libcxx/include/__algorithm/ranges_count_if.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_COUNT_IF_H
  10 #define _LIBCPP___ALGORITHM_RANGES_COUNT_IF_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/incrementable_traits.h>
  18 #include <__iterator/iterator_traits.h>
  19 #include <__iterator/projected.h>
  20 #include <__ranges/access.h>
  21 #include <__ranges/concepts.h>
  22 #include <__utility/move.h>
  23
  24 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  25 #  pragma GCC system_header
  26 #endif
  27
  28 #if _LIBCPP_STD_VER >= 20
  29
  30 _LIBCPP_BEGIN_NAMESPACE_STD
  31
  32 namespace ranges {
  33 template <class _Iter, class _Sent, class _Proj, class _Pred>
  34 _LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Iter>
  35 __count_if_impl(_Iter __first, _Sent __last, _Pred& __pred, _Proj& __proj) {
  36   iter_difference_t<_Iter> __counter(0);
  37   for (; __first != __last; ++__first) {
  38     if (std::invoke(__pred, std::invoke(__proj, *__first)))
  39       ++__counter;
  40   }
  41   return __counter;
  42 }
  43
  44 namespace __count_if {
  45 struct __fn {
  46   template <input_iterator _Iter,
  47             sentinel_for<_Iter> _Sent,
  48             class _Proj = identity,
  49             indirect_unary_predicate<projected<_Iter, _Proj>> _Predicate>
  50   _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Iter>
  51   operator()(_Iter __first, _Sent __last, _Predicate __pred, _Proj __proj = {}) const {
  52     return ranges::__count_if_impl(std::move(__first), std::move(__last), __pred, __proj);
  53   }
  54
  55   template <input_range _Range,
  56             class _Proj = identity,
  57             indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>> _Predicate>
  58   _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr range_difference_t<_Range>
  59   operator()(_Range&& __r, _Predicate __pred, _Proj __proj = {}) const {
  60     return ranges::__count_if_impl(ranges::begin(__r), ranges::end(__r), __pred, __proj);
  61   }
  62 };
  63 } // namespace __count_if
  64
  65 inline namespace __cpo {
  66 inline constexpr auto count_if = __count_if::__fn{};
  67 } // namespace __cpo
  68 } // namespace ranges
  69
  70 _LIBCPP_END_NAMESPACE_STD
  71
  72 #endif // _LIBCPP_STD_VER >= 20
  73
  74 #endif // _LIBCPP___ALGORITHM_RANGES_COUNT_IF_H