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 | |
32 | namespace JSC { |
33 | |
34 | // A smart pointer whose get() function returns 0 for cells awaiting destruction. |
35 | template <typename T> class WeakGCPtr : Noncopyable { |
36 | public: |
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 | |
64 | private: |
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 | |
75 | template <typename T> inline WeakGCPtr<T>& WeakGCPtr<T>::operator=(T* optr) |
76 | { |
77 | assign(ptr: optr); |
78 | return *this; |
79 | } |
80 | |
81 | template <typename T, typename U> inline bool operator==(const WeakGCPtr<T>& a, const WeakGCPtr<U>& b) |
82 | { |
83 | return a.get() == b.get(); |
84 | } |
85 | |
86 | template <typename T, typename U> inline bool operator==(const WeakGCPtr<T>& a, U* b) |
87 | { |
88 | return a.get() == b; |
89 | } |
90 | |
91 | template <typename T, typename U> inline bool operator==(T* a, const WeakGCPtr<U>& b) |
92 | { |
93 | return a == b.get(); |
94 | } |
95 | |
96 | template <typename T, typename U> inline bool operator!=(const WeakGCPtr<T>& a, const WeakGCPtr<U>& b) |
97 | { |
98 | return a.get() != b.get(); |
99 | } |
100 | |
101 | template <typename T, typename U> inline bool operator!=(const WeakGCPtr<T>& a, U* b) |
102 | { |
103 | return a.get() != b; |
104 | } |
105 | |
106 | template <typename T, typename U> inline bool operator!=(T* a, const WeakGCPtr<U>& b) |
107 | { |
108 | return a != b.get(); |
109 | } |
110 | |
111 | template <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 | |
116 | template <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 | |
121 | template <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 | |