is_base_of.hpp

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// SPDX-License-Identifier: BSL-1.0
// SPDX-FileCopyrightText: Copyright (C) 2019 Tobias Hienzsch
 
#ifndef TETL_TYPE_TRAITS_IS_BASE_OF_HPP
#define TETL_TYPE_TRAITS_IS_BASE_OF_HPP
 
#include <etl/_type_traits/bool_constant.hpp>
#include <etl/_type_traits/is_class.hpp>
 
namespace etl {
 
namespace detail {
template <typename B>
auto test_pre_ptr_convertible(B const volatile*) -> true_type;
template <typename>
auto test_pre_ptr_convertible(void const volatile*) -> false_type;
 
template <typename, typename>
auto test_pre_is_base_of(...) -> true_type;
template <typename B, typename D>
auto test_pre_is_base_of(int) -> decltype(test_pre_ptr_convertible<B>(static_cast<D*>(nullptr)));
} // namespace detail
 
/// \brief If Derived is derived from Base or if both are the same non-union
/// class (in both cases ignoring cv-qualification), provides the member
/// constant value equal to true. Otherwise value is false.
///
/// \details If both Base and Derived are non-union class types, and they are
/// not the same type (ignoring cv-qualification), Derived shall be a complete
/// type; otherwise the behavior is undefined.
///
/// https://en.cppreference.com/w/cpp/types/is_base_of
template <typename Base, typename Derived>
struct is_base_of
    : bool_constant<
          is_class_v<Base> and is_class_v<Derived>and decltype(detail::test_pre_is_base_of<Base, Derived>(0))::value
      > { };
 
template <typename Base, typename Derived>
inline constexpr bool is_base_of_v = is_base_of<Base, Derived>::value;
 
} // namespace etl
 
#endif // TETL_TYPE_TRAITS_IS_BASE_OF_HPP