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 "wtf/Assertions.h"
30#include "wtf/NullPtr.h"
31#include "wtf/OwnPtrCommon.h"
32#include "wtf/TypeTraits.h"
33
34namespace WTF {
35
36    // Unlike most of our smart pointers, PassOwnPtr can take either the pointer type or the pointed-to type.
37
38    template<typename T> class OwnPtr;
39    template<typename T> class PassOwnPtr;
40    template<typename T> PassOwnPtr<T> adoptPtr(T*);
41
42    template<typename T> class PassOwnPtr {
43        WTF_DISALLOW_CONSTRUCTION_FROM_ZERO(PassOwnPtr);
44    public:
45        typedef typename RemovePointer<T>::Type ValueType;
46        typedef ValueType* PtrType;
47
48        PassOwnPtr() : m_ptr(0) { }
49        PassOwnPtr(std::nullptr_t) : m_ptr(0) { }
50
51        // It somewhat breaks the type system to allow transfer of ownership out of
52        // a const PassOwnPtr. However, it makes it much easier to work with PassOwnPtr
53        // temporaries, and we don't have a need to use real const PassOwnPtrs anyway.
54        PassOwnPtr(const PassOwnPtr& o) : m_ptr(o.leakPtr()) { }
55        template<typename U> PassOwnPtr(const PassOwnPtr<U>& o) : m_ptr(o.leakPtr()) { }
56
57        ~PassOwnPtr() { deleteOwnedPtr(m_ptr); }
58
59        PtrType get() const { return m_ptr; }
60
61        PtrType leakPtr() const WARN_UNUSED_RETURN;
62
63        ValueType& operator*() const { ASSERT(m_ptr); return *m_ptr; }
64        PtrType operator->() const { ASSERT(m_ptr); return m_ptr; }
65
66        bool operator!() const { return !m_ptr; }
67
68        // This conversion operator allows implicit conversion to bool but not to other integer types.
69        typedef PtrType PassOwnPtr::*UnspecifiedBoolType;
70        operator UnspecifiedBoolType() const { return m_ptr ? &PassOwnPtr::m_ptr : 0; }
71
72        PassOwnPtr& operator=(const PassOwnPtr&) { COMPILE_ASSERT(!sizeof(T*), PassOwnPtr_should_never_be_assigned_to); return *this; }
73
74        template<typename U> friend PassOwnPtr<U> adoptPtr(U*);
75
76    private:
77        explicit PassOwnPtr(PtrType ptr) : m_ptr(ptr) { }
78
79        // We should never have two OwnPtrs for the same underlying object (otherwise we'll get
80        // double-destruction), so these equality operators should never be needed.
81        template<typename U> bool operator==(const PassOwnPtr<U>&) { COMPILE_ASSERT(!sizeof(U*), OwnPtrs_should_never_be_equal); return false; }
82        template<typename U> bool operator!=(const PassOwnPtr<U>&) { COMPILE_ASSERT(!sizeof(U*), OwnPtrs_should_never_be_equal); return false; }
83        template<typename U> bool operator==(const OwnPtr<U>&) { COMPILE_ASSERT(!sizeof(U*), OwnPtrs_should_never_be_equal); return false; }
84        template<typename U> bool operator!=(const OwnPtr<U>&) { COMPILE_ASSERT(!sizeof(U*), OwnPtrs_should_never_be_equal); return false; }
85
86        mutable PtrType m_ptr;
87    };
88
89    template<typename T> inline typename PassOwnPtr<T>::PtrType PassOwnPtr<T>::leakPtr() const
90    {
91        PtrType ptr = m_ptr;
92        m_ptr = 0;
93        return ptr;
94    }
95
96    template<typename T, typename U> inline bool operator==(const PassOwnPtr<T>& a, const PassOwnPtr<U>& b)
97    {
98        return a.get() == b.get();
99    }
100
101    template<typename T, typename U> inline bool operator==(const PassOwnPtr<T>& a, const OwnPtr<U>& b)
102    {
103        return a.get() == b.get();
104    }
105
106    template<typename T, typename U> inline bool operator==(const OwnPtr<T>& a, const PassOwnPtr<U>& b)
107    {
108        return a.get() == b.get();
109    }
110
111    template<typename T, typename U> inline bool operator==(const PassOwnPtr<T>& a, U* b)
112    {
113        return a.get() == b;
114    }
115
116    template<typename T, typename U> inline bool operator==(T* a, const PassOwnPtr<U>& b)
117    {
118        return a == b.get();
119    }
120
121    template<typename T, typename U> inline bool operator!=(const PassOwnPtr<T>& a, const PassOwnPtr<U>& b)
122    {
123        return a.get() != b.get();
124    }
125
126    template<typename T, typename U> inline bool operator!=(const PassOwnPtr<T>& a, const OwnPtr<U>& b)
127    {
128        return a.get() != b.get();
129    }
130
131    template<typename T, typename U> inline bool operator!=(const OwnPtr<T>& a, const PassOwnPtr<U>& b)
132    {
133        return a.get() != b.get();
134    }
135
136    template<typename T, typename U> inline bool operator!=(const PassOwnPtr<T>& a, U* b)
137    {
138        return a.get() != b;
139    }
140
141    template<typename T, typename U> inline bool operator!=(T* a, const PassOwnPtr<U>& b)
142    {
143        return a != b.get();
144    }
145
146    template<typename T> inline PassOwnPtr<T> adoptPtr(T* ptr)
147    {
148        return PassOwnPtr<T>(ptr);
149    }
150
151    template<typename T, typename U> inline PassOwnPtr<T> static_pointer_cast(const PassOwnPtr<U>& p)
152    {
153        return adoptPtr(static_cast<T*>(p.leakPtr()));
154    }
155
156    template<typename T, typename U> inline PassOwnPtr<T> const_pointer_cast(const PassOwnPtr<U>& p)
157    {
158        return adoptPtr(const_cast<T*>(p.leakPtr()));
159    }
160
161    template<typename T> inline T* getPtr(const PassOwnPtr<T>& p)
162    {
163        return p.get();
164    }
165
166} // namespace WTF
167
168using WTF::PassOwnPtr;
169using WTF::adoptPtr;
170using WTF::const_pointer_cast;
171using WTF::static_pointer_cast;
172
173#endif // WTF_PassOwnPtr_h
174