1/*
2 * Copyright (C) 2009, 2010 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. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef WTF_PassOwnPtr_h
27#define WTF_PassOwnPtr_h
28
29#include "Assertions.h"
30#include "NullPtr.h"
31#include "OwnPtrCommon.h"
32#include "TypeTraits.h"
33
34// Remove this once we make all WebKit code compatible with stricter rules about PassOwnPtr.
35#define LOOSE_PASS_OWN_PTR
36
37namespace WTF {
38
39    // Unlike most of our smart pointers, PassOwnPtr can take either the pointer type or the pointed-to type.
40
41    template<typename T> class OwnPtr;
42    template<typename T> class PassOwnPtr;
43    template<typename T> PassOwnPtr<T> adoptPtr(T*);
44
45    template<typename T> class PassOwnPtr {
46    public:
47        typedef typename RemovePointer<T>::Type ValueType;
48        typedef ValueType* PtrType;
49
50        PassOwnPtr() : m_ptr(0) { }
51
52        // It somewhat breaks the type system to allow transfer of ownership out of
53        // a const PassOwnPtr. However, it makes it much easier to work with PassOwnPtr
54        // temporaries, and we don't have a need to use real const PassOwnPtrs anyway.
55        PassOwnPtr(const PassOwnPtr& o) : m_ptr(o.leakPtr()) { }
56        template<typename U> PassOwnPtr(const PassOwnPtr<U>& o) : m_ptr(o.leakPtr()) { }
57
58        ~PassOwnPtr() { deleteOwnedPtr(m_ptr); }
59
60        PtrType get() const { return m_ptr; }
61
62        void clear();
63        PtrType leakPtr() const WARN_UNUSED_RETURN;
64
65        ValueType& operator*() const { ASSERT(m_ptr); return *m_ptr; }
66        PtrType operator->() const { ASSERT(m_ptr); 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 PtrType PassOwnPtr::*UnspecifiedBoolType;
72        operator UnspecifiedBoolType() const { return m_ptr ? &PassOwnPtr::m_ptr : 0; }
73
74        PassOwnPtr& operator=(const PassOwnPtr<T>&);
75#if !defined(LOOSE_PASS_OWN_PTR) || !HAVE(NULLPTR)
76        PassOwnPtr& operator=(std::nullptr_t) { clear(); return *this; }
77#endif
78        template<typename U> PassOwnPtr& operator=(const PassOwnPtr<U>&);
79
80        template<typename U> friend PassOwnPtr<U> adoptPtr(U*);
81
82#ifdef LOOSE_PASS_OWN_PTR
83        PassOwnPtr(PtrType ptr) : m_ptr(ptr) { }
84        PassOwnPtr& operator=(PtrType);
85#endif
86
87    private:
88#ifndef LOOSE_PASS_OWN_PTR
89        explicit PassOwnPtr(PtrType ptr) : m_ptr(ptr) { }
90#endif
91
92        mutable PtrType m_ptr;
93    };
94
95    template<typename T> inline void PassOwnPtr<T>::clear()
96    {
97        PtrType ptr = m_ptr;
98        m_ptr = 0;
99        deleteOwnedPtr(ptr);
100    }
101
102    template<typename T> inline typename PassOwnPtr<T>::PtrType PassOwnPtr<T>::leakPtr() const
103    {
104        PtrType ptr = m_ptr;
105        m_ptr = 0;
106        return ptr;
107    }
108
109#ifdef LOOSE_PASS_OWN_PTR
110    template<typename T> inline PassOwnPtr<T>& PassOwnPtr<T>::operator=(PtrType optr)
111    {
112        PtrType ptr = m_ptr;
113        m_ptr = optr;
114        ASSERT(!ptr || m_ptr != ptr);
115        if (ptr)
116            deleteOwnedPtr(ptr);
117        return *this;
118    }
119#endif
120
121    template<typename T> inline PassOwnPtr<T>& PassOwnPtr<T>::operator=(const PassOwnPtr<T>& optr)
122    {
123        PtrType ptr = m_ptr;
124        m_ptr = optr.leakPtr();
125        ASSERT(!ptr || m_ptr != ptr);
126        if (ptr)
127            deleteOwnedPtr(ptr);
128        return *this;
129    }
130
131    template<typename T> template<typename U> inline PassOwnPtr<T>& PassOwnPtr<T>::operator=(const PassOwnPtr<U>& optr)
132    {
133        PtrType ptr = m_ptr;
134        m_ptr = optr.leakPtr();
135        ASSERT(!ptr || m_ptr != ptr);
136        if (ptr)
137            deleteOwnedPtr(ptr);
138        return *this;
139    }
140
141    template<typename T, typename U> inline bool operator==(const PassOwnPtr<T>& a, const PassOwnPtr<U>& b)
142    {
143        return a.get() == b.get();
144    }
145
146    template<typename T, typename U> inline bool operator==(const PassOwnPtr<T>& a, const OwnPtr<U>& b)
147    {
148        return a.get() == b.get();
149    }
150
151    template<typename T, typename U> inline bool operator==(const OwnPtr<T>& a, const PassOwnPtr<U>& b)
152    {
153        return a.get() == b.get();
154    }
155
156    template<typename T, typename U> inline bool operator==(const PassOwnPtr<T>& a, U* b)
157    {
158        return a.get() == b;
159    }
160
161    template<typename T, typename U> inline bool operator==(T* a, const PassOwnPtr<U>& b)
162    {
163        return a == b.get();
164    }
165
166    template<typename T, typename U> inline bool operator!=(const PassOwnPtr<T>& a, const PassOwnPtr<U>& b)
167    {
168        return a.get() != b.get();
169    }
170
171    template<typename T, typename U> inline bool operator!=(const PassOwnPtr<T>& a, const OwnPtr<U>& b)
172    {
173        return a.get() != b.get();
174    }
175
176    template<typename T, typename U> inline bool operator!=(const OwnPtr<T>& a, const PassOwnPtr<U>& b)
177    {
178        return a.get() != b.get();
179    }
180
181    template<typename T, typename U> inline bool operator!=(const PassOwnPtr<T>& a, U* b)
182    {
183        return a.get() != b;
184    }
185
186    template<typename T, typename U> inline bool operator!=(T* a, const PassOwnPtr<U>& b)
187    {
188        return a != b.get();
189    }
190
191    template<typename T> inline PassOwnPtr<T> adoptPtr(T* ptr)
192    {
193        return PassOwnPtr<T>(ptr);
194    }
195
196    template<typename T, typename U> inline PassOwnPtr<T> static_pointer_cast(const PassOwnPtr<U>& p)
197    {
198        return adoptPtr(static_cast<T*>(p.leakPtr()));
199    }
200
201    template<typename T, typename U> inline PassOwnPtr<T> const_pointer_cast(const PassOwnPtr<U>& p)
202    {
203        return adoptPtr(const_cast<T*>(p.leakPtr()));
204    }
205
206    template<typename T> inline T* getPtr(const PassOwnPtr<T>& p)
207    {
208        return p.get();
209    }
210
211} // namespace WTF
212
213using WTF::PassOwnPtr;
214using WTF::adoptPtr;
215using WTF::const_pointer_cast;
216using WTF::static_pointer_cast;
217
218#endif // WTF_PassOwnPtr_h
219