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 /*
  *  Copyright (C) 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Library General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  *  Library General Public License for more details.
  *
  *  You should have received a copy of the GNU Library General Public License
  *  along with this library; see the file COPYING.LIB.  If not, write to
  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  *  Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef WTF_RefPtr_h
 #define WTF_RefPtr_h
 
 #include <algorithm>
 #include <wtf/AlwaysInline.h>
 #include <wtf/PassRefPtr.h>
 
 namespace WTF
 {
 
 enum PlacementNewAdoptType { PlacementNewAdopt };
 
 template <typename T> class PassRefPtr;
 
 enum HashTableDeletedValueType { HashTableDeletedValue };
 
 template <typename T> class RefPtr
 {
 public:
     RefPtr() : m_ptr(nullptr) { }
     RefPtr(T *ptr) : m_ptr(ptr)
     {
         if (ptr) {
             ptr->ref();
         }
     }
     RefPtr(const RefPtr &o) : m_ptr(o.m_ptr)
     {
         if (T *ptr = m_ptr) {
             ptr->ref();
         }
     }
     // see comment in PassRefPtr.h for why this takes const reference
     template <typename U> RefPtr(const PassRefPtr<U> &);
 
     // Special constructor for cases where we overwrite an object in place.
     RefPtr(PlacementNewAdoptType) { }
 
     // Hash table deleted values, which are only constructed and never copied or destroyed.
     RefPtr(HashTableDeletedValueType) : m_ptr(hashTableDeletedValue()) { }
     bool isHashTableDeletedValue() const
     {
         return m_ptr == hashTableDeletedValue();
     }
 
     ~RefPtr()
     {
         if (T *ptr = m_ptr) {
             ptr->deref();
         }
     }
 
     template <typename U> RefPtr(const RefPtr<U> &o) : m_ptr(o.get())
     {
         if (T *ptr = m_ptr) {
             ptr->ref();
         }
     }
 
     T *get() const
     {
         return m_ptr;
     }
 
     void clear()
     {
         if (T *ptr = m_ptr) {
             ptr->deref();
         } m_ptr = nullptr;
     }
     PassRefPtr<T> release()
     {
         PassRefPtr<T> tmp = adoptRef(m_ptr);
         m_ptr = nullptr;
         return tmp;
     }
 
     T &operator*() const
     {
         return *m_ptr;
     }
     ALWAYS_INLINE T *operator->() const
     {
         return m_ptr;
     }
 
     bool operator!() const
     {
         return !m_ptr;
     }
 
     // This conversion operator allows implicit conversion to bool but not to other integer types.
     typedef T *RefPtr::*UnspecifiedBoolType;
     operator UnspecifiedBoolType() const
     {
         return m_ptr ? &RefPtr::m_ptr : nullptr;
     }
 
     RefPtr &operator=(const RefPtr &);
     RefPtr &operator=(T *);
     RefPtr &operator=(const PassRefPtr<T> &);
     template <typename U> RefPtr &operator=(const RefPtr<U> &);
     template <typename U> RefPtr &operator=(const PassRefPtr<U> &);
 
     void swap(RefPtr &);
 
 private:
     static T *hashTableDeletedValue()
     {
         return reinterpret_cast<T *>(-1);
     }
 
     T *m_ptr;
 };
 
 template <typename T> template <typename U> inline RefPtr<T>::RefPtr(const PassRefPtr<U> &o)
     : m_ptr(o.releaseRef())
 {
 }
 
 template <typename T> inline RefPtr<T> &RefPtr<T>::operator=(const RefPtr<T> &o)
 {
     T *optr = o.get();
     if (optr) {
         optr->ref();
     }
     T *ptr = m_ptr;
     m_ptr = optr;
     if (ptr) {
         ptr->deref();
     }
     return *this;
 }
 
 template <typename T> template <typename U> inline RefPtr<T> &RefPtr<T>::operator=(const RefPtr<U> &o)
 {
     T *optr = o.get();
     if (optr) {
         optr->ref();
     }
     T *ptr = m_ptr;
     m_ptr = optr;
     if (ptr) {
         ptr->deref();
     }
     return *this;
 }
 
 template <typename T> inline RefPtr<T> &RefPtr<T>::operator=(T *optr)
 {
     if (optr) {
         optr->ref();
     }
     T *ptr = m_ptr;
     m_ptr = optr;
     if (ptr) {
         ptr->deref();
     }
     return *this;
 }
 
 template <typename T> inline RefPtr<T> &RefPtr<T>::operator=(const PassRefPtr<T> &o)
 {
     T *ptr = m_ptr;
     m_ptr = o.releaseRef();
     if (ptr) {
         ptr->deref();
     }
     return *this;
 }
 
 template <typename T> template <typename U> inline RefPtr<T> &RefPtr<T>::operator=(const PassRefPtr<U> &o)
 {
     T *ptr = m_ptr;
     m_ptr = o.releaseRef();
     if (ptr) {
         ptr->deref();
     }
     return *this;
 }
 
 template <class T> inline void RefPtr<T>::swap(RefPtr<T> &o)
 {
     std::swap(m_ptr, o.m_ptr);
 }
 
 template <class T> inline void swap(RefPtr<T> &a, RefPtr<T> &b)
 {
     a.swap(b);
 }
 
 template <typename T, typename U> inline bool operator==(const RefPtr<T> &a, const RefPtr<U> &b)
 {
     return a.get() == b.get();
 }
 
 template <typename T, typename U> inline bool operator==(const RefPtr<T> &a, U *b)
 {
     return a.get() == b;
 }
 
 template <typename T, typename U> inline bool operator==(T *a, const RefPtr<U> &b)
 {
     return a == b.get();
 }
 
 template <typename T, typename U> inline bool operator!=(const RefPtr<T> &a, const RefPtr<U> &b)
 {
     return a.get() != b.get();
 }
 
 template <typename T, typename U> inline bool operator!=(const RefPtr<T> &a, U *b)
 {
     return a.get() != b;
 }
 
 template <typename T, typename U> inline bool operator!=(T *a, const RefPtr<U> &b)
 {
     return a != b.get();
 }
 
 template <typename T, typename U> inline RefPtr<T> static_pointer_cast(const RefPtr<U> &p)
 {
     return RefPtr<T>(static_cast<T *>(p.get()));
 }
 
 template <typename T, typename U> inline RefPtr<T> const_pointer_cast(const RefPtr<U> &p)
 {
     return RefPtr<T>(const_cast<T *>(p.get()));
 }
 
 template <typename T> inline T *getPtr(const RefPtr<T> &p)
 {
     return p.get();
 }
 
 } // namespace WTF
 
 using WTF::RefPtr;
 using WTF::static_pointer_cast;
 using WTF::const_pointer_cast;
 
 #endif // WTF_RefPtr_h