wtf/ListRefPtr.h

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