fix(life_cycle): remove cyclic dependency

fixes angular#477

Closes angular#530

Author: Bertrand Laporte

modules/angular2/src/core/application.js

@@ -78,7 +78,7 @@ function _injectorBindings(appComponentType) {
           [appViewToken]),
       bind(appComponentType).toFactory((rootView) => rootView.elementInjectors[0].getComponent(),
           [appViewToken]),
-      bind(LifeCycle).toFactory((cd) => new LifeCycle(cd, assertionsEnabled()), [appChangeDetectorToken])
+      bind(LifeCycle).toFactory(() => new LifeCycle(null, assertionsEnabled()),[])
   ];
 }
 
@@ -108,9 +108,11 @@ export function bootstrap(appComponentType: Type, bindings=null, givenBootstrapE
 
     var appInjector = _createAppInjector(appComponentType, bindings);
 
-    PromiseWrapper.then(appInjector.asyncGet(LifeCycle),
-      (lc) => {
-        lc.registerWith(zone);
+    PromiseWrapper.then(appInjector.asyncGet(appViewToken),
+      (rootView) => {
+        // retrieve life cycle: may have already been created if injected in root component
+        var lc=appInjector.get(LifeCycle); 
+        lc.registerWith(zone, rootView.changeDetector);
         lc.tick(); //the first tick that will bootstrap the app
 
         bootstrapProcess.complete(appInjector);

modules/angular2/src/core/life_cycle/life_cycle.js

@@ -2,24 +2,29 @@ import {FIELD, print} from 'angular2/src/facade/lang';
 import {ChangeDetector} from 'angular2/change_detection';
 import {VmTurnZone} from 'angular2/src/core/zone/vm_turn_zone';
 import {ListWrapper} from 'angular2/src/facade/collection';
+import {isPresent} from 'angular2/src/facade/lang';
 
 export class LifeCycle {
   _changeDetector:ChangeDetector;
   _enforceNoNewChanges:boolean;
 
-  constructor(changeDetector:ChangeDetector, enforceNoNewChanges:boolean = false) {
-    this._changeDetector = changeDetector;
+  constructor(changeDetector:ChangeDetector = null, enforceNoNewChanges:boolean = false) {
+    this._changeDetector = changeDetector; // may be null when instantiated from application bootstrap
     this._enforceNoNewChanges = enforceNoNewChanges;
   }
 
-  registerWith(zone:VmTurnZone) {
+  registerWith(zone:VmTurnZone, changeDetector:ChangeDetector = null) {
     // temporary error handler, we should inject one
     var errorHandler = (exception, stackTrace) => {
       var longStackTrace = ListWrapper.join(stackTrace, "\n\n-----async gap-----\n");
       print(`${exception}\n\n${longStackTrace}`);
       throw exception;
     };
 
+    if (isPresent(changeDetector)) {
+      this._changeDetector=changeDetector;
+    }
+
     zone.initCallbacks({
       onErrorHandler: errorHandler,
       onTurnDone: () => this.tick()
@@ -32,4 +37,4 @@ export class LifeCycle {
       this._changeDetector.checkNoChanges();
     }
   }
-}
+}

modules/angular2/test/core/application_spec.js

@@ -7,6 +7,7 @@ import {ListWrapper} from 'angular2/src/facade/collection';
 import {PromiseWrapper} from 'angular2/src/facade/async';
 import {bind, Inject} from 'angular2/di';
 import {TemplateConfig} from 'angular2/src/core/annotations/template_config';
+import {LifeCycle} from 'angular2/src/core/life_cycle/life_cycle';
 
 @Component({
   selector: 'hello-app',
@@ -51,6 +52,21 @@ class HelloRootCmp3 {
   }
 }
 
+@Component({
+  selector: 'hello-app',
+  template: new TemplateConfig({
+    inline: '',
+    directives: []
+  })
+})
+class HelloRootCmp4 {
+  lc;
+
+  constructor(@Inject(LifeCycle) lc) {
+    this.lc = lc;
+  }
+}
+
 export function main() {
   var fakeDoc, el, el2, testBindings;
 
@@ -126,5 +142,14 @@ export function main() {
         done();
       });
     });
+
+    it("should avoid cyclic dependencies when root component requires Lifecycle through DI", (done) => {
+      var injectorPromise = bootstrap(HelloRootCmp4, testBindings);
+
+      injectorPromise.then((injector) => {
+        expect(injector.get(HelloRootCmp4).lc).toBe(injector.get(LifeCycle));
+        done();
+      });
+    });
   });
 }