/*

 *  Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 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 "AlwaysInline.h"

namespace WTF {

    template<typename T> class RefPtr;

    template<typename T> class PassRefPtr;

    template<typename T> PassRefPtr<T> adoptRef(T*);

    inline void adopted(const void*) { }

#if !COMPILER(WINSCW)

#if !PLATFORM(QT)

    #define REF_DEREF_INLINE ALWAYS_INLINE

#else

    // Using ALWAYS_INLINE broke the Qt build. This may be a GCC bug.

    // See https://bugs.webkit.org/show_bug.cgi?id=37253 for details.

    #define REF_DEREF_INLINE inline

#endif

#else

    // No inlining for WINSCW compiler to prevent the compiler agressively resolving

    // T::ref() and T::deref(), which will fail compiling when PassRefPtr<T> is used as

    // a class member or function arguments before T is defined.

    #define REF_DEREF_INLINE

#endif

    template<typename T> REF_DEREF_INLINE void refIfNotNull(T* ptr)

    {

        if (UNLIKELY(ptr != 0))

            ptr->ref();

    }

    template<typename T> REF_DEREF_INLINE void derefIfNotNull(T* ptr)

    {

        if (UNLIKELY(ptr != 0))

            ptr->deref();

    }

    #undef REF_DEREF_INLINE

    template<typename T> class PassRefPtr {

    public:

        PassRefPtr() : m_ptr(0) { }

        PassRefPtr(T* ptr) : m_ptr(ptr) { refIfNotNull(ptr); }

        // 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 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() { derefIfNotNull(m_ptr); }

        template<typename U> PassRefPtr(const RefPtr<U>&);

        T* get() const { return m_ptr; }

        void clear();

        T* leakRef() const WARN_UNUSED_RETURN;

        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 : 0; }

        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*);

        // FIXME: Remove releaseRef once we change all callers to call leakRef instead.

        T* releaseRef() const WARN_UNUSED_RETURN { return leakRef(); }

    private:

        // adopting constructor

        PassRefPtr(T* ptr, bool) : m_ptr(ptr) { }

        mutable T* m_ptr;

    };

    // NonNullPassRefPtr: Optimized for passing non-null pointers. A NonNullPassRefPtr

    // begins life non-null, and can only become null through a call to releaseRef()

    // or clear().

    // FIXME: NonNullPassRefPtr could just inherit from PassRefPtr. However,

    // if we use inheritance, GCC's optimizer fails to realize that destruction

    // of a released NonNullPassRefPtr is a no-op. So, for now, just copy the

    // most important code from PassRefPtr.

    template<typename T> class NonNullPassRefPtr {

    public:

        NonNullPassRefPtr(T* ptr)

            : m_ptr(ptr)

        {

            ASSERT(m_ptr);

            m_ptr->ref();

        }

        template<typename U> NonNullPassRefPtr(const RefPtr<U>& o)

            : m_ptr(o.get())

        {

            ASSERT(m_ptr);

            m_ptr->ref();

        }

        NonNullPassRefPtr(const NonNullPassRefPtr& o)

            : m_ptr(o.releaseRef())

        {

            ASSERT(m_ptr);

        }

        template<typename U> NonNullPassRefPtr(const NonNullPassRefPtr<U>& o)

            : m_ptr(o.releaseRef())

        {

            ASSERT(m_ptr);

        }

        template<typename U> NonNullPassRefPtr(const PassRefPtr<U>& o)

            : m_ptr(o.releaseRef())

        {

            ASSERT(m_ptr);

        }

        ALWAYS_INLINE ~NonNullPassRefPtr() { derefIfNotNull(m_ptr); }

        T* get() const { return m_ptr; }

        void clear();

        T* leakRef() const WARN_UNUSED_RETURN { T* tmp = m_ptr; m_ptr = 0; return tmp; }

        T& operator*() const { return *m_ptr; }

        T* operator->() const { return m_ptr; }

        // FIXME: Remove releaseRef once we change all callers to call leakRef instead.

        T* releaseRef() const WARN_UNUSED_RETURN { return leakRef(); }

    private:

        mutable T* m_ptr;

    };

    template<typename T> template<typename U> inline PassRefPtr<T>::PassRefPtr(const RefPtr<U>& o)

        : m_ptr(o.get())

    {

        T* ptr = m_ptr;

        refIfNotNull(ptr);

    }

    template<typename T> inline void PassRefPtr<T>::clear()

    {

        T* ptr = m_ptr;

        m_ptr = 0;

        derefIfNotNull(ptr);

    }

    template<typename T> inline T* PassRefPtr<T>::leakRef() const

    {

        T* ptr = m_ptr;

        m_ptr = 0;

        return ptr;

    }

    template<typename T> template<typename U> inline PassRefPtr<T>& PassRefPtr<T>::operator=(const RefPtr<U>& o)

    {

        T* optr = o.get();

        refIfNotNull(optr);

        T* ptr = m_ptr;

        m_ptr = optr;

        derefIfNotNull(ptr);

        return *this;

    }

    template<typename T> inline PassRefPtr<T>& PassRefPtr<T>::operator=(T* optr)

    {

        refIfNotNull(optr);

        T* ptr = m_ptr;

        m_ptr = optr;

        derefIfNotNull(ptr);

        return *this;

    }

    template<typename T> inline PassRefPtr<T>& PassRefPtr<T>::operator=(const PassRefPtr<T>& ref)

    {

        T* ptr = m_ptr;

        m_ptr = ref.releaseRef();

        derefIfNotNull(ptr);

        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();

        derefIfNotNull(ptr);

        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)

    {

        adopted(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();

    }

    template<typename T> inline void NonNullPassRefPtr<T>::clear()

    {

        T* ptr = m_ptr;

        m_ptr = 0;

        derefIfNotNull(ptr);

    }

} // namespace WTF

using WTF::PassRefPtr;

using WTF::NonNullPassRefPtr;

using WTF::adoptRef;

using WTF::static_pointer_cast;

using WTF::const_pointer_cast;

#endif // WTF_PassRefPtr_h