/*
 *  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
