect(stringifyInstruction(registry.generate(['firstCmp'], RootHostCmp)))
+          .toEqual('first/second/third');
+    });
+
     it('should generate URLs with params', () => {
       registry.config(
           RootHostCmp,
@@ -255,6 +279,28 @@ class DummyAsyncCmp {
 class DummyCmpA {}
 class DummyCmpB {}
 
+@RouteConfig([
+  new Redirect({path: '/', redirectTo: '/third'}),
+  new Route({path: '/third', component: DummyCmpB, as: 'thirdCmp'})
+])
+class DummyRedirectCmp {
+}
+
+
+@RouteConfig([
+  new Redirect({path: '/', redirectTo: '/second'}),
+  new Route({path: '/second/...', component: DummyRedirectCmp, as: 'secondCmp'})
+])
+class DummyMultipleRedirectCmp {
+}
+
+@RouteConfig([
+  new Redirect({path: '/', redirectTo: '/second'}),
+  new Route({path: '/second', component: DummyCmpB, as: 'secondCmp'})
+])
+class DummyParentRedirectCmp {
+}
+
 @RouteConfig([new Route({path: '/second', component: DummyCmpB, as: 'secondCmp'})])
 class DummyParentCmp {
 }