Weak Cells

src/objects.h

 // Copyright 2012 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.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 125 matching lines @@
 //       - CallHandlerInfo
 //       - TemplateInfo
 //         - FunctionTemplateInfo
 //         - ObjectTemplateInfo
 //       - Script
 //       - SignatureInfo
 //       - TypeSwitchInfo
 //       - DebugInfo
 //       - BreakPointInfo
 //       - CodeCache
+//     - WeakCell
 //
 // Formats of Object*:
 //  Smi:        [31 bit signed int] 0
 //  HeapObject: [32 bit direct pointer] (4 byte aligned) | 01
 
 namespace v8 {
 namespace internal {
 
 enum KeyedAccessStoreMode {
   STANDARD_STORE,
@@ skipping 262 matching lines @@
   V(CODE_CACHE_TYPE)                                            \
   V(POLYMORPHIC_CODE_CACHE_TYPE)                                \
   V(TYPE_FEEDBACK_INFO_TYPE)                                    \
   V(ALIASED_ARGUMENTS_ENTRY_TYPE)                               \
   V(BOX_TYPE)                                                   \
                                                                 \
   V(FIXED_ARRAY_TYPE)                                           \
   V(FIXED_DOUBLE_ARRAY_TYPE)                                    \
   V(CONSTANT_POOL_ARRAY_TYPE)                                   \
   V(SHARED_FUNCTION_INFO_TYPE)                                  \
+  V(WEAK_CELL_TYPE)                                             \
                                                                 \
   V(JS_MESSAGE_OBJECT_TYPE)                                     \
                                                                 \
   V(JS_VALUE_TYPE)                                              \
   V(JS_DATE_TYPE)                                               \
   V(JS_OBJECT_TYPE)                                             \
   V(JS_CONTEXT_EXTENSION_OBJECT_TYPE)                           \
   V(JS_GENERATOR_OBJECT_TYPE)                                   \
   V(JS_MODULE_TYPE)                                             \
   V(JS_GLOBAL_OBJECT_TYPE)                                      \
@@ skipping 276 matching lines @@
   CODE_CACHE_TYPE,
   POLYMORPHIC_CODE_CACHE_TYPE,
   TYPE_FEEDBACK_INFO_TYPE,
   ALIASED_ARGUMENTS_ENTRY_TYPE,
   BOX_TYPE,
   DEBUG_INFO_TYPE,
   BREAK_POINT_INFO_TYPE,
   FIXED_ARRAY_TYPE,
   CONSTANT_POOL_ARRAY_TYPE,
   SHARED_FUNCTION_INFO_TYPE,
+  WEAK_CELL_TYPE,
 
   // All the following types are subtypes of JSReceiver, which corresponds to
   // objects in the JS sense. The first and the last type in this range are
   // the two forms of function. This organization enables using the same
   // compares for checking the JS_RECEIVER/SPEC_OBJECT range and the
   // NONCALLABLE_JS_OBJECT range.
   JS_FUNCTION_PROXY_TYPE,  // FIRST_JS_RECEIVER_TYPE, FIRST_JS_PROXY_TYPE
   JS_PROXY_TYPE,           // LAST_JS_PROXY_TYPE
   JS_VALUE_TYPE,           // FIRST_JS_OBJECT_TYPE
   JS_MESSAGE_OBJECT_TYPE,
@@ skipping 243 matching lines @@
   V(MapCache)                      \
   V(Primitive)                     \
   V(GlobalObject)                  \
   V(JSGlobalObject)                \
   V(JSBuiltinsObject)              \
   V(JSGlobalProxy)                 \
   V(UndetectableObject)            \
   V(AccessCheckNeeded)             \
   V(Cell)                          \
   V(PropertyCell)                  \
+  V(WeakCell)                      \
   V(ObjectHashTable)               \
   V(WeakHashTable)                 \
   V(OrderedHashTable)
 
 // Object is the abstract superclass for all classes in the
 // object hierarchy.
 // Object does not use any virtual functions to avoid the
 // allocation of the C++ vtable.
 // Since both Smi and HeapObject are subclasses of Object no
 // data members can be present in Object.
@@ skipping 8563 matching lines @@
   typedef FixedBodyDescriptor<kValueOffset,
                               kSize,
                               kSize> BodyDescriptor;
 
  private:
   DECL_ACCESSORS(type_raw, Object)
   DISALLOW_IMPLICIT_CONSTRUCTORS(PropertyCell);
 };
 
 
+class WeakCell : public HeapObject {
+ public:
+  inline HeapObject* value() const;
+
+  // This should not be called by anyone except GC.
+  inline void clear(HeapObject* undefined);
+
+  // This should not be called by anyone except allocator.
+  inline void initialize(HeapObject* value);
+
+  DECL_ACCESSORS(next, Object)
+
+  DECLARE_CAST(WeakCell)
+
+  DECLARE_PRINTER(WeakCell)
+  DECLARE_VERIFIER(WeakCell)
+
+  // Layout description.
+  static const int kValueOffset = HeapObject::kHeaderSize;
+  static const int kNextOffset = kValueOffset + kPointerSize;
+  static const int kSize = kNextOffset + kPointerSize;
+
+  typedef FixedBodyDescriptor<kValueOffset, kSize, kSize> BodyDescriptor;
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(WeakCell);
+};
+
+
 // The JSProxy describes EcmaScript Harmony proxies
 class JSProxy: public JSReceiver {
  public:
   // [handler]: The handler property.
   DECL_ACCESSORS(handler, Object)
 
   // [hash]: The hash code property (undefined if not initialized yet).
   DECL_ACCESSORS(hash, Object)
 
   DECLARE_CAST(JSProxy)
@@ skipping 1285 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_