wtf/ListRefPtr.h

   1 /*
   2  *  Copyright (C) 2005, 2006, 2008 Apple Inc. All rights reserved.
   3  *
   4  *  This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU Library General Public
   6  *  License as published by the Free Software Foundation; either
   7  *  version 2 of the License, or (at your option) any later version.
   8  *
   9  *  This library is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  *  Library General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU Library General Public License
  15  *  along with this library; see the file COPYING.LIB.  If not, write to
  16  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17  *  Boston, MA 02110-1301, USA.
  18  *
  19  */
  20
  21 #ifndef WTF_ListRefPtr_h
  22 #define WTF_ListRefPtr_h
  23
  24 #include <wtf/RefPtr.h>
  25
  26 namespace WTF {
  27
  28     // Specialized version of RefPtr desgined for use in singly-linked lists.
  29     // Derefs the list iteratively to avoid recursive derefing that can overflow the stack.
  30     template <typename T> class ListRefPtr : public RefPtr<T> {
  31     public:
  32         ListRefPtr() : RefPtr<T>() {}
  33         ListRefPtr(T* ptr) : RefPtr<T>(ptr) {}
  34         ListRefPtr(const RefPtr<T>& o) : RefPtr<T>(o) {}
  35         // see comment in PassRefPtr.h for why this takes const reference
  36         template <typename U> ListRefPtr(const PassRefPtr<U>& o) : RefPtr<T>(o) {}
  37
  38         ~ListRefPtr();
  39
  40         ListRefPtr& operator=(T* optr) { RefPtr<T>::operator=(optr); return *this; }
  41         ListRefPtr& operator=(const RefPtr<T>& o) { RefPtr<T>::operator=(o); return *this; }
  42         ListRefPtr& operator=(const PassRefPtr<T>& o) { RefPtr<T>::operator=(o); return *this; }
  43         template <typename U> ListRefPtr& operator=(const RefPtr<U>& o) { RefPtr<T>::operator=(o); return *this; }
  44         template <typename U> ListRefPtr& operator=(const PassRefPtr<U>& o) { RefPtr<T>::operator=(o); return *this; }
  45     };
  46
  47     // Remove inline for winscw compiler to prevent the compiler agressively resolving
  48     // T::ref() in RefPtr<T>'s copy constructor.  The bug is reported at:
  49     // https://xdabug001.ext.nokia.com/bugzilla/show_bug.cgi?id=9812.
  50     template <typename T>
  51 #if !COMPILER(WINSCW)
  52     inline
  53 #endif
  54     ListRefPtr<T>::~ListRefPtr()
  55     {
  56         RefPtr<T> reaper = this->release();
  57         while (reaper && reaper->hasOneRef())
  58             reaper = reaper->releaseNext(); // implicitly protects reaper->next, then derefs reaper
  59     }
  60
  61     template <typename T> inline T* getPtr(const ListRefPtr<T>& p)
  62     {
  63         return p.get();
  64     }
  65
  66 } // namespace WTF
  67
  68 using WTF::ListRefPtr;
  69
  70 #endif // WTF_ListRefPtr_h