libcxx/include/__algorithm/pstl_count.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_PSTL_COUNT_H
  10 #define _LIBCPP___ALGORITHM_PSTL_COUNT_H
  11
  12 #include <__algorithm/count.h>
  13 #include <__algorithm/for_each.h>
  14 #include <__algorithm/pstl_backend.h>
  15 #include <__algorithm/pstl_for_each.h>
  16 #include <__algorithm/pstl_frontend_dispatch.h>
  17 #include <__atomic/atomic.h>
  18 #include <__config>
  19 #include <__functional/operations.h>
  20 #include <__iterator/iterator_traits.h>
  21 #include <__numeric/pstl_transform_reduce.h>
  22 #include <__type_traits/enable_if.h>
  23 #include <__type_traits/is_execution_policy.h>
  24 #include <__type_traits/remove_cvref.h>
  25 #include <__utility/move.h>
  26 #include <optional>
  27
  28 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  29 #  pragma GCC system_header
  30 #endif
  31
  32 #if !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
  33
  34 _LIBCPP_BEGIN_NAMESPACE_STD
  35
  36 template <class>
  37 void __pstl_count_if(); // declaration needed for the frontend dispatch below
  38
  39 template <class _ExecutionPolicy,
  40           class _ForwardIterator,
  41           class _Predicate,
  42           class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
  43           enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
  44 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__iter_diff_t<_ForwardIterator>> __count_if(
  45     _ExecutionPolicy&& __policy, _ForwardIterator&& __first, _ForwardIterator&& __last, _Predicate&& __pred) noexcept {
  46   using __diff_t = __iter_diff_t<_ForwardIterator>;
  47   return std::__pstl_frontend_dispatch(
  48       _LIBCPP_PSTL_CUSTOMIZATION_POINT(__pstl_count_if, _RawPolicy),
  49       [&](_ForwardIterator __g_first, _ForwardIterator __g_last, _Predicate __g_pred) -> optional<__diff_t> {
  50         return std::__transform_reduce(
  51             __policy,
  52             std::move(__g_first),
  53             std::move(__g_last),
  54             __diff_t(),
  55             std::plus{},
  56             [&](__iter_reference<_ForwardIterator> __element) -> bool { return __g_pred(__element); });
  57       },
  58       std::move(__first),
  59       std::move(__last),
  60       std::move(__pred));
  61 }
  62
  63 template <class _ExecutionPolicy,
  64           class _ForwardIterator,
  65           class _Predicate,
  66           class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
  67           enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
  68 _LIBCPP_HIDE_FROM_ABI __iter_diff_t<_ForwardIterator>
  69 count_if(_ExecutionPolicy&& __policy, _ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) {
  70   auto __res = std::__count_if(__policy, std::move(__first), std::move(__last), std::move(__pred));
  71   if (!__res)
  72     std::__throw_bad_alloc();
  73   return *std::move(__res);
  74 }
  75
  76 template <class>
  77 void __pstl_count(); // declaration needed for the frontend dispatch below
  78
  79 template <class _ExecutionPolicy,
  80           class _ForwardIterator,
  81           class _Tp,
  82           class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
  83           enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
  84 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI optional<__iter_diff_t<_ForwardIterator>>
  85 __count(_ExecutionPolicy&& __policy, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value) {
  86   return std::__pstl_frontend_dispatch(
  87       _LIBCPP_PSTL_CUSTOMIZATION_POINT(__pstl_count, _RawPolicy),
  88       [&](_ForwardIterator __g_first, _ForwardIterator __g_last, const _Tp& __g_value)
  89           -> optional<__iter_diff_t<_ForwardIterator>> {
  90         return std::count_if(__policy, __g_first, __g_last, [&](__iter_reference<_ForwardIterator> __v) {
  91           return __v == __g_value;
  92         });
  93       },
  94       std::move(__first),
  95       std::move(__last),
  96       __value);
  97 }
  98
  99 template <class _ExecutionPolicy,
 100           class _ForwardIterator,
 101           class _Tp,
 102           class _RawPolicy                                    = __remove_cvref_t<_ExecutionPolicy>,
 103           enable_if_t<is_execution_policy_v<_RawPolicy>, int> = 0>
 104 _LIBCPP_HIDE_FROM_ABI __iter_diff_t<_ForwardIterator>
 105 count(_ExecutionPolicy&& __policy, _ForwardIterator __first, _ForwardIterator __last, const _Tp& __value) {
 106   auto __res = std::__count(__policy, std::move(__first), std::move(__last), __value);
 107   if (!__res)
 108     std::__throw_bad_alloc();
 109   return *__res;
 110 }
 111
 112 _LIBCPP_END_NAMESPACE_STD
 113
 114 #endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_PSTL) && _LIBCPP_STD_VER >= 17
 115
 116 #endif // _LIBCPP___ALGORITHM_PSTL_COUNT_H