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
281