Win32_variadicFunctor.h

/*
* Copyright (c), Microsoft Open Technologies, 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:
*  - Redistributions of source code must retain the above copyright notice,
*    this list of conditions and the following disclaimer.
*  - 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER 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.
*/
#pragma once

#include <Windows.h>
#include <string>
#include <map>
using namespace std;

class DLLMap : map<string, HMODULE> {
public:
	static DLLMap& getInstance();

private:
	DLLMap();
	DLLMap(DLLMap const&);	  // Don't implement to guarantee singleton semantics
	void operator=(DLLMap const&); // Don't implement to guarantee singleton semantics

public:
	LPVOID getProcAddress(const string& dll, const string& functionName);
	virtual ~DLLMap();
};


template <typename R, typename... T>
class dllfunctor_stdcall {
public:
	dllfunctor_stdcall(const string& dll, const string& function)
	{
		_f = (R(__stdcall *)(T...))DLLMap::getInstance().getProcAddress(dll, function.c_str());
	}
	R operator()(T... args) { return _f(args...); }

private:
	R(__stdcall *_f)(T...);
};