fields.hh

#ifndef VTESTBED_BASE_FIELDS_HH
#define VTESTBED_BASE_FIELDS_HH

#include <cmath>
#include <istream>
#include <type_traits>

namespace vtb {

    namespace base {

        template <class T>
        struct unsigned_field {

            static_assert(std::is_unsigned<T>::value, "bad type");

            typedef T value_type;
            typedef typename std::make_signed<T>::type signed_value_type;

            value_type& value;

            inline friend std::istream&
            operator>>(std::istream& in, const unsigned_field& rhs) {
                signed_value_type tmp = 0; in >> tmp;
                if (tmp < 0) { in.setstate(std::ios::failbit); }
                else { rhs.value = static_cast<value_type>(tmp); }
                return in;
            }

        };

        template <class T>
        unsigned_field<T>
        make_unsigned_field(T& value) {
            return unsigned_field<T>{value};
        }

        template <class T>
        struct floating_point_field {

            static_assert(std::is_floating_point<T>::value, "bad type");

            typedef T value_type;

            value_type& value;

            inline friend std::istream&
            operator>>(std::istream& in, const floating_point_field& rhs) {
                value_type tmp = 0; in >> tmp;
                if (!std::isfinite(tmp)) { in.setstate(std::ios::failbit); }
                else { rhs.value = tmp; }
                return in;
            }

        };

        template <class T>
        floating_point_field<T>
        make_floating_point_field(T& value) {
            return floating_point_field<T>{value};
        }

    }

}

#endif // vim:filetype=cpp