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Diffstat (limited to 'libcxx/include/__ranges/elements_view.h')
| -rw-r--r-- | libcxx/include/__ranges/elements_view.h | 423 |
1 files changed, 423 insertions, 0 deletions
diff --git a/libcxx/include/__ranges/elements_view.h b/libcxx/include/__ranges/elements_view.h new file mode 100644 index 000000000000..3afd6ddbe8f2 --- /dev/null +++ b/libcxx/include/__ranges/elements_view.h @@ -0,0 +1,423 @@ +// -*- C++ -*- +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +#ifndef _LIBCPP___RANGES_ELEMENTS_VIEW_H +#define _LIBCPP___RANGES_ELEMENTS_VIEW_H + +#include <__compare/three_way_comparable.h> +#include <__concepts/constructible.h> +#include <__concepts/convertible_to.h> +#include <__concepts/derived_from.h> +#include <__concepts/equality_comparable.h> +#include <__config> +#include <__fwd/get.h> +#include <__iterator/concepts.h> +#include <__iterator/iterator_traits.h> +#include <__ranges/access.h> +#include <__ranges/all.h> +#include <__ranges/concepts.h> +#include <__ranges/enable_borrowed_range.h> +#include <__ranges/range_adaptor.h> +#include <__ranges/size.h> +#include <__ranges/view_interface.h> +#include <__tuple_dir/tuple_element.h> +#include <__tuple_dir/tuple_like.h> +#include <__tuple_dir/tuple_size.h> +#include <__type_traits/is_reference.h> +#include <__type_traits/maybe_const.h> +#include <__type_traits/remove_cv.h> +#include <__type_traits/remove_cvref.h> +#include <__type_traits/remove_reference.h> +#include <__utility/declval.h> +#include <__utility/forward.h> +#include <__utility/move.h> +#include <cstddef> + +#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) +# pragma GCC system_header +#endif + +_LIBCPP_BEGIN_NAMESPACE_STD + +#if _LIBCPP_STD_VER >= 20 + +namespace ranges { + +template <class _View, size_t _Np, bool _Const> +class __elements_view_iterator; + +template <class _View, size_t _Np, bool _Const> +class __elements_view_sentinel; + +template <class _Tp, size_t _Np> +concept __has_tuple_element = __tuple_like<_Tp> && _Np < tuple_size<_Tp>::value; + +template <class _Tp, size_t _Np> +concept __returnable_element = is_reference_v<_Tp> || move_constructible<tuple_element_t<_Np, _Tp>>; + +template <input_range _View, size_t _Np> + requires view<_View> && __has_tuple_element<range_value_t<_View>, _Np> && + __has_tuple_element<remove_reference_t<range_reference_t<_View>>, _Np> && + __returnable_element<range_reference_t<_View>, _Np> +class elements_view : public view_interface<elements_view<_View, _Np>> { +public: + _LIBCPP_HIDE_FROM_ABI elements_view() + requires default_initializable<_View> + = default; + + _LIBCPP_HIDE_FROM_ABI constexpr explicit elements_view(_View __base) : __base_(std::move(__base)) {} + + _LIBCPP_HIDE_FROM_ABI constexpr _View base() const& + requires copy_constructible<_View> + { + return __base_; + } + + _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); } + + _LIBCPP_HIDE_FROM_ABI constexpr auto begin() + requires(!__simple_view<_View>) + { + return __iterator</*_Const=*/false>(ranges::begin(__base_)); + } + + _LIBCPP_HIDE_FROM_ABI constexpr auto begin() const + requires range<const _View> + { + return __iterator</*_Const=*/true>(ranges::begin(__base_)); + } + + _LIBCPP_HIDE_FROM_ABI constexpr auto end() + requires(!__simple_view<_View> && !common_range<_View>) + { + return __sentinel</*_Const=*/false>{ranges::end(__base_)}; + } + + _LIBCPP_HIDE_FROM_ABI constexpr auto end() + requires(!__simple_view<_View> && common_range<_View>) + { + return __iterator</*_Const=*/false>{ranges::end(__base_)}; + } + + _LIBCPP_HIDE_FROM_ABI constexpr auto end() const + requires range<const _View> + { + return __sentinel</*_Const=*/true>{ranges::end(__base_)}; + } + + _LIBCPP_HIDE_FROM_ABI constexpr auto end() const + requires common_range<const _View> + { + return __iterator</*_Const=*/true>{ranges::end(__base_)}; + } + + _LIBCPP_HIDE_FROM_ABI constexpr auto size() + requires sized_range<_View> + { + return ranges::size(__base_); + } + + _LIBCPP_HIDE_FROM_ABI constexpr auto size() const + requires sized_range<const _View> + { + return ranges::size(__base_); + } + +private: + template <bool _Const> + using __iterator = __elements_view_iterator<_View, _Np, _Const>; + + template <bool _Const> + using __sentinel = __elements_view_sentinel<_View, _Np, _Const>; + + _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View(); +}; + +template <class, size_t> +struct __elements_view_iterator_category_base {}; + +template <forward_range _Base, size_t _Np> +struct __elements_view_iterator_category_base<_Base, _Np> { + static consteval auto __get_iterator_category() { + using _Result = decltype(std::get<_Np>(*std::declval<iterator_t<_Base>>())); + using _Cat = typename iterator_traits<iterator_t<_Base>>::iterator_category; + + if constexpr (!is_lvalue_reference_v<_Result>) { + return input_iterator_tag{}; + } else if constexpr (derived_from<_Cat, random_access_iterator_tag>) { + return random_access_iterator_tag{}; + } else { + return _Cat{}; + } + } + + using iterator_category = decltype(__get_iterator_category()); +}; + +template <class _View, size_t _Np, bool _Const> +class __elements_view_iterator : public __elements_view_iterator_category_base<__maybe_const<_Const, _View>, _Np> { + template <class, size_t, bool > + friend class __elements_view_iterator; + + template <class, size_t, bool > + friend class __elements_view_sentinel; + + using _Base = __maybe_const<_Const, _View>; + + iterator_t<_Base> __current_ = iterator_t<_Base>(); + + _LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) __get_element(const iterator_t<_Base>& __i) { + if constexpr (is_reference_v<range_reference_t<_Base>>) { + return std::get<_Np>(*__i); + } else { + using _Element = remove_cv_t<tuple_element_t<_Np, range_reference_t<_Base>>>; + return static_cast<_Element>(std::get<_Np>(*__i)); + } + } + + static consteval auto __get_iterator_concept() { + if constexpr (random_access_range<_Base>) { + return random_access_iterator_tag{}; + } else if constexpr (bidirectional_range<_Base>) { + return bidirectional_iterator_tag{}; + } else if constexpr (forward_range<_Base>) { + return forward_iterator_tag{}; + } else { + return input_iterator_tag{}; + } + } + +public: + using iterator_concept = decltype(__get_iterator_concept()); + using value_type = remove_cvref_t<tuple_element_t<_Np, range_value_t<_Base>>>; + using difference_type = range_difference_t<_Base>; + + _LIBCPP_HIDE_FROM_ABI __elements_view_iterator() + requires default_initializable<iterator_t<_Base>> + = default; + + _LIBCPP_HIDE_FROM_ABI constexpr explicit __elements_view_iterator(iterator_t<_Base> __current) + : __current_(std::move(__current)) {} + + _LIBCPP_HIDE_FROM_ABI constexpr __elements_view_iterator(__elements_view_iterator<_View, _Np, !_Const> __i) + requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>> + : __current_(std::move(__i.__current_)) {} + + _LIBCPP_HIDE_FROM_ABI constexpr const iterator_t<_Base>& base() const& noexcept { return __current_; } + + _LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_Base> base() && { return std::move(__current_); } + + _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator*() const { return __get_element(__current_); } + + _LIBCPP_HIDE_FROM_ABI constexpr __elements_view_iterator& operator++() { + ++__current_; + return *this; + } + + _LIBCPP_HIDE_FROM_ABI constexpr void operator++(int) { ++__current_; } + + _LIBCPP_HIDE_FROM_ABI constexpr __elements_view_iterator operator++(int) + requires forward_range<_Base> + { + auto temp = *this; + ++__current_; + return temp; + } + + _LIBCPP_HIDE_FROM_ABI constexpr __elements_view_iterator& operator--() + requires bidirectional_range<_Base> + { + --__current_; + return *this; + } + + _LIBCPP_HIDE_FROM_ABI constexpr __elements_view_iterator operator--(int) + requires bidirectional_range<_Base> + { + auto temp = *this; + --__current_; + return temp; + } + + _LIBCPP_HIDE_FROM_ABI constexpr __elements_view_iterator& operator+=(difference_type __n) + requires random_access_range<_Base> + { + __current_ += __n; + return *this; + } + + _LIBCPP_HIDE_FROM_ABI constexpr __elements_view_iterator& operator-=(difference_type __n) + requires random_access_range<_Base> + { + __current_ -= __n; + return *this; + } + + _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator[](difference_type __n) const + requires random_access_range<_Base> + { + return __get_element(__current_ + __n); + } + + _LIBCPP_HIDE_FROM_ABI friend constexpr bool + operator==(const __elements_view_iterator& __x, const __elements_view_iterator& __y) + requires equality_comparable<iterator_t<_Base>> + { + return __x.__current_ == __y.__current_; + } + + _LIBCPP_HIDE_FROM_ABI friend constexpr bool + operator<(const __elements_view_iterator& __x, const __elements_view_iterator& __y) + requires random_access_range<_Base> + { + return __x.__current_ < __y.__current_; + } + + _LIBCPP_HIDE_FROM_ABI friend constexpr bool + operator>(const __elements_view_iterator& __x, const __elements_view_iterator& __y) + requires random_access_range<_Base> + { + return __y < __x; + } + + _LIBCPP_HIDE_FROM_ABI friend constexpr bool + operator<=(const __elements_view_iterator& __x, const __elements_view_iterator& __y) + requires random_access_range<_Base> + { + return !(__y < __x); + } + + _LIBCPP_HIDE_FROM_ABI friend constexpr bool + operator>=(const __elements_view_iterator& __x, const __elements_view_iterator& __y) + requires random_access_range<_Base> + { + return !(__x < __y); + } + + _LIBCPP_HIDE_FROM_ABI friend constexpr auto + operator<=>(const __elements_view_iterator& __x, const __elements_view_iterator& __y) + requires random_access_range<_Base> && three_way_comparable<iterator_t<_Base>> + { + return __x.__current_ <=> __y.__current_; + } + + _LIBCPP_HIDE_FROM_ABI friend constexpr __elements_view_iterator + operator+(const __elements_view_iterator& __x, difference_type __y) + requires random_access_range<_Base> + { + return __elements_view_iterator{__x} += __y; + } + + _LIBCPP_HIDE_FROM_ABI friend constexpr __elements_view_iterator + operator+(difference_type __x, const __elements_view_iterator& __y) + requires random_access_range<_Base> + { + return __y + __x; + } + + _LIBCPP_HIDE_FROM_ABI friend constexpr __elements_view_iterator + operator-(const __elements_view_iterator& __x, difference_type __y) + requires random_access_range<_Base> + { + return __elements_view_iterator{__x} -= __y; + } + + _LIBCPP_HIDE_FROM_ABI friend constexpr difference_type + operator-(const __elements_view_iterator& __x, const __elements_view_iterator& __y) + requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>> + { + return __x.__current_ - __y.__current_; + } +}; + +template <class _View, size_t _Np, bool _Const> +class __elements_view_sentinel { +private: + using _Base = __maybe_const<_Const, _View>; + _LIBCPP_NO_UNIQUE_ADDRESS sentinel_t<_Base> __end_ = sentinel_t<_Base>(); + + template <class, size_t, bool > + friend class __elements_view_sentinel; + + template <bool _AnyConst> + _LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) + __get_current(const __elements_view_iterator<_View, _Np, _AnyConst>& __iter) { + return (__iter.__current_); + } + +public: + _LIBCPP_HIDE_FROM_ABI __elements_view_sentinel() = default; + + _LIBCPP_HIDE_FROM_ABI constexpr explicit __elements_view_sentinel(sentinel_t<_Base> __end) + : __end_(std::move(__end)) {} + + _LIBCPP_HIDE_FROM_ABI constexpr __elements_view_sentinel(__elements_view_sentinel<_View, _Np, !_Const> __other) + requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>> + : __end_(std::move(__other.__end_)) {} + + _LIBCPP_HIDE_FROM_ABI constexpr sentinel_t<_Base> base() const { return __end_; } + + template <bool _OtherConst> + requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> + _LIBCPP_HIDE_FROM_ABI friend constexpr bool + operator==(const __elements_view_iterator<_View, _Np, _OtherConst>& __x, const __elements_view_sentinel& __y) { + return __get_current(__x) == __y.__end_; + } + + template <bool _OtherConst> + requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> + _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> + operator-(const __elements_view_iterator<_View, _Np, _OtherConst>& __x, const __elements_view_sentinel& __y) { + return __get_current(__x) - __y.__end_; + } + + template <bool _OtherConst> + requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> + _LIBCPP_HIDE_FROM_ABI friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>> + operator-(const __elements_view_sentinel& __x, const __elements_view_iterator<_View, _Np, _OtherConst>& __y) { + return __x.__end_ - __get_current(__y); + } +}; + +template <class _Tp, size_t _Np> +inline constexpr bool enable_borrowed_range<elements_view<_Tp, _Np>> = enable_borrowed_range<_Tp>; + +template <class _Tp> +using keys_view = elements_view<_Tp, 0>; +template <class _Tp> +using values_view = elements_view<_Tp, 1>; + +namespace views { +namespace __elements { + +template <size_t _Np> +struct __fn : __range_adaptor_closure<__fn<_Np>> { + template <class _Range> + [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range) const + /**/ noexcept(noexcept(elements_view<all_t<_Range&&>, _Np>(std::forward<_Range>(__range)))) + /*------*/ -> decltype(elements_view<all_t<_Range&&>, _Np>(std::forward<_Range>(__range))) { + /*-------------*/ return elements_view<all_t<_Range&&>, _Np>(std::forward<_Range>(__range)); + } +}; +} // namespace __elements + +inline namespace __cpo { +template <size_t _Np> +inline constexpr auto elements = __elements::__fn<_Np>{}; +inline constexpr auto keys = elements<0>; +inline constexpr auto values = elements<1>; +} // namespace __cpo +} // namespace views +} // namespace ranges + +#endif // _LIBCPP_STD_VER >= 20 + +_LIBCPP_END_NAMESPACE_STD + +#endif // _LIBCPP___RANGES_ELEMENTS_VIEW_H |