base_const_views.h

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#ifndef MYSQL_SETS_BASE_CONST_VIEWS_H
#define MYSQL_SETS_BASE_CONST_VIEWS_H
 
/// @file
/// Experimental API header
 
#include <ranges>                                  // enable_view
#include "mysql/sets/set_categories.h"             // Is_set_category
#include "mysql/sets/set_categories_and_traits.h"  // Is_set
#include "mysql/sets/set_traits.h"                 // Is_bounded_set_traits
 
/// @addtogroup GroupLibsMysqlSets
/// @{
 
namespace mysql::sets {
 
// ==== Empty sets ====
 
/// Forward declaration of primary template for views over empty sets.
///
/// This may be specialized to set categories for which we need it.
template <Is_set_category, Is_set_traits>
class Empty_set_view;
 
/// Return a reference to a singleton object representing the view containing
/// the empty set, for the given Set category and Set traits.
template <Is_set_category Set_category_t, Is_set_traits Set_traits_t>
[[nodiscard]] auto &make_empty_set_view() {
  static Empty_set_view<Set_category_t, Set_traits_t> ret;
  return ret;
}
 
/// Return the result of make_empty_set_view for the set category and set traits
/// of the given set type.
template <Is_set Set_t>
[[nodiscard]] auto &make_empty_set_view_like() {
  return make_empty_set_view<typename Set_t::Set_category_t,
                             typename Set_t::Set_traits_t>();
}
 
// ==== Full sets ====
 
/// Forward declaration of primary template for views over "full" sets, i.e.,
/// the complement of the empty set.
///
/// This may be specialized to set categories for which we need it. Note that
/// not all set categories can have "full sets".
template <Is_set_category, Is_set_traits>
class Full_set_view;
 
/// Return a reference to a singleton object representing the view containing
/// the empty set, for the given Set category and Set traits.
template <Is_set_category Set_category_t, Is_bounded_set_traits Set_traits_t>
[[nodiscard]] auto &make_full_set_view() {
  static Full_set_view<Set_category_t, Set_traits_t> ret;
  return ret;
}
 
/// Return the result of make_full_set_view for the set category and set traits
/// of the given set type.
template <Is_set Set_t>
[[nodiscard]] auto &make_full_set_view_like() {
  return make_full_set_view<typename Set_t::Set_category_t,
                            typename Set_t::Set_traits_t>();
}
 
}  // namespace mysql::sets
 
// ==== Declarations of view ====
 
/// @cond DOXYGEN_DOES_NOT_UNDERSTAND_THIS
/// Declare that Empty_view is a view.
template <class Set_category_t, class Set_traits_t>
constexpr bool std::ranges::enable_view<
    mysql::sets::Empty_set_view<Set_category_t, Set_traits_t>> = true;
 
/// Declare that Full_view is a view.
template <class Set_category_t, class Set_traits_t>
constexpr bool std::ranges::enable_view<
    mysql::sets::Full_set_view<Set_category_t, Set_traits_t>> = true;
/// @endcond
 
// addtogroup GroupLibsMysqlSets
/// @}
 
#endif  // ifndef MYSQL_SETS_BASE_CONST_VIEWS_H