refactor(change_detection): generate handleEvent only when necessary

modules/angular2/src/change_detection/abstract_change_detector.ts

@@ -67,7 +67,13 @@ export class AbstractChangeDetector<T> implements ChangeDetector {
   remove(): void { this.parent.removeChild(this); }
 
   handleEvent(eventName: string, elIndex: number, locals: Locals): boolean {
-    throw new BaseException("Not implemented");
+    var res = this.handleEventInternal(eventName, elIndex, locals);
+    this.markPathToRootAsCheckOnce();
+    return res;
+  }
+
+  handleEventInternal(eventName: string, elIndex: number, locals: Locals): boolean {
+    return false;
   }
 
   detectChanges(): void { this.runDetectChanges(false); }

modules/angular2/src/change_detection/change_detection_jit_generator.ts

@@ -50,13 +50,6 @@ export class ChangeDetectorJITGenerator {
 
       ${this._typeName}.prototype = Object.create(${ABSTRACT_CHANGE_DETECTOR}.prototype);
 
-      ${this._typeName}.prototype.handleEvent = function(eventName, elIndex, locals) {
-        var ${this._names.getPreventDefaultAccesor()} = false;
-        ${this._names.genInitEventLocals()}
-        ${this._genHandleEvent()}
-        return ${this._names.getPreventDefaultAccesor()};
-      }
-
       ${this._typeName}.prototype.detectChangesInRecordsInternal = function(throwOnChange) {
         ${this._names.genInitLocals()}
         var ${IS_CHANGED_LOCAL} = false;
@@ -67,6 +60,8 @@ export class ChangeDetectorJITGenerator {
         ${this._names.getAlreadyCheckedName()} = true;
       }
 
+      ${this._maybeGenHandleEventInternal()}
+
       ${this._genCheckNoChanges()}
 
       ${this._maybeGenCallOnAllChangesDone()}
@@ -84,8 +79,20 @@ export class ChangeDetectorJITGenerator {
         AbstractChangeDetector, ChangeDetectionUtil, this.records, this.directiveRecords);
   }
 
-  _genHandleEvent(): string {
-    return this.eventBindings.map(eb => this._genEventBinding(eb)).join("\n");
+  _maybeGenHandleEventInternal(): string {
+    if (this.eventBindings.length > 0) {
+      var handlers = this.eventBindings.map(eb => this._genEventBinding(eb)).join("\n");
+      return `
+        ${this._typeName}.prototype.handleEvent = function(eventName, elIndex, locals) {
+          var ${this._names.getPreventDefaultAccesor()} = false;
+          ${this._names.genInitEventLocals()}
+          ${handlers}
+          return ${this._names.getPreventDefaultAccesor()};
+        }
+      `;
+    } else {
+      return '';
+    }
   }
 
   _genEventBinding(eb: EventBinding): string {

modules/angular2/src/change_detection/dynamic_change_detector.ts

@@ -31,7 +31,7 @@ export class DynamicChangeDetector extends AbstractChangeDetector<any> {
     this.dehydrateDirectives(false);
   }
 
-  handleEvent(eventName: string, elIndex: number, locals: Locals): boolean {
+  handleEventInternal(eventName: string, elIndex: number, locals: Locals): boolean {
     var preventDefault = false;
 
     this._matchingEventBindings(eventName, elIndex)
@@ -41,6 +41,7 @@ export class DynamicChangeDetector extends AbstractChangeDetector<any> {
             preventDefault = true;
           }
         });
+
     return preventDefault;
   }
 

modules/angular2/src/transform/template_compiler/change_detector_codegen.dart

@@ -125,13 +125,6 @@ class _CodegenState {
           dehydrateDirectives(false);
         }
 
-        bool handleEvent(eventName, elIndex, locals) {
-          var ${_names.getPreventDefaultAccesor()} = false;
-          ${_names.genInitEventLocals()}
-          ${_genHandleEvent()}
-          return ${this._names.getPreventDefaultAccesor()};
-        }
-
         void detectChangesInRecordsInternal(throwOnChange) {
           ${_names.genInitLocals()}
           var $_IS_CHANGED_LOCAL = false;
@@ -142,6 +135,8 @@ class _CodegenState {
           ${_names.getAlreadyCheckedName()} = true;
         }
 
+        ${_maybeGenHandleEventInternal()}
+
         ${_genCheckNoChanges()}
 
         ${_maybeGenCallOnAllChangesDone()}
@@ -161,8 +156,20 @@ class _CodegenState {
     ''');
   }
 
-  String _genHandleEvent() {
-    return _eventBindings.map((eb) => _genEventBinding(eb)).join("\n");
+  String _maybeGenHandleEventInternal() {
+    if (_eventBindings.length > 0) {
+      var handlers = _eventBindings.map((eb) => _genEventBinding(eb)).join("\n");
+      return '''
+        handleEventInternal(eventName, elIndex, locals) {
+          var ${this._names.getPreventDefaultAccesor()} = false;
+          ${this._names.genInitEventLocals()}
+          ${handlers}
+          return ${this._names.getPreventDefaultAccesor()};
+        }
+      ''';
+    } else {
+      return '';
+    }
   }
 
   String _genEventBinding(EventBinding eb) {

modules/angular2/test/change_detection/change_detector_spec.ts

@@ -899,6 +899,7 @@ export function main() {
           res = val.changeDetector.handleEvent("event", 0, locals);
           expect(res).toBe(false);
         });
+
       });
     });
   });

modules/angular2/test/transform/integration/two_annotations_files/expected/bar.ng_deps.dart

@@ -36,11 +36,6 @@ class _MyComponent_ChangeDetector0
     dehydrateDirectives(false);
   }
 
-  bool handleEvent(eventName, elIndex, locals) {
-    var preventDefault = false;
-    return preventDefault;
-  }
-
   void detectChangesInRecordsInternal(throwOnChange) {
     var l_context = this.context, l_myNum0, c_myNum0, l_interpolate1;
     c_myNum0 = false;