Add v8::Object::GetRealNamedPropertyAttributes()

Add v8::Object::GetRealNamedPropertyAttributes() and
v8::Object::GetRealNamedPropertyAttributesInPrototypeChain().

See nodejs/node#864 for background.

Review URL: https://codereview.chromium.org/942003003

Cr-Commit-Position: refs/heads/master@{#26855}

Author: ben

include/v8.h

@@ -2617,13 +2617,28 @@ class V8_EXPORT Object : public Value {
    */
   Local<Value> GetRealNamedPropertyInPrototypeChain(Handle<String> key);
 
+  /**
+   * Gets the property attributes of a real property in the prototype chain,
+   * which can be None or any combination of ReadOnly, DontEnum and DontDelete.
+   * Interceptors in the prototype chain are not called.
+   */
+  Maybe<PropertyAttribute> GetRealNamedPropertyAttributesInPrototypeChain(
+      Handle<String> key);
+
   /**
    * If result.IsEmpty() no real property was located on the object or
    * in the prototype chain.
    * This means interceptors in the prototype chain are not called.
    */
   Local<Value> GetRealNamedProperty(Handle<String> key);
 
+  /**
+   * Gets the property attributes of a real property which can be
+   * None or any combination of ReadOnly, DontEnum and DontDelete.
+   * Interceptors in the prototype chain are not called.
+   */
+  Maybe<PropertyAttribute> GetRealNamedPropertyAttributes(Handle<String> key);
+
   /** Tests for a named lookup interceptor.*/
   bool HasNamedLookupInterceptor();
 

src/api.cc

@@ -3756,6 +3756,14 @@ static Local<Value> GetPropertyByLookup(i::LookupIterator* it) {
 }
 
 
+static Maybe<PropertyAttribute> GetPropertyAttributesByLookup(
+    i::LookupIterator* it) {
+  Maybe<PropertyAttributes> attr = i::JSReceiver::GetPropertyAttributes(it);
+  if (!it->IsFound()) return Maybe<PropertyAttribute>();
+  return Maybe<PropertyAttribute>(static_cast<PropertyAttribute>(attr.value));
+}
+
+
 Local<Value> v8::Object::GetRealNamedPropertyInPrototypeChain(
     Handle<String> key) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
@@ -3774,6 +3782,24 @@ Local<Value> v8::Object::GetRealNamedPropertyInPrototypeChain(
 }
 
 
+Maybe<PropertyAttribute>
+v8::Object::GetRealNamedPropertyAttributesInPrototypeChain(Handle<String> key) {
+  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
+  ON_BAILOUT(isolate,
+             "v8::Object::GetRealNamedPropertyAttributesInPrototypeChain()",
+             return Maybe<PropertyAttribute>());
+  ENTER_V8(isolate);
+  i::Handle<i::JSObject> self_obj = Utils::OpenHandle(this);
+  i::Handle<i::String> key_obj = Utils::OpenHandle(*key);
+  i::PrototypeIterator iter(isolate, self_obj);
+  if (iter.IsAtEnd()) return Maybe<PropertyAttribute>();
+  i::Handle<i::Object> proto = i::PrototypeIterator::GetCurrent(iter);
+  i::LookupIterator it(self_obj, key_obj, i::Handle<i::JSReceiver>::cast(proto),
+                       i::LookupIterator::PROTOTYPE_CHAIN_SKIP_INTERCEPTOR);
+  return GetPropertyAttributesByLookup(&it);
+}
+
+
 Local<Value> v8::Object::GetRealNamedProperty(Handle<String> key) {
   i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
   ON_BAILOUT(isolate, "v8::Object::GetRealNamedProperty()",
@@ -3787,6 +3813,20 @@ Local<Value> v8::Object::GetRealNamedProperty(Handle<String> key) {
 }
 
 
+Maybe<PropertyAttribute> v8::Object::GetRealNamedPropertyAttributes(
+    Handle<String> key) {
+  i::Isolate* isolate = Utils::OpenHandle(this)->GetIsolate();
+  ON_BAILOUT(isolate, "v8::Object::GetRealNamedPropertyAttributes()",
+             return Maybe<PropertyAttribute>());
+  ENTER_V8(isolate);
+  i::Handle<i::JSObject> self_obj = Utils::OpenHandle(this);
+  i::Handle<i::String> key_obj = Utils::OpenHandle(*key);
+  i::LookupIterator it(self_obj, key_obj,
+                       i::LookupIterator::PROTOTYPE_CHAIN_SKIP_INTERCEPTOR);
+  return GetPropertyAttributesByLookup(&it);
+}
+
+
 // Turns on access checks by copying the map and setting the check flag.
 // Because the object gets a new map, existing inline cache caching
 // the old map of this object will fail.

test/cctest/test-api.cc

@@ -61,12 +61,15 @@ using ::v8::FunctionTemplate;
 using ::v8::Handle;
 using ::v8::HandleScope;
 using ::v8::Local;
-using ::v8::Name;
+using ::v8::Maybe;
 using ::v8::Message;
 using ::v8::MessageCallback;
+using ::v8::Name;
+using ::v8::None;
 using ::v8::Object;
 using ::v8::ObjectTemplate;
 using ::v8::Persistent;
+using ::v8::PropertyAttribute;
 using ::v8::Script;
 using ::v8::StackTrace;
 using ::v8::String;
@@ -10869,16 +10872,32 @@ THREADED_TEST(VariousGetPropertiesAndThrowingCallbacks) {
   try_catch.Reset();
   CHECK(result.IsEmpty());
 
+  Maybe<PropertyAttribute> attr =
+      instance->GetRealNamedPropertyAttributes(v8_str("f"));
+  CHECK(!try_catch.HasCaught());
+  CHECK(attr.has_value);
+  CHECK_EQ(attr.value, None);
+
   result = another->GetRealNamedProperty(v8_str("f"));
   CHECK(try_catch.HasCaught());
   try_catch.Reset();
   CHECK(result.IsEmpty());
 
+  attr = another->GetRealNamedPropertyAttributes(v8_str("f"));
+  CHECK(!try_catch.HasCaught());
+  CHECK(attr.has_value);
+  CHECK_EQ(attr.value, None);
+
   result = another->GetRealNamedPropertyInPrototypeChain(v8_str("f"));
   CHECK(try_catch.HasCaught());
   try_catch.Reset();
   CHECK(result.IsEmpty());
 
+  attr = another->GetRealNamedPropertyAttributesInPrototypeChain(v8_str("f"));
+  CHECK(!try_catch.HasCaught());
+  CHECK(attr.has_value);
+  CHECK_EQ(attr.value, None);
+
   result = another->Get(v8_str("f"));
   CHECK(try_catch.HasCaught());
   try_catch.Reset();
@@ -10889,6 +10908,11 @@ THREADED_TEST(VariousGetPropertiesAndThrowingCallbacks) {
   try_catch.Reset();
   CHECK(result.IsEmpty());
 
+  attr = with_js_getter->GetRealNamedPropertyAttributes(v8_str("f"));
+  CHECK(!try_catch.HasCaught());
+  CHECK(attr.has_value);
+  CHECK_EQ(attr.value, None);
+
   result = with_js_getter->Get(v8_str("f"));
   CHECK(try_catch.HasCaught());
   try_catch.Reset();