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 > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
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
35 iter_difference_t<_Iter> __count_if_impl(_Iter __first, _Sent __last,
36                                              _Pred& __pred, _Proj& __proj) {
37   iter_difference_t<_Iter> __counter(0);
38   for (; __first != __last; ++__first) {
39     if (std::invoke(__pred, std::invoke(__proj, *__first)))
40       ++__counter;
41   }
42   return __counter;
43 }
44 
45 namespace __count_if {
46 struct __fn {
47   template <input_iterator _Iter, sentinel_for<_Iter> _Sent, class _Proj = identity,
48             indirect_unary_predicate<projected<_Iter, _Proj>> _Predicate>
49   _LIBCPP_HIDE_FROM_ABI constexpr
50   iter_difference_t<_Iter> operator()(_Iter __first, _Sent __last, _Predicate __pred, _Proj __proj = {}) const {
51     return ranges::__count_if_impl(std::move(__first), std::move(__last), __pred, __proj);
52   }
53 
54   template <input_range _Range, class _Proj = identity,
55             indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>> _Predicate>
56   _LIBCPP_HIDE_FROM_ABI constexpr
57   range_difference_t<_Range> operator()(_Range&& __r, _Predicate __pred, _Proj __proj = {}) const {
58     return ranges::__count_if_impl(ranges::begin(__r), ranges::end(__r), __pred, __proj);
59   }
60 };
61 } // namespace __count_if
62 
63 inline namespace __cpo {
64   inline constexpr auto count_if = __count_if::__fn{};
65 } // namespace __cpo
66 } // namespace ranges
67 
68 _LIBCPP_END_NAMESPACE_STD
69 
70 #endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
71 
72 #endif // _LIBCPP___ALGORITHM_RANGES_COUNT_IF_H
73