count_if.h 1.1 KB

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  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. #ifndef _LIBCPP___ALGORITHM_COUNT_IF_H
  10. #define _LIBCPP___ALGORITHM_COUNT_IF_H
  11. #include <__config>
  12. #include <__iterator/iterator_traits.h>
  13. #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  14. # pragma GCC system_header
  15. #endif
  16. _LIBCPP_BEGIN_NAMESPACE_STD
  17. template <class _InputIterator, class _Predicate>
  18. _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
  19. typename iterator_traits<_InputIterator>::difference_type
  20. count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred) {
  21. typename iterator_traits<_InputIterator>::difference_type __r(0);
  22. for (; __first != __last; ++__first)
  23. if (__pred(*__first))
  24. ++__r;
  25. return __r;
  26. }
  27. _LIBCPP_END_NAMESPACE_STD
  28. #endif // _LIBCPP___ALGORITHM_COUNT_IF_H