Add Persistent::ClearAndLeak.

include/v8.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 677 matching lines @@
    * was previously assigned.
    */
   // TODO(dcarney): remove before cutover
   V8_INLINE(uint16_t WrapperClassId(Isolate* isolate) const);
 
   /**
    * Disposes the current contents of the handle and replaces it.
    */
   V8_INLINE(void Reset(Isolate* isolate, const Handle<T>& other));
 
+  V8_INLINE(T* LeakPersistent());

[Sven Panne, 2013/05/10 12:00:02]

Please add a comment that it is necessary to re-wrap the pointer later and
Dispose it, otherwise one keeps a Node live indefinitely.

[marja, 2013/05/10 13:02:26]

Done.

+
 #ifndef V8_USE_UNSAFE_HANDLES
 
 #ifndef V8_ALLOW_ACCESS_TO_PERSISTENT_IMPLICIT
 
  private:
 #endif
   // TODO(dcarney): make unlinkable before cutover
   V8_INLINE(Persistent(const Persistent& that)) : val_(that.val_) {}
   // TODO(dcarney): make unlinkable before cutover
   V8_INLINE(Persistent& operator=(const Persistent& that)) {  // NOLINT
@@ skipping 4669 matching lines @@
   I::UpdateNodeFlag(reinterpret_cast<internal::Object**>(this->val_),
                     true,
                     I::kNodeIsPartiallyDependentShift);
 }
 
 template <class T>
 void Persistent<T>::SetWrapperClassId(uint16_t class_id) {
   SetWrapperClassId(Isolate::GetCurrent(), class_id);
 }
 
+
 template <class T>
 void Persistent<T>::Reset(Isolate* isolate, const Handle<T>& other) {
   Dispose(isolate);
 #ifdef V8_USE_UNSAFE_HANDLES
   *this = *New(isolate, other);
 #else
   if (other.IsEmpty()) {
     this->val_ = NULL;
     return;
   }
   internal::Object** p = reinterpret_cast<internal::Object**>(other.val_);
   this->val_ = reinterpret_cast<T*>(
       V8::GlobalizeReference(reinterpret_cast<internal::Isolate*>(isolate), p));
 #endif
 }
 
+
+template <class T>
+T* Persistent<T>::LeakPersistent() {

[Sven Panne, 2013/05/10 12:00:02]

As discussed offline, we should better name it "ClearAndLeak".

[marja, 2013/05/10 13:02:26]

Done.

+  T* old;
+#ifdef V8_USE_UNSAFE_HANDLES
+  old = this->operator*();

[Sven Panne, 2013/05/10 12:00:02]

Can we use '*this' here? If not, a comment might be good...

[marja, 2013/05/10 13:02:26]

"this" is not Persistent, but Persistent*, so "*this" won't be the right thing.
But we can use "**this". It's just not very clear. (Changed to **this, however.)

+  *this = Persistent<T>();
+#else
+  old = val_;
+  val_ = NULL;
+#endif
+  return old;
+}
+
+
 template <class T>
 void Persistent<T>::SetWrapperClassId(Isolate* isolate, uint16_t class_id) {
   typedef internal::Internals I;
   if (this->IsEmpty()) return;
   if (!I::IsInitialized(isolate)) return;
   internal::Object** obj = reinterpret_cast<internal::Object**>(this->val_);
   uint8_t* addr = reinterpret_cast<uint8_t*>(obj) + I::kNodeClassIdOffset;
   *reinterpret_cast<uint16_t*>(addr) = class_id;
 }
 
@@ skipping 551 matching lines @@
 
 
 }  // namespace v8
 
 
 #undef V8EXPORT
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_