/*

 * Copyright (C) 2007 Apple Inc. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY

 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY

 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 

 */

#ifndef COMPtr_h

#define COMPtr_h

#define NOMINMAX

#include <guiddef.h>

#include <unknwn.h>

#include <WTF/Assertions.h>

typedef long HRESULT;

// FIXME: Should we put this into the WebCore namespace and use "using" on it

// as we do with things in WTF? 

enum AdoptCOMTag { AdoptCOM };

enum QueryTag { Query };

template <typename T> class COMPtr {

public:

    COMPtr() : m_ptr(0) { }

    COMPtr(T* ptr) : m_ptr(ptr) { if (m_ptr) m_ptr->AddRef(); }

    COMPtr(AdoptCOMTag, T* ptr) : m_ptr(ptr) { }

    COMPtr(const COMPtr& o) : m_ptr(o.m_ptr) { if (T* ptr = m_ptr) ptr->AddRef(); }

    inline COMPtr(QueryTag, IUnknown* ptr) : m_ptr(copyQueryInterfaceRef(ptr)) { }

    template <typename U> inline COMPtr(QueryTag, const COMPtr<U>& ptr) : m_ptr(copyQueryInterfaceRef(ptr.get())) { }

    ~COMPtr() { if (m_ptr) m_ptr->Release(); }

    T* get() const { return m_ptr; }

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

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

    T** operator&() { ASSERT(!m_ptr); 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* (COMPtr::*UnspecifiedBoolType)() const;

    operator UnspecifiedBoolType() const { return m_ptr ? &COMPtr::get : 0; }

    COMPtr& operator=(const COMPtr&);

    COMPtr& operator=(T*);

    template <typename U> COMPtr& operator=(const COMPtr<U>&);

    void query(IUnknown* ptr) { adoptRef(copyQueryInterfaceRef(ptr)); }

    template <typename U> inline void query(const COMPtr<U>& ptr) { query(ptr.get()); }

    HRESULT copyRefTo(T**);

    void adoptRef(T*);

private:

    static T* copyQueryInterfaceRef(IUnknown*);

    T* m_ptr;

};

template <typename T> inline T* COMPtr<T>::copyQueryInterfaceRef(IUnknown* ptr)

{

    if (!ptr)

        return 0;

    T* result;

    if (FAILED(ptr->QueryInterface(&result)))

        return 0;

    return result;

}

template <typename T> inline HRESULT COMPtr<T>::copyRefTo(T** ptr)

{

    if (!ptr)

        return E_POINTER;

    *ptr = m_ptr;

    if (m_ptr)

        m_ptr->AddRef();

    return S_OK;

}

template <typename T> inline void COMPtr<T>::adoptRef(T *ptr)

{

    if (m_ptr)

        m_ptr->Release();

    m_ptr = ptr;

}

template <typename T> inline COMPtr<T>& COMPtr<T>::operator=(const COMPtr<T>& o)

{

    T* optr = o.get();

    if (optr)

        optr->AddRef();

    T* ptr = m_ptr;

    m_ptr = optr;

    if (ptr)

        ptr->Release();

    return *this;

}

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

{

    T* optr = o.get();

    if (optr)

        optr->AddRef();

    T* ptr = m_ptr;

    m_ptr = optr;

    if (ptr)

        ptr->Release();

    return *this;

}

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

{

    if (optr)

        optr->AddRef();

    T* ptr = m_ptr;

    m_ptr = optr;

    if (ptr)

        ptr->Release();

    return *this;

}

template <typename T, typename U> inline bool operator==(const COMPtr<T>& a, const COMPtr<U>& b)

{

    return a.get() == b.get();

}

template <typename T, typename U> inline bool operator==(const COMPtr<T>& a, U* b)

{

    return a.get() == b;

}

template <typename T, typename U> inline bool operator==(T* a, const COMPtr<U>& b) 

{

    return a == b.get();

}

template <typename T, typename U> inline bool operator!=(const COMPtr<T>& a, const COMPtr<U>& b)

{

    return a.get() != b.get();

}

template <typename T, typename U> inline bool operator!=(const COMPtr<T>& a, U* b)

{

    return a.get() != b;

}

template <typename T, typename U> inline bool operator!=(T* a, const COMPtr<U>& b)

{

    return a != b.get();

}

#endif