Provide private symbols through internal APIs

src/objects.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 341 matching lines @@
   V(CONS_INTERNALIZED_STRING_TYPE)                                             \
   V(CONS_ASCII_INTERNALIZED_STRING_TYPE)                                       \
   V(EXTERNAL_INTERNALIZED_STRING_TYPE)                                         \
   V(EXTERNAL_ASCII_INTERNALIZED_STRING_TYPE)                                   \
   V(EXTERNAL_INTERNALIZED_STRING_WITH_ONE_BYTE_DATA_TYPE)                      \
   V(SHORT_EXTERNAL_INTERNALIZED_STRING_TYPE)                                   \
   V(SHORT_EXTERNAL_ASCII_INTERNALIZED_STRING_TYPE)                             \
   V(SHORT_EXTERNAL_INTERNALIZED_STRING_WITH_ONE_BYTE_DATA_TYPE)                \
                                                                                \
   V(SYMBOL_TYPE)                                                               \
+                                                                               \
   V(MAP_TYPE)                                                                  \
   V(CODE_TYPE)                                                                 \
   V(ODDBALL_TYPE)                                                              \
   V(CELL_TYPE)                                                                 \
   V(PROPERTY_CELL_TYPE)                                                        \
                                                                                \
   V(HEAP_NUMBER_TYPE)                                                          \
   V(FOREIGN_TYPE)                                                              \
   V(BYTE_ARRAY_TYPE)                                                           \
   V(FREE_SPACE_TYPE)                                                           \
@@ skipping 312 matching lines @@
       | kNotInternalizedTag,
   SHORT_EXTERNAL_STRING_TYPE =
       SHORT_EXTERNAL_INTERNALIZED_STRING_TYPE | kNotInternalizedTag,
   SHORT_EXTERNAL_ASCII_STRING_TYPE =
       SHORT_EXTERNAL_ASCII_INTERNALIZED_STRING_TYPE | kNotInternalizedTag,
   SHORT_EXTERNAL_STRING_WITH_ONE_BYTE_DATA_TYPE =
       SHORT_EXTERNAL_INTERNALIZED_STRING_WITH_ONE_BYTE_DATA_TYPE
       | kNotInternalizedTag,
 
   // Non-string names
-  SYMBOL_TYPE = kNotStringTag,  // LAST_NAME_TYPE, FIRST_NONSTRING_TYPE
+  SYMBOL_TYPE = kNotStringTag,  // FIRST_NONSTRING_TYPE, LAST_NAME_TYPE
 
   // Objects allocated in their own spaces (never in new space).
   MAP_TYPE,
   CODE_TYPE,
   ODDBALL_TYPE,
   CELL_TYPE,
   PROPERTY_CELL_TYPE,
 
   // "Data", objects that cannot contain non-map-word pointers to heap
   // objects.
@@ skipping 7624 matching lines @@
   DISALLOW_IMPLICIT_CONSTRUCTORS(Name);
 };
 
 
 // ES6 symbols.
 class Symbol: public Name {
  public:
   // [name]: the print name of a symbol, or undefined if none.
   DECL_ACCESSORS(name, Object)
 
+  DECL_ACCESSORS(flags, Smi)
+
+  // [is_private]: whether this is a private symbol.
+  DECL_BOOLEAN_ACCESSORS(is_private)
+
   // Casting.
   static inline Symbol* cast(Object* obj);
 
   // Dispatched behavior.
   DECLARE_PRINTER(Symbol)
   DECLARE_VERIFIER(Symbol)
 
   // Layout description.
   static const int kNameOffset = Name::kSize;
-  static const int kSize = kNameOffset + kPointerSize;
+  static const int kFlagsOffset = kNameOffset + kPointerSize;
+  static const int kSize = kFlagsOffset + kPointerSize;
 
-  typedef FixedBodyDescriptor<kNameOffset, kNameOffset + kPointerSize, kSize>
-          BodyDescriptor;
+  typedef FixedBodyDescriptor<kNameOffset, kFlagsOffset, kSize> BodyDescriptor;
 
  private:
+  static const int kPrivateBit = 0;
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(Symbol);
 };
 
 
 class ConsString;
 
 // The String abstract class captures JavaScript string values:
 //
 // Ecma-262:
 //  4.3.16 String Value
@@ skipping 2073 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_