enumeration_utils.h

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#ifndef MYSQL_UTILS_ENUMERATION_UTILS_H
#define MYSQL_UTILS_ENUMERATION_UTILS_H
 
/// @file
/// Experimental API header
 
#include <string>
#include <utility>
#include "mysql/utils/return_status.h"
 
/// @addtogroup GroupLibsMysqlUtils
/// @{
 
namespace mysql::utils {
 
/// true if Enum_t is an enumeration type (scoped or not).
///
/// This is equivalent to is_enum_v, but as a concept, is syntactically valid in
/// more contexts.
template <class Enum_t>
concept Is_enum = std::is_enum_v<Enum_t>;
 
/// @brief Helper function that converts enum type to underlying integer type
/// @note This function may be removed after switching to C++23
/// @tparam Enum_type Type of the enumeration parameter that gets converted into
/// the underlying type value
template <Is_enum Enum_type>
constexpr decltype(auto) to_underlying(Enum_type enum_value) {
  using EnumValueType = std::underlying_type_t<Enum_type>;
  return static_cast<EnumValueType>(enum_value);
}
 
/// @brief Template function that returns maximum *valid* constant that can
/// appear in the enumeration type. It must be specialized for each
/// enumeration type serialized
/// @tparam Enum_type Type of the enumeration that will be returned
/// @return Last valid enumeration constant within Enum_type
template <Is_enum Enum_type>
constexpr Enum_type enum_max();
 
/// @brief Helper function that converts value of enumeration underlying type
///        into enumeration type constant
/// @tparam Enum_type Type of the enumeration that Integral_type parameter is
/// converted into
template <Is_enum Enum_type>
constexpr std::pair<Enum_type, Return_status> to_enumeration(
    std::integral auto value) {
  if (value > to_underlying(enum_max<Enum_type>())) {
    return std::make_pair(enum_max<Enum_type>(), Return_status::error);
  }
  return std::make_pair(static_cast<Enum_type>(value), Return_status::ok);
}
 
}  // namespace mysql::utils
 
/// @}
 
#endif  // MYSQL_UTILS_ENUMERATION_UTILS_H