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
36namespace 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
81