feat(router): extend support for lazy loading children (#10705)

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

@@ -6,12 +6,14 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {ComponentFactoryResolver, Injector, NgModuleFactoryLoader, OpaqueToken} from '@angular/core';
+import {Compiler, ComponentFactoryResolver, Injector, NgModuleFactory, NgModuleFactoryLoader, OpaqueToken} from '@angular/core';
 import {Observable} from 'rxjs/Observable';
 import {fromPromise} from 'rxjs/observable/fromPromise';
+import {of } from 'rxjs/observable/of';
+
+import {LoadChildren, Route} from './config';
+import {flatten, wrapIntoObservable} from './utils/collection';
 
-import {Route} from './config';
-import {flatten} from './utils/collection';
 
 
 /**
@@ -27,13 +29,24 @@ export class LoadedRouterConfig {
 }
 
 export class RouterConfigLoader {
-  constructor(private loader: NgModuleFactoryLoader) {}
+  constructor(private loader: NgModuleFactoryLoader, private compiler: Compiler) {}
 
-  load(parentInjector: Injector, path: string): Observable<LoadedRouterConfig> {
-    return fromPromise(this.loader.load(path).then(r => {
+  load(parentInjector: Injector, loadChildren: LoadChildren): Observable<LoadedRouterConfig> {
+    return this.loadModuleFactory(loadChildren).map(r => {
       const ref = r.create(parentInjector);
       return new LoadedRouterConfig(
           flatten(ref.injector.get(ROUTES)), ref.injector, ref.componentFactoryResolver);
-    }));
+    });
   }
-}
+
+  private loadModuleFactory(loadChildren: LoadChildren): Observable<NgModuleFactory<any>> {
+    if (typeof loadChildren === 'string') {
+      return fromPromise(this.loader.load(loadChildren));
+    } else {
+      const offlineMode = this.compiler instanceof Compiler;
+      return wrapIntoObservable(loadChildren())
+          .mergeMap(
+              t => offlineMode ? of (<any>t) : fromPromise(this.compiler.compileModuleAsync(t)));
+    }
+  }
+}