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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 ScopedPersistent_h
     32 #define ScopedPersistent_h
     33 
     34 #include <v8.h>
     35 #include "wtf/Noncopyable.h"
     36 
     37 namespace WebCore {
     38 
     39 template<typename T>
     40 class ScopedPersistent {
     41     WTF_MAKE_NONCOPYABLE(ScopedPersistent);
     42 public:
     43     ScopedPersistent() { }
     44 
     45     explicit ScopedPersistent(v8::Handle<T> handle)
     46         : m_handle(v8::Isolate::GetCurrent(), handle)
     47     {
     48     }
     49 
     50     ~ScopedPersistent()
     51     {
     52         clear();
     53     }
     54 
     55     ALWAYS_INLINE v8::Local<T> newLocal(v8::Isolate* isolate) const
     56     {
     57         return v8::Local<T>::New(isolate, m_handle);
     58     }
     59 
     60     template<typename P>
     61     void makeWeak(P* parameters, void (*callback)(v8::Isolate*, v8::Persistent<T>*, P*))
     62     {
     63         m_handle.MakeWeak(parameters, callback);
     64     }
     65 
     66     bool isEmpty() const { return m_handle.IsEmpty(); }
     67 
     68     void set(v8::Isolate* isolate, v8::Handle<T> handle)
     69     {
     70         m_handle.Reset(isolate, handle);
     71     }
     72 
     73     // Note: This is clear in the OwnPtr sense, not the v8::Handle sense.
     74     void clear()
     75     {
     76         if (m_handle.IsEmpty())
     77             return;
     78         m_handle.Dispose();
     79         m_handle.Clear();
     80     }
     81 
     82     bool operator==(const ScopedPersistent<T>& other)
     83     {
     84         return m_handle == other.m_handle;
     85     }
     86 
     87 private:
     88     // FIXME: This function does an unsafe handle access. Remove it.
     89     friend class V8AbstractEventListener;
     90     friend class V8PerIsolateData;
     91     ALWAYS_INLINE v8::Persistent<T>& getUnsafe()
     92     {
     93         return m_handle;
     94     }
     95 
     96     v8::Persistent<T> m_handle;
     97 };
     98 
     99 } // namespace WebCore
    100 
    101 #endif // ScopedPersistent_h
    102