libcxx/include/__algorithm/stable_sort.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_STABLE_SORT_H
  10 #define _LIBCPP___ALGORITHM_STABLE_SORT_H
  11
  12 #include <__algorithm/comp.h>
  13 #include <__algorithm/comp_ref_type.h>
  14 #include <__algorithm/inplace_merge.h>
  15 #include <__algorithm/iterator_operations.h>
  16 #include <__algorithm/sort.h>
  17 #include <__config>
  18 #include <__debug_utils/strict_weak_ordering_check.h>
  19 #include <__iterator/iterator_traits.h>
  20 #include <__memory/destruct_n.h>
  21 #include <__memory/temporary_buffer.h>
  22 #include <__memory/unique_ptr.h>
  23 #include <__type_traits/is_trivially_assignable.h>
  24 #include <__utility/move.h>
  25 #include <__utility/pair.h>
  26 #include <new>
  27
  28 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  29 #  pragma GCC system_header
  30 #endif
  31
  32 _LIBCPP_PUSH_MACROS
  33 #include <__undef_macros>
  34
  35 _LIBCPP_BEGIN_NAMESPACE_STD
  36
  37 template <class _AlgPolicy, class _Compare, class _BidirectionalIterator>
  38 _LIBCPP_HIDE_FROM_ABI void __insertion_sort_move(
  39     _BidirectionalIterator __first1,
  40     _BidirectionalIterator __last1,
  41     typename iterator_traits<_BidirectionalIterator>::value_type* __first2,
  42     _Compare __comp) {
  43   using _Ops = _IterOps<_AlgPolicy>;
  44
  45   typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
  46   if (__first1 != __last1) {
  47     __destruct_n __d(0);
  48     unique_ptr<value_type, __destruct_n&> __h(__first2, __d);
  49     value_type* __last2 = __first2;
  50     ::new ((void*)__last2) value_type(_Ops::__iter_move(__first1));
  51     __d.template __incr<value_type>();
  52     for (++__last2; ++__first1 != __last1; ++__last2) {
  53       value_type* __j2 = __last2;
  54       value_type* __i2 = __j2;
  55       if (__comp(*__first1, *--__i2)) {
  56         ::new ((void*)__j2) value_type(std::move(*__i2));
  57         __d.template __incr<value_type>();
  58         for (--__j2; __i2 != __first2 && __comp(*__first1, *--__i2); --__j2)
  59           *__j2 = std::move(*__i2);
  60         *__j2 = _Ops::__iter_move(__first1);
  61       } else {
  62         ::new ((void*)__j2) value_type(_Ops::__iter_move(__first1));
  63         __d.template __incr<value_type>();
  64       }
  65     }
  66     __h.release();
  67   }
  68 }
  69
  70 template <class _AlgPolicy, class _Compare, class _InputIterator1, class _InputIterator2>
  71 _LIBCPP_HIDE_FROM_ABI void __merge_move_construct(
  72     _InputIterator1 __first1,
  73     _InputIterator1 __last1,
  74     _InputIterator2 __first2,
  75     _InputIterator2 __last2,
  76     typename iterator_traits<_InputIterator1>::value_type* __result,
  77     _Compare __comp) {
  78   using _Ops = _IterOps<_AlgPolicy>;
  79
  80   typedef typename iterator_traits<_InputIterator1>::value_type value_type;
  81   __destruct_n __d(0);
  82   unique_ptr<value_type, __destruct_n&> __h(__result, __d);
  83   for (; true; ++__result) {
  84     if (__first1 == __last1) {
  85       for (; __first2 != __last2; ++__first2, (void)++__result, __d.template __incr<value_type>())
  86         ::new ((void*)__result) value_type(_Ops::__iter_move(__first2));
  87       __h.release();
  88       return;
  89     }
  90     if (__first2 == __last2) {
  91       for (; __first1 != __last1; ++__first1, (void)++__result, __d.template __incr<value_type>())
  92         ::new ((void*)__result) value_type(_Ops::__iter_move(__first1));
  93       __h.release();
  94       return;
  95     }
  96     if (__comp(*__first2, *__first1)) {
  97       ::new ((void*)__result) value_type(_Ops::__iter_move(__first2));
  98       __d.template __incr<value_type>();
  99       ++__first2;
 100     } else {
 101       ::new ((void*)__result) value_type(_Ops::__iter_move(__first1));
 102       __d.template __incr<value_type>();
 103       ++__first1;
 104     }
 105   }
 106 }
 107
 108 template <class _AlgPolicy, class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
 109 _LIBCPP_HIDE_FROM_ABI void __merge_move_assign(
 110     _InputIterator1 __first1,
 111     _InputIterator1 __last1,
 112     _InputIterator2 __first2,
 113     _InputIterator2 __last2,
 114     _OutputIterator __result,
 115     _Compare __comp) {
 116   using _Ops = _IterOps<_AlgPolicy>;
 117
 118   for (; __first1 != __last1; ++__result) {
 119     if (__first2 == __last2) {
 120       for (; __first1 != __last1; ++__first1, (void)++__result)
 121         *__result = _Ops::__iter_move(__first1);
 122       return;
 123     }
 124     if (__comp(*__first2, *__first1)) {
 125       *__result = _Ops::__iter_move(__first2);
 126       ++__first2;
 127     } else {
 128       *__result = _Ops::__iter_move(__first1);
 129       ++__first1;
 130     }
 131   }
 132   for (; __first2 != __last2; ++__first2, (void)++__result)
 133     *__result = _Ops::__iter_move(__first2);
 134 }
 135
 136 template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
 137 void __stable_sort(_RandomAccessIterator __first,
 138                    _RandomAccessIterator __last,
 139                    _Compare __comp,
 140                    typename iterator_traits<_RandomAccessIterator>::difference_type __len,
 141                    typename iterator_traits<_RandomAccessIterator>::value_type* __buff,
 142                    ptrdiff_t __buff_size);
 143
 144 template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
 145 void __stable_sort_move(_RandomAccessIterator __first1,
 146                         _RandomAccessIterator __last1,
 147                         _Compare __comp,
 148                         typename iterator_traits<_RandomAccessIterator>::difference_type __len,
 149                         typename iterator_traits<_RandomAccessIterator>::value_type* __first2) {
 150   using _Ops = _IterOps<_AlgPolicy>;
 151
 152   typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
 153   switch (__len) {
 154   case 0:
 155     return;
 156   case 1:
 157     ::new ((void*)__first2) value_type(_Ops::__iter_move(__first1));
 158     return;
 159   case 2:
 160     __destruct_n __d(0);
 161     unique_ptr<value_type, __destruct_n&> __h2(__first2, __d);
 162     if (__comp(*--__last1, *__first1)) {
 163       ::new ((void*)__first2) value_type(_Ops::__iter_move(__last1));
 164       __d.template __incr<value_type>();
 165       ++__first2;
 166       ::new ((void*)__first2) value_type(_Ops::__iter_move(__first1));
 167     } else {
 168       ::new ((void*)__first2) value_type(_Ops::__iter_move(__first1));
 169       __d.template __incr<value_type>();
 170       ++__first2;
 171       ::new ((void*)__first2) value_type(_Ops::__iter_move(__last1));
 172     }
 173     __h2.release();
 174     return;
 175   }
 176   if (__len <= 8) {
 177     std::__insertion_sort_move<_AlgPolicy, _Compare>(__first1, __last1, __first2, __comp);
 178     return;
 179   }
 180   typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
 181   _RandomAccessIterator __m                                             = __first1 + __l2;
 182   std::__stable_sort<_AlgPolicy, _Compare>(__first1, __m, __comp, __l2, __first2, __l2);
 183   std::__stable_sort<_AlgPolicy, _Compare>(__m, __last1, __comp, __len - __l2, __first2 + __l2, __len - __l2);
 184   std::__merge_move_construct<_AlgPolicy, _Compare>(__first1, __m, __m, __last1, __first2, __comp);
 185 }
 186
 187 template <class _Tp>
 188 struct __stable_sort_switch {
 189   static const unsigned value = 128 * is_trivially_copy_assignable<_Tp>::value;
 190 };
 191
 192 template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
 193 void __stable_sort(_RandomAccessIterator __first,
 194                    _RandomAccessIterator __last,
 195                    _Compare __comp,
 196                    typename iterator_traits<_RandomAccessIterator>::difference_type __len,
 197                    typename iterator_traits<_RandomAccessIterator>::value_type* __buff,
 198                    ptrdiff_t __buff_size) {
 199   typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
 200   typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
 201   switch (__len) {
 202   case 0:
 203   case 1:
 204     return;
 205   case 2:
 206     if (__comp(*--__last, *__first))
 207       _IterOps<_AlgPolicy>::iter_swap(__first, __last);
 208     return;
 209   }
 210   if (__len <= static_cast<difference_type>(__stable_sort_switch<value_type>::value)) {
 211     std::__insertion_sort<_AlgPolicy, _Compare>(__first, __last, __comp);
 212     return;
 213   }
 214   typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
 215   _RandomAccessIterator __m                                             = __first + __l2;
 216   if (__len <= __buff_size) {
 217     __destruct_n __d(0);
 218     unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
 219     std::__stable_sort_move<_AlgPolicy, _Compare>(__first, __m, __comp, __l2, __buff);
 220     __d.__set(__l2, (value_type*)nullptr);
 221     std::__stable_sort_move<_AlgPolicy, _Compare>(__m, __last, __comp, __len - __l2, __buff + __l2);
 222     __d.__set(__len, (value_type*)nullptr);
 223     std::__merge_move_assign<_AlgPolicy, _Compare>(
 224         __buff, __buff + __l2, __buff + __l2, __buff + __len, __first, __comp);
 225     //         std::__merge<_Compare>(move_iterator<value_type*>(__buff),
 226     //                                  move_iterator<value_type*>(__buff + __l2),
 227     //                                  move_iterator<_RandomAccessIterator>(__buff + __l2),
 228     //                                  move_iterator<_RandomAccessIterator>(__buff + __len),
 229     //                                  __first, __comp);
 230     return;
 231   }
 232   std::__stable_sort<_AlgPolicy, _Compare>(__first, __m, __comp, __l2, __buff, __buff_size);
 233   std::__stable_sort<_AlgPolicy, _Compare>(__m, __last, __comp, __len - __l2, __buff, __buff_size);
 234   std::__inplace_merge<_AlgPolicy>(__first, __m, __last, __comp, __l2, __len - __l2, __buff, __buff_size);
 235 }
 236
 237 template <class _AlgPolicy, class _RandomAccessIterator, class _Compare>
 238 inline _LIBCPP_HIDE_FROM_ABI void
 239 __stable_sort_impl(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare& __comp) {
 240   using value_type      = typename iterator_traits<_RandomAccessIterator>::value_type;
 241   using difference_type = typename iterator_traits<_RandomAccessIterator>::difference_type;
 242
 243   difference_type __len = __last - __first;
 244   pair<value_type*, ptrdiff_t> __buf(0, 0);
 245   unique_ptr<value_type, __return_temporary_buffer> __h;
 246   if (__len > static_cast<difference_type>(__stable_sort_switch<value_type>::value)) {
 247     // TODO: Remove the use of std::get_temporary_buffer
 248     _LIBCPP_SUPPRESS_DEPRECATED_PUSH
 249     __buf = std::get_temporary_buffer<value_type>(__len);
 250     _LIBCPP_SUPPRESS_DEPRECATED_POP
 251     __h.reset(__buf.first);
 252   }
 253
 254   std::__stable_sort<_AlgPolicy, __comp_ref_type<_Compare> >(__first, __last, __comp, __len, __buf.first, __buf.second);
 255   std::__check_strict_weak_ordering_sorted(__first, __last, __comp);
 256 }
 257
 258 template <class _RandomAccessIterator, class _Compare>
 259 inline _LIBCPP_HIDE_FROM_ABI void
 260 stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
 261   std::__stable_sort_impl<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __comp);
 262 }
 263
 264 template <class _RandomAccessIterator>
 265 inline _LIBCPP_HIDE_FROM_ABI void stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last) {
 266   std::stable_sort(__first, __last, __less<>());
 267 }
 268
 269 _LIBCPP_END_NAMESPACE_STD
 270
 271 _LIBCPP_POP_MACROS
 272
 273 #endif // _LIBCPP___ALGORITHM_STABLE_SORT_H