Object.observe: notify of __proto__ changes

src/accessors.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 740 matching lines @@
   ReadOnlySetAccessor,
   0
 };
 
 
 //
 // Accessors::ObjectPrototype
 //
 
 
-MaybeObject* Accessors::ObjectGetPrototype(Object* receiver, void*) {
+static inline Object* GetPrototypeSkipHiddenPrototypes(Object* receiver) {
   Object* current = receiver->GetPrototype();
   while (current->IsJSObject() &&
          JSObject::cast(current)->map()->is_hidden_prototype()) {
     current = current->GetPrototype();
   }
   return current;
 }
 
 
-MaybeObject* Accessors::ObjectSetPrototype(JSObject* receiver,
-                                           Object* value,
-                                           void*) {
-  const bool skip_hidden_prototypes = true;
-  // To be consistent with other Set functions, return the value.
-  return receiver->SetPrototype(value, skip_hidden_prototypes);
+MaybeObject* Accessors::ObjectGetPrototype(Object* receiver, void*) {
+  return GetPrototypeSkipHiddenPrototypes(receiver);
 }
 
 
+MaybeObject* Accessors::ObjectSetPrototype(JSObject* receiver_raw,
+                                           Object* value_raw,
+                                           void*) {
+  const bool kSkipHiddenPrototypes = true;
+  // To be consistent with other Set functions, return the value.
+  if (!(FLAG_harmony_observation && receiver_raw->map()->is_observed()))
+    return receiver_raw->SetPrototype(value_raw, kSkipHiddenPrototypes);
+
+  Isolate* isolate = receiver_raw->GetIsolate();
+  HandleScope scope(isolate);
+  Handle<JSObject> receiver(receiver_raw);
+  Handle<Object> value(value_raw);
+  Handle<Object> old_value(GetPrototypeSkipHiddenPrototypes(*receiver));
+
+  MaybeObject* result = receiver->SetPrototype(*value, kSkipHiddenPrototypes);
+  Handle<Object> hresult;
+  if (!result->ToHandle(&hresult, isolate)) return result;
+
+  Handle<Object> new_value(GetPrototypeSkipHiddenPrototypes(*receiver));
+  if (!new_value->SameValue(*old_value)) {
+    JSObject::EnqueueChangeRecord(receiver, "prototype",
+                                  isolate->factory()->Proto_symbol(),
+                                  old_value);
+  }
+  return *hresult;
+}
+
+
 const AccessorDescriptor Accessors::ObjectPrototype = {
   ObjectGetPrototype,
   ObjectSetPrototype,
   0
 };
 
 
 //
 // Accessors::MakeModuleExport
 //
@@ skipping 52 matching lines @@
   info->set_data(Smi::FromInt(index));
   Handle<Object> getter = v8::FromCData(&ModuleGetExport);
   Handle<Object> setter = v8::FromCData(&ModuleSetExport);
   info->set_getter(*getter);
   if (!(attributes & ReadOnly)) info->set_setter(*setter);
   return info;
 }
 
 
 } }  // namespace v8::internal