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_PUSH_MACROS
  39 #include <__undef_macros>
  40
  41 _LIBCPP_BEGIN_NAMESPACE_STD
  42
  43 #if _LIBCPP_STD_VER >= 20
  44
  45 namespace ranges {
  46
  47 template <view _View, class _Pred>
  48   requires input_range<_View> && is_object_v<_Pred> && indirect_unary_predicate<const _Pred, iterator_t<_View>>
  49 class _LIBCPP_ABI_LLVM18_NO_UNIQUE_ADDRESS take_while_view : public view_interface<take_while_view<_View, _Pred>> {
  50   template <bool>
  51   class __sentinel;
  52
  53   _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();
  54   _LIBCPP_NO_UNIQUE_ADDRESS __movable_box<_Pred> __pred_;
  55
  56 public:
  57   _LIBCPP_HIDE_FROM_ABI take_while_view()
  58     requires default_initializable<_View> && default_initializable<_Pred>
  59   = default;
  60
  61   _LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23 take_while_view(_View __base, _Pred __pred)
  62       : __base_(std::move(__base)), __pred_(std::in_place, std::move(__pred)) {}
  63
  64   _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
  65     requires copy_constructible<_View>
  66   {
  67     return __base_;
  68   }
  69
  70   _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
  71
  72   _LIBCPP_HIDE_FROM_ABI constexpr const _Pred& pred() const { return *__pred_; }
  73
  74   _LIBCPP_HIDE_FROM_ABI constexpr auto begin()
  75     requires(!__simple_view<_View>)
  76   {
  77     return ranges::begin(__base_);
  78   }
  79
  80   _LIBCPP_HIDE_FROM_ABI constexpr auto begin() const
  81     requires range<const _View> && indirect_unary_predicate<const _Pred, iterator_t<const _View>>
  82   {
  83     return ranges::begin(__base_);
  84   }
  85
  86   _LIBCPP_HIDE_FROM_ABI constexpr auto end()
  87     requires(!__simple_view<_View>)
  88   {
  89     return __sentinel</*_Const=*/false>(ranges::end(__base_), std::addressof(*__pred_));
  90   }
  91
  92   _LIBCPP_HIDE_FROM_ABI constexpr auto end() const
  93     requires range<const _View> && indirect_unary_predicate<const _Pred, iterator_t<const _View>>
  94   {
  95     return __sentinel</*_Const=*/true>(ranges::end(__base_), std::addressof(*__pred_));
  96   }
  97 };
  98
  99 template <class _Range, class _Pred>
 100 take_while_view(_Range&&, _Pred) -> take_while_view<views::all_t<_Range>, _Pred>;
 101
 102 template <view _View, class _Pred>
 103   requires input_range<_View> && is_object_v<_Pred> && indirect_unary_predicate<const _Pred, iterator_t<_View>>
 104 template <bool _Const>
 105 class take_while_view<_View, _Pred>::__sentinel {
 106   using _Base = __maybe_const<_Const, _View>;
 107
 108   sentinel_t<_Base> __end_ = sentinel_t<_Base>();
 109   const _Pred* __pred_     = nullptr;
 110
 111   friend class __sentinel<!_Const>;
 112
 113 public:
 114   _LIBCPP_HIDE_FROM_ABI __sentinel() = default;
 115
 116   _LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(sentinel_t<_Base> __end, const _Pred* __pred)
 117       : __end_(std::move(__end)), __pred_(__pred) {}
 118
 119   _LIBCPP_HIDE_FROM_ABI constexpr __sentinel(__sentinel<!_Const> __s)
 120     requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>>
 121       : __end_(std::move(__s.__end_)), __pred_(__s.__pred_) {}
 122
 123   _LIBCPP_HIDE_FROM_ABI constexpr sentinel_t<_Base> base() const { return __end_; }
 124
 125   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const iterator_t<_Base>& __x, const __sentinel& __y) {
 126     return __x == __y.__end_ || !std::invoke(*__y.__pred_, *__x);
 127   }
 128
 129   template <bool _OtherConst = !_Const>
 130     requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
 131   _LIBCPP_HIDE_FROM_ABI friend constexpr bool
 132   operator==(const iterator_t<__maybe_const<_OtherConst, _View>>& __x, const __sentinel& __y) {
 133     return __x == __y.__end_ || !std::invoke(*__y.__pred_, *__x);
 134   }
 135 };
 136
 137 namespace views {
 138 namespace __take_while {
 139
 140 struct __fn {
 141   template <class _Range, class _Pred>
 142   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Pred&& __pred) const
 143       noexcept(noexcept(/**/ take_while_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred))))
 144           -> decltype(/*--*/ take_while_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred))) {
 145     return /*-------------*/ take_while_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred));
 146   }
 147
 148   template <class _Pred>
 149     requires constructible_from<decay_t<_Pred>, _Pred>
 150   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Pred&& __pred) const
 151       noexcept(is_nothrow_constructible_v<decay_t<_Pred>, _Pred>) {
 152     return __pipeable(std::__bind_back(*this, std::forward<_Pred>(__pred)));
 153   }
 154 };
 155
 156 } // namespace __take_while
 157
 158 inline namespace __cpo {
 159 inline constexpr auto take_while = __take_while::__fn{};
 160 } // namespace __cpo
 161 } // namespace views
 162 } // namespace ranges
 163
 164 #endif // _LIBCPP_STD_VER >= 20
 165
 166 _LIBCPP_END_NAMESPACE_STD
 167
 168 _LIBCPP_POP_MACROS
 169
 170 #endif // _LIBCPP___RANGES_TAKE_WHILE_VIEW_H