chore(facade): add enum index lookup support

modules/angular2/src/facade/lang.dart

@@ -54,6 +54,11 @@ dynamic deserializeEnum(num val, Map<num, dynamic> values) {
   return values[val];
 }
 
+String resolveEnumToken(enumValue, val) {
+  // turn Enum.Token -> Token
+  return val.toString().replaceFirst(new RegExp('^.+\\.'),'');
+}
+
 class StringWrapper {
   static String fromCharCode(int code) {
     return new String.fromCharCode(code);

modules/angular2/src/facade/lang.ts

@@ -195,6 +195,10 @@ export function deserializeEnum(val, values: Map<number, any>): any {
   return val;
 }
 
+export function resolveEnumToken(enumValue, val): string {
+  return enumValue[val];
+}
+
 export class StringWrapper {
   static fromCharCode(code: number): string { return String.fromCharCode(code); }
 
@@ -468,4 +472,4 @@ export function isPrimitive(obj: any): boolean {
 
 export function hasConstructor(value: Object, type: Type): boolean {
   return value.constructor === type;
-}
+}

modules/angular2/test/facade/lang_spec.ts

@@ -5,9 +5,15 @@ import {
   RegExpMatcherWrapper,
   StringWrapper,
   CONST_EXPR,
-  hasConstructor
+  hasConstructor,
+  resolveEnumToken
 } from 'angular2/src/facade/lang';
 
+enum UsefulEnum {
+  MyToken,
+  MyOtherToken
+}
+
 class MySuperclass {}
 class MySubclass extends MySuperclass {}
 
@@ -124,6 +130,16 @@ export function main() {
       });
     });
 
+    describe('resolveEnumToken', () => {
+      it("should resolve a token given an enum and index values", () => {
+        var token = UsefulEnum.MyToken;
+        expect(resolveEnumToken(UsefulEnum, token)).toEqual('MyToken');
+
+        token = UsefulEnum.MyOtherToken;
+        expect(resolveEnumToken(UsefulEnum, token)).toEqual('MyOtherToken');
+      });
+    });
+
     describe('hasConstructor', () => {
       it("should be true when the type matches",
          () => { expect(hasConstructor(new MySuperclass(), MySuperclass)).toEqual(true); });