/*
 *  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
