aggregate.h

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#pragma once
#include <cstddef>
#include <string>
#include <string_view>
#include <type_traits>
 
#include <librepr/util/collections/list.h>
#include <librepr/util/collections/reftuple.h>
#include <librepr/util/concepts.h>
#include <librepr/name/member.h>
 
// TODO
#include <librepr/customization.h>
#include <librepr/customization/reflection.h>
 
#include "category.h"
#include "detail/arity.h"
#include "detail/to_reftuple.h"
 
namespace librepr {
 
template <typename T>
concept reflect_names = requires { requires librepr::Settings<T>::aggregate_member_names; };
 
template <typename T>
struct Reflect;
 
namespace category {
 
template <typename Member, typename Parent, std::size_t Index>
struct DataMember : Member {
  using descend     = Member;
  using type        = typename Member::type;
  using parent      = Parent;
  using parent_type = typename Parent::type;
 
  [[nodiscard]] std::string_view name() const { 
    return member_name<parent_type, Index>; 
  }
 
  using Member::visit;
};
 
}  // namespace category
 
template <typename T>
  requires(std::is_aggregate_v<T> && !(std::is_array_v<T> || has_custom_members<T> || detail::has_repr_member<T>))
struct Reflect<T> : category::Type<T> {
  constexpr static auto member_count = librepr::detail::arity<T>;
 
  using member_tuple = decltype(librepr::detail::to_reftuple(std::declval<T>()));
  static_assert(!std::is_same_v<member_tuple, void>, "Aggregate reflection failed");
 
  using member_types                = typename pack::rebox<member_tuple, TypeList>::template map<std::remove_reference_t>;
  using type                        = T;
  using members                     = typename member_types::template map<librepr::Reflect>;
  constexpr static bool can_descend = true;
 
  template <typename V>
  static void visit(V&& visitor, T& obj) {
    auto decomposed = librepr::detail::to_reftuple(obj);
    static_assert(members::size == decltype(decomposed)::size,
                  "Decomposed obj does not match reflected member amount.");
 
    members::enumerate([&visitor, &decomposed]<typename M, std::size_t Index> {
      visitor(category::Value<category::DataMember<M, Reflect, Index>>{librepr::get<Index>(decomposed)});
    });
  }
 
  template <typename V>
  static void visit(V&& visitor) {
    members::enumerate(
        [&visitor]<typename M, std::size_t Index> { visitor(category::DataMember<M, Reflect, Index>{}); });
  }
};
}  // namespace librepr