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 _LIBCPP_PUSH_MACROS
29 #include <__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   _LIBCPP_NODISCARD_EXT _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   _LIBCPP_NODISCARD_EXT _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___ALGORITHM_RANGES_COUNT_IF_H
80