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
  34     enum HashTableDeletedValueType { HashTableDeletedValue };
  35
  36     template <typename T> class RefPtr : public FastAllocBase {
  37     public:
  38         RefPtr() : m_ptr(0) { }
  39         RefPtr(T* ptr) : m_ptr(ptr) { if (ptr) ptr->ref(); }
  40         RefPtr(const RefPtr& o) : m_ptr(o.m_ptr) { if (T* ptr = m_ptr) ptr->ref(); }
  41         // see comment in PassRefPtr.h for why this takes const reference
  42         template <typename U> RefPtr(const PassRefPtr<U>&);
  43
  44         // Special constructor for cases where we overwrite an object in place.
  45         RefPtr(PlacementNewAdoptType) { }
  46
  47         // Hash table deleted values, which are only constructed and never copied or destroyed.
  48         RefPtr(HashTableDeletedValueType) : m_ptr(hashTableDeletedValue()) { }
  49         bool isHashTableDeletedValue() const { return m_ptr == hashTableDeletedValue(); }
  50
  51         ~RefPtr() { if (T* ptr = m_ptr) ptr->deref(); }
  52
  53         template <typename U> RefPtr(const RefPtr<U>& o) : m_ptr(o.get()) { if (T* ptr = m_ptr) ptr->ref(); }
  54
  55         T* get() const { return m_ptr; }
  56
  57         void clear() { if (T* ptr = m_ptr) ptr->deref(); m_ptr = 0; }
  58         PassRefPtr<T> release() { PassRefPtr<T> tmp = adoptRef(m_ptr); m_ptr = 0; return tmp; }
  59
  60         T& operator*() const { return *m_ptr; }
  61         ALWAYS_INLINE T* operator->() const { return m_ptr; }
  62
  63         bool operator!() const { return !m_ptr; }
  64
  65         // This conversion operator allows implicit conversion to bool but not to other integer types.
  66 #if COMPILER(WINSCW)
  67         operator bool() const { return m_ptr; }
  68 #else
  69         typedef T* RefPtr::*UnspecifiedBoolType;
  70         operator UnspecifiedBoolType() const { return m_ptr ? &RefPtr::m_ptr : 0; }
  71 #endif
  72
  73         RefPtr& operator=(const RefPtr&);
  74         RefPtr& operator=(T*);
  75         RefPtr& operator=(const PassRefPtr<T>&);
  76         template <typename U> RefPtr& operator=(const RefPtr<U>&);
  77         template <typename U> RefPtr& operator=(const PassRefPtr<U>&);
  78
  79         void swap(RefPtr&);
  80
  81     private:
  82         static T* hashTableDeletedValue() { return reinterpret_cast<T*>(-1); }
  83
  84         T* m_ptr;
  85     };
  86
  87     template <typename T> template <typename U> inline RefPtr<T>::RefPtr(const PassRefPtr<U>& o)
  88         : m_ptr(o.releaseRef())
  89     {
  90     }
  91
  92     template <typename T> inline RefPtr<T>& RefPtr<T>::operator=(const RefPtr<T>& o)
  93     {
  94         T* optr = o.get();
  95         if (optr)
  96             optr->ref();
  97         T* ptr = m_ptr;
  98         m_ptr = optr;
  99         if (ptr)
 100             ptr->deref();
 101         return *this;
 102     }
 103
 104     template <typename T> template <typename U> inline RefPtr<T>& RefPtr<T>::operator=(const RefPtr<U>& o)
 105     {
 106         T* optr = o.get();
 107         if (optr)
 108             optr->ref();
 109         T* ptr = m_ptr;
 110         m_ptr = optr;
 111         if (ptr)
 112             ptr->deref();
 113         return *this;
 114     }
 115
 116     template <typename T> inline RefPtr<T>& RefPtr<T>::operator=(T* optr)
 117     {
 118         if (optr)
 119             optr->ref();
 120         T* ptr = m_ptr;
 121         m_ptr = optr;
 122         if (ptr)
 123             ptr->deref();
 124         return *this;
 125     }
 126
 127     template <typename T> inline RefPtr<T>& RefPtr<T>::operator=(const PassRefPtr<T>& o)
 128     {
 129         T* ptr = m_ptr;
 130         m_ptr = o.releaseRef();
 131         if (ptr)
 132             ptr->deref();
 133         return *this;
 134     }
 135
 136     template <typename T> template <typename U> inline RefPtr<T>& RefPtr<T>::operator=(const PassRefPtr<U>& 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 <class T> inline void RefPtr<T>::swap(RefPtr<T>& o)
 146     {
 147         std::swap(m_ptr, o.m_ptr);
 148     }
 149
 150     template <class T> inline void swap(RefPtr<T>& a, RefPtr<T>& b)
 151     {
 152         a.swap(b);
 153     }
 154
 155     template <typename T, typename U> inline bool operator==(const RefPtr<T>& a, const RefPtr<U>& b)
 156     {
 157         return a.get() == b.get();
 158     }
 159
 160     template <typename T, typename U> inline bool operator==(const RefPtr<T>& a, U* b)
 161     {
 162         return a.get() == b;
 163     }
 164
 165     template <typename T, typename U> inline bool operator==(T* a, const RefPtr<U>& b)
 166     {
 167         return a == b.get();
 168     }
 169
 170     template <typename T, typename U> inline bool operator!=(const RefPtr<T>& a, const RefPtr<U>& b)
 171     {
 172         return a.get() != b.get();
 173     }
 174
 175     template <typename T, typename U> inline bool operator!=(const RefPtr<T>& a, U* b)
 176     {
 177         return a.get() != b;
 178     }
 179
 180     template <typename T, typename U> inline bool operator!=(T* a, const RefPtr<U>& b)
 181     {
 182         return a != b.get();
 183     }
 184
 185     template <typename T, typename U> inline RefPtr<T> static_pointer_cast(const RefPtr<U>& p)
 186     {
 187         return RefPtr<T>(static_cast<T*>(p.get()));
 188     }
 189
 190     template <typename T, typename U> inline RefPtr<T> const_pointer_cast(const RefPtr<U>& p)
 191     {
 192         return RefPtr<T>(const_cast<T*>(p.get()));
 193     }
 194
 195     template <typename T> inline T* getPtr(const RefPtr<T>& p)
 196     {
 197         return p.get();
 198     }
 199
 200 } // namespace WTF
 201
 202 using WTF::RefPtr;
 203 using WTF::static_pointer_cast;
 204 using WTF::const_pointer_cast;
 205
 206 #endif // WTF_RefPtr_h