[ESnext] Implement Object Rest

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index ae814762cae6efabdf03d010640c87e65635994a..8bdb4b04ea0c81ce9aa0d94a62c17ef9e1b96403 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -2003,8 +2003,22 @@ Maybe<bool> JSReceiver::HasInPrototypeChain(Isolate* isolate,
 
 namespace {
 
+bool HasElementInArguments(Arguments* arguments,
+                           Handle<Object> search_element) {
+  // TODO(gsathya): Maybe optimize this to be a hashtable.
+  for (int i = 0; i < arguments->length(); i++) {
+    if (*search_element == (*arguments)[i]) {

[adamk, 2017/01/12 22:43:08]

Pointer equality isn't sufficient for strings. Use Object::SameValue() instead.

[gsathya, 2017/01/17 19:28:59]

Done.

+      return true;
+    }
+  }
+
+  return false;
+}
+
 MUST_USE_RESULT Maybe<bool> FastAssign(Handle<JSReceiver> target,
-                                       Handle<Object> source, bool use_set) {
+                                       Handle<Object> source,
+                                       Arguments* excluded_properties,
+                                       bool use_set) {
   // Non-empty strings are the only non-JSReceivers that need to be handled
   // explicitly by Object.assign.
   if (!source->IsJSReceiver()) {
@@ -2077,6 +2091,11 @@ MUST_USE_RESULT Maybe<bool> FastAssign(Handle<JSReceiver> target,
       if (result.IsNothing()) return result;
       if (stable && call_to_js) stable = from->map() == *map;
     } else {
+      if (excluded_properties != nullptr &&
+          HasElementInArguments(excluded_properties, next_key)) {
+        continue;
+      }
+
       // 4a ii 2. Perform ? CreateDataProperty(target, nextKey, propValue).
       bool success;
       LookupIterator it = LookupIterator::PropertyOrElement(
@@ -2090,15 +2109,16 @@ MUST_USE_RESULT Maybe<bool> FastAssign(Handle<JSReceiver> target,
 
   return Just(true);
 }
-
 }  // namespace
 
 // static
 Maybe<bool> JSReceiver::SetOrCopyDataProperties(Isolate* isolate,
                                                 Handle<JSReceiver> target,
                                                 Handle<Object> source,
+                                                Arguments* excluded_properties,
                                                 bool use_set) {
-  Maybe<bool> fast_assign = FastAssign(target, source, use_set);
+  Maybe<bool> fast_assign =
+      FastAssign(target, source, excluded_properties, use_set);
   if (fast_assign.IsNothing()) return Nothing<bool>();
   if (fast_assign.FromJust()) return Just(true);
 
@@ -2135,6 +2155,11 @@ Maybe<bool> JSReceiver::SetOrCopyDataProperties(Isolate* isolate,
                                  isolate, target, next_key, prop_value, STRICT),
             Nothing<bool>());
       } else {
+        if (excluded_properties != nullptr &&
+            HasElementInArguments(excluded_properties, next_key)) {
+          continue;
+        }
+
         // 4a ii 2. Perform ! CreateDataProperty(target, nextKey, propValue).
         bool success;
         LookupIterator it = LookupIterator::PropertyOrElement(