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      1 /*
      2  * Copyright (C) 2000 Lars Knoll (knoll (at) kde.org)
      3  *           (C) 2000 Antti Koivisto (koivisto (at) kde.org)
      4  *           (C) 2000 Dirk Mueller (mueller (at) kde.org)
      5  * Copyright (C) 2003, 2005, 2008 Apple Inc. All rights reserved.
      6  *
      7  * This library is free software; you can redistribute it and/or
      8  * modify it under the terms of the GNU Library General Public
      9  * License as published by the Free Software Foundation; either
     10  * version 2 of the License, or (at your option) any later version.
     11  *
     12  * This library is distributed in the hope that it will be useful,
     13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     15  * Library General Public License for more details.
     16  *
     17  * You should have received a copy of the GNU Library General Public License
     18  * along with this library; see the file COPYING.LIB.  If not, write to
     19  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     20  * Boston, MA 02110-1301, USA.
     21  *
     22  */
     23 
     24 #ifndef DataRef_h
     25 #define DataRef_h
     26 
     27 #include <wtf/RefPtr.h>
     28 
     29 namespace WebCore {
     30 
     31 template <typename T> class DataRef {
     32 public:
     33     const T* get() const { return m_data.get(); }
     34 
     35     const T& operator*() const { return *get(); }
     36     const T* operator->() const { return get(); }
     37 
     38     T* access()
     39     {
     40         if (!m_data->hasOneRef())
     41             m_data = m_data->copy();
     42         return m_data.get();
     43     }
     44 
     45     void init()
     46     {
     47         ASSERT(!m_data);
     48         m_data = T::create();
     49     }
     50 
     51     bool operator==(const DataRef<T>& o) const
     52     {
     53         ASSERT(m_data);
     54         ASSERT(o.m_data);
     55         return m_data == o.m_data || *m_data == *o.m_data;
     56     }
     57 
     58     bool operator!=(const DataRef<T>& o) const
     59     {
     60         ASSERT(m_data);
     61         ASSERT(o.m_data);
     62         return m_data != o.m_data && *m_data != *o.m_data;
     63     }
     64 
     65 private:
     66     RefPtr<T> m_data;
     67 };
     68 
     69 } // namespace WebCore
     70 
     71 #endif // DataRef_h
     72