libcxx/include/__cxx03/__algorithm/count_if.h

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef _LIBCPP___ALGORITHM_COUNT_IF_H
  11 #define _LIBCPP___ALGORITHM_COUNT_IF_H
  12
  13 #include <__cxx03/__config>
  14 #include <__cxx03/__iterator/iterator_traits.h>
  15
  16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  17 #  pragma GCC system_header
  18 #endif
  19
  20 _LIBCPP_BEGIN_NAMESPACE_STD
  21
  22 template <class _InputIterator, class _Predicate>
  23 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
  24 typename iterator_traits<_InputIterator>::difference_type
  25 count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred) {
  26   typename iterator_traits<_InputIterator>::difference_type __r(0);
  27   for (; __first != __last; ++__first)
  28     if (__pred(*__first))
  29       ++__r;
  30   return __r;
  31 }
  32
  33 _LIBCPP_END_NAMESPACE_STD
  34
  35 #endif // _LIBCPP___ALGORITHM_COUNT_IF_H