make_bit_array

index_trait.hpp

#pragma once

#include<type_traits>

// Copyright plasma-effect 2015
// Distributed under the Boost Software License, Version 1.0.
// (See http://www.boost.org/LICENSE_1_0.txt)

namespace plasma
{
	namespace index_trait
	{
		template<class, class>struct index_merge;
		template<std::size_t... Is0, std::size_t... Is1>struct index_merge<std::index_sequence<Is0...>, std::index_sequence<Is1...>>
		{
			typedef std::index_sequence<Is0..., Is1...> type;
		};
		template<class T0, class T1>using index_merge_t = typename index_merge<T0, T1>::type;

		template<class T, template<std::size_t>class Func > struct index_foreach;
		template<std::size_t... Is, template<std::size_t>class Func>struct index_foreach<std::index_sequence<Is...>, Func>
		{
			typedef std::index_sequence<Func<Is>::value...> type;
		};
		template<class T, template<std::size_t>class Func>using index_foreach_t = typename index_foreach<T, Func>::type;
	}
}

make_bit_array.hpp

#pragma once

#include"index_trait.hpp"
#include<array>

// Copyright plasma-effect 2015
// Distributed under the Boost Software License, Version 1.0.
// (See http://www.boost.org/LICENSE_1_0.txt)

namespace plasma
{
	namespace detail
	{
		template<std::size_t V>struct add_value
		{
			template<std::size_t I>struct func_t
			{
				static constexpr std::size_t value = V + I;
			};
		};

		template<std::size_t Start, std::size_t Flag>struct make_bit_index
		{
			typedef index_trait::index_merge_t <
				index_trait::index_foreach_t<
					typename make_bit_index<(Start >>1), Flag - 1>::type, 
					typename add_value<Start>::func_t>,
				typename make_bit_index<(Start >>1), Flag>::type> type;
		};
		template<std::size_t Start>struct make_bit_index<Start, 0>
		{
			typedef std::index_sequence<0> type;
		};
		template<std::size_t Flag>struct make_bit_index<0, Flag>
		{
			typedef std::index_sequence<> type;
		};
		template<>struct make_bit_index<0, 0>
		{
			typedef std::index_sequence<0> type;
		};


		template<class T>struct make_array_from_index;
		template<std::size_t... Is>struct make_array_from_index<std::index_sequence<Is...>>
		{
			static std::array<std::size_t, sizeof...(Is)> run()
			{
				return std::array<std::size_t, sizeof...(Is)>{Is...};
			}
		};
	}
	template<std::size_t Size, std::size_t Flag>auto make_bit_array()
	{
		return detail::make_array_from_index<detail::make_bit_index<1 << (Size - 1), Flag>::type>::run();
	}
}

test.cpp

#include<random>
#include<iostream>
#include<bitset>
#include"make_bit_array.hpp"

int main()
{
	for (auto v : plasma::make_bit_array<4, 2>())
	{
		std::cout << static_cast<std::bitset<4>>(v) << std::endl;
	}
}