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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/radix_sort.h>
17#include <__algorithm/sort.h>
18#include <__config>
19#include <__cstddef/ptrdiff_t.h>
20#include <__debug_utils/strict_weak_ordering_check.h>
21#include <__iterator/iterator_traits.h>
22#include <__memory/construct_at.h>
23#include <__memory/destruct_n.h>
24#include <__memory/unique_ptr.h>
25#include <__memory/unique_temporary_buffer.h>
26#include <__type_traits/desugars_to.h>
27#include <__type_traits/enable_if.h>
28#include <__type_traits/is_constant_evaluated.h>
29#include <__type_traits/is_same.h>
30#include <__type_traits/is_trivially_assignable.h>
31#include <__utility/move.h>
32#include <__utility/pair.h>
33
34#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
35# pragma GCC system_header
36#endif
37
38_LIBCPP_PUSH_MACROS
39#include <__undef_macros>
40
41_LIBCPP_BEGIN_NAMESPACE_STD
42
43template <class _AlgPolicy, class _Compare, class _BidirectionalIterator>
44_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void __insertion_sort_move(
45 _BidirectionalIterator __first1,
46 _BidirectionalIterator __last1,
47 typename iterator_traits<_BidirectionalIterator>::value_type* __first2,
48 _Compare __comp) {
49 using _Ops = _IterOps<_AlgPolicy>;
50
51 typedef typename iterator_traits<_BidirectionalIterator>::value_type value_type;
52 if (__first1 != __last1) {
53 __destruct_n __d(0);
54 unique_ptr<value_type, __destruct_n&> __h(__first2, __d);
55 value_type* __last2 = __first2;
56 std::__construct_at(__last2, _Ops::__iter_move(__first1));
57 __d.template __incr<value_type>();
58 for (++__last2; ++__first1 != __last1; ++__last2) {
59 value_type* __j2 = __last2;
60 value_type* __i2 = __j2;
61 if (__comp(*__first1, *--__i2)) {
62 std::__construct_at(__j2, std::move(*__i2));
63 __d.template __incr<value_type>();
64 for (--__j2; __i2 != __first2 && __comp(*__first1, *--__i2); --__j2)
65 *__j2 = std::move(*__i2);
66 *__j2 = _Ops::__iter_move(__first1);
67 } else {
68 std::__construct_at(__j2, _Ops::__iter_move(__first1));
69 __d.template __incr<value_type>();
70 }
71 }
72 __h.release();
73 }
74}
75
76template <class _AlgPolicy, class _Compare, class _InputIterator1, class _InputIterator2>
77_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void __merge_move_construct(
78 _InputIterator1 __first1,
79 _InputIterator1 __last1,
80 _InputIterator2 __first2,
81 _InputIterator2 __last2,
82 typename iterator_traits<_InputIterator1>::value_type* __result,
83 _Compare __comp) {
84 using _Ops = _IterOps<_AlgPolicy>;
85
86 typedef typename iterator_traits<_InputIterator1>::value_type value_type;
87 __destruct_n __d(0);
88 unique_ptr<value_type, __destruct_n&> __h(__result, __d);
89 for (; true; ++__result) {
90 if (__first1 == __last1) {
91 for (; __first2 != __last2; ++__first2, (void)++__result, __d.template __incr<value_type>())
92 std::__construct_at(__result, _Ops::__iter_move(__first2));
93 __h.release();
94 return;
95 }
96 if (__first2 == __last2) {
97 for (; __first1 != __last1; ++__first1, (void)++__result, __d.template __incr<value_type>())
98 std::__construct_at(__result, _Ops::__iter_move(__first1));
99 __h.release();
100 return;
101 }
102 if (__comp(*__first2, *__first1)) {
103 std::__construct_at(__result, _Ops::__iter_move(__first2));
104 __d.template __incr<value_type>();
105 ++__first2;
106 } else {
107 std::__construct_at(__result, _Ops::__iter_move(__first1));
108 __d.template __incr<value_type>();
109 ++__first1;
110 }
111 }
112}
113
114template <class _AlgPolicy, class _Compare, class _InputIterator1, class _InputIterator2, class _OutputIterator>
115_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void __merge_move_assign(
116 _InputIterator1 __first1,
117 _InputIterator1 __last1,
118 _InputIterator2 __first2,
119 _InputIterator2 __last2,
120 _OutputIterator __result,
121 _Compare __comp) {
122 using _Ops = _IterOps<_AlgPolicy>;
123
124 for (; __first1 != __last1; ++__result) {
125 if (__first2 == __last2) {
126 for (; __first1 != __last1; ++__first1, (void)++__result)
127 *__result = _Ops::__iter_move(__first1);
128 return;
129 }
130 if (__comp(*__first2, *__first1)) {
131 *__result = _Ops::__iter_move(__first2);
132 ++__first2;
133 } else {
134 *__result = _Ops::__iter_move(__first1);
135 ++__first1;
136 }
137 }
138 for (; __first2 != __last2; ++__first2, (void)++__result)
139 *__result = _Ops::__iter_move(__first2);
140}
141
142template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
143_LIBCPP_CONSTEXPR_SINCE_CXX26 void __stable_sort(
144 _RandomAccessIterator __first,
145 _RandomAccessIterator __last,
146 _Compare __comp,
147 typename iterator_traits<_RandomAccessIterator>::difference_type __len,
148 typename iterator_traits<_RandomAccessIterator>::value_type* __buff,
149 ptrdiff_t __buff_size);
150
151template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
152_LIBCPP_CONSTEXPR_SINCE_CXX26 void __stable_sort_move(
153 _RandomAccessIterator __first1,
154 _RandomAccessIterator __last1,
155 _Compare __comp,
156 typename iterator_traits<_RandomAccessIterator>::difference_type __len,
157 typename iterator_traits<_RandomAccessIterator>::value_type* __first2) {
158 using _Ops = _IterOps<_AlgPolicy>;
159
160 typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
161 switch (__len) {
162 case 0:
163 return;
164 case 1:
165 std::__construct_at(__first2, _Ops::__iter_move(__first1));
166 return;
167 case 2:
168 __destruct_n __d(0);
169 unique_ptr<value_type, __destruct_n&> __h2(__first2, __d);
170 if (__comp(*--__last1, *__first1)) {
171 std::__construct_at(__first2, _Ops::__iter_move(__last1));
172 __d.template __incr<value_type>();
173 ++__first2;
174 std::__construct_at(__first2, _Ops::__iter_move(__first1));
175 } else {
176 std::__construct_at(__first2, _Ops::__iter_move(__first1));
177 __d.template __incr<value_type>();
178 ++__first2;
179 std::__construct_at(__first2, _Ops::__iter_move(__last1));
180 }
181 __h2.release();
182 return;
183 }
184 if (__len <= 8) {
185 std::__insertion_sort_move<_AlgPolicy, _Compare>(__first1, __last1, __first2, __comp);
186 return;
187 }
188 typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
189 _RandomAccessIterator __m = __first1 + __l2;
190 std::__stable_sort<_AlgPolicy, _Compare>(__first1, __m, __comp, __l2, __first2, __l2);
191 std::__stable_sort<_AlgPolicy, _Compare>(__m, __last1, __comp, __len - __l2, __first2 + __l2, __len - __l2);
192 std::__merge_move_construct<_AlgPolicy, _Compare>(__first1, __m, __m, __last1, __first2, __comp);
193}
194
195template <class _Tp>
196struct __stable_sort_switch {
197 static const unsigned value = 128 * is_trivially_copy_assignable<_Tp>::value;
198};
199
200#if _LIBCPP_STD_VER >= 17
201template <class _Tp>
202_LIBCPP_HIDE_FROM_ABI constexpr unsigned __radix_sort_min_bound() {
203 static_assert(__is_ordered_integer_representable_v<_Tp>);
204 if constexpr (sizeof(_Tp) == 1) {
205 return 1 << 8;
206 }
207
208 return 1 << 10;
209}
210
211template <class _Tp>
212_LIBCPP_HIDE_FROM_ABI constexpr unsigned __radix_sort_max_bound() {
213 static_assert(__is_ordered_integer_representable_v<_Tp>);
214 if constexpr (sizeof(_Tp) >= 8) {
215 return 1 << 15;
216 }
217
218 return 1 << 16;
219}
220#endif // _LIBCPP_STD_VER >= 17
221
222template <class _AlgPolicy, class _Compare, class _RandomAccessIterator>
223_LIBCPP_CONSTEXPR_SINCE_CXX26 void __stable_sort(
224 _RandomAccessIterator __first,
225 _RandomAccessIterator __last,
226 _Compare __comp,
227 typename iterator_traits<_RandomAccessIterator>::difference_type __len,
228 typename iterator_traits<_RandomAccessIterator>::value_type* __buff,
229 ptrdiff_t __buff_size) {
230 typedef typename iterator_traits<_RandomAccessIterator>::value_type value_type;
231 typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
232 switch (__len) {
233 case 0:
234 case 1:
235 return;
236 case 2:
237 if (__comp(*--__last, *__first))
238 _IterOps<_AlgPolicy>::iter_swap(__first, __last);
239 return;
240 }
241 if (__len <= static_cast<difference_type>(__stable_sort_switch<value_type>::value)) {
242 std::__insertion_sort<_AlgPolicy, _Compare>(__first, __last, __comp);
243 return;
244 }
245
246#if _LIBCPP_STD_VER >= 17
247 constexpr auto __default_comp = __desugars_to_v<__less_tag, _Compare, value_type, value_type >;
248 constexpr auto __radix_sortable =
249 __is_ordered_integer_representable_v<value_type> &&
250 is_same_v< value_type&, __iter_reference<_RandomAccessIterator>>;
251 if constexpr (__default_comp && __radix_sortable) {
252 if (__len <= __buff_size && __len >= static_cast<difference_type>(std::__radix_sort_min_bound<value_type>()) &&
253 __len <= static_cast<difference_type>(std::__radix_sort_max_bound<value_type>())) {
254 if (__libcpp_is_constant_evaluated()) {
255 for (auto* __p = __buff; __p < __buff + __buff_size; ++__p) {
256 std::__construct_at(__p);
257 }
258 }
259
260 std::__radix_sort(__first, __last, __buff);
261 return;
262 }
263 }
264#endif // _LIBCPP_STD_VER >= 17
265
266 typename iterator_traits<_RandomAccessIterator>::difference_type __l2 = __len / 2;
267 _RandomAccessIterator __m = __first + __l2;
268 if (__len <= __buff_size) {
269 __destruct_n __d(0);
270 unique_ptr<value_type, __destruct_n&> __h2(__buff, __d);
271 std::__stable_sort_move<_AlgPolicy, _Compare>(__first, __m, __comp, __l2, __buff);
272 __d.__set(__l2, (value_type*)nullptr);
273 std::__stable_sort_move<_AlgPolicy, _Compare>(__m, __last, __comp, __len - __l2, __buff + __l2);
274 __d.__set(__len, (value_type*)nullptr);
275 std::__merge_move_assign<_AlgPolicy, _Compare>(
276 __buff, __buff + __l2, __buff + __l2, __buff + __len, __first, __comp);
277 // std::__merge<_Compare>(move_iterator<value_type*>(__buff),
278 // move_iterator<value_type*>(__buff + __l2),
279 // move_iterator<_RandomAccessIterator>(__buff + __l2),
280 // move_iterator<_RandomAccessIterator>(__buff + __len),
281 // __first, __comp);
282 return;
283 }
284 std::__stable_sort<_AlgPolicy, _Compare>(__first, __m, __comp, __l2, __buff, __buff_size);
285 std::__stable_sort<_AlgPolicy, _Compare>(__m, __last, __comp, __len - __l2, __buff, __buff_size);
286 std::__inplace_merge<_AlgPolicy>(__first, __m, __last, __comp, __l2, __len - __l2, __buff, __buff_size);
287}
288
289template <class _AlgPolicy, class _RandomAccessIterator, class _Compare>
290_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void
291__stable_sort_impl(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare& __comp) {
292 using value_type = typename iterator_traits<_RandomAccessIterator>::value_type;
293 using difference_type = typename iterator_traits<_RandomAccessIterator>::difference_type;
294
295 difference_type __len = __last - __first;
296 __unique_temporary_buffer<value_type> __unique_buf;
297 pair<value_type*, ptrdiff_t> __buf(0, 0);
298 if (__len > static_cast<difference_type>(__stable_sort_switch<value_type>::value)) {
299 __unique_buf = std::__allocate_unique_temporary_buffer<value_type>(__len);
300 __buf.first = __unique_buf.get();
301 __buf.second = __unique_buf.get_deleter().__count_;
302 }
303
304 std::__stable_sort<_AlgPolicy, __comp_ref_type<_Compare> >(__first, __last, __comp, __len, __buf.first, __buf.second);
305 std::__check_strict_weak_ordering_sorted(__first, __last, __comp);
306}
307
308template <class _RandomAccessIterator, class _Compare>
309_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void
310stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last, _Compare __comp) {
311 std::__stable_sort_impl<_ClassicAlgPolicy>(std::move(__first), std::move(__last), __comp);
312}
313
314template <class _RandomAccessIterator>
315_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void
316stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last) {
317 std::stable_sort(__first, __last, __less<>());
318}
319
320_LIBCPP_END_NAMESPACE_STD
321_LIBCPP_POP_MACROS
322
323#endif // _LIBCPP___ALGORITHM_STABLE_SORT_H
324

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source code of libcxx/include/__algorithm/stable_sort.h