1/*
2 * Copyright (C) 2009, 2012, 2013 Apple 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
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef Weak_h
27#define Weak_h
28
29#include "JSExportMacros.h"
30#include <cstddef>
31#include <wtf/Noncopyable.h>
32
33namespace JSC {
34
35class WeakImpl;
36class WeakHandleOwner;
37
38// This is a free function rather than a Weak<T> member function so we can put it in Weak.cpp.
39JS_EXPORT_PRIVATE void weakClearSlowCase(WeakImpl*&);
40
41template<typename T> class Weak {
42 WTF_MAKE_NONCOPYABLE(Weak);
43public:
44 Weak()
45 : m_impl(0)
46 {
47 }
48
49 Weak(std::nullptr_t)
50 : m_impl(0)
51 {
52 }
53
54 Weak(T*, WeakHandleOwner* = 0, void* context = 0);
55
56 enum HashTableDeletedValueTag { HashTableDeletedValue };
57 bool isHashTableDeletedValue() const;
58 Weak(HashTableDeletedValueTag);
59
60 Weak(Weak&&);
61
62 ~Weak()
63 {
64 clear();
65 }
66
67 void swap(Weak&);
68
69 Weak& operator=(Weak&&);
70
71 bool operator!() const;
72 T* operator->() const;
73 T& operator*() const;
74 T* get() const;
75
76 bool was(T*) const;
77
78 explicit operator bool() const;
79
80 WeakImpl* leakImpl() WARN_UNUSED_RETURN;
81 void clear()
82 {
83 if (!m_impl)
84 return;
85 weakClearSlowCase(m_impl);
86 }
87
88private:
89 static WeakImpl* hashTableDeletedValue();
90
91 WeakImpl* m_impl;
92};
93
94} // namespace JSC
95
96#endif // Weak_h
97