ClickHouse/base/poco/Foundation/include/Poco/MetaProgramming.h

//
// MetaProgramming.h
//
// Library: Foundation
// Package: Core
// Module:  MetaProgramming
//
// Common definitions useful for Meta Template Programming
//
// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_MetaProgramming_INCLUDED
#define Foundation_MetaProgramming_INCLUDED


#include "Poco/Foundation.h"


namespace Poco {


template <typename T>
struct IsReference
	/// Use this struct to determine if a template type is a reference.
{
	enum
	{
		VALUE = 0
	};
};


template <typename T>
struct IsReference<T&>
{
	enum 
	{
		VALUE = 1
	};
};


template <typename T>
struct IsReference<const T&>
{
	enum 
	{
		VALUE = 1
	};
};


template <typename T>
struct IsConst
	/// Use this struct to determine if a template type is a const type.
{
	enum
	{
		VALUE = 0
	};
};


template <typename T>
struct IsConst<const T&>
{
	enum 
	{
		VALUE = 1
	};
};


template <typename T>
struct IsConst<const T>
{
	enum 
	{
		VALUE = 1
	};
};


template <typename T, int i>
struct IsConst<const T[i]>
	/// Specialization for const char arrays
{
	enum
	{
		VALUE = 1
	};
};


template <typename T>
struct TypeWrapper
	/// Use the type wrapper if you want to decouple constness and references from template types.
{
	typedef T TYPE;
	typedef const T CONSTTYPE;
	typedef T& REFTYPE;
	typedef const T& CONSTREFTYPE;
};


template <typename T>
struct TypeWrapper<const T>
{
	typedef T TYPE;
	typedef const T CONSTTYPE;
	typedef T& REFTYPE;
	typedef const T& CONSTREFTYPE;
};


template <typename T>
struct TypeWrapper<const T&>
{
	typedef T TYPE;
	typedef const T CONSTTYPE;
	typedef T& REFTYPE;
	typedef const T& CONSTREFTYPE;
};


template <typename T>
struct TypeWrapper<T&>
{
	typedef T TYPE;
	typedef const T CONSTTYPE;
	typedef T& REFTYPE;
	typedef const T& CONSTREFTYPE;
};


} // namespace Poco


#endif // Foundation_MetaProgramming_INCLUDED