IntegerEnum

IntegerEnum.hpp

#pragma once

namespace ie
{
	namespace detail
	{
		struct Value
		{
			constexpr Value() = default;
			constexpr Value(const int& other) :
				value(other)
			{}
		protected:
			int value = 0;
		};
	}
}


#define INTEGER_ENUM(...)\
struct : ie::detail::Value{\
	using  _ENUM=enum { __VA_ARGS__ };\
	using Value::Value;\
	decltype(auto) operator +=(int value) { *this = this->value + value;	return *this; }\
	decltype(auto) operator -=(int value) { *this = this->value - value;	return *this; }\
	decltype(auto) operator *=(int value) { *this = this->value * value;	return *this; }\
	decltype(auto) operator /=(int value) { *this = this->value / value;	return *this; }\
	decltype(auto) operator %=(int value) { *this = this->value % value;	return *this; }\
	decltype(auto) operator ++() { *this = this->value + 1;	return *this; }\
	decltype(auto) operator --() { *this = this->value - 1;	return *this; }\
	decltype(auto) operator ++(int) { auto ret = *this;	*this = this->value + 1; return ret; }\
	decltype(auto) operator --(int) { auto ret = *this;	*this = this->value - 1; return ret; }\
	constexpr operator _ENUM()const{ return static_cast<_ENUM>(value); }\
}

/*
using Example = INTEGER_ENUM(
A,
B,
Default = A
);
*/

Sample.cpp

#include<iostream>
#include<string>


#include"IntegerEnum.hpp"

using Example = INTEGER_ENUM(
	A,
	B,
	C=10,
	Default = A
);
//enum class 同様名前の衝突なし
using Example2 = INTEGER_ENUM(
	A,
	B
);
int main()
{
	Example test1 = Example::Default; 

	test1 += 2;					//整数の演算可能

	constexpr  Example c{ 0 };	//constexpr対応

	//enumのように扱える
	int a[Example::C];
	int b = Example::A;
	
	return 0;
}