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 /*
  *  Copyright (C) 2005, 2006, 2007 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_PassRefPtr_h
 #define WTF_PassRefPtr_h
 
 #include <wtf/AlwaysInline.h>
 
 namespace WTF
 {
 
 template<typename T> class RefPtr;
 template<typename T> class PassRefPtr;
 template <typename T> PassRefPtr<T> adoptRef(T *);
 
 template<typename T> class PassRefPtr
 {
 public:
     PassRefPtr() : m_ptr(nullptr) {}
     PassRefPtr(T *ptr) : m_ptr(ptr)
     {
         if (ptr) {
             ptr->ref();
         }
     }
     // It somewhat breaks the type system to allow transfer of ownership out of
     // a const PassRefPtr. However, it makes it much easier to work with PassRefPtr
     // temporaries, and we don't really have a need to use real const PassRefPtrs
     // anyway.
     PassRefPtr(const PassRefPtr &o) : m_ptr(o.releaseRef()) {}
     template <typename U> PassRefPtr(const PassRefPtr<U> &o) : m_ptr(o.releaseRef()) { }
 
     ALWAYS_INLINE ~PassRefPtr()
     {
         if (T *ptr = m_ptr) {
             ptr->deref();
         }
     }
 
     template <class U>
     PassRefPtr(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;
     }
     T *releaseRef() const
     {
         T *tmp = m_ptr;
         m_ptr = nullptr;
         return tmp;
     }
 
     T &operator*() const
     {
         return *m_ptr;
     }
     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 *PassRefPtr::*UnspecifiedBoolType;
     operator UnspecifiedBoolType() const
     {
         return m_ptr ? &PassRefPtr::m_ptr : nullptr;
     }
 
     PassRefPtr &operator=(T *);
     PassRefPtr &operator=(const PassRefPtr &);
     template <typename U> PassRefPtr &operator=(const PassRefPtr<U> &);
     template <typename U> PassRefPtr &operator=(const RefPtr<U> &);
 
     friend PassRefPtr adoptRef<T>(T *);
 private:
     // adopting constructor
     PassRefPtr(T *ptr, bool) : m_ptr(ptr) {}
     mutable T *m_ptr;
 };
 
 template <typename T> template <typename U> inline PassRefPtr<T> &PassRefPtr<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 PassRefPtr<T> &PassRefPtr<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 PassRefPtr<T> &PassRefPtr<T>::operator=(const PassRefPtr<T> &ref)
 {
     T *ptr = m_ptr;
     m_ptr = ref.releaseRef();
     if (ptr) {
         ptr->deref();
     }
     return *this;
 }
 
 template <typename T> template <typename U> inline PassRefPtr<T> &PassRefPtr<T>::operator=(const PassRefPtr<U> &ref)
 {
     T *ptr = m_ptr;
     m_ptr = ref.releaseRef();
     if (ptr) {
         ptr->deref();
     }
     return *this;
 }
 
 template <typename T, typename U> inline bool operator==(const PassRefPtr<T> &a, const PassRefPtr<U> &b)
 {
     return a.get() == b.get();
 }
 
 template <typename T, typename U> inline bool operator==(const PassRefPtr<T> &a, const RefPtr<U> &b)
 {
     return a.get() == b.get();
 }
 
 template <typename T, typename U> inline bool operator==(const RefPtr<T> &a, const PassRefPtr<U> &b)
 {
     return a.get() == b.get();
 }
 
 template <typename T, typename U> inline bool operator==(const PassRefPtr<T> &a, U *b)
 {
     return a.get() == b;
 }
 
 template <typename T, typename U> inline bool operator==(T *a, const PassRefPtr<U> &b)
 {
     return a == b.get();
 }
 
 template <typename T, typename U> inline bool operator!=(const PassRefPtr<T> &a, const PassRefPtr<U> &b)
 {
     return a.get() != b.get();
 }
 
 template <typename T, typename U> inline bool operator!=(const PassRefPtr<T> &a, const RefPtr<U> &b)
 {
     return a.get() != b.get();
 }
 
 template <typename T, typename U> inline bool operator!=(const RefPtr<T> &a, const PassRefPtr<U> &b)
 {
     return a.get() != b.get();
 }
 
 template <typename T, typename U> inline bool operator!=(const PassRefPtr<T> &a, U *b)
 {
     return a.get() != b;
 }
 
 template <typename T, typename U> inline bool operator!=(T *a, const PassRefPtr<U> &b)
 {
     return a != b.get();
 }
 
 template <typename T> inline PassRefPtr<T> adoptRef(T *p)
 {
     return PassRefPtr<T>(p, true);
 }
 
 template <typename T, typename U> inline PassRefPtr<T> static_pointer_cast(const PassRefPtr<U> &p)
 {
     return adoptRef(static_cast<T *>(p.releaseRef()));
 }
 
 template <typename T, typename U> inline PassRefPtr<T> const_pointer_cast(const PassRefPtr<U> &p)
 {
     return adoptRef(const_cast<T *>(p.releaseRef()));
 }
 
 template <typename T> inline T *getPtr(const PassRefPtr<T> &p)
 {
     return p.get();
 }
 
 } // namespace WTF
 
 using WTF::PassRefPtr;
 using WTF::adoptRef;
 using WTF::static_pointer_cast;
 using WTF::const_pointer_cast;
 
 #endif // WTF_PassRefPtr_h