flag_bits_v.h

 
#pragma once
 
#include <type_traits>
#include <climits> 
#include <concepts>
 
#if !__has_cpp_attribute(nodiscard)
#error "This library requires [[nodiscard]]"
#endif
 
namespace ghassanpl
{
    template<typename T>
    concept integral_or_enum = (std::is_integral_v<T> && !std::is_same_v<std::decay_t<T>, bool>) || std::is_enum_v<T>;
 
    namespace detail
    {
        template <typename T> 
        requires integral_or_enum<T>
        constexpr auto to_underlying_type(T t) noexcept
        {
            if constexpr (std::is_enum_v<T>)
                return static_cast<std::underlying_type_t<T>>(t);
            else
                return t;
        }
 
        template <typename INT_TYPE, auto BIT_NUM>
        concept allowed_bit_num = BIT_NUM >= 0 && BIT_NUM < CHAR_BIT * sizeof(INT_TYPE);
 
        template <typename RESULT_TYPE, auto... VALUES>
        concept valid_flag_bits_v_arguments =
            std::integral<RESULT_TYPE> && !std::same_as<std::decay_t<RESULT_TYPE>, bool> && 
            (integral_or_enum<decltype(VALUES)> && ...) &&
            (detail::allowed_bit_num<RESULT_TYPE, static_cast<decltype(detail::to_underlying_type(VALUES))>(VALUES)> && ...);
    }
 
    template <typename RESULT_TYPE, auto... VALUES> 
    requires detail::valid_flag_bits_v_arguments<RESULT_TYPE, VALUES...>
    constexpr inline RESULT_TYPE flag_bits_v = ((RESULT_TYPE(1) << (detail::to_underlying_type(VALUES))) | ... | 0);
 
    template <auto INT_VALUE, auto VALUE>
    requires detail::valid_flag_bits_v_arguments<decltype(INT_VALUE), VALUE>
    constexpr inline auto is_flag_set_v = (INT_VALUE & flag_bits_v<decltype(INT_VALUE), VALUE>) != 0;
 
    template <auto INT_VALUE, auto... VALUES>
    requires detail::valid_flag_bits_v_arguments<decltype(INT_VALUE), VALUES...>
    constexpr inline auto are_any_flags_set_v = (INT_VALUE & flag_bits_v<decltype(INT_VALUE), VALUES...>) != decltype(INT_VALUE){};//((is_flag_set_v<INT_VALUE, VALUES>) || ...);
 
    template <auto INT_VALUE, auto... VALUES>
    requires detail::valid_flag_bits_v_arguments<decltype(INT_VALUE), VALUES...>
    constexpr inline auto are_all_flags_set_v = (INT_VALUE & flag_bits_v<decltype(INT_VALUE), VALUES...>) == flag_bits_v<decltype(INT_VALUE), VALUES...>;//((is_flag_set_v<INT_VALUE, VALUES>) && ...);
 
    template <auto INT_VALUE, auto... VALUES>
    requires detail::valid_flag_bits_v_arguments<decltype(INT_VALUE), VALUES...>
    constexpr inline auto set_flag_v = INT_VALUE | (flag_bits_v<decltype(INT_VALUE), VALUES...>);
 
    template <auto INT_VALUE, auto... VALUES>
    requires detail::valid_flag_bits_v_arguments<decltype(INT_VALUE), VALUES...>
    constexpr inline auto unset_flag_v = INT_VALUE & ~(flag_bits_v<decltype(INT_VALUE), VALUES...>);
 
    template <auto INT_VALUE, auto... VALUES>
    requires detail::valid_flag_bits_v_arguments<decltype(INT_VALUE), VALUES...>
    constexpr inline auto toggle_flag_v = INT_VALUE ^ (flag_bits_v<decltype(INT_VALUE), VALUES...>);
 
    template <auto INT_VALUE, bool TO, auto... VALUES>
    requires detail::valid_flag_bits_v_arguments<decltype(INT_VALUE), VALUES...>
    constexpr inline auto set_flag_to_v = TO ?
        (INT_VALUE | (flag_bits_v<decltype(INT_VALUE), VALUES...>)) :
        (INT_VALUE & ~(flag_bits_v<decltype(INT_VALUE), VALUES...>));
}