[json] use OrderedHashSet for replacer property list.

src/json-stringifier.cc

 // Copyright 2016 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/json-stringifier.h"
 
 #include "src/conversions.h"
 #include "src/lookup.h"
 #include "src/messages.h"
 #include "src/objects-inl.h"
@@ skipping 83 matching lines @@
   if (!gap->IsUndefined(isolate_) && !InitializeGap(gap)) {
     return MaybeHandle<Object>();
   }
   Result result = SerializeObject(object);
   if (result == UNCHANGED) return factory()->undefined_value();
   if (result == SUCCESS) return builder_.Finish();
   DCHECK(result == EXCEPTION);
   return MaybeHandle<Object>();
 }
 
-bool IsInList(Handle<String> key, List<Handle<String> >* list) {
-  // TODO(yangguo): This is O(n^2) for n properties in the list. Deal with this
-  // if this becomes an issue.
-  for (const Handle<String>& existing : *list) {
-    if (String::Equals(existing, key)) return true;
-  }
-  return false;
-}
-
 bool JsonStringifier::InitializeReplacer(Handle<Object> replacer) {
   DCHECK(property_list_.is_null());
   DCHECK(replacer_function_.is_null());
   Maybe<bool> is_array = Object::IsArray(replacer);
   if (is_array.IsNothing()) return false;
   if (is_array.FromJust()) {
     HandleScope handle_scope(isolate_);
-    List<Handle<String> > list;
+    Handle<OrderedHashSet> set = factory()->NewOrderedHashSet();
     Handle<Object> length_obj;
     ASSIGN_RETURN_ON_EXCEPTION_VALUE(
         isolate_, length_obj,
         Object::GetLengthFromArrayLike(isolate_, replacer), false);
     uint32_t length;
     if (!length_obj->ToUint32(&length)) length = kMaxUInt32;
     for (uint32_t i = 0; i < length; i++) {
       Handle<Object> element;
       Handle<String> key;
       ASSIGN_RETURN_ON_EXCEPTION_VALUE(
           isolate_, element, Object::GetElement(isolate_, replacer, i), false);
       if (element->IsNumber() || element->IsString()) {
         ASSIGN_RETURN_ON_EXCEPTION_VALUE(
             isolate_, key, Object::ToString(isolate_, element), false);
       } else if (element->IsJSValue()) {
         Handle<Object> value(Handle<JSValue>::cast(element)->value(), isolate_);
         if (value->IsNumber() || value->IsString()) {
           ASSIGN_RETURN_ON_EXCEPTION_VALUE(
               isolate_, key, Object::ToString(isolate_, element), false);
         }
       }
       if (key.is_null()) continue;
-      if (!IsInList(key, &list)) list.Add(key);
+      // Object keys are internalized, so do it here.
+      key = factory()->InternalizeString(key);
+      set = OrderedHashSet::Add(set, key);
     }
-    property_list_ = factory()->NewUninitializedFixedArray(list.length());
-    for (int i = 0; i < list.length(); i++) {
-      property_list_->set(i, *list[i]);
-    }
+    property_list_ = OrderedHashSet::ConvertToKeysArray(
+        set, GetKeysConversion::kKeepNumbers);
     property_list_ = handle_scope.CloseAndEscape(property_list_);
   } else if (replacer->IsCallable()) {
     replacer_function_ = Handle<JSReceiver>::cast(replacer);
   }
   return true;
 }
 
 bool JsonStringifier::InitializeGap(Handle<Object> gap) {
   DCHECK_NULL(gap_);
   HandleScope scope(isolate_);
@@ skipping 554 matching lines @@
     if (object->IsOneByteRepresentationUnderneath()) {
       SerializeString_<uint8_t, uc16>(object);
     } else {
       SerializeString_<uc16, uc16>(object);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8