libcxx/include/__algorithm/ranges_find_last.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___ALGORITHM_RANGES_FIND_LAST_H
  10 #define _LIBCPP___ALGORITHM_RANGES_FIND_LAST_H
  11
  12 #include <__config>
  13 #include <__functional/identity.h>
  14 #include <__functional/invoke.h>
  15 #include <__functional/ranges_operations.h>
  16 #include <__iterator/concepts.h>
  17 #include <__iterator/indirectly_comparable.h>
  18 #include <__iterator/next.h>
  19 #include <__iterator/prev.h>
  20 #include <__iterator/projected.h>
  21 #include <__ranges/access.h>
  22 #include <__ranges/concepts.h>
  23 #include <__ranges/subrange.h>
  24 #include <__utility/forward.h>
  25 #include <__utility/move.h>
  26
  27 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  28 #  pragma GCC system_header
  29 #endif
  30
  31 _LIBCPP_PUSH_MACROS
  32 #include <__undef_macros>
  33
  34 #if _LIBCPP_STD_VER >= 23
  35
  36 _LIBCPP_BEGIN_NAMESPACE_STD
  37
  38 namespace ranges {
  39
  40 template <class _Iter, class _Sent, class _Pred, class _Proj>
  41 _LIBCPP_HIDE_FROM_ABI constexpr subrange<_Iter>
  42 __find_last_impl(_Iter __first, _Sent __last, _Pred __pred, _Proj& __proj) {
  43   if (__first == __last) {
  44     return subrange<_Iter>(__first, __first);
  45   }
  46
  47   if constexpr (bidirectional_iterator<_Iter>) {
  48     auto __last_it = ranges::next(__first, __last);
  49     for (auto __it = ranges::prev(__last_it); __it != __first; --__it) {
  50       if (__pred(std::invoke(__proj, *__it))) {
  51         return subrange<_Iter>(std::move(__it), std::move(__last_it));
  52       }
  53     }
  54     if (__pred(std::invoke(__proj, *__first))) {
  55       return subrange<_Iter>(std::move(__first), std::move(__last_it));
  56     }
  57     return subrange<_Iter>(__last_it, __last_it);
  58   } else {
  59     bool __found = false;
  60     _Iter __found_it;
  61     for (; __first != __last; ++__first) {
  62       if (__pred(std::invoke(__proj, *__first))) {
  63         __found    = true;
  64         __found_it = __first;
  65       }
  66     }
  67
  68     if (__found) {
  69       return subrange<_Iter>(std::move(__found_it), std::move(__first));
  70     } else {
  71       return subrange<_Iter>(__first, __first);
  72     }
  73   }
  74 }
  75
  76 struct __find_last {
  77   template <class _Type>
  78   struct __op {
  79     const _Type& __value;
  80     template <class _Elem>
  81     _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator()(_Elem&& __elem) const {
  82       return std::forward<_Elem>(__elem) == __value;
  83     }
  84   };
  85
  86   template <forward_iterator _Iter, sentinel_for<_Iter> _Sent, class _Type, class _Proj = identity>
  87     requires indirect_binary_predicate<ranges::equal_to, projected<_Iter, _Proj>, const _Type*>
  88   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr static subrange<_Iter>
  89   operator()(_Iter __first, _Sent __last, const _Type& __value, _Proj __proj = {}) {
  90     return ranges::__find_last_impl(std::move(__first), std::move(__last), __op<_Type>{__value}, __proj);
  91   }
  92
  93   template <forward_range _Range, class _Type, class _Proj = identity>
  94     requires indirect_binary_predicate<ranges::equal_to, projected<iterator_t<_Range>, _Proj>, const _Type*>
  95   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr static borrowed_subrange_t<_Range>
  96   operator()(_Range&& __range, const _Type& __value, _Proj __proj = {}) {
  97     return ranges::__find_last_impl(ranges::begin(__range), ranges::end(__range), __op<_Type>{__value}, __proj);
  98   }
  99 };
 100
 101 struct __find_last_if {
 102   template <class _Pred>
 103   struct __op {
 104     _Pred& __pred;
 105     template <class _Elem>
 106     _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator()(_Elem&& __elem) const {
 107       return std::invoke(__pred, std::forward<_Elem>(__elem));
 108     }
 109   };
 110
 111   template <forward_iterator _Iter,
 112             sentinel_for<_Iter> _Sent,
 113             class _Proj = identity,
 114             indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
 115   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr static subrange<_Iter>
 116   operator()(_Iter __first, _Sent __last, _Pred __pred, _Proj __proj = {}) {
 117     return ranges::__find_last_impl(std::move(__first), std::move(__last), __op<_Pred>{__pred}, __proj);
 118   }
 119
 120   template <forward_range _Range,
 121             class _Proj = identity,
 122             indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>> _Pred>
 123   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr static borrowed_subrange_t<_Range>
 124   operator()(_Range&& __range, _Pred __pred, _Proj __proj = {}) {
 125     return ranges::__find_last_impl(ranges::begin(__range), ranges::end(__range), __op<_Pred>{__pred}, __proj);
 126   }
 127 };
 128
 129 struct __find_last_if_not {
 130   template <class _Pred>
 131   struct __op {
 132     _Pred& __pred;
 133     template <class _Elem>
 134     _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator()(_Elem&& __elem) const {
 135       return !std::invoke(__pred, std::forward<_Elem>(__elem));
 136     }
 137   };
 138
 139   template <forward_iterator _Iter,
 140             sentinel_for<_Iter> _Sent,
 141             class _Proj = identity,
 142             indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
 143   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr static subrange<_Iter>
 144   operator()(_Iter __first, _Sent __last, _Pred __pred, _Proj __proj = {}) {
 145     return ranges::__find_last_impl(std::move(__first), std::move(__last), __op<_Pred>{__pred}, __proj);
 146   }
 147
 148   template <forward_range _Range,
 149             class _Proj = identity,
 150             indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>> _Pred>
 151   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr static borrowed_subrange_t<_Range>
 152   operator()(_Range&& __range, _Pred __pred, _Proj __proj = {}) {
 153     return ranges::__find_last_impl(ranges::begin(__range), ranges::end(__range), __op<_Pred>{__pred}, __proj);
 154   }
 155 };
 156
 157 inline namespace __cpo {
 158 inline constexpr auto find_last        = __find_last{};
 159 inline constexpr auto find_last_if     = __find_last_if{};
 160 inline constexpr auto find_last_if_not = __find_last_if_not{};
 161 } // namespace __cpo
 162 } // namespace ranges
 163
 164 _LIBCPP_END_NAMESPACE_STD
 165
 166 #endif // _LIBCPP_STD_VER >= 23
 167
 168 _LIBCPP_POP_MACROS
 169
 170 #endif // _LIBCPP___ALGORITHM_RANGES_FIND_LAST_H