[es6] Partially implement Reflect.defineProperty.

src/builtins.cc

Index: src/builtins.cc
diff --git a/src/builtins.cc b/src/builtins.cc
index 3530b59def0323b2930d547331c7cca76135e2fc..d8a434f43b4b319d5f26bfaaf354e3c43c21c503 100644
--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -17,6 +17,7 @@
 #include "src/isolate-inl.h"
 #include "src/messages.h"
 #include "src/profiler/cpu-profiler.h"
+#include "src/property-descriptor.h"
 #include "src/prototype.h"
 #include "src/vm-state-inl.h"
 
@@ -1444,6 +1445,38 @@ BUILTIN(ArrayConcat) {
 }
 
 
+// ES6 section 26.1.3 Reflect.defineProperty
+BUILTIN(ReflectDefineProperty) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(4, args.length());
+  Handle<Object> target = args.at<Object>(1);
+  Handle<Object> key = args.at<Object>(2);
+  Handle<Object> attributes = args.at<Object>(3);
+

[Jakob Kummerow, 2015/10/23 12:03:42]

Suggestion: add verbatim spec steps as comments, e.g.:

// 1. If Type(target) is not Object, throw a TypeError exception.

to make it easy to see why the implementation does what it does.

+  if (!target->IsJSReceiver()) {
+    THROW_NEW_ERROR_RETURN_FAILURE(
+        isolate, NewTypeError(MessageTemplate::kCalledOnNonObject,
+                              isolate->factory()->NewStringFromAsciiChecked(
+                                  "Reflect.defineProperty")));
+  }
+
+  Handle<Name> name;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, name,
+                                     Object::ToName(isolate, key));

[Jakob Kummerow, 2015/10/23 12:03:42]

Using ToPropertyKey (currently a static function in objects.cc, but we can move
it) would be more efficient for index keys as it avoids needless
int->string->int conversions.

[neis, 2015/10/29 15:17:25]

Thanks, good point.  I'll do that in a separate CL since it affects many Reflect
functions.

+
+  PropertyDescriptor desc;
+  if (!PropertyDescriptor::ToPropertyDescriptor(isolate, attributes, &desc)) {
+    return isolate->heap()->exception();
+  }
+
+  bool result = JSReceiver::DefineOwnProperty(
+      isolate, Handle<JSReceiver>::cast(target), name, &desc, DONT_THROW);
+  if (isolate->has_pending_exception()) return isolate->heap()->exception();
+  // TODO(neis): Make DefineOwnProperty return Maybe<bool>.
+  return *isolate->factory()->ToBoolean(result);
+}
+
+
 // ES6 section 26.1.4 Reflect.deleteProperty
 BUILTIN(ReflectDeleteProperty) {
   HandleScope scope(isolate);