set_error_member.hpp 2.8 KB

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  1. //
  2. // traits/set_error_member.hpp
  3. // ~~~~~~~~~~~~~~~~~~~~~~~~~~~
  4. //
  5. // Copyright (c) 2003-2022 Christopher M. Kohlhoff (chris at kohlhoff dot com)
  6. //
  7. // Distributed under the Boost Software License, Version 1.0. (See accompanying
  8. // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  9. //
  10. #ifndef ASIO_TRAITS_SET_ERROR_MEMBER_HPP
  11. #define ASIO_TRAITS_SET_ERROR_MEMBER_HPP
  12. #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  13. # pragma once
  14. #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  15. #include "asio/detail/config.hpp"
  16. #include "asio/detail/type_traits.hpp"
  17. #if defined(ASIO_HAS_DECLTYPE) \
  18. && defined(ASIO_HAS_NOEXCEPT) \
  19. && defined(ASIO_HAS_WORKING_EXPRESSION_SFINAE)
  20. # define ASIO_HAS_DEDUCED_SET_ERROR_MEMBER_TRAIT 1
  21. #endif // defined(ASIO_HAS_DECLTYPE)
  22. // && defined(ASIO_HAS_NOEXCEPT)
  23. // && defined(ASIO_HAS_WORKING_EXPRESSION_SFINAE)
  24. #include "asio/detail/push_options.hpp"
  25. namespace asio {
  26. namespace traits {
  27. template <typename T, typename E, typename = void>
  28. struct set_error_member_default;
  29. template <typename T, typename E, typename = void>
  30. struct set_error_member;
  31. } // namespace traits
  32. namespace detail {
  33. struct no_set_error_member
  34. {
  35. ASIO_STATIC_CONSTEXPR(bool, is_valid = false);
  36. ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false);
  37. };
  38. #if defined(ASIO_HAS_DEDUCED_SET_ERROR_MEMBER_TRAIT)
  39. template <typename T, typename E, typename = void>
  40. struct set_error_member_trait : no_set_error_member
  41. {
  42. };
  43. template <typename T, typename E>
  44. struct set_error_member_trait<T, E,
  45. typename void_type<
  46. decltype(declval<T>().set_error(declval<E>()))
  47. >::type>
  48. {
  49. ASIO_STATIC_CONSTEXPR(bool, is_valid = true);
  50. using result_type = decltype(
  51. declval<T>().set_error(declval<E>()));
  52. ASIO_STATIC_CONSTEXPR(bool, is_noexcept = noexcept(
  53. declval<T>().set_error(declval<E>())));
  54. };
  55. #else // defined(ASIO_HAS_DEDUCED_SET_ERROR_MEMBER_TRAIT)
  56. template <typename T, typename E, typename = void>
  57. struct set_error_member_trait :
  58. conditional<
  59. is_same<T, typename remove_reference<T>::type>::value
  60. && is_same<E, typename decay<E>::type>::value,
  61. typename conditional<
  62. is_same<T, typename add_const<T>::type>::value,
  63. no_set_error_member,
  64. traits::set_error_member<typename add_const<T>::type, E>
  65. >::type,
  66. traits::set_error_member<
  67. typename remove_reference<T>::type,
  68. typename decay<E>::type>
  69. >::type
  70. {
  71. };
  72. #endif // defined(ASIO_HAS_DEDUCED_SET_ERROR_MEMBER_TRAIT)
  73. } // namespace detail
  74. namespace traits {
  75. template <typename T, typename E, typename>
  76. struct set_error_member_default :
  77. detail::set_error_member_trait<T, E>
  78. {
  79. };
  80. template <typename T, typename E, typename>
  81. struct set_error_member :
  82. set_error_member_default<T, E>
  83. {
  84. };
  85. } // namespace traits
  86. } // namespace asio
  87. #include "asio/detail/pop_options.hpp"
  88. #endif // ASIO_TRAITS_SET_ERROR_MEMBER_HPP