feat(injector): add support for default bindings

Author: vsavkin

modules/di/src/injector.js

@@ -19,11 +19,12 @@ function _isWaiting(obj):boolean {
 
 
 export class Injector {
- constructor(bindings:List, parent:Injector = null) {
+ constructor(bindings:List, {parent=null, defaultBindings=false}={}) {
  var flatten = _flattenBindings(bindings, MapWrapper.create());
  this._bindings = this._createListOfBindings(flatten);
  this._instances = this._createInstances();
  this._parent = parent;
+ this._defaultBindings = defaultBindings;
 
  this._asyncStrategy = new _AsyncInjectorStrategy(this);
  this._syncStrategy = new _SyncInjectorStrategy(this);
@@ -38,7 +39,7 @@ export class Injector {
  }
 
  createChild(bindings:List):Injector {
- return new Injector(bindings, this);
+ return new Injector(bindings, {parent: this});
  }
 
 
@@ -92,8 +93,15 @@ export class Injector {
  }
 
  _getBinding(key:Key) {
- if (this._bindings.length <= key.id) return null;
- return ListWrapper.get(this._bindings, key.id);
+ var binding = this._bindings.length <= key.id ?
+ null :
+ ListWrapper.get(this._bindings, key.id);
+
+ if (isBlank(binding) && this._defaultBindings) {
+ return bind(key.token).toClass(key.token);
+ } else {
+ return binding;
+ }
  }
 
  _markAsConstructing(key:Key) {

modules/di/test/di/injector_spec.js

@@ -215,6 +215,25 @@ export function main() {
  expect(injector.get(Car)).toBeAnInstanceOf(Car);
  });
 
+ describe("default bindings", function () {
+ it("should be used when no matching binding found", function () {
+ var injector = new Injector([], {defaultBindings: true});
+
+ var car = injector.get(Car);
+
+ expect(car).toBeAnInstanceOf(Car);
+ });
+
+ it("should use the matching binding when it is available", function () {
+ var injector = new Injector([
+ bind(Car).toClass(SportsCar)
+ ], {defaultBindings: true});
+
+ var car = injector.get(Car);
+
+ expect(car).toBeAnInstanceOf(SportsCar);
+ });
+ });
 
  describe("child", function () {
  it('should load instances from parent injector', function () {
@@ -239,6 +258,17 @@ export function main() {
  expect(engineFromParent).not.toBe(engineFromChild);
  expect(engineFromChild).toBeAnInstanceOf(TurboEngine);
  });
+
+ it("should create child injectors without default bindings", function () {
+ var parent = new Injector([], {defaultBindings: true});
+ var child = parent.createChild([]);
+
+ //child delegates to parent the creation of Car
+ var childCar = child.get(Car);
+ var parentCar = parent.get(Car);
+
+ expect(childCar).toBe(parentCar);
+ });
  });
 
  describe("lazy", function () {

tools/transpiler/src/codegeneration/ClassTransformer.js

@@ -62,7 +62,7 @@ export class ClassTransformer extends ParseTreeTransformer {
  // so that we can use them to set the types of simple-assigned fields.
  elementTree.parameterList.parameters.forEach(function(p) {
  var binding = p.parameter.binding;
- if (binding.identifierToken) {
+ if (binding && binding.identifierToken) {
  argumentTypesMap[binding.identifierToken.value] = p.typeAnnotation;
  }
  });