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 OwnHandle_h

    32 #define OwnHandle_h

    33 

    34 #include <v8.h>

    35 

    36 namespace WebCore {

    37 

    38     template<typename T>

    39     class OwnHandle {

    40     public:

    41         OwnHandle() { }

    42         explicit OwnHandle(v8::Handle<T> handle) : m_handle(v8::Persistent<T>::New(handle)) { }

    43         ~OwnHandle() { clear(); }

    44 

    45         v8::Handle<T> get() const { return m_handle; }

    46         void set(v8::Handle<T> handle) { clear(); m_handle = v8::Persistent<T>::New(handle); }

    47 

    48         // Note: This is clear in the OwnPtr sense, not the v8::Handle sense.

    49         void clear()

    50         {

    51             if (m_handle.IsEmpty())

    52                 return;

    53             if (m_handle.IsWeak())

    54                 m_handle.ClearWeak();

    55             m_handle.Dispose();

    56             m_handle.Clear();

    57         }

    58 

    59         // Make the underlying handle weak.  The client doesn't get a callback,

    60         // we just make the handle empty.

    61         void makeWeak()

    62         {

    63             if (m_handle.IsEmpty())

    64                 return;

    65             m_handle.MakeWeak(this, &OwnHandle<T>::weakCallback);

    66         }

    67 

    68     private:

    69         static void weakCallback(v8::Persistent<v8::Value> object, void* ownHandle)

    70         {

    71             OwnHandle<T>* handle = static_cast<OwnHandle<T>*>(ownHandle);

    72             handle->clear();

    73         }

    74 

    75         v8::Persistent<T> m_handle;

    76     };

    77 

    78 } // namespace WebCore

    79 

    80 #endif // OwnHandle_h