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_PUSH_MACROS
33 #include <__undef_macros>
34 
35 _LIBCPP_BEGIN_NAMESPACE_STD
36 
37 template <class _AlgPolicy, class _Compare, class _BidirectionalIterator>
__insertion_sort_move(_BidirectionalIterator __first1,_BidirectionalIterator __last1,typename iterator_traits<_BidirectionalIterator>::value_type * __first2,_Compare __comp)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>
__merge_move_construct(_InputIterator1 __first1,_InputIterator1 __last1,_InputIterator2 __first2,_InputIterator2 __last2,typename iterator_traits<_InputIterator1>::value_type * __result,_Compare __comp)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>
__merge_move_assign(_InputIterator1 __first1,_InputIterator1 __last1,_InputIterator2 __first2,_InputIterator2 __last2,_OutputIterator __result,_Compare __comp)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>
__stable_sort_move(_RandomAccessIterator __first1,_RandomAccessIterator __last1,_Compare __comp,typename iterator_traits<_RandomAccessIterator>::difference_type __len,typename iterator_traits<_RandomAccessIterator>::value_type * __first2)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>
__stable_sort(_RandomAccessIterator __first,_RandomAccessIterator __last,_Compare __comp,typename iterator_traits<_RandomAccessIterator>::difference_type __len,typename iterator_traits<_RandomAccessIterator>::value_type * __buff,ptrdiff_t __buff_size)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
__stable_sort_impl(_RandomAccessIterator __first,_RandomAccessIterator __last,_Compare & __comp)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
stable_sort(_RandomAccessIterator __first,_RandomAccessIterator __last,_Compare __comp)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>
stable_sort(_RandomAccessIterator __first,_RandomAccessIterator __last)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
274