underlying_type.hpp

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// Copyright 2024, Toyota Motor Corporation
//
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
#ifndef INCLUDE_GUARD_ARENE_BASE_STDLIB_INCLUDE_STDLIB_DETAIL_UNDERLYING_TYPE_HPP_
#define INCLUDE_GUARD_ARENE_BASE_STDLIB_INCLUDE_STDLIB_DETAIL_UNDERLYING_TYPE_HPP_
 
// parasoft-begin-suppress CERT_CPP-DCL58-a-2 "Part of a standard library implementation"
// parasoft-begin-suppress AUTOSAR-A17_6_1-a-2 "Part of a standard library implementation"
 
#include "arene/base/constraints.hpp"
#include "stdlib/include/stdlib_detail/enable_if.hpp"
#include "stdlib/include/stdlib_detail/is_enum.hpp"
 
// IWYU pragma: private, include <type_traits>
// IWYU pragma: friend "stdlib_detail/.*"
 
namespace std {
namespace underlying_type_detail {
 
// parasoft-begin-suppress AUTOSAR-A2_7_3-a "False positive: all declarations
// and typedefs *are* preceded by a comment with @brief"
 
/// @brief Helper trait used to implement @c std::underlying_type
/// @tparam T The type to get the underlying type of
///
/// The primary template does not define member @c type.
///
template <typename T, typename = arene::base::constraints<>>
struct underlying_type {};
 
/// @brief Helper trait specialization used to implement @c std::underlying_type
///     if @c T is an enumeration type
/// @tparam T The type to get the underlying type of
///
template <typename T>
struct underlying_type<T, arene::base::constraints<enable_if_t<is_enum_v<T>>>> {
  /// @brief The underlying integer type
  using type = __underlying_type(T);
};
 
}  // namespace underlying_type_detail
 
/// @brief Obtains the underlying integer type for a given enumeration type
/// @tparam T Enumeration type
///
/// Provides member type alias @c type that names the underlying type of @c T if
/// @c T is an enumeration type. If @c T is not an enumeration type, there is no
/// member @c type.
///
template <typename T>
using underlying_type = underlying_type_detail::underlying_type<T>;
 
/// @brief An alias for the underlying type of @c T, if @c T is an enumeration type
/// @tparam T The type to get the underlying type of
///
template <typename T>
using underlying_type_t = typename underlying_type<T>::type;
 
// parasoft-end-suppress AUTOSAR-A2_7_3-a
 
}  // namespace std
 
#endif  // INCLUDE_GUARD_ARENE_BASE_STDLIB_INCLUDE_STDLIB_DETAIL_UNDERLYING_TYPE_HPP_