[ESnext] Implement Object spread

src/runtime/runtime-object.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/debug/debug.h"
 #include "src/isolate-inl.h"
@@ skipping 732 matching lines @@
     JSFunction::SetName(getter, name, isolate->factory()->get_string());
   }
 
   RETURN_FAILURE_ON_EXCEPTION(
       isolate,
       JSObject::DefineAccessor(object, name, getter,
                                isolate->factory()->null_value(), attrs));
   return isolate->heap()->undefined_value();
 }
 
+RUNTIME_FUNCTION(Runtime_CopyDataProperties) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 2);
+  CONVERT_ARG_HANDLE_CHECKED(JSReceiver, target, 0);
+  CONVERT_ARG_HANDLE_CHECKED(Object, source, 1);
+
+  // 2. If source is undefined or null, let keys be an empty List.
+  if (source->IsUndefined(isolate) || source->IsNull(isolate)) {
+    return isolate->heap()->undefined_value();
+  }
+
+  // 3. Else,
+  // 3a. Let from be ToObject(nextSource).
+  // Only non-empty strings and JSReceivers have enumerable properties.
+  Handle<JSReceiver> from = Object::ToObject(isolate, source).ToHandleChecked();

[adamk, 2016/12/29 00:48:45]

I think everything from here down should be shared with the ObjectAssign
builtin; it looks like everything except the Set vs Create is the same.

[gsathya, 2016/12/29 06:40:56]

Done.

+  // 3b. Let keys be ? from.[[OwnPropertyKeys]]().
+  Handle<FixedArray> keys;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, keys,
+      KeyAccumulator::GetKeys(from, KeyCollectionMode::kOwnOnly, ALL_PROPERTIES,
+                              GetKeysConversion::kKeepNumbers));
+
+  // 4. Repeat for each element nextKey of keys in List order,
+  for (int j = 0; j < keys->length(); ++j) {
+    Handle<Object> next_key(keys->get(j), isolate);
+    // 4a i. Let desc be ? from.[[GetOwnProperty]](nextKey).
+    PropertyDescriptor desc;
+    Maybe<bool> found =
+        JSReceiver::GetOwnPropertyDescriptor(isolate, from, next_key, &desc);
+    if (found.IsNothing()) return isolate->heap()->exception();
+    // 4a ii. If desc is not undefined and desc.[[Enumerable]] is true, then
+    if (found.FromJust() && desc.enumerable()) {
+      // 4a ii 1. Let propValue be ? Get(from, nextKey).
+      Handle<Object> prop_value;
+      ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+          isolate, prop_value,
+          Runtime::GetObjectProperty(isolate, from, next_key));
+
+      // 4a ii 2. Perform ? CreateDataProperty(target, nextKey, propValue).
+      bool success;
+      LookupIterator it = LookupIterator::PropertyOrElement(
+          isolate, target, next_key, &success, LookupIterator::OWN);
+      if (!success) return isolate->heap()->exception();
+      MAYBE_RETURN(JSReceiver::CreateDataProperty(&it, prop_value,
+                                                  Object::THROW_ON_ERROR),
+                   isolate->heap()->exception());
+    }
+  }
+
+  return isolate->heap()->undefined_value();
+}
 
 RUNTIME_FUNCTION(Runtime_DefineSetterPropertyUnchecked) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 4);
   CONVERT_ARG_HANDLE_CHECKED(JSObject, object, 0);
   CONVERT_ARG_HANDLE_CHECKED(Name, name, 1);
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, setter, 2);
   CONVERT_PROPERTY_ATTRIBUTES_CHECKED(attrs, 3);
 
   if (String::cast(setter->shared()->name())->length() == 0) {
@@ skipping 168 matching lines @@
   if (!success) return isolate->heap()->exception();
   MAYBE_RETURN(
       JSReceiver::CreateDataProperty(&it, value, Object::THROW_ON_ERROR),
       isolate->heap()->exception());
   return *value;
 }
 
 
 }  // namespace internal
 }  // namespace v8