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_BEGIN_NAMESPACE_STD 33 34 #if _LIBCPP_STD_VER >= 20 35 36 namespace ranges { 37 38 template<view _View> 39 requires (!common_range<_View> && copyable<iterator_t<_View>>) 40 class common_view : public view_interface<common_view<_View>> { 41 _View __base_ = _View(); 42 43 public: 44 _LIBCPP_HIDE_FROM_ABI 45 common_view() requires default_initializable<_View> = default; 46 47 _LIBCPP_HIDE_FROM_ABI common_view(_View __v)48 constexpr explicit common_view(_View __v) : __base_(std::move(__v)) { } 49 50 _LIBCPP_HIDE_FROM_ABI base()51 constexpr _View base() const& requires copy_constructible<_View> { return __base_; } 52 53 _LIBCPP_HIDE_FROM_ABI base()54 constexpr _View base() && { return std::move(__base_); } 55 56 _LIBCPP_HIDE_FROM_ABI begin()57 constexpr auto begin() { 58 if constexpr (random_access_range<_View> && sized_range<_View>) 59 return ranges::begin(__base_); 60 else 61 return common_iterator<iterator_t<_View>, sentinel_t<_View>>(ranges::begin(__base_)); 62 } 63 64 _LIBCPP_HIDE_FROM_ABI begin()65 constexpr auto begin() const requires range<const _View> { 66 if constexpr (random_access_range<const _View> && sized_range<const _View>) 67 return ranges::begin(__base_); 68 else 69 return common_iterator<iterator_t<const _View>, sentinel_t<const _View>>(ranges::begin(__base_)); 70 } 71 72 _LIBCPP_HIDE_FROM_ABI end()73 constexpr auto end() { 74 if constexpr (random_access_range<_View> && sized_range<_View>) 75 return ranges::begin(__base_) + ranges::size(__base_); 76 else 77 return common_iterator<iterator_t<_View>, sentinel_t<_View>>(ranges::end(__base_)); 78 } 79 80 _LIBCPP_HIDE_FROM_ABI end()81 constexpr auto end() const requires range<const _View> { 82 if constexpr (random_access_range<const _View> && sized_range<const _View>) 83 return ranges::begin(__base_) + ranges::size(__base_); 84 else 85 return common_iterator<iterator_t<const _View>, sentinel_t<const _View>>(ranges::end(__base_)); 86 } 87 88 _LIBCPP_HIDE_FROM_ABI size()89 constexpr auto size() requires sized_range<_View> { 90 return ranges::size(__base_); 91 } 92 93 _LIBCPP_HIDE_FROM_ABI size()94 constexpr auto size() const requires sized_range<const _View> { 95 return ranges::size(__base_); 96 } 97 }; 98 99 template<class _Range> 100 common_view(_Range&&) 101 -> common_view<views::all_t<_Range>>; 102 103 template<class _View> 104 inline constexpr bool enable_borrowed_range<common_view<_View>> = enable_borrowed_range<_View>; 105 106 namespace views { 107 namespace __common { 108 struct __fn : __range_adaptor_closure<__fn> { 109 template<class _Range> 110 requires common_range<_Range> 111 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 112 constexpr auto operator()(_Range&& __range) const 113 noexcept(noexcept(views::all(std::forward<_Range>(__range)))) 114 -> decltype( views::all(std::forward<_Range>(__range))) 115 { return views::all(std::forward<_Range>(__range)); } 116 117 template<class _Range> 118 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI 119 constexpr auto operator()(_Range&& __range) const 120 noexcept(noexcept(common_view{std::forward<_Range>(__range)})) 121 -> decltype( common_view{std::forward<_Range>(__range)}) 122 { return common_view{std::forward<_Range>(__range)}; } 123 }; 124 } // namespace __common 125 126 inline namespace __cpo { 127 inline constexpr auto common = __common::__fn{}; 128 } // namespace __cpo 129 } // namespace views 130 } // namespace ranges 131 132 #endif // _LIBCPP_STD_VER >= 20 133 134 _LIBCPP_END_NAMESPACE_STD 135 136 #endif // _LIBCPP___RANGES_COMMON_VIEW_H 137