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
 9#ifndef _LIBCPP___ALGORITHM_PARTITION_POINT_H
10#define _LIBCPP___ALGORITHM_PARTITION_POINT_H
11
12#include <__algorithm/half_positive.h>
13#include <__config>
14#include <__iterator/advance.h>
15#include <__iterator/distance.h>
16#include <__iterator/iterator_traits.h>
17
18#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
19#  pragma GCC system_header
20#endif
21
22_LIBCPP_BEGIN_NAMESPACE_STD
23
24template <class _ForwardIterator, class _Predicate>
25_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator
26partition_point(_ForwardIterator __first, _ForwardIterator __last, _Predicate __pred) {
27  typedef typename iterator_traits<_ForwardIterator>::difference_type difference_type;
28  difference_type __len = std::distance(__first, __last);
29  while (__len != 0) {
30    difference_type __l2 = std::__half_positive(__len);
31    _ForwardIterator __m = __first;
32    std::advance(__m, __l2);
33    if (__pred(*__m)) {
34      __first = ++__m;
35      __len -= __l2 + 1;
36    } else
37      __len = __l2;
38  }
39  return __first;
40}
41
42_LIBCPP_END_NAMESPACE_STD
43
44#endif // _LIBCPP___ALGORITHM_PARTITION_POINT_H