libcxx/include/__ranges/take_while_view.h

   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_TAKE_WHILE_VIEW_H
  11 #define _LIBCPP___RANGES_TAKE_WHILE_VIEW_H
  12
  13 #include <__concepts/constructible.h>
  14 #include <__concepts/convertible_to.h>
  15 #include <__config>
  16 #include <__functional/bind_back.h>
  17 #include <__functional/invoke.h>
  18 #include <__iterator/concepts.h>
  19 #include <__memory/addressof.h>
  20 #include <__ranges/access.h>
  21 #include <__ranges/all.h>
  22 #include <__ranges/concepts.h>
  23 #include <__ranges/movable_box.h>
  24 #include <__ranges/range_adaptor.h>
  25 #include <__ranges/view_interface.h>
  26 #include <__type_traits/decay.h>
  27 #include <__type_traits/is_nothrow_constructible.h>
  28 #include <__type_traits/is_object.h>
  29 #include <__type_traits/maybe_const.h>
  30 #include <__utility/forward.h>
  31 #include <__utility/in_place.h>
  32 #include <__utility/move.h>
  33
  34 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  35 #  pragma GCC system_header
  36 #endif
  37
  38 _LIBCPP_BEGIN_NAMESPACE_STD
  39
  40 #if _LIBCPP_STD_VER >= 20
  41
  42 namespace ranges {
  43
  44 template <view _View, class _Pred>
  45   requires input_range<_View> && is_object_v<_Pred> && indirect_unary_predicate<const _Pred, iterator_t<_View>>
  46 class take_while_view : public view_interface<take_while_view<_View, _Pred>> {
  47   template <bool>
  48   class __sentinel;
  49
  50   _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();
  51   _LIBCPP_NO_UNIQUE_ADDRESS __movable_box<_Pred> __pred_;
  52
  53 public:
  54   _LIBCPP_HIDE_FROM_ABI take_while_view()
  55     requires default_initializable<_View> && default_initializable<_Pred>
  56   = default;
  57
  58   _LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23 take_while_view(_View __base, _Pred __pred)
  59       : __base_(std::move(__base)), __pred_(std::in_place, std::move(__pred)) {}
  60
  61   _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
  62     requires copy_constructible<_View>
  63   {
  64     return __base_;
  65   }
  66
  67   _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
  68
  69   _LIBCPP_HIDE_FROM_ABI constexpr const _Pred& pred() const { return *__pred_; }
  70
  71   _LIBCPP_HIDE_FROM_ABI constexpr auto begin()
  72     requires(!__simple_view<_View>)
  73   {
  74     return ranges::begin(__base_);
  75   }
  76
  77   _LIBCPP_HIDE_FROM_ABI constexpr auto begin() const
  78     requires range<const _View> && indirect_unary_predicate<const _Pred, iterator_t<const _View>>
  79   {
  80     return ranges::begin(__base_);
  81   }
  82
  83   _LIBCPP_HIDE_FROM_ABI constexpr auto end()
  84     requires(!__simple_view<_View>)
  85   {
  86     return __sentinel</*_Const=*/false>(ranges::end(__base_), std::addressof(*__pred_));
  87   }
  88
  89   _LIBCPP_HIDE_FROM_ABI constexpr auto end() const
  90     requires range<const _View> && indirect_unary_predicate<const _Pred, iterator_t<const _View>>
  91   {
  92     return __sentinel</*_Const=*/true>(ranges::end(__base_), std::addressof(*__pred_));
  93   }
  94 };
  95
  96 template <class _Range, class _Pred>
  97 take_while_view(_Range&&, _Pred) -> take_while_view<views::all_t<_Range>, _Pred>;
  98
  99 template <view _View, class _Pred>
 100   requires input_range<_View> && is_object_v<_Pred> && indirect_unary_predicate<const _Pred, iterator_t<_View>>
 101 template <bool _Const>
 102 class take_while_view<_View, _Pred>::__sentinel {
 103   using _Base = __maybe_const<_Const, _View>;
 104
 105   sentinel_t<_Base> __end_ = sentinel_t<_Base>();
 106   const _Pred* __pred_     = nullptr;
 107
 108   friend class __sentinel<!_Const>;
 109
 110 public:
 111   _LIBCPP_HIDE_FROM_ABI __sentinel() = default;
 112
 113   _LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(sentinel_t<_Base> __end, const _Pred* __pred)
 114       : __end_(std::move(__end)), __pred_(__pred) {}
 115
 116   _LIBCPP_HIDE_FROM_ABI constexpr __sentinel(__sentinel<!_Const> __s)
 117     requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>>
 118       : __end_(std::move(__s.__end_)), __pred_(__s.__pred_) {}
 119
 120   _LIBCPP_HIDE_FROM_ABI constexpr sentinel_t<_Base> base() const { return __end_; }
 121
 122   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const iterator_t<_Base>& __x, const __sentinel& __y) {
 123     return __x == __y.__end_ || !std::invoke(*__y.__pred_, *__x);
 124   }
 125
 126   template <bool _OtherConst = !_Const>
 127     requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
 128   _LIBCPP_HIDE_FROM_ABI friend constexpr bool
 129   operator==(const iterator_t<__maybe_const<_OtherConst, _View>>& __x, const __sentinel& __y) {
 130     return __x == __y.__end_ || !std::invoke(*__y.__pred_, *__x);
 131   }
 132 };
 133
 134 namespace views {
 135 namespace __take_while {
 136
 137 struct __fn {
 138   template <class _Range, class _Pred>
 139   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Pred&& __pred) const
 140       noexcept(noexcept(/**/ take_while_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred))))
 141           -> decltype(/*--*/ take_while_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred))) {
 142     return /*-------------*/ take_while_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred));
 143   }
 144
 145   template <class _Pred>
 146     requires constructible_from<decay_t<_Pred>, _Pred>
 147   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Pred&& __pred) const
 148       noexcept(is_nothrow_constructible_v<decay_t<_Pred>, _Pred>) {
 149     return __range_adaptor_closure_t(std::__bind_back(*this, std::forward<_Pred>(__pred)));
 150   }
 151 };
 152
 153 } // namespace __take_while
 154
 155 inline namespace __cpo {
 156 inline constexpr auto take_while = __take_while::__fn{};
 157 } // namespace __cpo
 158 } // namespace views
 159 } // namespace ranges
 160
 161 #endif // _LIBCPP_STD_VER >= 20
 162
 163 _LIBCPP_END_NAMESPACE_STD
 164
 165 #endif // _LIBCPP___RANGES_TAKE_WHILE_VIEW_H