Provide private symbols through internal APIs

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index d9d36e0f4be1147ad8d5e3eee2c9625f6b024c1e..e8723a593a010344919603d5777af6bab9c079cf 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -189,6 +189,11 @@ TYPE_CHECKER(HeapNumber, HEAP_NUMBER_TYPE)
 TYPE_CHECKER(Symbol, SYMBOL_TYPE)
 
 
+bool Object::IsPrivate() {
+  return IsSymbol() && Symbol::cast(this)->name()->IsBox();
+}
+
+
 bool Object::IsString() {
   return Object::IsHeapObject()
     && HeapObject::cast(this)->map()->instance_type() < FIRST_NONSTRING_TYPE;
@@ -2602,6 +2607,7 @@ CAST_ACCESSOR(ExternalString)
 CAST_ACCESSOR(ExternalAsciiString)
 CAST_ACCESSOR(ExternalTwoByteString)
 CAST_ACCESSOR(Symbol)
+CAST_ACCESSOR(Private)
 CAST_ACCESSOR(Name)
 CAST_ACCESSOR(JSReceiver)
 CAST_ACCESSOR(JSObject)
@@ -2692,6 +2698,18 @@ bool Name::Equals(Name* other) {
 ACCESSORS(Symbol, name, Object, kNameOffset)
 
 
+Object* Private::name() {
+  ASSERT(IsPrivate());
+  return Box::cast(Symbol::name())->value();

[Yang, 2013/10/29 12:47:26]

could we assert in those accessors that the value is either undefined or a
string?

[rossberg, 2013/10/29 15:08:19]

Yeah, that is nasty. I decided to remove the whole Box hack and simply add a
flags field to the Symbol representation. Screw premature optimisation.

+}
+
+
+void Private::set_name(Object* value, WriteBarrierMode mode) {
+  ASSERT(IsPrivate());
+  return Box::cast(Symbol::name())->set_value(value, mode);
+}
+
+
 bool String::Equals(String* other) {
   if (other == this) return true;
   if (this->IsInternalizedString() && other->IsInternalizedString()) {