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_DROP_WHILE_VIEW_H 11 #define _LIBCPP___RANGES_DROP_WHILE_VIEW_H 12 13 #include <__algorithm/ranges_find_if_not.h> 14 #include <__assert> 15 #include <__concepts/constructible.h> 16 #include <__config> 17 #include <__functional/bind_back.h> 18 #include <__functional/reference_wrapper.h> 19 #include <__iterator/concepts.h> 20 #include <__ranges/access.h> 21 #include <__ranges/all.h> 22 #include <__ranges/concepts.h> 23 #include <__ranges/enable_borrowed_range.h> 24 #include <__ranges/movable_box.h> 25 #include <__ranges/non_propagating_cache.h> 26 #include <__ranges/range_adaptor.h> 27 #include <__ranges/view_interface.h> 28 #include <__type_traits/conditional.h> 29 #include <__type_traits/decay.h> 30 #include <__type_traits/is_nothrow_constructible.h> 31 #include <__type_traits/is_object.h> 32 #include <__utility/forward.h> 33 #include <__utility/in_place.h> 34 #include <__utility/move.h> 35 36 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 37 # pragma GCC system_header 38 #endif 39 40 _LIBCPP_BEGIN_NAMESPACE_STD 41 42 #if _LIBCPP_STD_VER >= 20 43 44 namespace ranges { 45 46 template <view _View, class _Pred> 47 requires input_range<_View> && is_object_v<_Pred> && indirect_unary_predicate<const _Pred, iterator_t<_View>> 48 class drop_while_view : public view_interface<drop_while_view<_View, _Pred>> { 49 public: 50 _LIBCPP_HIDE_FROM_ABI drop_while_view() 51 requires default_initializable<_View> && default_initializable<_Pred> 52 = default; 53 54 _LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23 drop_while_view(_View __base, _Pred __pred) 55 : __base_(std::move(__base)), __pred_(std::in_place, std::move(__pred)) {} 56 57 _LIBCPP_HIDE_FROM_ABI constexpr _View base() const& 58 requires copy_constructible<_View> 59 { 60 return __base_; 61 } 62 63 _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); } 64 65 _LIBCPP_HIDE_FROM_ABI constexpr const _Pred& pred() const { return *__pred_; } 66 67 _LIBCPP_HIDE_FROM_ABI constexpr auto begin() { 68 _LIBCPP_ASSERT_UNCATEGORIZED( 69 __pred_.__has_value(), 70 "drop_while_view needs to have a non-empty predicate before calling begin() -- did a previous " 71 "assignment to this drop_while_view fail?"); 72 if constexpr (_UseCache) { 73 if (!__cached_begin_.__has_value()) { 74 __cached_begin_.__emplace(ranges::find_if_not(__base_, std::cref(*__pred_))); 75 } 76 return *__cached_begin_; 77 } else { 78 return ranges::find_if_not(__base_, std::cref(*__pred_)); 79 } 80 } 81 82 _LIBCPP_HIDE_FROM_ABI constexpr auto end() { return ranges::end(__base_); } 83 84 private: 85 _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View(); 86 _LIBCPP_NO_UNIQUE_ADDRESS __movable_box<_Pred> __pred_; 87 88 static constexpr bool _UseCache = forward_range<_View>; 89 using _Cache = _If<_UseCache, __non_propagating_cache<iterator_t<_View>>, __empty_cache>; 90 _LIBCPP_NO_UNIQUE_ADDRESS _Cache __cached_begin_ = _Cache(); 91 }; 92 93 template <class _View, class _Pred> 94 inline constexpr bool enable_borrowed_range<drop_while_view<_View, _Pred>> = enable_borrowed_range<_View>; 95 96 template <class _Range, class _Pred> 97 drop_while_view(_Range&&, _Pred) -> drop_while_view<views::all_t<_Range>, _Pred>; 98 99 namespace views { 100 namespace __drop_while { 101 102 struct __fn { 103 template <class _Range, class _Pred> 104 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Pred&& __pred) const 105 noexcept(noexcept(/**/ drop_while_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred)))) 106 -> decltype(/*--*/ drop_while_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred))) { 107 return /*-------------*/ drop_while_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred)); 108 } 109 110 template <class _Pred> 111 requires constructible_from<decay_t<_Pred>, _Pred> 112 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Pred&& __pred) const 113 noexcept(is_nothrow_constructible_v<decay_t<_Pred>, _Pred>) { 114 return __range_adaptor_closure_t(std::__bind_back(*this, std::forward<_Pred>(__pred))); 115 } 116 }; 117 118 } // namespace __drop_while 119 120 inline namespace __cpo { 121 inline constexpr auto drop_while = __drop_while::__fn{}; 122 } // namespace __cpo 123 } // namespace views 124 } // namespace ranges 125 126 #endif // _LIBCPP_STD_VER >= 20 127 128 _LIBCPP_END_NAMESPACE_STD 129 130 #endif // _LIBCPP___RANGES_DROP_WHILE_VIEW_H 131