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// **************************************************************************
// * This file is part of the FreeFileSync project. It is distributed under *
// * GNU General Public License: http://www.gnu.org/licenses/gpl.html *
// * Copyright (C) 2008-2011 ZenJu (zhnmju123 AT gmx.de) *
// **************************************************************************
//
#ifndef SMART_COM_PTR_H
#define SMART_COM_PTR_H
#include <Objbase.h>
#include <algorithm>
namespace util
{
/*
ComPtr: RAII class handling COM objects
Example:
--------
ComPtr<IUPnPDeviceFinder> devFinder;
if (FAILED(::CoCreateInstance(CLSID_UPnPDeviceFinder,
NULL,
CLSCTX_ALL,
IID_PPV_ARGS(devFinder.init()))))
return -1;
ComPtr<IEnumUnknown> devEnum = com_dynamic_cast<IEnumUnknown>(devColl);
if (!devEnum)
return -1;
*/
template <class T>
class ComPtr
{
public:
ComPtr() : ptr(NULL) {}
ComPtr(const ComPtr& rhs) : ptr(rhs.ptr) { if (ptr) ptr->AddRef(); }
ComPtr& operator=(const ComPtr& rhs)
{
ComPtr(rhs).swap(*this);
return *this;
}
~ComPtr() { if (ptr) ptr->Release(); }
T** init() //get pointer for use with ::CoCreateInstance()
{
ComPtr<T>().swap(*this);
return &ptr;
}
T* get() const { return ptr; }
T* release() //throw()
{
T* tmp = ptr;
ptr = NULL;
return tmp;
}
void swap(ComPtr& rhs) { std::swap(ptr, rhs.ptr); } //throw()
T* operator->() const { return ptr; }
private:
T* ptr;
struct ConversionToBool { int dummy; };
public:
//use member pointer as implicit conversion to bool (C++ Templates - Vandevoorde/Josuttis; chapter 20)
operator int ConversionToBool::* () const { return ptr != NULL ? &ConversionToBool::dummy : NULL; }
};
template <class S, class T>
ComPtr<S> com_dynamic_cast(const ComPtr<T>& other); //throw()
//################# Inline Implementation #############################
//we cannot specialize std::swap() for a class template and are not allowed to overload it => offer swap in own namespace
template <class T> inline
void swap(util::ComPtr<T>& lhs, util::ComPtr<T>& rhs)
{
lhs.swap(rhs);
}
template <class S, class T> inline
ComPtr<S> com_dynamic_cast(const ComPtr<T>& other) //throw()
{
ComPtr<S> outPtr;
if (other)
other->QueryInterface(IID_PPV_ARGS(outPtr.init()));
return outPtr;
}
}
#endif //SMART_COM_PTR_H
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