1/*
2 *  Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
3 *
4 *  This library is free software; you can redistribute it and/or
5 *  modify it under the terms of the GNU Library General Public
6 *  License as published by the Free Software Foundation; either
7 *  version 2 of the License, or (at your option) any later version.
8 *
9 *  This library is distributed in the hope that it will be useful,
10 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
11 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12 *  Library General Public License for more details.
13 *
14 *  You should have received a copy of the GNU Library General Public License
15 *  along with this library; see the file COPYING.LIB.  If not, write to
16 *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
17 *  Boston, MA 02110-1301, USA.
18 *
19 */
20
21// RefPtr and PassRefPtr are documented at http://webkit.org/coding/RefPtr.html
22
23#ifndef WTF_RefPtr_h
24#define WTF_RefPtr_h
25
26#include <algorithm>
27#include "wtf/FastAllocBase.h"
28#include "wtf/HashTableDeletedValueType.h"
29#include "wtf/PassRefPtr.h"
30
31namespace WTF {
32
33    template<typename T> class PassRefPtr;
34
35    template<typename T> class RefPtr {
36        WTF_MAKE_FAST_ALLOCATED;
37    public:
38        ALWAYS_INLINE RefPtr() : m_ptr(0) { }
39        ALWAYS_INLINE RefPtr(T* ptr) : m_ptr(ptr) { refIfNotNull(ptr); }
40        ALWAYS_INLINE RefPtr(const RefPtr& o) : m_ptr(o.m_ptr) { refIfNotNull(m_ptr); }
41        template<typename U> RefPtr(const RefPtr<U>& o, EnsurePtrConvertibleArgDecl(U, T)) : m_ptr(o.get()) { refIfNotNull(m_ptr); }
42
43        // See comments in PassRefPtr.h for an explanation of why this takes a const reference.
44        template<typename U> RefPtr(const PassRefPtr<U>&, EnsurePtrConvertibleArgDecl(U, T));
45
46        // Hash table deleted values, which are only constructed and never copied or destroyed.
47        RefPtr(HashTableDeletedValueType) : m_ptr(hashTableDeletedValue()) { }
48        bool isHashTableDeletedValue() const { return m_ptr == hashTableDeletedValue(); }
49
50        ALWAYS_INLINE ~RefPtr() { derefIfNotNull(m_ptr); }
51
52        T* get() const { return m_ptr; }
53
54        void clear();
55        PassRefPtr<T> release() { PassRefPtr<T> tmp = adoptRef(m_ptr); m_ptr = 0; return tmp; }
56
57        T& operator*() const { return *m_ptr; }
58        ALWAYS_INLINE T* operator->() const { return m_ptr; }
59
60        bool operator!() const { return !m_ptr; }
61
62        // This conversion operator allows implicit conversion to bool but not to other integer types.
63        typedef T* (RefPtr::*UnspecifiedBoolType);
64        operator UnspecifiedBoolType() const { return m_ptr ? &RefPtr::m_ptr : 0; }
65
66        RefPtr& operator=(const RefPtr&);
67        RefPtr& operator=(T*);
68        RefPtr& operator=(const PassRefPtr<T>&);
69#if !COMPILER_SUPPORTS(CXX_NULLPTR)
70        RefPtr& operator=(std::nullptr_t) { clear(); return *this; }
71#endif
72        template<typename U> EnsurePtrConvertibleType(RefPtr<T>&, U, T) operator=(const RefPtr<U>&);
73        template<typename U> EnsurePtrConvertibleType(RefPtr<T>&, U, T) operator=(const PassRefPtr<U>&);
74
75        void swap(RefPtr&);
76
77        static T* hashTableDeletedValue() { return reinterpret_cast<T*>(-1); }
78
79    private:
80        T* m_ptr;
81    };
82
83    template<typename T> template<typename U> inline RefPtr<T>::RefPtr(const PassRefPtr<U>& o, EnsurePtrConvertibleArgDefn(U, T))
84        : m_ptr(o.leakRef())
85    {
86    }
87
88    template<typename T> inline void RefPtr<T>::clear()
89    {
90        T* ptr = m_ptr;
91        m_ptr = 0;
92        derefIfNotNull(ptr);
93    }
94
95    template<typename T> inline RefPtr<T>& RefPtr<T>::operator=(const RefPtr<T>& o)
96    {
97        T* optr = o.get();
98        refIfNotNull(optr);
99        T* ptr = m_ptr;
100        m_ptr = optr;
101        derefIfNotNull(ptr);
102        return *this;
103    }
104
105    template<typename T> template<typename U> inline EnsurePtrConvertibleType(RefPtr<T>&, U, T) RefPtr<T>::operator=(const RefPtr<U>& o)
106    {
107        T* optr = o.get();
108        refIfNotNull(optr);
109        T* ptr = m_ptr;
110        m_ptr = optr;
111        derefIfNotNull(ptr);
112        return *this;
113    }
114
115    template<typename T> inline RefPtr<T>& RefPtr<T>::operator=(T* optr)
116    {
117        refIfNotNull(optr);
118        T* ptr = m_ptr;
119        m_ptr = optr;
120        derefIfNotNull(ptr);
121        return *this;
122    }
123
124    template<typename T> inline RefPtr<T>& RefPtr<T>::operator=(const PassRefPtr<T>& o)
125    {
126        T* ptr = m_ptr;
127        m_ptr = o.leakRef();
128        derefIfNotNull(ptr);
129        return *this;
130    }
131
132    template<typename T> template<typename U> inline EnsurePtrConvertibleType(RefPtr<T>&, U, T) RefPtr<T>::operator=(const PassRefPtr<U>& o)
133    {
134        T* ptr = m_ptr;
135        m_ptr = o.leakRef();
136        derefIfNotNull(ptr);
137        return *this;
138    }
139
140    template<class T> inline void RefPtr<T>::swap(RefPtr<T>& o)
141    {
142        std::swap(m_ptr, o.m_ptr);
143    }
144
145    template<class T> inline void swap(RefPtr<T>& a, RefPtr<T>& b)
146    {
147        a.swap(b);
148    }
149
150    template<typename T, typename U> inline bool operator==(const RefPtr<T>& a, const RefPtr<U>& b)
151    {
152        return a.get() == b.get();
153    }
154
155    template<typename T, typename U> inline bool operator==(const RefPtr<T>& a, U* b)
156    {
157        return a.get() == b;
158    }
159
160    template<typename T, typename U> inline bool operator==(T* a, const RefPtr<U>& b)
161    {
162        return a == b.get();
163    }
164
165    template<typename T, typename U> inline bool operator!=(const RefPtr<T>& a, const RefPtr<U>& b)
166    {
167        return a.get() != b.get();
168    }
169
170    template<typename T, typename U> inline bool operator!=(const RefPtr<T>& a, U* b)
171    {
172        return a.get() != b;
173    }
174
175    template<typename T, typename U> inline bool operator!=(T* a, const RefPtr<U>& b)
176    {
177        return a != b.get();
178    }
179
180    template<typename T, typename U> inline RefPtr<T> static_pointer_cast(const RefPtr<U>& p)
181    {
182        return RefPtr<T>(static_cast<T*>(p.get()));
183    }
184
185    template<typename T> inline RefPtr<T> const_pointer_cast(const RefPtr<T>& p)
186    {
187        return RefPtr<T>(const_cast<T*>(p.get()));
188    }
189
190    template<typename T> inline T* getPtr(const RefPtr<T>& p)
191    {
192        return p.get();
193    }
194
195} // namespace WTF
196
197using WTF::RefPtr;
198using WTF::static_pointer_cast;
199using WTF::const_pointer_cast;
200
201#endif // WTF_RefPtr_h
202