1/*
2 * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
3 * Copyright (C) 2013 Intel Corporation. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
18 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
19 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
20 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
21 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
22 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#ifndef WTF_PassOwnPtr_h
28#define WTF_PassOwnPtr_h
29
30#include "wtf/NullPtr.h"
31#include "wtf/OwnPtrCommon.h"
32
33namespace WTF {
34
35    template<typename T> class OwnPtr;
36    template<typename T> class PassOwnPtr;
37    template<typename T> PassOwnPtr<T> adoptPtr(T*);
38    template<typename T> PassOwnPtr<T[]> adoptArrayPtr(T*);
39
40    template<typename T> class PassOwnPtr {
41        WTF_DISALLOW_CONSTRUCTION_FROM_ZERO(PassOwnPtr);
42    public:
43        typedef typename RemoveExtent<T>::Type ValueType;
44        typedef ValueType* PtrType;
45
46        PassOwnPtr() : m_ptr(0) { }
47        PassOwnPtr(std::nullptr_t) : m_ptr(0) { }
48
49        // It somewhat breaks the type system to allow transfer of ownership out of
50        // a const PassOwnPtr. However, it makes it much easier to work with PassOwnPtr
51        // temporaries, and we don't have a need to use real const PassOwnPtrs anyway.
52        PassOwnPtr(const PassOwnPtr& o) : m_ptr(o.leakPtr()) { }
53        template<typename U> PassOwnPtr(const PassOwnPtr<U>&, EnsurePtrConvertibleArgDecl(U, T));
54
55        ~PassOwnPtr() { OwnedPtrDeleter<T>::deletePtr(m_ptr); }
56
57        PtrType get() const { return m_ptr; }
58
59        PtrType leakPtr() const WARN_UNUSED_RETURN;
60
61        ValueType& operator*() const { ASSERT(m_ptr); return *m_ptr; }
62        PtrType operator->() const { ASSERT(m_ptr); return m_ptr; }
63
64        bool operator!() const { return !m_ptr; }
65
66        // This conversion operator allows implicit conversion to bool but not to other integer types.
67        typedef PtrType PassOwnPtr::*UnspecifiedBoolType;
68        operator UnspecifiedBoolType() const { return m_ptr ? &PassOwnPtr::m_ptr : 0; }
69
70        template<typename U> friend PassOwnPtr<U> adoptPtr(U*);
71        template<typename U> friend PassOwnPtr<U[]> adoptArrayPtr(U*);
72        template<typename U> friend class OwnPtr;
73
74    private:
75        explicit PassOwnPtr(PtrType ptr) : m_ptr(ptr) { }
76
77        PassOwnPtr& operator=(const PassOwnPtr&) { COMPILE_ASSERT(!sizeof(T*), PassOwnPtr_should_never_be_assigned_to); return *this; }
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>&) const { COMPILE_ASSERT(!sizeof(U*), OwnPtrs_should_never_be_equal); return false; }
82        template<typename U> bool operator!=(const PassOwnPtr<U>&) const { COMPILE_ASSERT(!sizeof(U*), OwnPtrs_should_never_be_equal); return false; }
83        template<typename U> bool operator==(const OwnPtr<U>&) const { COMPILE_ASSERT(!sizeof(U*), OwnPtrs_should_never_be_equal); return false; }
84        template<typename U> bool operator!=(const OwnPtr<U>&) const { COMPILE_ASSERT(!sizeof(U*), OwnPtrs_should_never_be_equal); return false; }
85
86        mutable PtrType m_ptr;
87    };
88
89    template<typename T> template<typename U> inline PassOwnPtr<T>::PassOwnPtr(const PassOwnPtr<U>& o, EnsurePtrConvertibleArgDefn(U, T))
90        : m_ptr(o.leakPtr())
91    {
92        COMPILE_ASSERT(!IsArray<T>::value, Pointers_to_array_must_never_be_converted);
93    }
94
95    template<typename T> inline typename PassOwnPtr<T>::PtrType PassOwnPtr<T>::leakPtr() const
96    {
97        PtrType ptr = m_ptr;
98        m_ptr = 0;
99        return ptr;
100    }
101
102    template<typename T, typename U> inline bool operator==(const PassOwnPtr<T>& a, U* b)
103    {
104        return a.get() == b;
105    }
106
107    template<typename T, typename U> inline bool operator==(T* a, const PassOwnPtr<U>& b)
108    {
109        return a == b.get();
110    }
111
112    template<typename T, typename U> inline bool operator!=(const PassOwnPtr<T>& a, U* b)
113    {
114        return a.get() != b;
115    }
116
117    template<typename T, typename U> inline bool operator!=(T* a, const PassOwnPtr<U>& b)
118    {
119        return a != b.get();
120    }
121
122    template<typename T> inline PassOwnPtr<T> adoptPtr(T* ptr)
123    {
124        return PassOwnPtr<T>(ptr);
125    }
126
127    template<typename T> inline PassOwnPtr<T[]> adoptArrayPtr(T* ptr)
128    {
129        return PassOwnPtr<T[]>(ptr);
130    }
131
132    template<typename T, typename U> inline PassOwnPtr<T> static_pointer_cast(const PassOwnPtr<U>& p)
133    {
134        COMPILE_ASSERT(!IsArray<T>::value, Pointers_to_array_must_never_be_converted);
135        return adoptPtr(static_cast<T*>(p.leakPtr()));
136    }
137
138    template<typename T> inline T* getPtr(const PassOwnPtr<T>& p)
139    {
140        return p.get();
141    }
142
143} // namespace WTF
144
145using WTF::PassOwnPtr;
146using WTF::adoptPtr;
147using WTF::adoptArrayPtr;
148using WTF::static_pointer_cast;
149
150#endif // WTF_PassOwnPtr_h
151