feat(router): add a function to resolve components

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

@@ -0,0 +1,28 @@
+import { RouterStateCandidate, ActivatedRouteCandidate } from './router_state';
+import { TreeNode } from './utils/tree';
+import { ComponentResolver } from '@angular/core';
+import { Observable } from 'rxjs/Observable';
+import 'rxjs/add/operator/map';
+import {forkJoin} from 'rxjs/observable/forkJoin';
+import {fromPromise} from 'rxjs/observable/fromPromise';
+import 'rxjs/add/operator/toPromise';
+
+export function resolve(resolver: ComponentResolver, state: RouterStateCandidate): Observable<RouterStateCandidate> {
+  return resolveNode(resolver, state._root).map(_ => state);
+}
+
+function resolveNode(resolver: ComponentResolver, node: TreeNode<ActivatedRouteCandidate>): Observable<any> {
+  if (node.children.length === 0) {
+    return fromPromise(resolver.resolveComponent(<any>node.value.component).then(factory => {
+      node.value._resolvedComponentFactory = factory;
+      return node.value;
+    }));
+    
+  } else {
+    const c = node.children.map(c => resolveNode(resolver, c).toPromise());
+    return forkJoin(c).map(_ => resolver.resolveComponent(<any>node.value.component).then(factory => {
+      node.value._resolvedComponentFactory = factory;
+      return node.value;
+    }));
+  }
+}