Object.observe: generate change records for indexed properties.

src/elements.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 546 matching lines @@
 
   MUST_USE_RESULT static MaybeObject* GetImpl(Object* receiver,
                                               JSObject* obj,
                                               uint32_t key,
                                               BackingStore* backing_store) {
     return (key < ElementsAccessorSubclass::GetCapacityImpl(backing_store))
            ? backing_store->get(key)
            : backing_store->GetHeap()->the_hole_value();
   }
 
+  MUST_USE_RESULT virtual PropertyAttributes GetAttributes(
+      Object* receiver,
+      JSObject* holder,
+      uint32_t key,
+      FixedArrayBase* backing_store) {
+    if (backing_store == NULL) {
+      backing_store = holder->elements();
+    }
+    return ElementsAccessorSubclass::GetAttributesImpl(
+        receiver, holder, key, BackingStore::cast(backing_store));
+  }
+
+  MUST_USE_RESULT static PropertyAttributes GetAttributesImpl(
+        Object* receiver,
+        JSObject* obj,
+        uint32_t key,
+        BackingStore* backing_store) {
+    return (key < ElementsAccessorSubclass::GetCapacityImpl(backing_store))
+           ? NONE : ABSENT;

[rossberg, 2012/11/07 18:41:42]

That was wrong.

[Michael Starzinger, 2012/11/07 19:43:49]

Nice catch.

+  }
+
   MUST_USE_RESULT virtual MaybeObject* SetLength(JSArray* array,
                                                  Object* length) {
     return ElementsAccessorSubclass::SetLengthImpl(
         array, length, BackingStore::cast(array->elements()));
   }
 
   MUST_USE_RESULT static MaybeObject* SetLengthImpl(
       JSObject* obj,
       Object* length,
       BackingStore* backing_store);
@@ skipping 559 matching lines @@
   MUST_USE_RESULT static MaybeObject* GetImpl(Object* receiver,
                                               JSObject* obj,
                                               uint32_t key,
                                               BackingStore* backing_store) {
     return
         key < ExternalElementsAccessorSubclass::GetCapacityImpl(backing_store)
         ? backing_store->get(key)
         : backing_store->GetHeap()->undefined_value();
   }
 
+
+  MUST_USE_RESULT static PropertyAttributes GetAttributesImpl(
+      Object* receiver,
+      JSObject* obj,
+      uint32_t key,
+      BackingStore* backing_store) {
+    return
+        key < ExternalElementsAccessorSubclass::GetCapacityImpl(backing_store)
+        ? NONE : ABSENT;
+  }
+
   MUST_USE_RESULT static MaybeObject* SetLengthImpl(
       JSObject* obj,
       Object* length,
       BackingStore* backing_store) {
     // External arrays do not support changing their length.
     UNREACHABLE();
     return obj;
   }
 
   MUST_USE_RESULT virtual MaybeObject* Delete(JSObject* obj,
@@ skipping 268 matching lines @@
                                            element,
                                            key,
                                            obj);
       } else {
         return element;
       }
     }
     return obj->GetHeap()->the_hole_value();
   }
 
+  MUST_USE_RESULT static PropertyAttributes GetAttributesImpl(
+      Object* receiver,
+      JSObject* obj,
+      uint32_t key,
+      SeededNumberDictionary* backing_store) {
+    int entry = backing_store->FindEntry(key);
+    if (entry != SeededNumberDictionary::kNotFound)

[Michael Starzinger, 2012/11/07 11:47:48]

Curly brackets around body.

[rossberg, 2012/11/07 18:41:42]

Done.

+      return backing_store->DetailsAt(entry).attributes();
+    return ABSENT;
+  }
+
   static bool HasElementImpl(Object* receiver,
                              JSObject* holder,
                              uint32_t key,
                              SeededNumberDictionary* backing_store) {
     return backing_store->FindEntry(key) !=
         SeededNumberDictionary::kNotFound;
   }
 
   static uint32_t GetKeyForIndexImpl(SeededNumberDictionary* dict,
                                      uint32_t index) {
@@ skipping 39 matching lines @@
         Context* context = Context::cast(parameter_map->get(0));
         int context_index = entry->aliased_context_slot();
         ASSERT(!context->get(context_index)->IsTheHole());
         return context->get(context_index);
       } else {
         return result;
       }
     }
   }
 
+  MUST_USE_RESULT static PropertyAttributes GetAttributesImpl(
+      Object* receiver,
+      JSObject* obj,
+      uint32_t key,
+      FixedArray* parameter_map) {
+    // Aliased parameters and non-aliased elements in a fast backing store
+    // behave as FAST_ELEMENT.  Non-aliased elements in a dictionary
+    // backing store behave as DICTIONARY_ELEMENT.
+    uint32_t length = parameter_map->length();
+    Object* probe = key < (length - 2) ? parameter_map->get(key + 2) : NULL;

[Michael Starzinger, 2012/11/07 11:47:48]

Better use the GetParameterMapArg() helper for that to not duplicate this magic
throughout the code.

[rossberg, 2012/11/07 18:41:42]

Done.

+    if (probe != NULL && !probe->IsTheHole()) return NONE;
+    // If not aliased, check the arguments.
+    FixedArray* arguments = FixedArray::cast(parameter_map->get(1));
+    if (arguments->IsDictionary()) {

[Michael Starzinger, 2012/11/07 11:47:48]

Better delegate to the elements accessor for the underlying backing store.

[rossberg, 2012/11/07 18:41:42]

Done.

+      SeededNumberDictionary* dictionary =
+          SeededNumberDictionary::cast(arguments);
+      int entry = dictionary->FindEntry(key);
+      if (entry != SeededNumberDictionary::kNotFound)
+        return dictionary->DetailsAt(entry).attributes();
+    }
+    return ABSENT;
+  }
+
   MUST_USE_RESULT static MaybeObject* SetLengthImpl(
       JSObject* obj,
       Object* length,
       FixedArray* parameter_map) {
     // TODO(mstarzinger): This was never implemented but will be used once we
     // correctly implement [[DefineOwnProperty]] on arrays.
     UNIMPLEMENTED();
     return obj;
   }
 
@@ skipping 184 matching lines @@
   if (!maybe_obj->To(&new_backing_store)) return maybe_obj;
   new_backing_store->set(0, length);
   { MaybeObject* result = array->SetContent(new_backing_store);
     if (result->IsFailure()) return result;
   }
   return array;
 }
 
 
 } }  // namespace v8::internal