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___RANGES_VIEW_INTERFACE_H 11 #define _LIBCPP___RANGES_VIEW_INTERFACE_H 12 13 #include <__assert> 14 #include <__concepts/derived_from.h> 15 #include <__concepts/same_as.h> 16 #include <__config> 17 #include <__iterator/concepts.h> 18 #include <__iterator/iterator_traits.h> 19 #include <__iterator/prev.h> 20 #include <__memory/pointer_traits.h> 21 #include <__ranges/access.h> 22 #include <__ranges/concepts.h> 23 #include <__ranges/empty.h> 24 #include <__ranges/size.h> 25 #include <__type_traits/is_class.h> 26 #include <__type_traits/make_unsigned.h> 27 #include <__type_traits/remove_cv.h> 28 29 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 30 # pragma GCC system_header 31 #endif 32 33 _LIBCPP_BEGIN_NAMESPACE_STD 34 35 #if _LIBCPP_STD_VER >= 20 36 37 namespace ranges { 38 39 template <class _Derived> 40 requires is_class_v<_Derived> && same_as<_Derived, remove_cv_t<_Derived>> 41 class view_interface { 42 _LIBCPP_HIDE_FROM_ABI constexpr _Derived& __derived() noexcept { 43 static_assert(sizeof(_Derived) && derived_from<_Derived, view_interface> && view<_Derived>); 44 return static_cast<_Derived&>(*this); 45 } 46 47 _LIBCPP_HIDE_FROM_ABI constexpr _Derived const& __derived() const noexcept { 48 static_assert(sizeof(_Derived) && derived_from<_Derived, view_interface> && view<_Derived>); 49 return static_cast<_Derived const&>(*this); 50 } 51 52 public: 53 template <class _D2 = _Derived> 54 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool empty() 55 requires sized_range<_D2> || forward_range<_D2> 56 { 57 if constexpr (sized_range<_D2>) { 58 return ranges::size(__derived()) == 0; 59 } else { 60 return ranges::begin(__derived()) == ranges::end(__derived()); 61 } 62 } 63 64 template <class _D2 = _Derived> 65 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool empty() const 66 requires sized_range<const _D2> || forward_range<const _D2> 67 { 68 if constexpr (sized_range<const _D2>) { 69 return ranges::size(__derived()) == 0; 70 } else { 71 return ranges::begin(__derived()) == ranges::end(__derived()); 72 } 73 } 74 75 template <class _D2 = _Derived> 76 _LIBCPP_HIDE_FROM_ABI constexpr explicit operator bool() 77 requires requires(_D2& __t) { ranges::empty(__t); } 78 { 79 return !ranges::empty(__derived()); 80 } 81 82 template <class _D2 = _Derived> 83 _LIBCPP_HIDE_FROM_ABI constexpr explicit operator bool() const 84 requires requires(const _D2& __t) { ranges::empty(__t); } 85 { 86 return !ranges::empty(__derived()); 87 } 88 89 template <class _D2 = _Derived> 90 _LIBCPP_HIDE_FROM_ABI constexpr auto data() 91 requires contiguous_iterator<iterator_t<_D2>> 92 { 93 return std::to_address(ranges::begin(__derived())); 94 } 95 96 template <class _D2 = _Derived> 97 _LIBCPP_HIDE_FROM_ABI constexpr auto data() const 98 requires range<const _D2> && contiguous_iterator<iterator_t<const _D2>> 99 { 100 return std::to_address(ranges::begin(__derived())); 101 } 102 103 template <class _D2 = _Derived> 104 _LIBCPP_HIDE_FROM_ABI constexpr auto size() 105 requires forward_range<_D2> && sized_sentinel_for<sentinel_t<_D2>, iterator_t<_D2>> 106 { 107 return std::__to_unsigned_like(ranges::end(__derived()) - ranges::begin(__derived())); 108 } 109 110 template <class _D2 = _Derived> 111 _LIBCPP_HIDE_FROM_ABI constexpr auto size() const 112 requires forward_range<const _D2> && sized_sentinel_for<sentinel_t<const _D2>, iterator_t<const _D2>> 113 { 114 return std::__to_unsigned_like(ranges::end(__derived()) - ranges::begin(__derived())); 115 } 116 117 template <class _D2 = _Derived> 118 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) front() 119 requires forward_range<_D2> 120 { 121 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 122 !empty(), "Precondition `!empty()` not satisfied. `.front()` called on an empty view."); 123 return *ranges::begin(__derived()); 124 } 125 126 template <class _D2 = _Derived> 127 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) front() const 128 requires forward_range<const _D2> 129 { 130 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 131 !empty(), "Precondition `!empty()` not satisfied. `.front()` called on an empty view."); 132 return *ranges::begin(__derived()); 133 } 134 135 template <class _D2 = _Derived> 136 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) back() 137 requires bidirectional_range<_D2> && common_range<_D2> 138 { 139 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 140 !empty(), "Precondition `!empty()` not satisfied. `.back()` called on an empty view."); 141 return *ranges::prev(ranges::end(__derived())); 142 } 143 144 template <class _D2 = _Derived> 145 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) back() const 146 requires bidirectional_range<const _D2> && common_range<const _D2> 147 { 148 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 149 !empty(), "Precondition `!empty()` not satisfied. `.back()` called on an empty view."); 150 return *ranges::prev(ranges::end(__derived())); 151 } 152 153 template <random_access_range _RARange = _Derived> 154 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator[](range_difference_t<_RARange> __index) { 155 return ranges::begin(__derived())[__index]; 156 } 157 158 template <random_access_range _RARange = const _Derived> 159 _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator[](range_difference_t<_RARange> __index) const { 160 return ranges::begin(__derived())[__index]; 161 } 162 }; 163 164 } // namespace ranges 165 166 #endif // _LIBCPP_STD_VER >= 20 167 168 _LIBCPP_END_NAMESPACE_STD 169 170 #endif // _LIBCPP___RANGES_VIEW_INTERFACE_H 171