refactor(UrlResolver): extract app url resolution into AppRootUrl

fixes #1732

modules/angular2/src/core/application.ts

@@ -44,6 +44,7 @@ import {ComponentUrlMapper} from 'angular2/src/core/compiler/component_url_mappe
 import {UrlResolver} from 'angular2/src/services/url_resolver';
 import {StyleUrlResolver} from 'angular2/src/render/dom/shadow_dom/style_url_resolver';
 import {StyleInliner} from 'angular2/src/render/dom/shadow_dom/style_inliner';
+import {AppRootUrl} from 'angular2/src/services/app_root_url';
 import {
   ComponentRef,
   DynamicComponentLoader
@@ -133,7 +134,8 @@ function _injectorBindings(appComponentType): List<Type | Binding | List<any>> {
     StyleUrlResolver,
     StyleInliner,
     DynamicComponentLoader,
-    Testability
+    Testability,
+    AppRootUrl
   ];
 }
 

modules/angular2/src/core/compiler/compiler.ts

@@ -23,6 +23,7 @@ import {View} from '../annotations_impl/view';
 import {ComponentUrlMapper} from './component_url_mapper';
 import {ProtoViewFactory} from './proto_view_factory';
 import {UrlResolver} from 'angular2/src/services/url_resolver';
+import {AppRootUrl} from 'angular2/src/services/app_root_url';
 
 import * as renderApi from 'angular2/src/render/api';
 
@@ -74,14 +75,15 @@ export class Compiler {
 
   constructor(reader: DirectiveResolver, cache: CompilerCache, templateResolver: TemplateResolver,
               componentUrlMapper: ComponentUrlMapper, urlResolver: UrlResolver,
-              render: renderApi.RenderCompiler, protoViewFactory: ProtoViewFactory) {
+              render: renderApi.RenderCompiler, protoViewFactory: ProtoViewFactory,
+              appUrl: AppRootUrl) {
     this._reader = reader;
     this._compilerCache = cache;
     this._compiling = new Map();
     this._templateResolver = templateResolver;
     this._componentUrlMapper = componentUrlMapper;
     this._urlResolver = urlResolver;
-    this._appUrl = urlResolver.resolve(null, './');
+    this._appUrl = appUrl.value;
     this._render = render;
     this._protoViewFactory = protoViewFactory;
   }

modules/angular2/src/services/app_root_url.ts

@@ -0,0 +1,18 @@
+import {Injectable} from 'angular2/di';
+import {isBlank} from 'angular2/src/facade/lang';
+import {DOM} from 'angular2/src/dom/dom_adapter';
+
+@Injectable()
+export class AppRootUrl {
+  private _value: string;
+
+  get value() {
+    if (isBlank(this._value)) {
+      var a = DOM.createElement('a');
+      DOM.resolveAndSetHref(a, './', null);
+      this._value = DOM.getHref(a);
+    }
+
+    return this._value;
+  }
+}

modules/angular2/src/services/url_resolver.ts

@@ -13,17 +13,7 @@ export class UrlResolver {
   }
 
   /**
-   * Resolves the `url` given the `baseUrl`.
-   *
-   * ## When the `baseUrl` is null
-   *
-   * `url` is resolved in the context of the current document.
-   * If the document location is 'http://www.foo.com/base' and the `url` is 'path/to/here', the
-   * resolved url will be
-   * 'http://www.foo.com/base/path/to/here'
-   *
-   * ## When the `baseUrl` is not null
-   *
+   * Resolves the `url` given the `baseUrl`:
    * - when the `url` is null, the `baseUrl` is returned,
    * - due to a limitation in the process used to resolve urls (a HTMLLinkElement), `url` must not
    * start with a `/`,
@@ -37,11 +27,6 @@ export class UrlResolver {
    * @returns {string} the resolved URL
    */
   resolve(baseUrl: string, url: string): string {
-    if (isBlank(baseUrl)) {
-      DOM.resolveAndSetHref(UrlResolver.a, url, null);
-      return DOM.getHref(UrlResolver.a);
-    }
-
     if (isBlank(url) || url == '') return baseUrl;
 
     if (url[0] == '/') {

modules/angular2/src/test_lib/test_injector.ts

@@ -22,6 +22,7 @@ import {
 import {XHR} from 'angular2/src/render/xhr';
 import {ComponentUrlMapper} from 'angular2/src/core/compiler/component_url_mapper';
 import {UrlResolver} from 'angular2/src/services/url_resolver';
+import {AppRootUrl} from 'angular2/src/services/app_root_url';
 import {StyleUrlResolver} from 'angular2/src/render/dom/shadow_dom/style_url_resolver';
 import {StyleInliner} from 'angular2/src/render/dom/shadow_dom/style_inliner';
 import {NgZone} from 'angular2/src/core/zone/ng_zone';
@@ -115,6 +116,7 @@ function _getAppBindings() {
     bind(XHR).toClass(MockXHR),
     ComponentUrlMapper,
     UrlResolver,
+    AppRootUrl,
     StyleUrlResolver,
     StyleInliner,
     TestBed,