cpphibernate/include/cpphibernate/schema/schema.inl

#pragma once

#include <cppcore/misc/indent.h>

#include "tables.h"
#include "schema.h"

namespace cpphibernate {
namespace schema {

    namespace __impl
    {

        /* schema_t */

        template<typename T_name, typename T_tables>
        constexpr schema_t<T_name, T_tables>
            ::schema_t(
                name_type&&    p_name,
                tables_type&&  p_tables)
                : name  (std::forward<name_type>  (p_name))
                , tables(std::forward<tables_type>(p_tables))
                { }

        template<typename T_name, typename T_tables>
        void schema_t<T_name, T_tables>
            ::print(std::ostream& os) const
        {
            using namespace ::cppcore;

            size_t index = 0;
            os  << indent << '{'
                << incindent
                    << indent << "\"name\": \"" << name << "\","
                    << indent << "\"tables\": "
                    << indent << '['
                    << incindent;
                    hana::for_each(tables, [&](auto& table){
                        if (index++ > 0) os << ",";
                        table.print(os);
                    });
            os      << decindent
                    << indent << ']'
                << decindent
                << indent << '}';
        }

        /* schema_builder */

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

        template<typename T_name, typename T_tables>
        struct schema_builder<
            mp::list<T_name, T_tables>,
            mp::enable_if_t<
                is_tables_v<mp::decay_t<T_tables>>>>
        {
            using name_type     = T_name;
            using tables_type   = T_tables;
            using schema_type   = schema_t<name_type, tables_type>;

            static constexpr decltype(auto) apply(
                name_type&&   name,
                tables_type&& tables)
            {
                return schema_type(
                    std::forward<name_type>  (name),
                    std::forward<tables_type>(tables));
            }
        };

        /* get_base_type_builder */

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

        template<typename T_schema, typename T_wrapped_dataset>
        struct get_base_type_builder<
            mp::list<T_schema, T_wrapped_dataset>,
            mp::enable_if_t<is_schema_v<mp::decay_t<T_schema>>>>
        {

            /* is_base_of */

            static constexpr decltype(auto) is_base_of = hana::integral(hana::metafunction<mp::is_base_of>);

            /* do_fold */

            struct do_fold_impl
            {
                template<typename T_type_1, typename T_type_2>
                constexpr decltype(auto) operator()(T_type_1&& type_1, T_type_2&& type_2) const
                {
                    auto check = hana::or_(is_base_of(type_1, type_2), is_base_of(type_2, type_1));
                    static_assert(decltype(check)::value, "A dataset must not have more than one base class!");
                    return hana::if_(is_base_of(type_1, type_2), type_2, type_1);
                }
            };

            static constexpr decltype(auto) do_fold = do_fold_impl { };

            /* get_base_types */

            template<typename T_datasets, typename T_dataset>
            static constexpr decltype(auto) get_base_types(T_datasets datasets, T_dataset dataset)
            {
                return hana::filter(
                    datasets,
                    [&](auto type){
                        return hana::and_(
                            is_base_of(type, dataset),
                            hana::not_equal(type, dataset));
                    });
            }

            /* apply */

            static constexpr decltype(auto) apply(
                const T_schema&          schema,
                const T_wrapped_dataset& wrapped_dataset)
            {
                decltype(auto) wrapped_datasets = hana::transform(
                                                    schema.tables,
                                                    schema::get_wrapped_dataset);
                decltype(auto) base_types = get_base_types(wrapped_datasets, wrapped_dataset);
                return hana::eval_if(
                    hana::size(base_types) <= hana::size_c<0>,
                        [&](auto _){ return hana::type_c<void>; },
                        [&](auto _){ return hana::fold(_(base_types), do_fold); });
            }
        };

        /* get_derived_types_builder */

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

        template<typename T_schema, typename T_dataset>
        struct get_derived_types_builder<
            mp::list<T_schema, T_dataset>,
            mp::enable_if_t<
                    schema::is_schema_v<mp::decay_t<T_schema>>
                &&  mp::is_same_v<hana::type_tag, hana::tag_of_t<T_dataset>>
            >>
        {
            struct has_base_impl
            {
                template<typename T_type>
                constexpr decltype(auto) operator()(T_type&&) const
                {
                    return decltype(hana::equal(
                        get_base_type(
                            std::declval<T_schema>(),
                            std::declval<T_type>()),
                        std::declval<T_dataset>())) { };
                }
            };

            static constexpr decltype(auto) has_base = has_base_impl { };

            static constexpr decltype(auto) apply(T_schema&& schema, T_dataset&& dataset)
            {
                constexpr decltype(auto) dataset_types =
                    decltype(hana::transform(schema.tables, schema::get_wrapped_dataset)) { };
                constexpr decltype(auto) derived_types =
                    decltype(hana::filter(dataset_types, has_base)) { };
                return derived_types;
            }
        };

        /* get_all_derived_types_builder */

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

        template<typename T_schema, typename T_dataset>
        struct get_all_derived_types_builder<
            mp::list<T_schema, T_dataset>,
            mp::enable_if_t<
                    schema::is_schema_v<mp::decay_t<T_schema>>
                &&  mp::is_same_v<hana::type_tag, hana::tag_of_t<T_dataset>>
            >>
        {
            struct is_derived_impl
            {
                using dataset_type = decay_unwrap_t<T_dataset>;

                template<typename T_type>
                constexpr decltype(auto) operator()(T_type&&) const
                {
                    return hana::bool_c<
                        std::is_base_of_v<dataset_type, decay_unwrap_t<T_type>>>;
                }
            };

            static constexpr decltype(auto) is_derived = is_derived_impl { };

            static constexpr decltype(auto) apply(T_schema&& schema, T_dataset&& dataset)
            {
                constexpr decltype(auto) dataset_types =
                    decltype(hana::transform(schema.tables, schema::get_wrapped_dataset)) { };
                constexpr decltype(auto) derived_types =
                    decltype(hana::filter(dataset_types, is_derived)) { };
                return derived_types;
            }
        };

    }

    /* is_schema */

    template<typename T>
    struct is_schema
        : public mp::is_base_of<__impl::tag_schema, T>
        { };

} }