polarity.h

 
//          Copyright John McFarlane 2019.
// 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_OVERFLOW_POLARITY_H)
#define CNL_IMPL_OVERFLOW_POLARITY_H
 
#include "config.h"
 
namespace cnl {
    namespace _impl {
        enum class polarity { negative = -1,
                              neutral = 0,
                              positive = 1 };
 
        [[nodiscard]] constexpr auto operator-(polarity const& p)
        {
            return static_cast<polarity>(-static_cast<int>(p));
        }
 
        [[nodiscard]] constexpr auto operator*(polarity const& lhs, polarity const& rhs)
        {
            return static_cast<polarity>(static_cast<int>(lhs) * static_cast<int>(rhs));
        }
 
        template<typename T>
        [[nodiscard]] constexpr auto measure_polarity(T const& value)
        {
            return (value > T{}) ? polarity::positive
                 : (value < T{}) ? polarity::negative
                                 : polarity::neutral;
        }
    }
}
 
#endif  // CNL_IMPL_OVERFLOW_POLARITY_H