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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 
33 namespace 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 
PassOwnPtr()46         PassOwnPtr() : m_ptr(0) { }
PassOwnPtr(std::nullptr_t)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.
PassOwnPtr(const PassOwnPtr & o)52         PassOwnPtr(const PassOwnPtr& o) : m_ptr(o.leakPtr()) { }
53         template<typename U> PassOwnPtr(const PassOwnPtr<U>&, EnsurePtrConvertibleArgDecl(U, T));
54 
~PassOwnPtr()55         ~PassOwnPtr() { OwnedPtrDeleter<T>::deletePtr(m_ptr); }
56 
get()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;
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:
PassOwnPtr(PtrType ptr)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>&) { 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 
PassOwnPtr(const PassOwnPtr<U> & o,EnsurePtrConvertibleArgDefn (U,T))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 
leakPtr()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 
adoptPtr(T * ptr)122     template<typename T> inline PassOwnPtr<T> adoptPtr(T* ptr)
123     {
124         return PassOwnPtr<T>(ptr);
125     }
126 
adoptArrayPtr(T * ptr)127     template<typename T> inline PassOwnPtr<T[]> adoptArrayPtr(T* ptr)
128     {
129         return PassOwnPtr<T[]>(ptr);
130     }
131 
static_pointer_cast(const PassOwnPtr<U> & p)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 
getPtr(const PassOwnPtr<T> & p)138     template<typename T> inline T* getPtr(const PassOwnPtr<T>& p)
139     {
140         return p.get();
141     }
142 
143 } // namespace WTF
144 
145 using WTF::PassOwnPtr;
146 using WTF::adoptPtr;
147 using WTF::adoptArrayPtr;
148 using WTF::static_pointer_cast;
149 
150 #endif // WTF_PassOwnPtr_h
151