| // -*- 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_TAKE_VIEW_H |
| #define _LIBCPP___RANGES_TAKE_VIEW_H |
| |
| #include <__algorithm/min.h> |
| #include <__config> |
| #include <__iterator/concepts.h> |
| #include <__iterator/counted_iterator.h> |
| #include <__iterator/default_sentinel.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/size.h> |
| #include <__ranges/view_interface.h> |
| #include <__utility/move.h> |
| #include <concepts> |
| #include <type_traits> |
| |
| #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| #pragma GCC system_header |
| #endif |
| |
| _LIBCPP_PUSH_MACROS |
| #include <__undef_macros> |
| |
| _LIBCPP_BEGIN_NAMESPACE_STD |
| |
| #if !defined(_LIBCPP_HAS_NO_RANGES) |
| |
| namespace ranges { |
| template<view _View> |
| class take_view : public view_interface<take_view<_View>> { |
| [[no_unique_address]] _View __base_ = _View(); |
| range_difference_t<_View> __count_ = 0; |
| |
| template<bool> class __sentinel; |
| |
| public: |
| _LIBCPP_HIDE_FROM_ABI |
| take_view() requires default_initializable<_View> = default; |
| |
| _LIBCPP_HIDE_FROM_ABI |
| constexpr take_view(_View __base, range_difference_t<_View> __count) |
| : __base_(_VSTD::move(__base)), __count_(__count) {} |
| |
| _LIBCPP_HIDE_FROM_ABI |
| constexpr _View base() const& requires copy_constructible<_View> { return __base_; } |
| |
| _LIBCPP_HIDE_FROM_ABI |
| constexpr _View base() && { return _VSTD::move(__base_); } |
| |
| _LIBCPP_HIDE_FROM_ABI |
| constexpr auto begin() requires (!__simple_view<_View>) { |
| if constexpr (sized_range<_View>) { |
| if constexpr (random_access_range<_View>) { |
| return ranges::begin(__base_); |
| } else { |
| using _DifferenceT = range_difference_t<_View>; |
| auto __size = size(); |
| return counted_iterator(ranges::begin(__base_), static_cast<_DifferenceT>(__size)); |
| } |
| } else { |
| return counted_iterator(ranges::begin(__base_), __count_); |
| } |
| } |
| |
| _LIBCPP_HIDE_FROM_ABI |
| constexpr auto begin() const requires range<const _View> { |
| if constexpr (sized_range<const _View>) { |
| if constexpr (random_access_range<const _View>) { |
| return ranges::begin(__base_); |
| } else { |
| using _DifferenceT = range_difference_t<const _View>; |
| auto __size = size(); |
| return counted_iterator(ranges::begin(__base_), static_cast<_DifferenceT>(__size)); |
| } |
| } else { |
| return counted_iterator(ranges::begin(__base_), __count_); |
| } |
| } |
| |
| _LIBCPP_HIDE_FROM_ABI |
| constexpr auto end() requires (!__simple_view<_View>) { |
| if constexpr (sized_range<_View>) { |
| if constexpr (random_access_range<_View>) { |
| return ranges::begin(__base_) + size(); |
| } else { |
| return default_sentinel; |
| } |
| } else { |
| return __sentinel<false>{ranges::end(__base_)}; |
| } |
| } |
| |
| _LIBCPP_HIDE_FROM_ABI |
| constexpr auto end() const requires range<const _View> { |
| if constexpr (sized_range<const _View>) { |
| if constexpr (random_access_range<const _View>) { |
| return ranges::begin(__base_) + size(); |
| } else { |
| return default_sentinel; |
| } |
| } else { |
| return __sentinel<true>{ranges::end(__base_)}; |
| } |
| } |
| |
| |
| _LIBCPP_HIDE_FROM_ABI |
| constexpr auto size() requires sized_range<_View> { |
| auto __n = ranges::size(__base_); |
| // TODO: use ranges::min here. |
| return _VSTD::min(__n, static_cast<decltype(__n)>(__count_)); |
| } |
| |
| _LIBCPP_HIDE_FROM_ABI |
| constexpr auto size() const requires sized_range<const _View> { |
| auto __n = ranges::size(__base_); |
| // TODO: use ranges::min here. |
| return _VSTD::min(__n, static_cast<decltype(__n)>(__count_)); |
| } |
| }; |
| |
| template<view _View> |
| template<bool _Const> |
| class take_view<_View>::__sentinel { |
| using _Base = __maybe_const<_Const, _View>; |
| template<bool _OtherConst> |
| using _Iter = counted_iterator<iterator_t<__maybe_const<_OtherConst, _View>>>; |
| [[no_unique_address]] sentinel_t<_Base> __end_ = sentinel_t<_Base>(); |
| |
| template<bool> |
| friend class take_view<_View>::__sentinel; |
| |
| public: |
| _LIBCPP_HIDE_FROM_ABI |
| __sentinel() = default; |
| |
| _LIBCPP_HIDE_FROM_ABI |
| constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(_VSTD::move(__end)) {} |
| |
| _LIBCPP_HIDE_FROM_ABI |
| constexpr __sentinel(__sentinel<!_Const> __s) |
| requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>> |
| : __end_(_VSTD::move(__s.__end_)) {} |
| |
| _LIBCPP_HIDE_FROM_ABI |
| constexpr sentinel_t<_Base> base() const { return __end_; } |
| |
| _LIBCPP_HIDE_FROM_ABI |
| friend constexpr bool operator==(const _Iter<_Const>& __lhs, const __sentinel& __rhs) { |
| return __lhs.count() == 0 || __lhs.base() == __rhs.__end_; |
| } |
| |
| template<bool _OtherConst = !_Const> |
| requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>> |
| _LIBCPP_HIDE_FROM_ABI |
| friend constexpr bool operator==(const _Iter<_Const>& __lhs, const __sentinel& __rhs) { |
| return __lhs.count() == 0 || __lhs.base() == __rhs.__end_; |
| } |
| }; |
| |
| template<class _Range> |
| take_view(_Range&&, range_difference_t<_Range>) -> take_view<views::all_t<_Range>>; |
| |
| template<class _Tp> |
| inline constexpr bool enable_borrowed_range<take_view<_Tp>> = enable_borrowed_range<_Tp>; |
| } // namespace ranges |
| |
| #endif // !defined(_LIBCPP_HAS_NO_RANGES) |
| |
| _LIBCPP_END_NAMESPACE_STD |
| |
| _LIBCPP_POP_MACROS |
| |
| #endif // _LIBCPP___RANGES_TAKE_VIEW_H |