v1/__algorithm/count_if.h

0001 // -*- C++ -*-
0002 //===----------------------------------------------------------------------===//
0003 //
0004 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0005 // See https://llvm.org/LICENSE.txt for license information.
0006 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0007 //
0008 //===----------------------------------------------------------------------===//
0009
0010 #ifndef _LIBCPP___ALGORITHM_COUNT_IF_H
0011 #define _LIBCPP___ALGORITHM_COUNT_IF_H
0012
0013 #include <__algorithm/iterator_operations.h>
0014 #include <__config>
0015 #include <__functional/identity.h>
0016 #include <__iterator/iterator_traits.h>
0017 #include <__type_traits/invoke.h>
0018
0019 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0020 #  pragma GCC system_header
0021 #endif
0022
0023 _LIBCPP_BEGIN_NAMESPACE_STD
0024
0025 template <class _AlgPolicy, class _Iter, class _Sent, class _Proj, class _Pred>
0026 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 __policy_iter_diff_t<_AlgPolicy, _Iter>
0027 __count_if(_Iter __first, _Sent __last, _Pred& __pred, _Proj& __proj) {
0028   __policy_iter_diff_t<_AlgPolicy, _Iter> __counter(0);
0029   for (; __first != __last; ++__first) {
0030     if (std::__invoke(__pred, std::__invoke(__proj, *__first)))
0031       ++__counter;
0032   }
0033   return __counter;
0034 }
0035
0036 template <class _InputIterator, class _Predicate>
0037 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
0038 typename iterator_traits<_InputIterator>::difference_type
0039 count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred) {
0040   __identity __proj;
0041   return std::__count_if<_ClassicAlgPolicy>(__first, __last, __pred, __proj);
0042 }
0043
0044 _LIBCPP_END_NAMESPACE_STD
0045
0046 #endif // _LIBCPP___ALGORITHM_COUNT_IF_H