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_copy_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_BEGIN_NAMESPACE_STD
  33
  34 template <class _AlgPolicy, class _Compare, class _BidirectionalIterator>
  35 _LIBCPP_HIDE_FROM_ABI
  36 void __insertion_sort_move(_BidirectionalIterator __first1, _BidirectionalIterator __last1,
  37                            typename iterator_traits<_BidirectionalIterator>::value_type* __first2, _Compare __comp) {
  38   using _Ops = _IterOps<_AlgPolicy>;
  39
  40   typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
  41   if (__first1 != __last1) {
  42     __destruct_n __d(0);
  43     unique_ptr<value_type, __destruct_n&> __h(__first2, __d);
  44     value_type* __last2 = __first2;
  45     ::new ((void*)__last2) value_type(_Ops::__iter_move(__first1));
  46     __d.template __incr<value_type>();
  47     for (++__last2; ++__first1 != __last1; ++__last2) {
  48       value_type* __j2 = __last2;
  49       value_type* __i2 = __j2;
  50       if (__comp(*__first1, *--__i2)) {
  51         ::new ((void*)__j2) value_type(std::move(*__i2));
  52         __d.template __incr<value_type>();
  53         for (--__j2; __i2 != __first2 && __comp(*__first1, *--__i2); --__j2)
  54           *__j2 = std::move(*__i2);
  55         *__j2 = _Ops::__iter_move(__first1);
  56       } else {
  57         ::new ((void*)__j2) value_type(_Ops::__iter_move(__first1));
  58         __d.template __incr<value_type>();
  59       }
  60     }
  61     __h.release();
  62   }
  63 }
  64
  65 template <class _AlgPolicy, class _Compare, class _InputIterator1, class _InputIterator2>
  66 _LIBCPP_HIDE_FROM_ABI void
  67 __merge_move_construct(_InputIterator1 __first1, _InputIterator1 __last1,
  68         _InputIterator2 __first2, _InputIterator2 __last2,
  69         typename iterator_traits<_InputIterator1>::value_type* __result, _Compare __comp)
  70 {
  71     using _Ops = _IterOps<_AlgPolicy>;
  72
  73     typedef typename iterator_traits<_InputIterator1>::value_type value_type;
  74     __destruct_n __d(0);
  75     unique_ptr<value_type, __destruct_n&> __h(__result, __d);
  76     for (; true; ++__result)
  77     {
  78         if (__first1 == __last1)
  79         {
  80             for (; __first2 != __last2; ++__first2, (void) ++__result, __d.template __incr<value_type>())
  81                 ::new ((void*)__result) value_type(_Ops::__iter_move(__first2));
  82             __h.release();
  83             return;
  84         }
  85         if (__first2 == __last2)
  86         {
  87             for (; __first1 != __last1; ++__first1, (void) ++__result, __d.template __incr<value_type>())
  88                 ::new ((void*)__result) value_type(_Ops::__iter_move(__first1));
  89             __h.release();
  90             return;
  91         }
  92         if (__comp(*__first2, *__first1))
  93         {
  94             ::new ((void*)__result) value_type(_Ops::__iter_move(__first2));
  95             __d.template __incr<value_type>();
  96             ++__first2;
  97         }
  98         else
  99         {
 100             ::new ((void*)__result) value_type(_Ops::__iter_move(__first1));
 101             __d.template __incr<value_type>();
 102             ++__first1;
 103         }
 104     }
 105 }
 106
 107 template <class _AlgPolicy, class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
 108 _LIBCPP_HIDE_FROM_ABI void
 109 __merge_move_assign(_InputIterator1 __first1, _InputIterator1 __last1,
 110         _InputIterator2 __first2, _InputIterator2 __last2,
 111         _OutputIterator __result, _Compare __comp)
 112 {
 113     using _Ops = _IterOps<_AlgPolicy>;
 114
 115     for (; __first1 != __last1; ++__result)
 116     {
 117         if (__first2 == __last2)
 118         {
 119             for (; __first1 != __last1; ++__first1, (void) ++__result)
 120                 *__result = _Ops::__iter_move(__first1);
 121             return;
 122         }
 123         if (__comp(*__first2, *__first1))
 124         {
 125             *__result = _Ops::__iter_move(__first2);
 126             ++__first2;
 127         }
 128         else
 129         {
 130             *__result = _Ops::__iter_move(__first1);
 131             ++__first1;
 132         }
 133     }
 134     for (; __first2 != __last2; ++__first2, (void) ++__result)
 135         *__result = _Ops::__iter_move(__first2);
 136 }
 137
 138 template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
 139 void
 140 __stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
 141               typename iterator_traits<_RandomAccessIterator>::difference_type __len,
 142               typename iterator_traits<_RandomAccessIterator>::value_type* __buff, ptrdiff_t __buff_size);
 143
 144 template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
 145 void
 146 __stable_sort_move(_RandomAccessIterator __first1, _RandomAccessIterator __last1, _Compare __comp,
 147                    typename iterator_traits<_RandomAccessIterator>::difference_type __len,
 148                    typename iterator_traits<_RandomAccessIterator>::value_type* __first2)
 149 {
 150     using _Ops = _IterOps<_AlgPolicy>;
 151
 152     typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
 153     switch (__len)
 154     {
 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         {
 165             ::new ((void*)__first2) value_type(_Ops::__iter_move(__last1));
 166             __d.template __incr<value_type>();
 167             ++__first2;
 168             ::new ((void*)__first2) value_type(_Ops::__iter_move(__first1));
 169         }
 170         else
 171         {
 172             ::new ((void*)__first2) value_type(_Ops::__iter_move(__first1));
 173             __d.template __incr<value_type>();
 174             ++__first2;
 175             ::new ((void*)__first2) value_type(_Ops::__iter_move(__last1));
 176         }
 177         __h2.release();
 178         return;
 179     }
 180     if (__len <= 8)
 181     {
 182         std::__insertion_sort_move<_AlgPolicy, _Compare>(__first1, __last1, __first2, __comp);
 183         return;
 184     }
 185     typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
 186     _RandomAccessIterator __m = __first1 + __l2;
 187     std::__stable_sort<_AlgPolicy, _Compare>(__first1, __m, __comp, __l2, __first2, __l2);
 188     std::__stable_sort<_AlgPolicy, _Compare>(__m, __last1, __comp, __len - __l2, __first2 + __l2, __len - __l2);
 189     std::__merge_move_construct<_AlgPolicy, _Compare>(__first1, __m, __m, __last1, __first2, __comp);
 190 }
 191
 192 template <class _Tp>
 193 struct __stable_sort_switch
 194 {
 195     static const unsigned value = 128*is_trivially_copy_assignable<_Tp>::value;
 196 };
 197
 198 template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
 199 void
 200 __stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp,
 201               typename iterator_traits<_RandomAccessIterator>::difference_type __len,
 202               typename iterator_traits<_RandomAccessIterator>::value_type* __buff, ptrdiff_t __buff_size)
 203 {
 204     typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
 205     typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
 206     switch (__len)
 207     {
 208     case 0:
 209     case 1:
 210         return;
 211     case 2:
 212         if (__comp(*--__last, *__first))
 213             _IterOps<_AlgPolicy>::iter_swap(__first, __last);
 214         return;
 215     }
 216     if (__len <= static_cast<difference_type>(__stable_sort_switch<value_type>::value))
 217     {
 218         std::__insertion_sort<_AlgPolicy, _Compare>(__first, __last, __comp);
 219         return;
 220     }
 221     typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
 222     _RandomAccessIterator __m = __first + __l2;
 223     if (__len <= __buff_size)
 224     {
 225         __destruct_n __d(0);
 226         unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
 227         std::__stable_sort_move<_AlgPolicy, _Compare>(__first, __m, __comp, __l2, __buff);
 228         __d.__set(__l2, (value_type*)nullptr);
 229         std::__stable_sort_move<_AlgPolicy, _Compare>(__m, __last, __comp, __len - __l2, __buff + __l2);
 230         __d.__set(__len, (value_type*)nullptr);
 231         std::__merge_move_assign<_AlgPolicy, _Compare>(
 232             __buff, __buff + __l2, __buff + __l2, __buff + __len, __first, __comp);
 233 //         _VSTD::__merge<_Compare>(move_iterator<value_type*>(__buff),
 234 //                                  move_iterator<value_type*>(__buff + __l2),
 235 //                                  move_iterator<_RandomAccessIterator>(__buff + __l2),
 236 //                                  move_iterator<_RandomAccessIterator>(__buff + __len),
 237 //                                  __first, __comp);
 238         return;
 239     }
 240     std::__stable_sort<_AlgPolicy, _Compare>(__first, __m, __comp, __l2, __buff, __buff_size);
 241     std::__stable_sort<_AlgPolicy, _Compare>(__m, __last, __comp, __len - __l2, __buff, __buff_size);
 242     std::__inplace_merge<_AlgPolicy>(__first, __m, __last, __comp, __l2, __len - __l2, __buff, __buff_size);
 243 }
 244
 245 template <class _AlgPolicy, class _RandomAccessIterator, class _Compare>
 246 inline _LIBCPP_HIDE_FROM_ABI
 247 void __stable_sort_impl(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare& __comp) {
 248   using value_type = typename iterator_traits<_RandomAccessIterator>::value_type;
 249   using difference_type = typename iterator_traits<_RandomAccessIterator>::difference_type;
 250
 251   difference_type __len = __last - __first;
 252   pair<value_type*, ptrdiff_t> __buf(0, 0);
 253   unique_ptr<value_type, __return_temporary_buffer> __h;
 254   if (__len > static_cast<difference_type>(__stable_sort_switch<value_type>::value)) {
 255 // TODO: Remove the use of std::get_temporary_buffer
 256 _LIBCPP_SUPPRESS_DEPRECATED_PUSH
 257       __buf = std::get_temporary_buffer<value_type>(__len);
 258 _LIBCPP_SUPPRESS_DEPRECATED_POP
 259       __h.reset(__buf.first);
 260   }
 261
 262   std::__stable_sort<_AlgPolicy, __comp_ref_type<_Compare> >(__first, __last, __comp, __len, __buf.first, __buf.second);
 263   std::__check_strict_weak_ordering_sorted(__first, __last, __comp);
 264 }
 265
 266 template <class _RandomAccessIterator, class _Compare>
 267 inline _LIBCPP_HIDE_FROM_ABI
 268 void stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
 269   std::__stable_sort_impl<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __comp);
 270 }
 271
 272 template <class _RandomAccessIterator>
 273 inline _LIBCPP_HIDE_FROM_ABI
 274 void stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last) {
 275   std::stable_sort(__first, __last, __less<>());
 276 }
 277
 278 _LIBCPP_END_NAMESPACE_STD
 279
 280 #endif // _LIBCPP___ALGORITHM_STABLE_SORT_H