libcxx/include/__cxx03/__algorithm/ranges_search_n.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_SEARCH_N_H
  10 #define _LIBCPP___ALGORITHM_RANGES_SEARCH_N_H
  11
  12 #include <__cxx03/__algorithm/iterator_operations.h>
  13 #include <__cxx03/__algorithm/search_n.h>
  14 #include <__cxx03/__config>
  15 #include <__cxx03/__functional/identity.h>
  16 #include <__cxx03/__functional/ranges_operations.h>
  17 #include <__cxx03/__iterator/advance.h>
  18 #include <__cxx03/__iterator/concepts.h>
  19 #include <__cxx03/__iterator/distance.h>
  20 #include <__cxx03/__iterator/incrementable_traits.h>
  21 #include <__cxx03/__iterator/indirectly_comparable.h>
  22 #include <__cxx03/__iterator/iterator_traits.h>
  23 #include <__cxx03/__ranges/access.h>
  24 #include <__cxx03/__ranges/concepts.h>
  25 #include <__cxx03/__ranges/size.h>
  26 #include <__cxx03/__ranges/subrange.h>
  27 #include <__cxx03/__utility/move.h>
  28 #include <__cxx03/__utility/pair.h>
  29
  30 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  31 #  pragma GCC system_header
  32 #endif
  33
  34 _LIBCPP_PUSH_MACROS
  35 #include <__cxx03/__undef_macros>
  36
  37 #if _LIBCPP_STD_VER >= 20
  38
  39 _LIBCPP_BEGIN_NAMESPACE_STD
  40
  41 namespace ranges {
  42 namespace __search_n {
  43 struct __fn {
  44   template <class _Iter1, class _Sent1, class _SizeT, class _Type, class _Pred, class _Proj>
  45   _LIBCPP_HIDE_FROM_ABI static constexpr subrange<_Iter1> __ranges_search_n_impl(
  46       _Iter1 __first, _Sent1 __last, _SizeT __count, const _Type& __value, _Pred& __pred, _Proj& __proj) {
  47     if (__count == 0)
  48       return {__first, __first};
  49
  50     if constexpr (sized_sentinel_for<_Sent1, _Iter1>) {
  51       auto __size = ranges::distance(__first, __last);
  52       if (__size < __count) {
  53         ranges::advance(__first, __last);
  54         return {__first, __first};
  55       }
  56
  57       if constexpr (random_access_iterator<_Iter1>) {
  58         auto __ret = std::__search_n_random_access_impl<_RangeAlgPolicy>(
  59             __first, __last, __count, __value, __pred, __proj, __size);
  60         return {std::move(__ret.first), std::move(__ret.second)};
  61       }
  62     }
  63
  64     auto __ret = std::__search_n_forward_impl<_RangeAlgPolicy>(__first, __last, __count, __value, __pred, __proj);
  65     return {std::move(__ret.first), std::move(__ret.second)};
  66   }
  67
  68   template <forward_iterator _Iter,
  69             sentinel_for<_Iter> _Sent,
  70             class _Type,
  71             class _Pred = ranges::equal_to,
  72             class _Proj = identity>
  73     requires indirectly_comparable<_Iter, const _Type*, _Pred, _Proj>
  74   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr subrange<_Iter>
  75   operator()(_Iter __first,
  76              _Sent __last,
  77              iter_difference_t<_Iter> __count,
  78              const _Type& __value,
  79              _Pred __pred = {},
  80              _Proj __proj = _Proj{}) const {
  81     return __ranges_search_n_impl(__first, __last, __count, __value, __pred, __proj);
  82   }
  83
  84   template <forward_range _Range, class _Type, class _Pred = ranges::equal_to, class _Proj = identity>
  85     requires indirectly_comparable<iterator_t<_Range>, const _Type*, _Pred, _Proj>
  86   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr borrowed_subrange_t<_Range> operator()(
  87       _Range&& __range, range_difference_t<_Range> __count, const _Type& __value, _Pred __pred = {}, _Proj __proj = {})
  88       const {
  89     auto __first = ranges::begin(__range);
  90     if (__count <= 0)
  91       return {__first, __first};
  92     if constexpr (sized_range<_Range>) {
  93       auto __size1 = ranges::size(__range);
  94       if (__size1 < static_cast<range_size_t<_Range>>(__count)) {
  95         ranges::advance(__first, ranges::end(__range));
  96         return {__first, __first};
  97       }
  98     }
  99
 100     return __ranges_search_n_impl(ranges::begin(__range), ranges::end(__range), __count, __value, __pred, __proj);
 101   }
 102 };
 103 } // namespace __search_n
 104
 105 inline namespace __cpo {
 106 inline constexpr auto search_n = __search_n::__fn{};
 107 } // namespace __cpo
 108 } // namespace ranges
 109
 110 _LIBCPP_END_NAMESPACE_STD
 111
 112 #endif // _LIBCPP_STD_VER >= 20
 113
 114 _LIBCPP_POP_MACROS
 115
 116 #endif // _LIBCPP___ALGORITHM_RANGES_SEARCH_N_H