cpphibernate/include/cpphibernate/schema/tables.inl

#pragma once

#include "tables.h"

namespace cpphibernate {
namespace schema {

    namespace __impl
    {

        /* tables_t */

        template<typename... T_tables>
        using tables_t = hana::tuple<T_tables...>;

        /* tables_builder */

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

        template<typename... T>
        struct tables_builder<
            mp::list<T...>,
            mp::enable_if_t<mp::is_true_v<
                is_table_v<mp::decay_t<T>>...>>>
        {
            template<typename... T_args>
            static constexpr decltype(auto) apply(T_args&&... args)
            {
                using tables_type = tables_t<T_args...>;
                return tables_type(std::forward<T_args>(args)...);
            }
        };

        /* find_table_builder */

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

        template<typename T_tables, typename T_dataset>
        struct find_table_builder<
            mp::list<T_tables, T_dataset>,
            mp::enable_if_t<
                    is_tables_v<mp::decay_t<T_tables>>
                &&  mp::is_same_v<hana::type_tag, hana::tag_of_t<T_dataset>>
            >>
        {
            template<size_t I, size_t N, typename = void>
            struct helper;

            template<size_t N>
            struct helper<N, N, void>
                { static_assert(N != N, "Table for given datatype does not exist!"); };

            template<size_t I, size_t N>
            struct helper<I, N, mp::enable_if_t<
                decltype(hana::not_equal(std::declval<T_tables>()[hana::size_c<I>].wrapped_dataset, T_dataset { }))::value>>
            {
                static constexpr decltype(auto) apply(T_tables&& tables)
                    { return helper<I+1, N>::apply(std::forward<T_tables>(tables)); }
            };

            template<size_t I, size_t N>
            struct helper<I, N, mp::enable_if_t<
                decltype(hana::equal(std::declval<T_tables>()[hana::size_c<I>].wrapped_dataset, T_dataset { }))::value>>
            {
                static constexpr decltype(auto) apply(T_tables&& tables)
                    { return std::forward<T_tables>(tables)[hana::size_c<I>]; }
            };

            static constexpr decltype(auto) apply(T_tables&& tables, T_dataset&&)
            {
                using count_type = mp::decay_t<decltype(hana::size(std::declval<T_tables>()))>;
                return helper<0, count_type::value>::apply(std::forward<T_tables>(tables));
            }
        };

        /* is_tables_impl */

        template<typename T, typename = void>
        struct is_tables_impl
            : mp::false_t
            { };

        template<typename... T>
        struct is_tables_impl<
            tables_t<T...>,
            mp::enable_if_t<mp::is_true_v<is_table_v<mp::decay_t<T>>...>>>
            : mp::true_t
            { };

    }

    /* is_tables */

    template<typename T>
    struct is_tables
        : public __impl::is_tables_impl<T>
        { };

} }