util/util.hpp

#pragma once

#include <type_traits>
#include <utility>

#include <cstddef>
#include <cstdint>

namespace util {

namespace detail {

template <typename T, T Offset, T... Ints>
inline constexpr std::integer_sequence<T, (Offset + Ints)...> add_offset(std::integer_sequence<T, Ints...>)
{
	return {};
}

} // namespace detail

template <typename T, T Offset, T N>
inline constexpr auto make_offset_integer_sequence()
{
	return detail::add_offset<T, Offset>(std::make_integer_sequence<T, N>{});
}

template <std::size_t Offset, std::size_t N>
inline constexpr auto make_offset_index_sequence()
{
	return make_offset_integer_sequence<std::size_t, Offset, N>();
}

template <typename Fn, std::size_t... Ints>
constexpr auto for_constexpr(Fn &&func, std::index_sequence<Ints...>)
{
	if constexpr (std::is_void_v<std::invoke_result_t<Fn, std::integral_constant<std::size_t, 0>>>) {
		(func(std::integral_constant<std::size_t, Ints>{}), ...);
	} else {
		if ((func(std::integral_constant<std::size_t, Ints>{}) && ...))
			return true;
		return false;
	}
}

template <typename...>
struct always_false : std::false_type {
};
template <typename... Ts>
inline constexpr auto always_false_v = always_false<Ts...>::value;

} // namespace util