wtf/OwnPtr.h

   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 namespace WTF {
  32
  33     // Unlike most of our smart pointers, OwnPtr can take either the pointer type or the pointed-to type.
  34
  35     template<typename T> class PassOwnPtr;
  36     template<typename T> PassOwnPtr<T> adoptPtr(T*);
  37
  38     template<typename T> class OwnPtr {
  39     public:
  40         typedef typename RemovePointer<T>::Type ValueType;
  41         typedef ValueType* PtrType;
  42
  43         OwnPtr() : m_ptr(0) { }
  44
  45         // See comment in PassOwnPtr.h for why this takes a const reference.
  46         template<typename U> OwnPtr(const PassOwnPtr<U>& o);
  47
  48         // This copy constructor is used implicitly by gcc when it generates
  49         // transients for assigning a PassOwnPtr<T> object to a stack-allocated
  50         // OwnPtr<T> object. It should never be called explicitly and gcc
  51         // should optimize away the constructor when generating code.
  52         OwnPtr(const OwnPtr<ValueType>&);
  53
  54         ~OwnPtr() { deleteOwnedPtr(m_ptr); }
  55
  56         PtrType get() const { return m_ptr; }
  57
  58         void clear();
  59         PassOwnPtr<T> release();
  60         PtrType leakPtr() WARN_UNUSED_RETURN;
  61
  62         ValueType& operator*() const { ASSERT(m_ptr); return *m_ptr; }
  63         PtrType operator->() const { ASSERT(m_ptr); return m_ptr; }
  64
  65         bool operator!() const { return !m_ptr; }
  66
  67         // This conversion operator allows implicit conversion to bool but not to other integer types.
  68         typedef PtrType OwnPtr::*UnspecifiedBoolType;
  69         operator UnspecifiedBoolType() const { return m_ptr ? &OwnPtr::m_ptr : 0; }
  70
  71         OwnPtr& operator=(const PassOwnPtr<T>&);
  72         OwnPtr& operator=(std::nullptr_t) { clear(); return *this; }
  73         template<typename U> OwnPtr& operator=(const PassOwnPtr<U>&);
  74
  75         void swap(OwnPtr& o) { std::swap(m_ptr, o.m_ptr); }
  76
  77 #ifdef LOOSE_OWN_PTR
  78         explicit OwnPtr(PtrType ptr) : m_ptr(ptr) { }
  79         void set(PtrType);
  80 #endif
  81
  82     private:
  83         OwnPtr& operator=(const OwnPtr<T>&);
  84
  85         // We should never have two OwnPtrs for the same underlying object (otherwise we'll get
  86         // double-destruction), so these equality operators should never be needed.
  87         template<typename U> bool operator==(const OwnPtr<U>&) { COMPILE_ASSERT(!sizeof(U*), OwnPtrs_should_never_be_equal); return false; }
  88         template<typename U> bool operator!=(const OwnPtr<U>&) { COMPILE_ASSERT(!sizeof(U*), OwnPtrs_should_never_be_equal); return false; }
  89         template<typename U> bool operator==(const PassOwnPtr<U>&) { COMPILE_ASSERT(!sizeof(U*), OwnPtrs_should_never_be_equal); return false; }
  90         template<typename U> bool operator!=(const PassOwnPtr<U>&) { COMPILE_ASSERT(!sizeof(U*), OwnPtrs_should_never_be_equal); return false; }
  91
  92         PtrType m_ptr;
  93     };
  94
  95     template<typename T> template<typename U> inline OwnPtr<T>::OwnPtr(const PassOwnPtr<U>& o)
  96         : m_ptr(o.leakPtr())
  97     {
  98     }
  99
 100     template<typename T> inline void OwnPtr<T>::clear()
 101     {
 102         PtrType ptr = m_ptr;
 103         m_ptr = 0;
 104         deleteOwnedPtr(ptr);
 105     }
 106
 107     template<typename T> inline PassOwnPtr<T> OwnPtr<T>::release()
 108     {
 109         PtrType ptr = m_ptr;
 110         m_ptr = 0;
 111         return adoptPtr(ptr);
 112     }
 113
 114     template<typename T> inline typename OwnPtr<T>::PtrType OwnPtr<T>::leakPtr()
 115     {
 116         PtrType ptr = m_ptr;
 117         m_ptr = 0;
 118         return ptr;
 119     }
 120
 121 #ifdef LOOSE_OWN_PTR
 122     template<typename T> inline void OwnPtr<T>::set(PtrType ptr)
 123     {
 124         ASSERT(!ptr || m_ptr != ptr);
 125         PtrType oldPtr = m_ptr;
 126         m_ptr = ptr;
 127         deleteOwnedPtr(oldPtr);
 128     }
 129 #endif
 130
 131     template<typename T> inline OwnPtr<T>& OwnPtr<T>::operator=(const PassOwnPtr<T>& o)
 132     {
 133         PtrType ptr = m_ptr;
 134         m_ptr = o.leakPtr();
 135         ASSERT(!ptr || m_ptr != ptr);
 136         deleteOwnedPtr(ptr);
 137         return *this;
 138     }
 139
 140     template<typename T> template<typename U> inline OwnPtr<T>& OwnPtr<T>::operator=(const PassOwnPtr<U>& o)
 141     {
 142         PtrType ptr = m_ptr;
 143         m_ptr = o.leakPtr();
 144         ASSERT(!ptr || m_ptr != ptr);
 145         deleteOwnedPtr(ptr);
 146         return *this;
 147     }
 148
 149     template<typename T> inline void swap(OwnPtr<T>& a, OwnPtr<T>& b)
 150     {
 151         a.swap(b);
 152     }
 153
 154     template<typename T, typename U> inline bool operator==(const OwnPtr<T>& a, U* b)
 155     {
 156         return a.get() == b;
 157     }
 158
 159     template<typename T, typename U> inline bool operator==(T* a, const OwnPtr<U>& b)
 160     {
 161         return a == b.get();
 162     }
 163
 164     template<typename T, typename U> inline bool operator!=(const OwnPtr<T>& a, U* b)
 165     {
 166         return a.get() != b;
 167     }
 168
 169     template<typename T, typename U> inline bool operator!=(T* a, const OwnPtr<U>& b)
 170     {
 171         return a != b.get();
 172     }
 173
 174     template<typename T> inline typename OwnPtr<T>::PtrType getPtr(const OwnPtr<T>& p)
 175     {
 176         return p.get();
 177     }
 178
 179 } // namespace WTF
 180
 181 using WTF::OwnPtr;
 182
 183 #endif // WTF_OwnPtr_h