ClickHouse/libs/libcommon/include/common/strong_typedef.h

#pragma once

#include <boost/operators.hpp>
#include <type_traits>

/** https://svn.boost.org/trac/boost/ticket/5182
  */

template <class T, class Tag>
struct StrongTypedef
	: boost::totally_ordered1< StrongTypedef<T, Tag>
							   , boost::totally_ordered2< StrongTypedef<T, Tag>, T> >
{
	using Self = StrongTypedef<T, Tag>;
	T t;

	template <class Enable = typename std::is_copy_constructible<T>::type>
	explicit StrongTypedef(const T & t_) : t(t_) {};
	template <class Enable = typename std::is_move_constructible<T>::type>
	explicit StrongTypedef(T && t_) : t(std::move(t_)) {};

	template <class Enable = typename std::is_default_constructible<T>::type>
	StrongTypedef(): t() {};

	StrongTypedef(const Self &) = default;
	StrongTypedef(Self &&) = default;

	Self & operator=(const Self &) = default;
	Self & operator=(Self &&) = default;

	template <class Enable = typename std::is_copy_assignable<T>::type>
	Self & operator=(const T & rhs) { t = rhs; return *this;}

	template <class Enable = typename std::is_move_assignable<T>::type>
	Self & operator=(T && rhs) { t = std::move(rhs); return *this;}

	operator const T & () const {return t; }
	operator T & () { return t; }

	bool operator==(const Self & rhs) const { return t == rhs.t; }
	bool operator<(const Self & rhs) const { return t < rhs.t; }

	T & toUnderType() { return t; }
	const T & toUnderType() const { return t; }
};

namespace std
{
	template <class T, class Tag>
	struct hash<StrongTypedef<T, Tag>>
	{
		size_t operator()(const StrongTypedef<T, Tag> & x) const
		{
			return std::hash<T>()(x.toUnderType());
		}
	};
}

#define STRONG_TYPEDEF(T, D) \
	struct D ## Tag {}; \
	using D = StrongTypedef<T, D ## Tag>; \