cpphibernate/include/cpphibernate/driver/mariadb/helper/nullable_helper.inl

namespace cpphibernate {
namespace mariadb {


    /* nullable_helper - cppcore::nullable */

    template<typename T_value>
    struct nullable_helper<cppcore::nullable<T_value>, void>
    {
        using nullable_type = cppcore::nullable<T_value>;
        using value_type    = T_value;

        static inline value_type* get(nullable_type& x)
            { return x.has_value() ? &x.value() : nullptr; }

        static inline const value_type* get(const nullable_type& x)
            { return x.has_value() ? &x.value() : nullptr; }

        static inline value_type& set(nullable_type& x, const value_type* value)
            { return *(x = *value); }

        static inline value_type& set(nullable_type& x, const value_type& value)
            { return *(x = value); }

        static inline value_type& set(nullable_type& x, value_type&& value)
            { return *(x = std::move(value)); }

        static void clear(nullable_type& x)
            { x.reset(); }
    };

    /* nullable_helper - std::unique_ptr/std::shared_ptr */

    template<typename T>
    struct nullable_helper<
        T,
        mp::enable_if_t<
                mp::is_specialization_of_v<T, std::unique_ptr>
            ||  mp::is_specialization_of_v<T, std::shared_ptr>>>
    {
        using nullable_type = T;
        using value_type    = typename nullable_type::element_type;

        static inline value_type* get(const nullable_type& x)
            { return x.get(); }

        static inline value_type& set(nullable_type& x, value_type* value)
        {
            x.reset(value);
            return *x;
        }

        static inline value_type& set(nullable_type& x, const value_type& value)
        {
            x.reset(new value_type(value));
            return *x;
        }

        static inline value_type& set(nullable_type& x, value_type&& value)
        {
            x.reset(new value_type(std::move(value)));
            return *x;
        }

        static void clear(nullable_type& x)
            { return x.reset(); }
    };

} }