1// -*- C++ -*- 2//===----------------------------------------------------------------------===// 3// 4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5// See https://llvm.org/LICENSE.txt for license information. 6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7// 8//===----------------------------------------------------------------------===// 9 10#ifndef _LIBCPP___ITERATOR_READABLE_TRAITS_H 11#define _LIBCPP___ITERATOR_READABLE_TRAITS_H 12 13#include <__concepts/same_as.h> 14#include <__config> 15#include <__type_traits/conditional.h> 16#include <__type_traits/is_array.h> 17#include <__type_traits/is_object.h> 18#include <__type_traits/is_primary_template.h> 19#include <__type_traits/remove_cv.h> 20#include <__type_traits/remove_cvref.h> 21#include <__type_traits/remove_extent.h> 22 23#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 24# pragma GCC system_header 25#endif 26 27_LIBCPP_BEGIN_NAMESPACE_STD 28 29#if _LIBCPP_STD_VER >= 20 30 31// [readable.traits] 32template <class> 33struct __cond_value_type {}; 34 35template <class _Tp> 36 requires is_object_v<_Tp> 37struct __cond_value_type<_Tp> { 38 using value_type = remove_cv_t<_Tp>; 39}; 40 41template <class _Tp> 42concept __has_member_value_type = requires { typename _Tp::value_type; }; 43 44template <class _Tp> 45concept __has_member_element_type = requires { typename _Tp::element_type; }; 46 47template <class> 48struct indirectly_readable_traits {}; 49 50template <class _Ip> 51 requires is_array_v<_Ip> 52struct indirectly_readable_traits<_Ip> { 53 using value_type = remove_cv_t<remove_extent_t<_Ip>>; 54}; 55 56template <class _Ip> 57struct indirectly_readable_traits<const _Ip> : indirectly_readable_traits<_Ip> {}; 58 59template <class _Tp> 60struct indirectly_readable_traits<_Tp*> : __cond_value_type<_Tp> {}; 61 62template <__has_member_value_type _Tp> 63struct indirectly_readable_traits<_Tp> : __cond_value_type<typename _Tp::value_type> {}; 64 65template <__has_member_element_type _Tp> 66struct indirectly_readable_traits<_Tp> : __cond_value_type<typename _Tp::element_type> {}; 67 68template <__has_member_value_type _Tp> 69 requires __has_member_element_type<_Tp> 70struct indirectly_readable_traits<_Tp> {}; 71 72template <__has_member_value_type _Tp> 73 requires __has_member_element_type<_Tp> && 74 same_as<remove_cv_t<typename _Tp::element_type>, remove_cv_t<typename _Tp::value_type>> 75struct indirectly_readable_traits<_Tp> : __cond_value_type<typename _Tp::value_type> {}; 76 77#endif // _LIBCPP_STD_VER >= 20 78 79_LIBCPP_END_NAMESPACE_STD 80 81#endif // _LIBCPP___ITERATOR_READABLE_TRAITS_H 82