libcxx/include/__cxx03/__algorithm/partition_point.h

   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 <__cxx03/__algorithm/half_positive.h>
  13 #include <__cxx03/__config>
  14 #include <__cxx03/__iterator/advance.h>
  15 #include <__cxx03/__iterator/distance.h>
  16 #include <__cxx03/__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
  24 template <class _ForwardIterator, class _Predicate>
  25 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator
  26 partition_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