Object.observe: generate change records for indexed properties.

src/elements.cc

Index: src/elements.cc
diff --git a/src/elements.cc b/src/elements.cc
index 3d188291030ddc66ec5ffc8828d59376dd666c31..08b04de9d7cfec86e7534c99a34ca4db0e545af3 100644
--- a/src/elements.cc
+++ b/src/elements.cc
@@ -564,6 +564,27 @@ class ElementsAccessorBase : public ElementsAccessor {
            : 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(
@@ -1143,6 +1164,17 @@ class ExternalElementsAccessor
         : 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,
@@ -1431,6 +1463,17 @@ class DictionaryElementsAccessor
     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,
@@ -1490,6 +1533,29 @@ class NonStrictArgumentsElementsAccessor : public ElementsAccessorBase<
     }
   }
 
+  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,