wtf/RefPtr.h

   1 /*
   2  *  Copyright (C) 2005, 2006, 2007, 2008 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_RefPtr_h
  22 #define WTF_RefPtr_h
  23
  24 #include <algorithm>
  25 #include "AlwaysInline.h"
  26 #include "FastAllocBase.h"
  27
  28 namespace WTF {
  29
  30     enum PlacementNewAdoptType { PlacementNewAdopt };
  31
  32     template <typename T> class PassRefPtr;
  33     template <typename T> class NonNullPassRefPtr;
  34
  35     enum HashTableDeletedValueType { HashTableDeletedValue };
  36
  37     template <typename T> class RefPtr : public FastAllocBase {
  38     public:
  39         RefPtr() : m_ptr(0) { }
  40         RefPtr(T* ptr) : m_ptr(ptr) { if (ptr) ptr->ref(); }
  41         RefPtr(const RefPtr& o) : m_ptr(o.m_ptr) { if (T* ptr = m_ptr) ptr->ref(); }
  42         // see comment in PassRefPtr.h for why this takes const reference
  43         template <typename U> RefPtr(const PassRefPtr<U>&);
  44         template <typename U> RefPtr(const NonNullPassRefPtr<U>&);
  45
  46         // Special constructor for cases where we overwrite an object in place.
  47         RefPtr(PlacementNewAdoptType) { }
  48
  49         // Hash table deleted values, which are only constructed and never copied or destroyed.
  50         RefPtr(HashTableDeletedValueType) : m_ptr(hashTableDeletedValue()) { }
  51         bool isHashTableDeletedValue() const { return m_ptr == hashTableDeletedValue(); }
  52
  53         ~RefPtr() { if (T* ptr = m_ptr) ptr->deref(); }
  54
  55         template <typename U> RefPtr(const RefPtr<U>& o) : m_ptr(o.get()) { if (T* ptr = m_ptr) ptr->ref(); }
  56
  57         T* get() const { return m_ptr; }
  58
  59         void clear() { if (T* ptr = m_ptr) ptr->deref(); m_ptr = 0; }
  60         PassRefPtr<T> release() { PassRefPtr<T> tmp = adoptRef(m_ptr); m_ptr = 0; return tmp; }
  61
  62         T& operator*() const { return *m_ptr; }
  63         ALWAYS_INLINE T* operator->() const { 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 #if COMPILER(WINSCW)
  69         operator bool() const { return m_ptr; }
  70 #else
  71         typedef T* RefPtr::*UnspecifiedBoolType;
  72         operator UnspecifiedBoolType() const { return m_ptr ? &RefPtr::m_ptr : 0; }
  73 #endif
  74
  75         RefPtr& operator=(const RefPtr&);
  76         RefPtr& operator=(T*);
  77         RefPtr& operator=(const PassRefPtr<T>&);
  78         RefPtr& operator=(const NonNullPassRefPtr<T>&);
  79         template <typename U> RefPtr& operator=(const RefPtr<U>&);
  80         template <typename U> RefPtr& operator=(const PassRefPtr<U>&);
  81         template <typename U> RefPtr& operator=(const NonNullPassRefPtr<U>&);
  82
  83         void swap(RefPtr&);
  84
  85     private:
  86         static T* hashTableDeletedValue() { return reinterpret_cast<T*>(-1); }
  87
  88         T* m_ptr;
  89     };
  90
  91     template <typename T> template <typename U> inline RefPtr<T>::RefPtr(const PassRefPtr<U>& o)
  92         : m_ptr(o.releaseRef())
  93     {
  94     }
  95
  96     template <typename T> template <typename U> inline RefPtr<T>::RefPtr(const NonNullPassRefPtr<U>& o)
  97         : m_ptr(o.releaseRef())
  98     {
  99     }
 100
 101     template <typename T> inline RefPtr<T>& RefPtr<T>::operator=(const RefPtr<T>& o)
 102     {
 103         T* optr = o.get();
 104         if (optr)
 105             optr->ref();
 106         T* ptr = m_ptr;
 107         m_ptr = optr;
 108         if (ptr)
 109             ptr->deref();
 110         return *this;
 111     }
 112
 113     template <typename T> template <typename U> inline RefPtr<T>& RefPtr<T>::operator=(const RefPtr<U>& o)
 114     {
 115         T* optr = o.get();
 116         if (optr)
 117             optr->ref();
 118         T* ptr = m_ptr;
 119         m_ptr = optr;
 120         if (ptr)
 121             ptr->deref();
 122         return *this;
 123     }
 124
 125     template <typename T> inline RefPtr<T>& RefPtr<T>::operator=(T* optr)
 126     {
 127         if (optr)
 128             optr->ref();
 129         T* ptr = m_ptr;
 130         m_ptr = optr;
 131         if (ptr)
 132             ptr->deref();
 133         return *this;
 134     }
 135
 136     template <typename T> inline RefPtr<T>& RefPtr<T>::operator=(const PassRefPtr<T>& o)
 137     {
 138         T* ptr = m_ptr;
 139         m_ptr = o.releaseRef();
 140         if (ptr)
 141             ptr->deref();
 142         return *this;
 143     }
 144
 145     template <typename T> inline RefPtr<T>& RefPtr<T>::operator=(const NonNullPassRefPtr<T>& o)
 146     {
 147         T* ptr = m_ptr;
 148         m_ptr = o.releaseRef();
 149         if (ptr)
 150             ptr->deref();
 151         return *this;
 152     }
 153
 154     template <typename T> template <typename U> inline RefPtr<T>& RefPtr<T>::operator=(const PassRefPtr<U>& o)
 155     {
 156         T* ptr = m_ptr;
 157         m_ptr = o.releaseRef();
 158         if (ptr)
 159             ptr->deref();
 160         return *this;
 161     }
 162
 163     template <typename T> template <typename U> inline RefPtr<T>& RefPtr<T>::operator=(const NonNullPassRefPtr<U>& o)
 164     {
 165         T* ptr = m_ptr;
 166         m_ptr = o.releaseRef();
 167         if (ptr)
 168             ptr->deref();
 169         return *this;
 170     }
 171
 172     template <class T> inline void RefPtr<T>::swap(RefPtr<T>& o)
 173     {
 174         std::swap(m_ptr, o.m_ptr);
 175     }
 176
 177     template <class T> inline void swap(RefPtr<T>& a, RefPtr<T>& b)
 178     {
 179         a.swap(b);
 180     }
 181
 182     template <typename T, typename U> inline bool operator==(const RefPtr<T>& a, const RefPtr<U>& b)
 183     {
 184         return a.get() == b.get();
 185     }
 186
 187     template <typename T, typename U> inline bool operator==(const RefPtr<T>& a, U* b)
 188     {
 189         return a.get() == b;
 190     }
 191
 192     template <typename T, typename U> inline bool operator==(T* a, const RefPtr<U>& b)
 193     {
 194         return a == b.get();
 195     }
 196
 197     template <typename T, typename U> inline bool operator!=(const RefPtr<T>& a, const RefPtr<U>& b)
 198     {
 199         return a.get() != b.get();
 200     }
 201
 202     template <typename T, typename U> inline bool operator!=(const RefPtr<T>& a, U* b)
 203     {
 204         return a.get() != b;
 205     }
 206
 207     template <typename T, typename U> inline bool operator!=(T* a, const RefPtr<U>& b)
 208     {
 209         return a != b.get();
 210     }
 211
 212     template <typename T, typename U> inline RefPtr<T> static_pointer_cast(const RefPtr<U>& p)
 213     {
 214         return RefPtr<T>(static_cast<T*>(p.get()));
 215     }
 216
 217     template <typename T, typename U> inline RefPtr<T> const_pointer_cast(const RefPtr<U>& p)
 218     {
 219         return RefPtr<T>(const_cast<T*>(p.get()));
 220     }
 221
 222     template <typename T> inline T* getPtr(const RefPtr<T>& p)
 223     {
 224         return p.get();
 225     }
 226
 227 } // namespace WTF
 228
 229 using WTF::RefPtr;
 230 using WTF::static_pointer_cast;
 231 using WTF::const_pointer_cast;
 232
 233 #endif // WTF_RefPtr_h