feat(di): added resolveAndInstantiate and instantiateResolved to Injector

These two methods can be used to create objects in the context of the injector without storing them in the injector.

Author: vsavkin

modules/angular2/src/di/binding.ts

@@ -400,9 +400,7 @@ function _extractToken(typeOrFunc, metadata /*List<any> | any*/, params: List<Li
   }
 
   var lowerBoundVisibility = null;
-  ;
   var upperBoundVisibility = null;
-  ;
 
   for (var i = 0; i < metadata.length; ++i) {
     var paramMetadata = metadata[i];

modules/angular2/src/di/injector.ts

@@ -552,11 +552,34 @@ export class Injector {
     return inj;
   }
 
+  /**
+   * Resolves a binding and instantiates an object in the context of the injector.
+   *
+   * @param `binding`: either a type or a binding.
+   * @returns an object created using binding.
+   */
+  resolveAndInstantiate(binding: Type | Binding) {
+    return this.instantiateResolved(Injector.resolve([binding])[0]);
+  }
+
+  /**
+   * Instantiates an object using a resolved bindin in the context of the injector.
+   *
+   * @param `binding`: a resolved binding
+   * @returns an object created using binding.
+   */
+  instantiateResolved(binding: ResolvedBinding): any {
+    return this._instantiate(binding, PUBLIC_AND_PRIVATE);
+  }
+
   _new(binding: ResolvedBinding, visibility: number): any {
     if (this._constructionCounter++ > this._strategy.getMaxNumberOfObjects()) {
       throw new CyclicDependencyError(this, binding.key);
     }
+    return this._instantiate(binding, visibility);
+  }
 
+  private _instantiate(binding: ResolvedBinding, visibility: number): any {
     var factory = binding.factory;
     var deps = binding.dependencies;
     var length = deps.length;

modules/angular2/test/di/injector_spec.ts

@@ -395,6 +395,29 @@ export function main() {
       });
     });
 
+    describe('resolveAndInstantiate', () => {
+      it('should instantiate an object in the context of the injector', () => {
+        var inj = Injector.resolveAndCreate([Engine]);
+        var car = inj.resolveAndInstantiate(Car);
+        expect(car).toBeAnInstanceOf(Car);
+        expect(car.engine).toBe(inj.get(Engine));
+      });
+
+      it('should not store the instantiated object in the injector', () => {
+        var inj = Injector.resolveAndCreate([Engine]);
+        inj.resolveAndInstantiate(Car);
+        expect(() => inj.get(Car)).toThrowError();
+      });
+    });
+
+    describe('instantiate', () => {
+      it('should instantiate an object in the context of the injector', () => {
+        var inj = Injector.resolveAndCreate([Engine]);
+        var car = inj.instantiateResolved(Injector.resolve([Car])[0]);
+        expect(car).toBeAnInstanceOf(Car);
+        expect(car.engine).toBe(inj.get(Engine));
+      });
+    });
 
     describe("depedency resolution", () => {
       describe("@Self()", () => {