__cxx03/__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___CXX03___ALGORITHM_COUNT_IF_H
0011 #define _LIBCPP___CXX03___ALGORITHM_COUNT_IF_H
0012
0013 #include <__cxx03/__config>
0014 #include <__cxx03/__iterator/iterator_traits.h>
0015
0016 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0017 #  pragma GCC system_header
0018 #endif
0019
0020 _LIBCPP_BEGIN_NAMESPACE_STD
0021
0022 template <class _InputIterator, class _Predicate>
0023 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
0024 typename iterator_traits<_InputIterator>::difference_type
0025 count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred) {
0026   typename iterator_traits<_InputIterator>::difference_type __r(0);
0027   for (; __first != __last; ++__first)
0028     if (__pred(*__first))
0029       ++__r;
0030   return __r;
0031 }
0032
0033 _LIBCPP_END_NAMESPACE_STD
0034
0035 #endif // _LIBCPP___CXX03___ALGORITHM_COUNT_IF_H