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 <__iterator/iterator_traits.h>
  22 #include <__type_traits/invoke.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_PUSH_MACROS
  32 #include <__undef_macros>
  33
  34 _LIBCPP_BEGIN_NAMESPACE_STD
  35
  36 template <class _AlgPolicy,
  37           class _Compare,
  38           class _InputIterator,
  39           class _Sentinel1,
  40           class _RandomAccessIterator,
  41           class _Sentinel2,
  42           class _Proj1,
  43           class _Proj2>
  44 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_InputIterator, _RandomAccessIterator> __partial_sort_copy(
  45     _InputIterator __first,
  46     _Sentinel1 __last,
  47     _RandomAccessIterator __result_first,
  48     _Sentinel2 __result_last,
  49     _Compare&& __comp,
  50     _Proj1&& __proj1,
  51     _Proj2&& __proj2) {
  52   _RandomAccessIterator __r = __result_first;
  53   auto&& __projected_comp   = std::__make_projected(__comp, __proj2);
  54
  55   if (__r != __result_last) {
  56     for (; __first != __last && __r != __result_last; ++__first, (void)++__r)
  57       *__r = *__first;
  58     std::__make_heap<_AlgPolicy>(__result_first, __r, __projected_comp);
  59     typename iterator_traits<_RandomAccessIterator>::difference_type __len = __r - __result_first;
  60     for (; __first != __last; ++__first)
  61       if (std::__invoke(__comp, std::__invoke(__proj1, *__first), std::__invoke(__proj2, *__result_first))) {
  62         *__result_first = *__first;
  63         std::__sift_down<_AlgPolicy>(__result_first, __projected_comp, __len, __result_first);
  64       }
  65     std::__sort_heap<_AlgPolicy>(__result_first, __r, __projected_comp);
  66   }
  67
  68   return pair<_InputIterator, _RandomAccessIterator>(
  69       _IterOps<_AlgPolicy>::next(std::move(__first), std::move(__last)), std::move(__r));
  70 }
  71
  72 template <class _InputIterator, class _RandomAccessIterator, class _Compare>
  73 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _RandomAccessIterator partial_sort_copy(
  74     _InputIterator __first,
  75     _InputIterator __last,
  76     _RandomAccessIterator __result_first,
  77     _RandomAccessIterator __result_last,
  78     _Compare __comp) {
  79   static_assert(__is_callable<_Compare&, decltype(*__first), decltype(*__result_first)>::value,
  80                 "The comparator has to be callable");
  81
  82   auto __result = std::__partial_sort_copy<_ClassicAlgPolicy>(
  83       __first,
  84       __last,
  85       __result_first,
  86       __result_last,
  87       static_cast<__comp_ref_type<_Compare> >(__comp),
  88       __identity(),
  89       __identity());
  90   return __result.second;
  91 }
  92
  93 template <class _InputIterator, class _RandomAccessIterator>
  94 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _RandomAccessIterator partial_sort_copy(
  95     _InputIterator __first,
  96     _InputIterator __last,
  97     _RandomAccessIterator __result_first,
  98     _RandomAccessIterator __result_last) {
  99   return std::partial_sort_copy(__first, __last, __result_first, __result_last, __less<>());
 100 }
 101
 102 _LIBCPP_END_NAMESPACE_STD
 103
 104 _LIBCPP_POP_MACROS
 105
 106 #endif // _LIBCPP___ALGORITHM_PARTIAL_SORT_COPY_H