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      1 /*
      2  * Copyright (C) 2010 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef WebPrivatePtr_h
     32 #define WebPrivatePtr_h
     33 
     34 #if WEBKIT_IMPLEMENTATION
     35 #include <wtf/PassRefPtr.h>
     36 #endif
     37 
     38 namespace WebKit {
     39 
     40 // This class is an implementation detail of the WebKit API.  It exists
     41 // to help simplify the implementation of WebKit interfaces that merely
     42 // wrap a reference counted WebCore class.
     43 template <typename T>
     44 class WebPrivatePtr {
     45 public:
     46     WebPrivatePtr() : m_ptr(0) { }
     47     ~WebPrivatePtr() { WEBKIT_ASSERT(!m_ptr); }
     48 
     49     bool isNull() const { return !m_ptr; }
     50 
     51 #if WEBKIT_IMPLEMENTATION
     52     WebPrivatePtr(const PassRefPtr<T>& prp)
     53         : m_ptr(prp.releaseRef())
     54     {
     55     }
     56 
     57     void reset()
     58     {
     59         assign(0);
     60     }
     61 
     62     WebPrivatePtr<T>& operator=(const WebPrivatePtr<T>& other)
     63     {
     64         T* p = other.m_ptr;
     65         if (p)
     66             p->ref();
     67         assign(p);
     68         return *this;
     69     }
     70 
     71     WebPrivatePtr<T>& operator=(const PassRefPtr<T>& prp)
     72     {
     73         assign(prp.releaseRef());
     74         return *this;
     75     }
     76 
     77     T* get() const
     78     {
     79         return m_ptr;
     80     }
     81 
     82     T* operator->() const
     83     {
     84         ASSERT(m_ptr);
     85         return m_ptr;
     86     }
     87 #endif
     88 
     89 private:
     90 #if WEBKIT_IMPLEMENTATION
     91     void assign(T* p)
     92     {
     93         // p is already ref'd for us by the caller
     94         if (m_ptr)
     95             m_ptr->deref();
     96         m_ptr = p;
     97     }
     98 #endif
     99 
    100     T* m_ptr;
    101 };
    102 
    103 } // namespace WebKit
    104 
    105 #endif
    106