set_categories.h

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#ifndef MYSQL_SETS_SET_CATEGORIES_H
#define MYSQL_SETS_SET_CATEGORIES_H
 
/// @file
/// Experimental API header
 
#include <concepts>                       // derived_from
#include "mysql/meta/optional_is_same.h"  // Optional_is_same
 
/// @addtogroup GroupLibsMysqlSets
/// @{
 
namespace mysql::sets {
 
/// Base class for all Set category tag classes.
///
/// Set categories are used to tag-dispatch to the correct algorithms when
/// computing operations on sets, such as unions and other set operations;
/// membership tests and other Boolean set predicates; string conversion; etc.
struct Base_set_category_tag {};
 
/// True if Test is a Set category tag, i.e., derived from
/// Base_set_category_tag.
template <class Test>
concept Is_set_category = std::derived_from<Test, Base_set_category_tag>;
 
/// True if Test has a member Set_category_t satisfying Is_set_category.
///
/// If the template argument Set_category_t is given, true only if
/// Test::Set_category_t is the same type as Set_category_t.
template <class Test, class Set_category_t = void>
concept Has_set_category =
    Is_set_category<typename Test::Set_category_t> &&
    mysql::meta::Optional_is_same<typename Test::Set_category_t,
                                  Set_category_t>;
 
/// True if the two Set classes have the same Set_category_t.
template <class Test1, class Test2>
concept Has_same_set_category =
    Has_set_category<Test1> && Has_set_category<Test2> &&
    std::same_as<typename Test1::Set_category_t,
                 typename Test2::Set_category_t>;
 
// ==== Specific kinds of set categories ====
 
/// Primary variable template for customization point that declares that a set
/// category is iterator-defined. See Is_iterator_defined_set for details.
///
/// To declare that a set category T is iterator-defined, specialize this like:
///
/// @code
/// template <>
/// inline constexpr bool is_iterator_defined_set_category<T> = true;
/// @endcode
template <Is_set_category>
inline constexpr bool is_iterator_defined_set_category = false;
 
}  // namespace mysql::sets
 
// addtogroup GroupLibsMysqlSets
/// @}
 
#endif  // ifndef MYSQL_SETS_SET_CATEGORIES_H