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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-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___ITERATOR_READABLE_TRAITS_H11#define _LIBCPP___ITERATOR_READABLE_TRAITS_H12 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_header25#endif26 27_LIBCPP_BEGIN_NAMESPACE_STD28 29#if _LIBCPP_STD_VER >= 2030 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 >= 2078 79_LIBCPP_END_NAMESPACE_STD80 81#endif // _LIBCPP___ITERATOR_READABLE_TRAITS_H82