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 "FastAllocBase.h"
28 #include "PassRefPtr.h"
29 
30 namespace WTF {
31 
32     enum PlacementNewAdoptType { PlacementNewAdopt };
33 
34     template<typename T> class PassRefPtr;
35     template<typename T> class NonNullPassRefPtr;
36 
37     enum HashTableDeletedValueType { HashTableDeletedValue };
38 
39     template<typename T> class RefPtr {
40         WTF_MAKE_FAST_ALLOCATED;
41     public:
RefPtr()42         ALWAYS_INLINE RefPtr() : m_ptr(0) { }
RefPtr(T * ptr)43         ALWAYS_INLINE RefPtr(T* ptr) : m_ptr(ptr) { refIfNotNull(ptr); }
RefPtr(const RefPtr & o)44         ALWAYS_INLINE RefPtr(const RefPtr& o) : m_ptr(o.m_ptr) { refIfNotNull(m_ptr); }
RefPtr(const RefPtr<U> & o)45         template<typename U> RefPtr(const RefPtr<U>& o) : m_ptr(o.get()) { refIfNotNull(m_ptr); }
46 
47         // See comments in PassRefPtr.h for an explanation of why these takes const references.
48         template<typename U> RefPtr(const PassRefPtr<U>&);
49         template<typename U> RefPtr(const NonNullPassRefPtr<U>&);
50 
51         // Special constructor for cases where we overwrite an object in place.
RefPtr(PlacementNewAdoptType)52         ALWAYS_INLINE RefPtr(PlacementNewAdoptType) { }
53 
54         // Hash table deleted values, which are only constructed and never copied or destroyed.
RefPtr(HashTableDeletedValueType)55         RefPtr(HashTableDeletedValueType) : m_ptr(hashTableDeletedValue()) { }
isHashTableDeletedValue()56         bool isHashTableDeletedValue() const { return m_ptr == hashTableDeletedValue(); }
57 
~RefPtr()58         ALWAYS_INLINE ~RefPtr() { derefIfNotNull(m_ptr); }
59 
get()60         T* get() const { return m_ptr; }
61 
62         void clear();
release()63         PassRefPtr<T> release() { PassRefPtr<T> tmp = adoptRef(m_ptr); m_ptr = 0; return tmp; }
64 
65         T& operator*() const { return *m_ptr; }
66         ALWAYS_INLINE T* operator->() const { return m_ptr; }
67 
68         bool operator!() const { return !m_ptr; }
69 
70         // This conversion operator allows implicit conversion to bool but not to other integer types.
71         typedef T* (RefPtr::*UnspecifiedBoolType);
UnspecifiedBoolType()72         operator UnspecifiedBoolType() const { return m_ptr ? &RefPtr::m_ptr : 0; }
73 
74         RefPtr& operator=(const RefPtr&);
75         RefPtr& operator=(T*);
76         RefPtr& operator=(const PassRefPtr<T>&);
77         RefPtr& operator=(const NonNullPassRefPtr<T>&);
78 #if !HAVE(NULLPTR)
79         RefPtr& operator=(std::nullptr_t) { clear(); return *this; }
80 #endif
81         template<typename U> RefPtr& operator=(const RefPtr<U>&);
82         template<typename U> RefPtr& operator=(const PassRefPtr<U>&);
83         template<typename U> RefPtr& operator=(const NonNullPassRefPtr<U>&);
84 
85         void swap(RefPtr&);
86 
hashTableDeletedValue()87         static T* hashTableDeletedValue() { return reinterpret_cast<T*>(-1); }
88 
89     private:
90         T* m_ptr;
91     };
92 
RefPtr(const PassRefPtr<U> & o)93     template<typename T> template<typename U> inline RefPtr<T>::RefPtr(const PassRefPtr<U>& o)
94         : m_ptr(o.leakRef())
95     {
96     }
97 
RefPtr(const NonNullPassRefPtr<U> & o)98     template<typename T> template<typename U> inline RefPtr<T>::RefPtr(const NonNullPassRefPtr<U>& o)
99         : m_ptr(o.leakRef())
100     {
101     }
102 
clear()103     template<typename T> inline void RefPtr<T>::clear()
104     {
105         T* ptr = m_ptr;
106         m_ptr = 0;
107         derefIfNotNull(ptr);
108     }
109 
110     template<typename T> inline RefPtr<T>& RefPtr<T>::operator=(const RefPtr<T>& o)
111     {
112         T* optr = o.get();
113         refIfNotNull(optr);
114         T* ptr = m_ptr;
115         m_ptr = optr;
116         derefIfNotNull(ptr);
117         return *this;
118     }
119 
120     template<typename T> template<typename U> inline RefPtr<T>& RefPtr<T>::operator=(const RefPtr<U>& o)
121     {
122         T* optr = o.get();
123         refIfNotNull(optr);
124         T* ptr = m_ptr;
125         m_ptr = optr;
126         derefIfNotNull(ptr);
127         return *this;
128     }
129 
130     template<typename T> inline RefPtr<T>& RefPtr<T>::operator=(T* optr)
131     {
132         refIfNotNull(optr);
133         T* ptr = m_ptr;
134         m_ptr = optr;
135         derefIfNotNull(ptr);
136         return *this;
137     }
138 
139     template<typename T> inline RefPtr<T>& RefPtr<T>::operator=(const PassRefPtr<T>& o)
140     {
141         T* ptr = m_ptr;
142         m_ptr = o.leakRef();
143         derefIfNotNull(ptr);
144         return *this;
145     }
146 
147     template<typename T> inline RefPtr<T>& RefPtr<T>::operator=(const NonNullPassRefPtr<T>& o)
148     {
149         T* ptr = m_ptr;
150         m_ptr = o.leakRef();
151         derefIfNotNull(ptr);
152         return *this;
153     }
154 
155     template<typename T> template<typename U> inline RefPtr<T>& RefPtr<T>::operator=(const PassRefPtr<U>& o)
156     {
157         T* ptr = m_ptr;
158         m_ptr = o.leakRef();
159         derefIfNotNull(ptr);
160         return *this;
161     }
162 
163     template<typename T> template<typename U> inline RefPtr<T>& RefPtr<T>::operator=(const NonNullPassRefPtr<U>& o)
164     {
165         T* ptr = m_ptr;
166         m_ptr = o.leakRef();
167         derefIfNotNull(ptr);
168         return *this;
169     }
170 
swap(RefPtr<T> & o)171     template<class T> inline void RefPtr<T>::swap(RefPtr<T>& o)
172     {
173         std::swap(m_ptr, o.m_ptr);
174     }
175 
swap(RefPtr<T> & a,RefPtr<T> & b)176     template<class T> inline void swap(RefPtr<T>& a, RefPtr<T>& b)
177     {
178         a.swap(b);
179     }
180 
181     template<typename T, typename U> inline bool operator==(const RefPtr<T>& a, const RefPtr<U>& b)
182     {
183         return a.get() == b.get();
184     }
185 
186     template<typename T, typename U> inline bool operator==(const RefPtr<T>& a, U* b)
187     {
188         return a.get() == b;
189     }
190 
191     template<typename T, typename U> inline bool operator==(T* a, const RefPtr<U>& b)
192     {
193         return a == b.get();
194     }
195 
196     template<typename T, typename U> inline bool operator!=(const RefPtr<T>& a, const RefPtr<U>& b)
197     {
198         return a.get() != b.get();
199     }
200 
201     template<typename T, typename U> inline bool operator!=(const RefPtr<T>& a, U* b)
202     {
203         return a.get() != b;
204     }
205 
206     template<typename T, typename U> inline bool operator!=(T* a, const RefPtr<U>& b)
207     {
208         return a != b.get();
209     }
210 
static_pointer_cast(const RefPtr<U> & p)211     template<typename T, typename U> inline RefPtr<T> static_pointer_cast(const RefPtr<U>& p)
212     {
213         return RefPtr<T>(static_cast<T*>(p.get()));
214     }
215 
const_pointer_cast(const RefPtr<U> & p)216     template<typename T, typename U> inline RefPtr<T> const_pointer_cast(const RefPtr<U>& p)
217     {
218         return RefPtr<T>(const_cast<T*>(p.get()));
219     }
220 
getPtr(const RefPtr<T> & p)221     template<typename T> inline T* getPtr(const RefPtr<T>& p)
222     {
223         return p.get();
224     }
225 
226 } // namespace WTF
227 
228 using WTF::RefPtr;
229 using WTF::static_pointer_cast;
230 using WTF::const_pointer_cast;
231 
232 #endif // WTF_RefPtr_h
233