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1 /*
2  *  Copyright (C) 2006, 2007, 2008, 2009, 2010 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 #ifndef WTF_OwnPtr_h
22 #define WTF_OwnPtr_h
23 
24 #include "Assertions.h"
25 #include "NullPtr.h"
26 #include "OwnPtrCommon.h"
27 #include "TypeTraits.h"
28 #include <algorithm>
29 #include <memory>
30 
31 // Remove this once we make all WebKit code compatible with stricter rules about OwnPtr.
32 #define LOOSE_OWN_PTR
33 
34 namespace WTF {
35 
36     // Unlike most of our smart pointers, OwnPtr can take either the pointer type or the pointed-to type.
37 
38     template<typename T> class PassOwnPtr;
39     template<typename T> PassOwnPtr<T> adoptPtr(T*);
40 
41     template<typename T> class OwnPtr {
42     public:
43         typedef typename RemovePointer<T>::Type ValueType;
44         typedef ValueType* PtrType;
45 
OwnPtr()46         OwnPtr() : m_ptr(0) { }
47 
48         // See comment in PassOwnPtr.h for why this takes a const reference.
49         template<typename U> OwnPtr(const PassOwnPtr<U>& o);
50 
51         // This copy constructor is used implicitly by gcc when it generates
52         // transients for assigning a PassOwnPtr<T> object to a stack-allocated
53         // OwnPtr<T> object. It should never be called explicitly and gcc
54         // should optimize away the constructor when generating code.
55         OwnPtr(const OwnPtr<ValueType>&);
56 
~OwnPtr()57         ~OwnPtr() { deleteOwnedPtr(m_ptr); }
58 
get()59         PtrType get() const { return m_ptr; }
60 
61         void clear();
62         PassOwnPtr<T> release();
63         PtrType leakPtr() 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 OwnPtr::*UnspecifiedBoolType;
UnspecifiedBoolType()72         operator UnspecifiedBoolType() const { return m_ptr ? &OwnPtr::m_ptr : 0; }
73 
74         OwnPtr& operator=(const PassOwnPtr<T>&);
75         OwnPtr& operator=(std::nullptr_t) { clear(); return *this; }
76         template<typename U> OwnPtr& operator=(const PassOwnPtr<U>&);
77 
swap(OwnPtr & o)78         void swap(OwnPtr& o) { std::swap(m_ptr, o.m_ptr); }
79 
80 #ifdef LOOSE_OWN_PTR
OwnPtr(PtrType ptr)81         explicit OwnPtr(PtrType ptr) : m_ptr(ptr) { }
82         void set(PtrType);
83 #endif
84 
85     private:
86         PtrType m_ptr;
87     };
88 
OwnPtr(const PassOwnPtr<U> & o)89     template<typename T> template<typename U> inline OwnPtr<T>::OwnPtr(const PassOwnPtr<U>& o)
90         : m_ptr(o.leakPtr())
91     {
92     }
93 
clear()94     template<typename T> inline void OwnPtr<T>::clear()
95     {
96         PtrType ptr = m_ptr;
97         m_ptr = 0;
98         deleteOwnedPtr(ptr);
99     }
100 
release()101     template<typename T> inline PassOwnPtr<T> OwnPtr<T>::release()
102     {
103         PtrType ptr = m_ptr;
104         m_ptr = 0;
105         return adoptPtr(ptr);
106     }
107 
leakPtr()108     template<typename T> inline typename OwnPtr<T>::PtrType OwnPtr<T>::leakPtr()
109     {
110         PtrType ptr = m_ptr;
111         m_ptr = 0;
112         return ptr;
113     }
114 
115 #ifdef LOOSE_OWN_PTR
set(PtrType ptr)116     template<typename T> inline void OwnPtr<T>::set(PtrType ptr)
117     {
118         ASSERT(!ptr || m_ptr != ptr);
119         PtrType oldPtr = m_ptr;
120         m_ptr = ptr;
121         deleteOwnedPtr(oldPtr);
122     }
123 #endif
124 
125     template<typename T> inline OwnPtr<T>& OwnPtr<T>::operator=(const PassOwnPtr<T>& o)
126     {
127         PtrType ptr = m_ptr;
128         m_ptr = o.leakPtr();
129         ASSERT(!ptr || m_ptr != ptr);
130         deleteOwnedPtr(ptr);
131         return *this;
132     }
133 
134     template<typename T> template<typename U> inline OwnPtr<T>& OwnPtr<T>::operator=(const PassOwnPtr<U>& o)
135     {
136         PtrType ptr = m_ptr;
137         m_ptr = o.leakPtr();
138         ASSERT(!ptr || m_ptr != ptr);
139         deleteOwnedPtr(ptr);
140         return *this;
141     }
142 
swap(OwnPtr<T> & a,OwnPtr<T> & b)143     template<typename T> inline void swap(OwnPtr<T>& a, OwnPtr<T>& b)
144     {
145         a.swap(b);
146     }
147 
148     template<typename T, typename U> inline bool operator==(const OwnPtr<T>& a, U* b)
149     {
150         return a.get() == b;
151     }
152 
153     template<typename T, typename U> inline bool operator==(T* a, const OwnPtr<U>& b)
154     {
155         return a == b.get();
156     }
157 
158     template<typename T, typename U> inline bool operator!=(const OwnPtr<T>& a, U* b)
159     {
160         return a.get() != b;
161     }
162 
163     template<typename T, typename U> inline bool operator!=(T* a, const OwnPtr<U>& b)
164     {
165         return a != b.get();
166     }
167 
getPtr(const OwnPtr<T> & p)168     template<typename T> inline typename OwnPtr<T>::PtrType getPtr(const OwnPtr<T>& p)
169     {
170         return p.get();
171     }
172 
173 } // namespace WTF
174 
175 using WTF::OwnPtr;
176 
177 #endif // WTF_OwnPtr_h
178