Add Object::IsDirty function in the API.

Review URL: http://codereview.chromium.org/209013

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2911 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

include/v8.h

@@ -1238,6 +1238,15 @@ class V8EXPORT Object : public Value {
   bool SetHiddenValue(Handle<String> key, Handle<Value> value);
   Local<Value> GetHiddenValue(Handle<String> key);
   bool DeleteHiddenValue(Handle<String> key);
+  
+  /**
+   * Returns true if this is an instance of an api function (one
+   * created from a function created from a function template) and has
+   * been modified since it was created.  Note that this method is
+   * conservative and may return true for objects that haven't actually
+   * been modified.
+   */
+  bool IsDirty();
 
   /**
    * Clone this object with a fast but shallow copy.  Values will point

src/api.cc

@@ -2156,6 +2156,11 @@ void v8::Object::TurnOnAccessCheck() {
 }
 
 
+bool v8::Object::IsDirty() {
+  return Utils::OpenHandle(this)->IsDirty();
+}
+
+
 Local<v8::Object> v8::Object::Clone() {
   ON_BAILOUT("v8::Object::Clone()", return Local<Object>());
   ENTER_V8;

src/objects.cc

@@ -476,6 +476,21 @@ Object* JSObject::DeleteNormalizedProperty(String* name, DeleteMode mode) {
 }
 
 
+bool JSObject::IsDirty() {
+  Object* cons_obj = map()->constructor();
+  if (!cons_obj->IsJSFunction())
+    return true;
+  JSFunction* fun = JSFunction::cast(cons_obj);
+  if (!fun->shared()->function_data()->IsFunctionTemplateInfo())
+    return true;
+  // If the object is fully fast case and has the same map it was
+  // created with then no changes can have been made to it.
+  return map() != fun->initial_map()
+      || !HasFastElements()
+      || !HasFastProperties();
+}
+
+
 Object* Object::GetProperty(Object* receiver,
                             LookupResult* result,
                             String* name,

src/objects.h

@@ -1427,6 +1427,10 @@ class JSObject: public HeapObject {
 
   // Tells whether this object needs to be loaded.
   inline bool IsLoaded();
+  
+  // Returns true if this is an instance of an api function and has
+  // been modified since it was created.  May give false positives.
+  bool IsDirty();
 
   bool HasProperty(String* name) {
     return GetPropertyAttribute(name) != ABSENT;