wtf/PassRefPtr.h

   1 /*
   2  *  Copyright (C) 2005, 2006, 2007 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_PassRefPtr_h
  22 #define WTF_PassRefPtr_h
  23
  24 #include "AlwaysInline.h"
  25
  26 namespace WTF {
  27
  28     template<typename T> class RefPtr;
  29     template<typename T> class PassRefPtr;
  30     template <typename T> PassRefPtr<T> adoptRef(T*);
  31
  32     template<typename T> class PassRefPtr {
  33     public:
  34         PassRefPtr() : m_ptr(0) {}
  35         PassRefPtr(T* ptr) : m_ptr(ptr) { if (ptr) ptr->ref(); }
  36         // It somewhat breaks the type system to allow transfer of ownership out of
  37         // a const PassRefPtr. However, it makes it much easier to work with PassRefPtr
  38         // temporaries, and we don't really have a need to use real const PassRefPtrs
  39         // anyway.
  40         PassRefPtr(const PassRefPtr& o) : m_ptr(o.releaseRef()) {}
  41         template <typename U> PassRefPtr(const PassRefPtr<U>& o) : m_ptr(o.releaseRef()) { }
  42
  43         ALWAYS_INLINE ~PassRefPtr() { if (UNLIKELY(m_ptr != 0)) m_ptr->deref(); }
  44
  45         template <class U>
  46         PassRefPtr(const RefPtr<U>& o) : m_ptr(o.get()) { if (T* ptr = m_ptr) ptr->ref(); }
  47
  48         T* get() const { return m_ptr; }
  49
  50         void clear() { if (T* ptr = m_ptr) ptr->deref(); m_ptr = 0; }
  51         T* releaseRef() const { T* tmp = m_ptr; m_ptr = 0; return tmp; }
  52
  53         T& operator*() const { return *m_ptr; }
  54         T* operator->() const { return m_ptr; }
  55
  56         bool operator!() const { return !m_ptr; }
  57
  58         // This conversion operator allows implicit conversion to bool but not to other integer types.
  59 #if COMPILER(WINSCW)
  60         operator bool() const { return m_ptr; }
  61 #else
  62         typedef T* PassRefPtr::*UnspecifiedBoolType;
  63         operator UnspecifiedBoolType() const { return m_ptr ? &PassRefPtr::m_ptr : 0; }
  64 #endif
  65         PassRefPtr& operator=(T*);
  66         PassRefPtr& operator=(const PassRefPtr&);
  67         template <typename U> PassRefPtr& operator=(const PassRefPtr<U>&);
  68         template <typename U> PassRefPtr& operator=(const RefPtr<U>&);
  69
  70         friend PassRefPtr adoptRef<T>(T*);
  71     private:
  72         // adopting constructor
  73         PassRefPtr(T* ptr, bool) : m_ptr(ptr) {}
  74         mutable T* m_ptr;
  75     };
  76
  77     template <typename T> template <typename U> inline PassRefPtr<T>& PassRefPtr<T>::operator=(const RefPtr<U>& o)
  78     {
  79         T* optr = o.get();
  80         if (optr)
  81             optr->ref();
  82         T* ptr = m_ptr;
  83         m_ptr = optr;
  84         if (ptr)
  85             ptr->deref();
  86         return *this;
  87     }
  88
  89     template <typename T> inline PassRefPtr<T>& PassRefPtr<T>::operator=(T* optr)
  90     {
  91         if (optr)
  92             optr->ref();
  93         T* ptr = m_ptr;
  94         m_ptr = optr;
  95         if (ptr)
  96             ptr->deref();
  97         return *this;
  98     }
  99
 100     template <typename T> inline PassRefPtr<T>& PassRefPtr<T>::operator=(const PassRefPtr<T>& ref)
 101     {
 102         T* ptr = m_ptr;
 103         m_ptr = ref.releaseRef();
 104         if (ptr)
 105             ptr->deref();
 106         return *this;
 107     }
 108
 109     template <typename T> template <typename U> inline PassRefPtr<T>& PassRefPtr<T>::operator=(const PassRefPtr<U>& ref)
 110     {
 111         T* ptr = m_ptr;
 112         m_ptr = ref.releaseRef();
 113         if (ptr)
 114             ptr->deref();
 115         return *this;
 116     }
 117
 118     template <typename T, typename U> inline bool operator==(const PassRefPtr<T>& a, const PassRefPtr<U>& b)
 119     {
 120         return a.get() == b.get();
 121     }
 122
 123     template <typename T, typename U> inline bool operator==(const PassRefPtr<T>& a, const RefPtr<U>& b)
 124     {
 125         return a.get() == b.get();
 126     }
 127
 128     template <typename T, typename U> inline bool operator==(const RefPtr<T>& a, const PassRefPtr<U>& b)
 129     {
 130         return a.get() == b.get();
 131     }
 132
 133     template <typename T, typename U> inline bool operator==(const PassRefPtr<T>& a, U* b)
 134     {
 135         return a.get() == b;
 136     }
 137
 138     template <typename T, typename U> inline bool operator==(T* a, const PassRefPtr<U>& b)
 139     {
 140         return a == b.get();
 141     }
 142
 143     template <typename T, typename U> inline bool operator!=(const PassRefPtr<T>& a, const PassRefPtr<U>& b)
 144     {
 145         return a.get() != b.get();
 146     }
 147
 148     template <typename T, typename U> inline bool operator!=(const PassRefPtr<T>& a, const RefPtr<U>& b)
 149     {
 150         return a.get() != b.get();
 151     }
 152
 153     template <typename T, typename U> inline bool operator!=(const RefPtr<T>& a, const PassRefPtr<U>& b)
 154     {
 155         return a.get() != b.get();
 156     }
 157
 158     template <typename T, typename U> inline bool operator!=(const PassRefPtr<T>& a, U* b)
 159     {
 160         return a.get() != b;
 161     }
 162
 163     template <typename T, typename U> inline bool operator!=(T* a, const PassRefPtr<U>& b)
 164     {
 165         return a != b.get();
 166     }
 167
 168     template <typename T> inline PassRefPtr<T> adoptRef(T* p)
 169     {
 170         return PassRefPtr<T>(p, true);
 171     }
 172
 173     template <typename T, typename U> inline PassRefPtr<T> static_pointer_cast(const PassRefPtr<U>& p)
 174     {
 175         return adoptRef(static_cast<T*>(p.releaseRef()));
 176     }
 177
 178     template <typename T, typename U> inline PassRefPtr<T> const_pointer_cast(const PassRefPtr<U>& p)
 179     {
 180         return adoptRef(const_cast<T*>(p.releaseRef()));
 181     }
 182
 183     template <typename T> inline T* getPtr(const PassRefPtr<T>& p)
 184     {
 185         return p.get();
 186     }
 187
 188 } // namespace WTF
 189
 190 using WTF::PassRefPtr;
 191 using WTF::adoptRef;
 192 using WTF::static_pointer_cast;
 193 using WTF::const_pointer_cast;
 194
 195 #endif // WTF_PassRefPtr_h