nested_set_const_views.h

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#ifndef MYSQL_SETS_NESTED_SET_CONST_VIEWS_H
#define MYSQL_SETS_NESTED_SET_CONST_VIEWS_H
 
/// @file
/// Experimental API header
 
#include "mysql/iterators/empty_sequence_iterator.h"  // Empty_sequence_iterator
#include "mysql/sets/base_const_views.h"              // Empty_set_view
#include "mysql/sets/nested_set_category.h"           // Nested_set_category_tag
#include "mysql/sets/nested_set_interface.h"          // Nested_set_interface
#include "mysql/sets/nested_set_meta.h"               // Is_nested_set_traits
 
/// @addtogroup GroupLibsMysqlSets
/// @{
 
namespace mysql::sets::detail {
 
/// Gives the mapped type for a nested Empty_set_view.
///
/// @tparam Set_traits_t Nested set traits.
template <Is_nested_set_traits Set_traits_t>
using Empty_nested_mapped_type =
    Empty_set_view<typename Set_traits_t::Mapped_category_t,
                   typename Set_traits_t::Mapped_traits_t>;
 
/// Gives the iterator type for a nested Empty_set_view.
///
/// @tparam Set_traits_t Nested set traits.
template <Is_nested_set_traits Set_traits_t>
using Empty_nested_iterator_type = mysql::iterators::Empty_sequence_iterator<
    std::pair<const typename Set_traits_t::Key_t,
              Empty_nested_mapped_type<Set_traits_t>>>;
 
}  // namespace mysql::sets::detail
 
namespace mysql::sets {
 
/// View over an empty Nested set
///
/// @tparam Set_traits_tp Nested set traits.
template <Is_nested_set_traits Set_traits_tp>
class Empty_set_view<Nested_set_category_tag, Set_traits_tp>
    : public Nested_view_interface<
          Empty_set_view<Nested_set_category_tag, Set_traits_tp>,
          detail::Empty_nested_iterator_type<Set_traits_tp>,
          detail::Empty_nested_iterator_type<Set_traits_tp>, Set_traits_tp> {
 public:
  using Key_t = typename Set_traits_tp::Key_t;
  using Mapped_t = detail::Empty_nested_mapped_type<Set_traits_tp>;
  using Iterator_t = detail::Empty_nested_iterator_type<Set_traits_tp>;
 
  [[nodiscard]] constexpr auto begin() const { return Iterator_t(); }
 
  [[nodiscard]] constexpr auto end() const { return Iterator_t(); }
 
  [[nodiscard]] constexpr Iterator_t find(const Key_t & /*key*/) const {
    return Iterator_t();
  }
 
  [[nodiscard]] constexpr Iterator_t find(Iterator_t & /*cursor*/,
                                          const Key_t & /*key*/) const {
    return Iterator_t();
  }
 
};  // class Empty_set_view
 
}  // namespace mysql::sets
 
// addtogroup GroupLibsMysqlSets
/// @}
 
#endif  // ifndef MYSQL_SETS_NESTED_SET_CONST_VIEWS_H