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