cpphibernate/include/cpphibernate/modifier/order_by.inl

#pragma once

#include "order_by.h"
#include "order_by/order_direction.h"

namespace cpphibernate
{

    namespace __impl
    {

        /* order_by_t */

        template<typename... T_order_directions>
        struct order_by_t
            : public tag_modifier
            , public tag_equality_comparable<tag_modifier>
        {
            using order_directions_type = hana::basic_tuple<T_order_directions...>;

            order_directions_type order_directions;
        };

        /* order_by_builder */

        template<typename X, typename>
        struct order_by_builder
        {
            template<typename... T_args>
            static constexpr decltype(auto) apply(T_args&&...)
                { static_assert(sizeof...(T_args) == -1, "Invalid parameters for order_by(...)!"); }
        };

        template<typename... T_order_directions>
        struct order_by_builder<
            mp::list<T_order_directions...>,
            mp::enable_if_t<mp::is_true_v<is_order_direction_v<mp::decay_t<T_order_directions>>...>>>
        {
            static constexpr decltype(auto) apply(T_order_directions&&...)
            {
                using order_by_type = order_by_t<mp::decay_t<T_order_directions>...>;
                return order_by_type { };
            }
        };

    }

    /* is_order_by_modifier */

    template<typename T>
    struct is_order_by_modifier
        : public mp::is_specialization_of<T, __impl::order_by_t>
        { };

}