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_COMMON_VIEW_H 11 #define _LIBCPP___RANGES_COMMON_VIEW_H 12 13 #include <__concepts/constructible.h> 14 #include <__concepts/copyable.h> 15 #include <__config> 16 #include <__iterator/common_iterator.h> 17 #include <__iterator/iterator_traits.h> 18 #include <__ranges/access.h> 19 #include <__ranges/all.h> 20 #include <__ranges/concepts.h> 21 #include <__ranges/enable_borrowed_range.h> 22 #include <__ranges/range_adaptor.h> 23 #include <__ranges/size.h> 24 #include <__ranges/view_interface.h> 25 #include <__utility/forward.h> 26 #include <__utility/move.h> 27 28 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 29 # pragma GCC system_header 30 #endif 31 32 _LIBCPP_PUSH_MACROS 33 #include <__undef_macros> 34 35 _LIBCPP_BEGIN_NAMESPACE_STD 36 37 #if _LIBCPP_STD_VER >= 20 38 39 namespace ranges { 40 41 template <view _View> 42 requires(!common_range<_View> && copyable<iterator_t<_View>>) 43 class common_view : public view_interface<common_view<_View>> { 44 _View __base_ = _View(); 45 46 public: 47 _LIBCPP_HIDE_FROM_ABI common_view() 48 requires default_initializable<_View> 49 = default; 50 common_view(_View __v)51 _LIBCPP_HIDE_FROM_ABI constexpr explicit common_view(_View __v) : __base_(std::move(__v)) {} 52 base()53 _LIBCPP_HIDE_FROM_ABI constexpr _View base() const& 54 requires copy_constructible<_View> 55 { 56 return __base_; 57 } 58 base()59 _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); } 60 begin()61 _LIBCPP_HIDE_FROM_ABI constexpr auto begin() { 62 if constexpr (random_access_range<_View> && sized_range<_View>) 63 return ranges::begin(__base_); 64 else 65 return common_iterator<iterator_t<_View>, sentinel_t<_View>>(ranges::begin(__base_)); 66 } 67 begin()68 _LIBCPP_HIDE_FROM_ABI constexpr auto begin() const 69 requires range<const _View> 70 { 71 if constexpr (random_access_range<const _View> && sized_range<const _View>) 72 return ranges::begin(__base_); 73 else 74 return common_iterator<iterator_t<const _View>, sentinel_t<const _View>>(ranges::begin(__base_)); 75 } 76 end()77 _LIBCPP_HIDE_FROM_ABI constexpr auto end() { 78 if constexpr (random_access_range<_View> && sized_range<_View>) 79 return ranges::begin(__base_) + ranges::size(__base_); 80 else 81 return common_iterator<iterator_t<_View>, sentinel_t<_View>>(ranges::end(__base_)); 82 } 83 end()84 _LIBCPP_HIDE_FROM_ABI constexpr auto end() const 85 requires range<const _View> 86 { 87 if constexpr (random_access_range<const _View> && sized_range<const _View>) 88 return ranges::begin(__base_) + ranges::size(__base_); 89 else 90 return common_iterator<iterator_t<const _View>, sentinel_t<const _View>>(ranges::end(__base_)); 91 } 92 size()93 _LIBCPP_HIDE_FROM_ABI constexpr auto size() 94 requires sized_range<_View> 95 { 96 return ranges::size(__base_); 97 } 98 size()99 _LIBCPP_HIDE_FROM_ABI constexpr auto size() const 100 requires sized_range<const _View> 101 { 102 return ranges::size(__base_); 103 } 104 }; 105 106 template <class _Range> 107 common_view(_Range&&) -> common_view<views::all_t<_Range>>; 108 109 template <class _View> 110 inline constexpr bool enable_borrowed_range<common_view<_View>> = enable_borrowed_range<_View>; 111 112 namespace views { 113 namespace __common { 114 struct __fn : __range_adaptor_closure<__fn> { 115 template <class _Range> 116 requires common_range<_Range> 117 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range) const noexcept( 118 noexcept(views::all(std::forward<_Range>(__range)))) -> decltype(views::all(std::forward<_Range>(__range))) { 119 return views::all(std::forward<_Range>(__range)); 120 } 121 122 template <class _Range> 123 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range) const noexcept(noexcept(common_view{ 124 std::forward<_Range>(__range)})) -> decltype(common_view{std::forward<_Range>(__range)}) { 125 return common_view{std::forward<_Range>(__range)}; 126 } 127 }; 128 } // namespace __common 129 130 inline namespace __cpo { 131 inline constexpr auto common = __common::__fn{}; 132 } // namespace __cpo 133 } // namespace views 134 } // namespace ranges 135 136 #endif // _LIBCPP_STD_VER >= 20 137 138 _LIBCPP_END_NAMESPACE_STD 139 140 _LIBCPP_POP_MACROS 141 142 #endif // _LIBCPP___RANGES_COMMON_VIEW_H 143