1/*
2 * Copyright (C) 2009 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 WeakGCPtr_h
27#define WeakGCPtr_h
28
29#include "Collector.h"
30#include <wtf/Noncopyable.h>
31
32namespace JSC {
33
34// A smart pointer whose get() function returns 0 for cells awaiting destruction.
35template <typename T> class WeakGCPtr : Noncopyable {
36public:
37 WeakGCPtr() : m_ptr(0) { }
38 WeakGCPtr(T* ptr) { assign(ptr); }
39
40 T* get() const
41 {
42 if (!m_ptr || !Heap::isCellMarked(cell: m_ptr))
43 return 0;
44 return m_ptr;
45 }
46
47 void clear() { m_ptr = 0; }
48
49 T& operator*() const { return *get(); }
50 T* operator->() const { return get(); }
51
52 bool operator!() const { return !get(); }
53
54 // This conversion operator allows implicit conversion to bool but not to other integer types.
55#if COMPILER(WINSCW)
56 operator bool() const { return m_ptr; }
57#else
58 typedef T* WeakGCPtr::*UnspecifiedBoolType;
59 operator UnspecifiedBoolType() const { return get() ? &WeakGCPtr::m_ptr : 0; }
60#endif
61
62 WeakGCPtr& operator=(T*);
63
64private:
65 void assign(T* ptr)
66 {
67 if (ptr)
68 Heap::markCell(cell: ptr);
69 m_ptr = ptr;
70 }
71
72 T* m_ptr;
73};
74
75template <typename T> inline WeakGCPtr<T>& WeakGCPtr<T>::operator=(T* optr)
76{
77 assign(ptr: optr);
78 return *this;
79}
80
81template <typename T, typename U> inline bool operator==(const WeakGCPtr<T>& a, const WeakGCPtr<U>& b)
82{
83 return a.get() == b.get();
84}
85
86template <typename T, typename U> inline bool operator==(const WeakGCPtr<T>& a, U* b)
87{
88 return a.get() == b;
89}
90
91template <typename T, typename U> inline bool operator==(T* a, const WeakGCPtr<U>& b)
92{
93 return a == b.get();
94}
95
96template <typename T, typename U> inline bool operator!=(const WeakGCPtr<T>& a, const WeakGCPtr<U>& b)
97{
98 return a.get() != b.get();
99}
100
101template <typename T, typename U> inline bool operator!=(const WeakGCPtr<T>& a, U* b)
102{
103 return a.get() != b;
104}
105
106template <typename T, typename U> inline bool operator!=(T* a, const WeakGCPtr<U>& b)
107{
108 return a != b.get();
109}
110
111template <typename T, typename U> inline WeakGCPtr<T> static_pointer_cast(const WeakGCPtr<U>& p)
112{
113 return WeakGCPtr<T>(static_cast<T*>(p.get()));
114}
115
116template <typename T, typename U> inline WeakGCPtr<T> const_pointer_cast(const WeakGCPtr<U>& p)
117{
118 return WeakGCPtr<T>(const_cast<T*>(p.get()));
119}
120
121template <typename T> inline T* getPtr(const WeakGCPtr<T>& p)
122{
123 return p.get();
124}
125
126} // namespace JSC
127
128#endif // WeakGCPtr_h
129

source code of qtscript/src/3rdparty/javascriptcore/JavaScriptCore/runtime/WeakGCPtr.h