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      1 /*
      2  * Copyright (C) 2009 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 SharedPersistent_h
     32 #define SharedPersistent_h
     33 
     34 #include <v8.h>
     35 #include <wtf/PassRefPtr.h>
     36 #include <wtf/RefCounted.h>
     37 
     38 namespace WebCore {
     39 
     40     // A shareable reference to a v8 persistent handle.  Using a shared
     41     // persistent any number of objects can share a reference to a v8
     42     // object and when it should no longer be accessible the object's
     43     // owner can clear it.
     44     template <typename T>
     45     class SharedPersistent : public RefCounted<SharedPersistent<T> > {
     46     public:
     47         void set(v8::Persistent<T> value)
     48         {
     49             m_value = value;
     50         }
     51         v8::Persistent<T> get()
     52         {
     53             return m_value;
     54         }
     55         void disposeHandle()
     56         {
     57             if (!m_value.IsEmpty()) {
     58               m_value.Dispose();
     59               m_value.Clear();
     60             }
     61         }
     62         static PassRefPtr<SharedPersistent<T> > create(v8::Persistent<T> value)
     63         {
     64             return adoptRef(new SharedPersistent<T>(value));
     65         }
     66         static PassRefPtr<SharedPersistent<T> > create()
     67         {
     68             return create(v8::Persistent<T>());
     69         }
     70     private:
     71         explicit SharedPersistent(v8::Persistent<T> value) : m_value(value) { }
     72         v8::Persistent<T> m_value;
     73     };
     74 
     75 } // namespace WebCore
     76 
     77 #endif // SharedPersistent_h
     78