digits.h

 
//          Copyright John McFarlane 2018.
// Distributed under the Boost Software License, Version 1.0.
//    (See accompanying file ../LICENSE_1_0.txt or copy at
//          http://www.boost.org/LICENSE_1_0.txt)
 
 
#if !defined(CNL_IMPL_NUM_TRAITS_DIGITS_H)
#define CNL_IMPL_NUM_TRAITS_DIGITS_H
 
#include "../numbers/signedness.h"
#include "../used_digits.h"
#include "is_composite.h"
 
#include <climits>
#include <concepts>
#include <type_traits>
 
namespace cnl {
    template<typename T>
    inline constexpr int digits_v = 0;
 
    namespace _impl {
        template<typename Integer>
        inline constexpr auto fundamental_digits = CHAR_BIT * sizeof(Integer) - numbers::signedness_v<Integer>;
    }
 
    template<std::integral Integer>
    inline constexpr int digits_v<Integer> = _impl::fundamental_digits<Integer>;
 
    namespace _impl {
        // cnl::_impl::fractional_digits
        template<class T>
        inline constexpr int fractional_digits = 0;
 
        // cnl::_impl::integer_digits
        template<class T>
        inline constexpr auto integer_digits = digits_v<T> - fractional_digits<T>;
    }
}
 
#endif  // CNL_IMPL_NUM_TRAITS_DIGITS_H