1/*
2 *  Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2013 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/HashTableDeletedValueType.h"
28#include "wtf/PassRefPtr.h"
29#include "wtf/RawPtr.h"
30
31namespace WTF {
32
33    template<typename T> class PassRefPtr;
34
35    template<typename T> class RefPtr {
36        WTF_DISALLOW_CONSTRUCTION_FROM_ZERO(RefPtr);
37        WTF_DISALLOW_ZERO_ASSIGNMENT(RefPtr);
38    public:
39        ALWAYS_INLINE RefPtr() : m_ptr(0) { }
40        ALWAYS_INLINE RefPtr(std::nullptr_t) : m_ptr(0) { }
41        ALWAYS_INLINE RefPtr(T* ptr) : m_ptr(ptr) { refIfNotNull(ptr); }
42        template<typename U> RefPtr(const RawPtr<U>& ptr, EnsurePtrConvertibleArgDecl(U, T)) : m_ptr(ptr.get()) { refIfNotNull(m_ptr); }
43        ALWAYS_INLINE explicit RefPtr(T& ref) : m_ptr(&ref) { m_ptr->ref(); }
44        ALWAYS_INLINE RefPtr(const RefPtr& o) : m_ptr(o.m_ptr) { refIfNotNull(m_ptr); }
45        template<typename U> RefPtr(const RefPtr<U>& o, EnsurePtrConvertibleArgDecl(U, T)) : m_ptr(o.get()) { refIfNotNull(m_ptr); }
46
47#if COMPILER_SUPPORTS(CXX_RVALUE_REFERENCES)
48        RefPtr(RefPtr&& o) : m_ptr(o.m_ptr) { o.m_ptr = 0; }
49        RefPtr& operator=(RefPtr&&);
50#endif
51
52        // See comments in PassRefPtr.h for an explanation of why this takes a const reference.
53        template<typename U> RefPtr(const PassRefPtr<U>&, EnsurePtrConvertibleArgDecl(U, T));
54
55        // Hash table deleted values, which are only constructed and never copied or destroyed.
56        RefPtr(HashTableDeletedValueType) : m_ptr(hashTableDeletedValue()) { }
57        bool isHashTableDeletedValue() const { return m_ptr == hashTableDeletedValue(); }
58
59        ALWAYS_INLINE ~RefPtr() { derefIfNotNull(m_ptr); }
60
61        ALWAYS_INLINE T* get() const { return m_ptr; }
62
63        void clear();
64        PassRefPtr<T> release() { PassRefPtr<T> tmp = adoptRef(m_ptr); m_ptr = 0; return tmp; }
65
66        T& operator*() const { return *m_ptr; }
67        ALWAYS_INLINE T* operator->() const { return m_ptr; }
68
69        bool operator!() const { return !m_ptr; }
70
71        // This conversion operator allows implicit conversion to bool but not to other integer types.
72        typedef T* (RefPtr::*UnspecifiedBoolType);
73        operator UnspecifiedBoolType() const { return m_ptr ? &RefPtr::m_ptr : 0; }
74
75        RefPtr& operator=(const RefPtr&);
76        RefPtr& operator=(T*);
77        RefPtr& operator=(const PassRefPtr<T>&);
78        RefPtr& operator=(std::nullptr_t) { clear(); return *this; }
79
80        template<typename U> RefPtr<T>& operator=(const RefPtr<U>&);
81        template<typename U> RefPtr<T>& operator=(const PassRefPtr<U>&);
82        template<typename U> RefPtr<T>& operator=(const RawPtr<U>&);
83
84        void swap(RefPtr&);
85
86        static T* hashTableDeletedValue() { return reinterpret_cast<T*>(-1); }
87
88    private:
89        T* m_ptr;
90    };
91
92    template<typename T> template<typename U> inline RefPtr<T>::RefPtr(const PassRefPtr<U>& o, EnsurePtrConvertibleArgDefn(U, T))
93        : m_ptr(o.leakRef())
94    {
95    }
96
97    template<typename T> inline void RefPtr<T>::clear()
98    {
99        T* ptr = m_ptr;
100        m_ptr = 0;
101        derefIfNotNull(ptr);
102    }
103
104    template<typename T> inline RefPtr<T>& RefPtr<T>::operator=(const RefPtr& o)
105    {
106        RefPtr ptr = o;
107        swap(ptr);
108        return *this;
109    }
110
111#if COMPILER_SUPPORTS(CXX_RVALUE_REFERENCES)
112    template<typename T> inline RefPtr<T>& RefPtr<T>::operator=(RefPtr&& o)
113    {
114        // FIXME: Instead of explicitly casting to RefPtr&& here, we should use std::move, but that requires us to
115        // have a standard library that supports move semantics.
116        RefPtr ptr = static_cast<RefPtr&&>(o);
117        swap(ptr);
118        return *this;
119    }
120#endif
121
122    template<typename T> template<typename U> inline RefPtr<T>& RefPtr<T>::operator=(const RefPtr<U>& o)
123    {
124        RefPtr ptr = o;
125        swap(ptr);
126        return *this;
127    }
128
129    template<typename T> inline RefPtr<T>& RefPtr<T>::operator=(T* optr)
130    {
131        RefPtr ptr = optr;
132        swap(ptr);
133        return *this;
134    }
135
136    template<typename T> inline RefPtr<T>& RefPtr<T>::operator=(const PassRefPtr<T>& o)
137    {
138        RefPtr ptr = o;
139        swap(ptr);
140        return *this;
141    }
142
143    template<typename T> template<typename U> inline RefPtr<T>& RefPtr<T>::operator=(const PassRefPtr<U>& o)
144    {
145        RefPtr ptr = o;
146        swap(ptr);
147        return *this;
148    }
149
150    template<typename T> template<typename U> inline RefPtr<T>& RefPtr<T>::operator=(const RawPtr<U>& o)
151    {
152        RefPtr ptr = o.get();
153        swap(ptr);
154        return *this;
155    }
156
157    template<class T> inline void RefPtr<T>::swap(RefPtr& o)
158    {
159        std::swap(m_ptr, o.m_ptr);
160    }
161
162    template<class T> inline void swap(RefPtr<T>& a, RefPtr<T>& b)
163    {
164        a.swap(b);
165    }
166
167    template<typename T, typename U> inline bool operator==(const RefPtr<T>& a, const RefPtr<U>& b)
168    {
169        return a.get() == b.get();
170    }
171
172    template<typename T, typename U> inline bool operator==(const RefPtr<T>& a, U* b)
173    {
174        return a.get() == b;
175    }
176
177    template<typename T, typename U> inline bool operator==(T* a, const RefPtr<U>& b)
178    {
179        return a == b.get();
180    }
181
182    template<typename T, typename U> inline bool operator!=(const RefPtr<T>& a, const RefPtr<U>& b)
183    {
184        return a.get() != b.get();
185    }
186
187    template<typename T, typename U> inline bool operator!=(const RefPtr<T>& a, U* b)
188    {
189        return a.get() != b;
190    }
191
192    template<typename T, typename U> inline bool operator!=(T* a, const RefPtr<U>& b)
193    {
194        return a != b.get();
195    }
196
197    template<typename T, typename U> inline RefPtr<T> static_pointer_cast(const RefPtr<U>& p)
198    {
199        return RefPtr<T>(static_cast<T*>(p.get()));
200    }
201
202    template<typename T> inline T* getPtr(const RefPtr<T>& p)
203    {
204        return p.get();
205    }
206
207    template<typename T> class RefPtrValuePeeker {
208    public:
209        ALWAYS_INLINE RefPtrValuePeeker(T* p): m_ptr(p) { }
210        ALWAYS_INLINE RefPtrValuePeeker(std::nullptr_t): m_ptr(0) { }
211        template<typename U> RefPtrValuePeeker(const RefPtr<U>& p): m_ptr(p.get()) { }
212        template<typename U> RefPtrValuePeeker(const PassRefPtr<U>& p): m_ptr(p.get()) { }
213
214        ALWAYS_INLINE operator T*() const { return m_ptr; }
215    private:
216        T* m_ptr;
217    };
218
219} // namespace WTF
220
221using WTF::RefPtr;
222using WTF::static_pointer_cast;
223
224#endif // WTF_RefPtr_h
225