partition_point.h 1.4 KB

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  1. //===----------------------------------------------------------------------===//
  2. //
  3. // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  4. // See https://llvm.org/LICENSE.txt for license information.
  5. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  6. //
  7. //===----------------------------------------------------------------------===//
  8. #ifndef _LIBCPP___ALGORITHM_PARTITION_POINT_H
  9. #define _LIBCPP___ALGORITHM_PARTITION_POINT_H
  10. #include <__algorithm/half_positive.h>
  11. #include <__config>
  12. #include <__iterator/advance.h>
  13. #include <__iterator/distance.h>
  14. #include <__iterator/iterator_traits.h>
  15. #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  16. # pragma GCC system_header
  17. #endif
  18. _LIBCPP_BEGIN_NAMESPACE_STD
  19. template <class _ForwardIterator, class _Predicate>
  20. _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator
  21. partition_point(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) {
  22. typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
  23. difference_type __len = std::distance(__first, __last);
  24. while (__len != 0) {
  25. difference_type __l2 = std::__half_positive(__len);
  26. _ForwardIterator __m = __first;
  27. std::advance(__m, __l2);
  28. if (__pred(*__m)) {
  29. __first = ++__m;
  30. __len -= __l2 + 1;
  31. } else
  32. __len = __l2;
  33. }
  34. return __first;
  35. }
  36. _LIBCPP_END_NAMESPACE_STD
  37. #endif // _LIBCPP___ALGORITHM_PARTITION_POINT_H