libcxx/include/__algorithm/partial_sort_copy.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_PARTIAL_SORT_COPY_H
  10 #define _LIBCPP___ALGORITHM_PARTIAL_SORT_COPY_H
  11
  12 #include <__algorithm/comp.h>
  13 #include <__algorithm/comp_ref_type.h>
  14 #include <__algorithm/iterator_operations.h>
  15 #include <__algorithm/make_heap.h>
  16 #include <__algorithm/make_projected.h>
  17 #include <__algorithm/sift_down.h>
  18 #include <__algorithm/sort_heap.h>
  19 #include <__config>
  20 #include <__functional/identity.h>
  21 #include <__functional/invoke.h>
  22 #include <__iterator/iterator_traits.h>
  23 #include <__type_traits/is_callable.h>
  24 #include <__utility/move.h>
  25 #include <__utility/pair.h>
  26
  27 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  28 #  pragma GCC system_header
  29 #endif
  30
  31 _LIBCPP_BEGIN_NAMESPACE_STD
  32
  33 template <class _AlgPolicy, class _Compare,
  34           class _InputIterator, class _Sentinel1, class _RandomAccessIterator, class _Sentinel2,
  35           class _Proj1, class _Proj2>
  36 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InputIterator, _RandomAccessIterator>
  37 __partial_sort_copy(_InputIterator __first, _Sentinel1 __last,
  38                     _RandomAccessIterator __result_first, _Sentinel2 __result_last,
  39                     _Compare&& __comp, _Proj1&& __proj1, _Proj2&& __proj2)
  40 {
  41     _RandomAccessIterator __r = __result_first;
  42     auto&& __projected_comp = std::__make_projected(__comp, __proj2);
  43
  44     if (__r != __result_last)
  45     {
  46         for (; __first != __last && __r != __result_last; ++__first, (void) ++__r)
  47             *__r = *__first;
  48         std::__make_heap<_AlgPolicy>(__result_first, __r, __projected_comp);
  49         typename iterator_traits<_RandomAccessIterator>::difference_type __len = __r - __result_first;
  50         for (; __first != __last; ++__first)
  51             if (std::__invoke(__comp, std::__invoke(__proj1, *__first), std::__invoke(__proj2, *__result_first))) {
  52                 *__result_first = *__first;
  53                 std::__sift_down<_AlgPolicy>(__result_first, __projected_comp, __len, __result_first);
  54             }
  55         std::__sort_heap<_AlgPolicy>(__result_first, __r, __projected_comp);
  56     }
  57
  58     return pair<_InputIterator, _RandomAccessIterator>(
  59         _IterOps<_AlgPolicy>::next(std::move(__first), std::move(__last)), std::move(__r));
  60 }
  61
  62 template <class _InputIterator, class _RandomAccessIterator, class _Compare>
  63 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
  64 _RandomAccessIterator
  65 partial_sort_copy(_InputIterator __first, _InputIterator __last,
  66                   _RandomAccessIterator __result_first, _RandomAccessIterator __result_last, _Compare __comp)
  67 {
  68   static_assert(__is_callable<_Compare, decltype(*__first), decltype(*__result_first)>::value,
  69                 "Comparator has to be callable");
  70
  71   auto __result = std::__partial_sort_copy<_ClassicAlgPolicy>(__first, __last, __result_first, __result_last,
  72       static_cast<__comp_ref_type<_Compare> >(__comp), __identity(), __identity());
  73   return __result.second;
  74 }
  75
  76 template <class _InputIterator, class _RandomAccessIterator>
  77 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
  78 _RandomAccessIterator
  79 partial_sort_copy(_InputIterator __first, _InputIterator __last,
  80                   _RandomAccessIterator __result_first, _RandomAccessIterator __result_last)
  81 {
  82     return _VSTD::partial_sort_copy(__first, __last, __result_first, __result_last, __less<>());
  83 }
  84
  85 _LIBCPP_END_NAMESPACE_STD
  86
  87 #endif // _LIBCPP___ALGORITHM_PARTIAL_SORT_COPY_H