libcxx/include/__cxx03/__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___CXX03___ALGORITHM_RANGES_COUNT_IF_H
  10 #define _LIBCPP___CXX03___ALGORITHM_RANGES_COUNT_IF_H
  11
  12 #include <__cxx03/__config>
  13 #include <__cxx03/__functional/identity.h>
  14 #include <__cxx03/__functional/invoke.h>
  15 #include <__cxx03/__functional/ranges_operations.h>
  16 #include <__cxx03/__iterator/concepts.h>
  17 #include <__cxx03/__iterator/incrementable_traits.h>
  18 #include <__cxx03/__iterator/iterator_traits.h>
  19 #include <__cxx03/__iterator/projected.h>
  20 #include <__cxx03/__ranges/access.h>
  21 #include <__cxx03/__ranges/concepts.h>
  22 #include <__cxx03/__utility/move.h>
  23
  24 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  25 #  pragma GCC system_header
  26 #endif
  27
  28 _LIBCPP_PUSH_MACROS
  29 #include <__cxx03/__undef_macros>
  30
  31 #if _LIBCPP_STD_VER >= 20
  32
  33 _LIBCPP_BEGIN_NAMESPACE_STD
  34
  35 namespace ranges {
  36 template <class _Iter, class _Sent, class _Proj, class _Pred>
  37 _LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Iter>
  38 __count_if_impl(_Iter __first, _Sent __last, _Pred& __pred, _Proj& __proj) {
  39   iter_difference_t<_Iter> __counter(0);
  40   for (; __first != __last; ++__first) {
  41     if (std::invoke(__pred, std::invoke(__proj, *__first)))
  42       ++__counter;
  43   }
  44   return __counter;
  45 }
  46
  47 namespace __count_if {
  48 struct __fn {
  49   template <input_iterator _Iter,
  50             sentinel_for<_Iter> _Sent,
  51             class _Proj = identity,
  52             indirect_unary_predicate<projected<_Iter, _Proj>> _Predicate>
  53   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Iter>
  54   operator()(_Iter __first, _Sent __last, _Predicate __pred, _Proj __proj = {}) const {
  55     return ranges::__count_if_impl(std::move(__first), std::move(__last), __pred, __proj);
  56   }
  57
  58   template <input_range _Range,
  59             class _Proj = identity,
  60             indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>> _Predicate>
  61   [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr range_difference_t<_Range>
  62   operator()(_Range&& __r, _Predicate __pred, _Proj __proj = {}) const {
  63     return ranges::__count_if_impl(ranges::begin(__r), ranges::end(__r), __pred, __proj);
  64   }
  65 };
  66 } // namespace __count_if
  67
  68 inline namespace __cpo {
  69 inline constexpr auto count_if = __count_if::__fn{};
  70 } // namespace __cpo
  71 } // namespace ranges
  72
  73 _LIBCPP_END_NAMESPACE_STD
  74
  75 #endif // _LIBCPP_STD_VER >= 20
  76
  77 _LIBCPP_POP_MACROS
  78
  79 #endif // _LIBCPP___CXX03___ALGORITHM_RANGES_COUNT_IF_H