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 48 common_view() requires default_initializable<_View> = default; 49 50 _LIBCPP_HIDE_FROM_ABI 51 constexpr explicit common_view(_View __v) : __base_(std::move(__v)) { } 52 53 _LIBCPP_HIDE_FROM_ABI 54 constexpr _View base() const& requires copy_constructible<_View> { return __base_; } 55 56 _LIBCPP_HIDE_FROM_ABI 57 constexpr _View base() && { return std::move(__base_); } 58 59 _LIBCPP_HIDE_FROM_ABI 60 constexpr auto begin() { 61 if constexpr (random_access_range<_View> && sized_range<_View>) 62 return ranges::begin(__base_); 63 else 64 return common_iterator<iterator_t<_View>, sentinel_t<_View>>(ranges::begin(__base_)); 65 } 66 67 _LIBCPP_HIDE_FROM_ABI 68 constexpr auto begin() const requires range<const _View> { 69 if constexpr (random_access_range<const _View> && sized_range<const _View>) 70 return ranges::begin(__base_); 71 else 72 return common_iterator<iterator_t<const _View>, sentinel_t<const _View>>(ranges::begin(__base_)); 73 } 74 75 _LIBCPP_HIDE_FROM_ABI 76 constexpr auto end() { 77 if constexpr (random_access_range<_View> && sized_range<_View>) 78 return ranges::begin(__base_) + ranges::size(__base_); 79 else 80 return common_iterator<iterator_t<_View>, sentinel_t<_View>>(ranges::end(__base_)); 81 } 82 83 _LIBCPP_HIDE_FROM_ABI 84 constexpr auto end() const requires range<const _View> { 85 if constexpr (random_access_range<const _View> && sized_range<const _View>) 86 return ranges::begin(__base_) + ranges::size(__base_); 87 else 88 return common_iterator<iterator_t<const _View>, sentinel_t<const _View>>(ranges::end(__base_)); 89 } 90 91 _LIBCPP_HIDE_FROM_ABI 92 constexpr auto size() requires sized_range<_View> { 93 return ranges::size(__base_); 94 } 95 96 _LIBCPP_HIDE_FROM_ABI 97 constexpr auto size() const requires sized_range<const _View> { 98 return ranges::size(__base_); 99 } 100 }; 101 102 template<class _Range> 103 common_view(_Range&&) 104 -> common_view<views::all_t<_Range>>; 105 106 template<class _View> 107 inline constexpr bool enable_borrowed_range<common_view<_View>> = enable_borrowed_range<_View>; 108 109 namespace views { 110 namespace __common { 111 struct __fn : __range_adaptor_closure<__fn> { 112 template<class _Range> 113 requires common_range<_Range> 114 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 115 constexpr auto operator()(_Range&& __range) const 116 noexcept(noexcept(views::all(std::forward<_Range>(__range)))) 117 -> decltype( views::all(std::forward<_Range>(__range))) 118 { return views::all(std::forward<_Range>(__range)); } 119 120 template<class _Range> 121 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 122 constexpr auto operator()(_Range&& __range) const 123 noexcept(noexcept(common_view{std::forward<_Range>(__range)})) 124 -> decltype( common_view{std::forward<_Range>(__range)}) 125 { return common_view{std::forward<_Range>(__range)}; } 126 }; 127 } // namespace __common 128 129 inline namespace __cpo { 130 inline constexpr auto common = __common::__fn{}; 131 } // namespace __cpo 132 } // namespace views 133 } // namespace ranges 134 135 #endif // _LIBCPP_STD_VER >= 20 136 137 _LIBCPP_END_NAMESPACE_STD 138 139 _LIBCPP_POP_MACROS 140 141 #endif // _LIBCPP___RANGES_COMMON_VIEW_H 142