libcxx/include/__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 <__algorithm/iterator_operations.h>
  14 #include <__config>
  15 #include <__functional/identity.h>
  16 #include <__iterator/iterator_traits.h>
  17 #include <__type_traits/invoke.h>
  18
  19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  20 #  pragma GCC system_header
  21 #endif
  22
  23 _LIBCPP_BEGIN_NAMESPACE_STD
  24
  25 template <class _AlgPolicy, class _Iter, class _Sent, class _Proj, class _Pred>
  26 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 __policy_iter_diff_t<_AlgPolicy, _Iter>
  27 __count_if(_Iter __first, _Sent __last, _Pred& __pred, _Proj& __proj) {
  28   __policy_iter_diff_t<_AlgPolicy, _Iter> __counter(0);
  29   for (; __first != __last; ++__first) {
  30     if (std::__invoke(__pred, std::__invoke(__proj, *__first)))
  31       ++__counter;
  32   }
  33   return __counter;
  34 }
  35
  36 template <class _InputIterator, class _Predicate>
  37 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
  38 typename iterator_traits<_InputIterator>::difference_type
  39 count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred) {
  40   __identity __proj;
  41   return std::__count_if<_ClassicAlgPolicy>(__first, __last, __pred, __proj);
  42 }
  43
  44 _LIBCPP_END_NAMESPACE_STD
  45
  46 #endif // _LIBCPP___ALGORITHM_COUNT_IF_H