1 // Core algorithmic facilities -*- C++ -*-
2
3 // Copyright (C) 2020-2021 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24
25 /** @file bits/ranges_algobase.h
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly. @headername{algorithm}
28 */
29
30 #ifndef _RANGES_ALGOBASE_H
31 #define _RANGES_ALGOBASE_H 1
32
33 #if __cplusplus > 201703L
34
35 #include <compare>
36 #include <iterator>
37 #include <bits/ranges_base.h> // ranges::begin, ranges::range etc.
38 #include <bits/invoke.h> // __invoke
39 #include <bits/cpp_type_traits.h> // __is_byte
40
41 #if __cpp_lib_concepts
_GLIBCXX_VISIBILITY(default)42 namespace std _GLIBCXX_VISIBILITY(default)
43 {
44 _GLIBCXX_BEGIN_NAMESPACE_VERSION
45 namespace ranges
46 {
47 namespace __detail
48 {
49 template<typename _Tp>
50 constexpr inline bool __is_normal_iterator = false;
51
52 template<typename _Iterator, typename _Container>
53 constexpr inline bool
54 __is_normal_iterator<__gnu_cxx::__normal_iterator<_Iterator,
55 _Container>> = true;
56
57 template<typename _Tp>
58 constexpr inline bool __is_reverse_iterator = false;
59
60 template<typename _Iterator>
61 constexpr inline bool
62 __is_reverse_iterator<reverse_iterator<_Iterator>> = true;
63
64 template<typename _Tp>
65 constexpr inline bool __is_move_iterator = false;
66
67 template<typename _Iterator>
68 constexpr inline bool
69 __is_move_iterator<move_iterator<_Iterator>> = true;
70 } // namespace __detail
71
72 struct __equal_fn
73 {
74 template<input_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
75 input_iterator _Iter2, sentinel_for<_Iter2> _Sent2,
76 typename _Pred = ranges::equal_to,
77 typename _Proj1 = identity, typename _Proj2 = identity>
78 requires indirectly_comparable<_Iter1, _Iter2, _Pred, _Proj1, _Proj2>
79 constexpr bool
80 operator()(_Iter1 __first1, _Sent1 __last1,
81 _Iter2 __first2, _Sent2 __last2, _Pred __pred = {},
82 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
83 {
84 // TODO: implement more specializations to at least have parity with
85 // std::equal.
86 if constexpr (__detail::__is_normal_iterator<_Iter1>
87 && same_as<_Iter1, _Sent1>)
88 return (*this)(__first1.base(), __last1.base(),
89 std::move(__first2), std::move(__last2),
90 std::move(__pred),
91 std::move(__proj1), std::move(__proj2));
92 else if constexpr (__detail::__is_normal_iterator<_Iter2>
93 && same_as<_Iter2, _Sent2>)
94 return (*this)(std::move(__first1), std::move(__last1),
95 __first2.base(), __last2.base(),
96 std::move(__pred),
97 std::move(__proj1), std::move(__proj2));
98 else if constexpr (sized_sentinel_for<_Sent1, _Iter1>
99 && sized_sentinel_for<_Sent2, _Iter2>)
100 {
101 auto __d1 = ranges::distance(__first1, __last1);
102 auto __d2 = ranges::distance(__first2, __last2);
103 if (__d1 != __d2)
104 return false;
105
106 using _ValueType1 = iter_value_t<_Iter1>;
107 constexpr bool __use_memcmp
108 = ((is_integral_v<_ValueType1> || is_pointer_v<_ValueType1>)
109 && __memcmpable<_Iter1, _Iter2>::__value
110 && is_same_v<_Pred, ranges::equal_to>
111 && is_same_v<_Proj1, identity>
112 && is_same_v<_Proj2, identity>);
113 if constexpr (__use_memcmp)
114 {
115 if (const size_t __len = (__last1 - __first1))
116 return !std::__memcmp(__first1, __first2, __len);
117 return true;
118 }
119 else
120 {
121 for (; __first1 != __last1; ++__first1, (void)++__first2)
122 if (!(bool)std::__invoke(__pred,
123 std::__invoke(__proj1, *__first1),
124 std::__invoke(__proj2, *__first2)))
125 return false;
126 return true;
127 }
128 }
129 else
130 {
131 for (; __first1 != __last1 && __first2 != __last2;
132 ++__first1, (void)++__first2)
133 if (!(bool)std::__invoke(__pred,
134 std::__invoke(__proj1, *__first1),
135 std::__invoke(__proj2, *__first2)))
136 return false;
137 return __first1 == __last1 && __first2 == __last2;
138 }
139 }
140
141 template<input_range _Range1, input_range _Range2,
142 typename _Pred = ranges::equal_to,
143 typename _Proj1 = identity, typename _Proj2 = identity>
144 requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>,
145 _Pred, _Proj1, _Proj2>
146 constexpr bool
147 operator()(_Range1&& __r1, _Range2&& __r2, _Pred __pred = {},
148 _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
149 {
150 return (*this)(ranges::begin(__r1), ranges::end(__r1),
151 ranges::begin(__r2), ranges::end(__r2),
152 std::move(__pred),
153 std::move(__proj1), std::move(__proj2));
154 }
155 };
156
157 inline constexpr __equal_fn equal{};
158
159 template<typename _Iter, typename _Out>
160 struct in_out_result
161 {
162 [[no_unique_address]] _Iter in;
163 [[no_unique_address]] _Out out;
164
165 template<typename _Iter2, typename _Out2>
166 requires convertible_to<const _Iter&, _Iter2>
167 && convertible_to<const _Out&, _Out2>
168 constexpr
169 operator in_out_result<_Iter2, _Out2>() const &
170 { return {in, out}; }
171
172 template<typename _Iter2, typename _Out2>
173 requires convertible_to<_Iter, _Iter2>
174 && convertible_to<_Out, _Out2>
175 constexpr
176 operator in_out_result<_Iter2, _Out2>() &&
177 { return {std::move(in), std::move(out)}; }
178 };
179
180 template<typename _Iter, typename _Out>
181 using copy_result = in_out_result<_Iter, _Out>;
182
183 template<typename _Iter, typename _Out>
184 using move_result = in_out_result<_Iter, _Out>;
185
186 template<typename _Iter1, typename _Iter2>
187 using move_backward_result = in_out_result<_Iter1, _Iter2>;
188
189 template<typename _Iter1, typename _Iter2>
190 using copy_backward_result = in_out_result<_Iter1, _Iter2>;
191
192 template<bool _IsMove,
193 bidirectional_iterator _Iter, sentinel_for<_Iter> _Sent,
194 bidirectional_iterator _Out>
195 requires (_IsMove
196 ? indirectly_movable<_Iter, _Out>
197 : indirectly_copyable<_Iter, _Out>)
198 constexpr conditional_t<_IsMove,
199 move_backward_result<_Iter, _Out>,
200 copy_backward_result<_Iter, _Out>>
201 __copy_or_move_backward(_Iter __first, _Sent __last, _Out __result);
202
203 template<bool _IsMove,
204 input_iterator _Iter, sentinel_for<_Iter> _Sent,
205 weakly_incrementable _Out>
206 requires (_IsMove
207 ? indirectly_movable<_Iter, _Out>
208 : indirectly_copyable<_Iter, _Out>)
209 constexpr conditional_t<_IsMove,
210 move_result<_Iter, _Out>,
211 copy_result<_Iter, _Out>>
212 __copy_or_move(_Iter __first, _Sent __last, _Out __result)
213 {
214 // TODO: implement more specializations to be at least on par with
215 // std::copy/std::move.
216 using __detail::__is_move_iterator;
217 using __detail::__is_reverse_iterator;
218 using __detail::__is_normal_iterator;
219 if constexpr (__is_move_iterator<_Iter> && same_as<_Iter, _Sent>)
220 {
221 auto [__in, __out]
222 = ranges::__copy_or_move<true>(std::move(__first).base(),
223 std::move(__last).base(),
224 std::move(__result));
225 return {move_iterator{std::move(__in)}, std::move(__out)};
226 }
227 else if constexpr (__is_reverse_iterator<_Iter> && same_as<_Iter, _Sent>
228 && __is_reverse_iterator<_Out>)
229 {
230 auto [__in,__out]
231 = ranges::__copy_or_move_backward<_IsMove>(std::move(__last).base(),
232 std::move(__first).base(),
233 std::move(__result).base());
234 return {reverse_iterator{std::move(__in)},
235 reverse_iterator{std::move(__out)}};
236 }
237 else if constexpr (__is_normal_iterator<_Iter> && same_as<_Iter, _Sent>)
238 {
239 auto [__in,__out]
240 = ranges::__copy_or_move<_IsMove>(__first.base(), __last.base(),
241 __result);
242 return {decltype(__first){__in}, std::move(__out)};
243 }
244 else if constexpr (__is_normal_iterator<_Out>)
245 {
246 auto [__in,__out]
247 = ranges::__copy_or_move<_IsMove>(__first, __last, __result.base());
248 return {std::move(__in), decltype(__result){__out}};
249 }
250 else if constexpr (sized_sentinel_for<_Sent, _Iter>)
251 {
252 #ifdef __cpp_lib_is_constant_evaluated
253 if (!std::is_constant_evaluated())
254 #endif
255 {
256 if constexpr (__memcpyable<_Iter, _Out>::__value)
257 {
258 using _ValueTypeI = iter_value_t<_Iter>;
259 static_assert(_IsMove
260 ? is_move_assignable_v<_ValueTypeI>
261 : is_copy_assignable_v<_ValueTypeI>);
262 auto __num = __last - __first;
263 if (__num)
264 __builtin_memmove(__result, __first,
265 sizeof(_ValueTypeI) * __num);
266 return {__first + __num, __result + __num};
267 }
268 }
269
270 for (auto __n = __last - __first; __n > 0; --__n)
271 {
272 if constexpr (_IsMove)
273 *__result = std::move(*__first);
274 else
275 *__result = *__first;
276 ++__first;
277 ++__result;
278 }
279 return {std::move(__first), std::move(__result)};
280 }
281 else
282 {
283 while (__first != __last)
284 {
285 if constexpr (_IsMove)
286 *__result = std::move(*__first);
287 else
288 *__result = *__first;
289 ++__first;
290 ++__result;
291 }
292 return {std::move(__first), std::move(__result)};
293 }
294 }
295
296 struct __copy_fn
297 {
298 template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
299 weakly_incrementable _Out>
300 requires indirectly_copyable<_Iter, _Out>
301 constexpr copy_result<_Iter, _Out>
302 operator()(_Iter __first, _Sent __last, _Out __result) const
303 {
304 return ranges::__copy_or_move<false>(std::move(__first),
305 std::move(__last),
306 std::move(__result));
307 }
308
309 template<input_range _Range, weakly_incrementable _Out>
310 requires indirectly_copyable<iterator_t<_Range>, _Out>
311 constexpr copy_result<borrowed_iterator_t<_Range>, _Out>
312 operator()(_Range&& __r, _Out __result) const
313 {
314 return (*this)(ranges::begin(__r), ranges::end(__r),
315 std::move(__result));
316 }
317 };
318
319 inline constexpr __copy_fn copy{};
320
321 struct __move_fn
322 {
323 template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
324 weakly_incrementable _Out>
325 requires indirectly_movable<_Iter, _Out>
326 constexpr move_result<_Iter, _Out>
327 operator()(_Iter __first, _Sent __last, _Out __result) const
328 {
329 return ranges::__copy_or_move<true>(std::move(__first),
330 std::move(__last),
331 std::move(__result));
332 }
333
334 template<input_range _Range, weakly_incrementable _Out>
335 requires indirectly_movable<iterator_t<_Range>, _Out>
336 constexpr move_result<borrowed_iterator_t<_Range>, _Out>
337 operator()(_Range&& __r, _Out __result) const
338 {
339 return (*this)(ranges::begin(__r), ranges::end(__r),
340 std::move(__result));
341 }
342 };
343
344 inline constexpr __move_fn move{};
345
346 template<bool _IsMove,
347 bidirectional_iterator _Iter, sentinel_for<_Iter> _Sent,
348 bidirectional_iterator _Out>
349 requires (_IsMove
350 ? indirectly_movable<_Iter, _Out>
351 : indirectly_copyable<_Iter, _Out>)
352 constexpr conditional_t<_IsMove,
353 move_backward_result<_Iter, _Out>,
354 copy_backward_result<_Iter, _Out>>
355 __copy_or_move_backward(_Iter __first, _Sent __last, _Out __result)
356 {
357 // TODO: implement more specializations to be at least on par with
358 // std::copy_backward/std::move_backward.
359 using __detail::__is_reverse_iterator;
360 using __detail::__is_normal_iterator;
361 if constexpr (__is_reverse_iterator<_Iter> && same_as<_Iter, _Sent>
362 && __is_reverse_iterator<_Out>)
363 {
364 auto [__in,__out]
365 = ranges::__copy_or_move<_IsMove>(std::move(__last).base(),
366 std::move(__first).base(),
367 std::move(__result).base());
368 return {reverse_iterator{std::move(__in)},
369 reverse_iterator{std::move(__out)}};
370 }
371 else if constexpr (__is_normal_iterator<_Iter> && same_as<_Iter, _Sent>)
372 {
373 auto [__in,__out]
374 = ranges::__copy_or_move_backward<_IsMove>(__first.base(),
375 __last.base(),
376 std::move(__result));
377 return {decltype(__first){__in}, std::move(__out)};
378 }
379 else if constexpr (__is_normal_iterator<_Out>)
380 {
381 auto [__in,__out]
382 = ranges::__copy_or_move_backward<_IsMove>(std::move(__first),
383 std::move(__last),
384 __result.base());
385 return {std::move(__in), decltype(__result){__out}};
386 }
387 else if constexpr (sized_sentinel_for<_Sent, _Iter>)
388 {
389 #ifdef __cpp_lib_is_constant_evaluated
390 if (!std::is_constant_evaluated())
391 #endif
392 {
393 if constexpr (__memcpyable<_Out, _Iter>::__value)
394 {
395 using _ValueTypeI = iter_value_t<_Iter>;
396 static_assert(_IsMove
397 ? is_move_assignable_v<_ValueTypeI>
398 : is_copy_assignable_v<_ValueTypeI>);
399 auto __num = __last - __first;
400 if (__num)
401 __builtin_memmove(__result - __num, __first,
402 sizeof(_ValueTypeI) * __num);
403 return {__first + __num, __result - __num};
404 }
405 }
406
407 auto __lasti = ranges::next(__first, __last);
408 auto __tail = __lasti;
409
410 for (auto __n = __last - __first; __n > 0; --__n)
411 {
412 --__tail;
413 --__result;
414 if constexpr (_IsMove)
415 *__result = std::move(*__tail);
416 else
417 *__result = *__tail;
418 }
419 return {std::move(__lasti), std::move(__result)};
420 }
421 else
422 {
423 auto __lasti = ranges::next(__first, __last);
424 auto __tail = __lasti;
425
426 while (__first != __tail)
427 {
428 --__tail;
429 --__result;
430 if constexpr (_IsMove)
431 *__result = std::move(*__tail);
432 else
433 *__result = *__tail;
434 }
435 return {std::move(__lasti), std::move(__result)};
436 }
437 }
438
439 struct __copy_backward_fn
440 {
441 template<bidirectional_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
442 bidirectional_iterator _Iter2>
443 requires indirectly_copyable<_Iter1, _Iter2>
444 constexpr copy_backward_result<_Iter1, _Iter2>
445 operator()(_Iter1 __first, _Sent1 __last, _Iter2 __result) const
446 {
447 return ranges::__copy_or_move_backward<false>(std::move(__first),
448 std::move(__last),
449 std::move(__result));
450 }
451
452 template<bidirectional_range _Range, bidirectional_iterator _Iter>
453 requires indirectly_copyable<iterator_t<_Range>, _Iter>
454 constexpr copy_backward_result<borrowed_iterator_t<_Range>, _Iter>
455 operator()(_Range&& __r, _Iter __result) const
456 {
457 return (*this)(ranges::begin(__r), ranges::end(__r),
458 std::move(__result));
459 }
460 };
461
462 inline constexpr __copy_backward_fn copy_backward{};
463
464 struct __move_backward_fn
465 {
466 template<bidirectional_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
467 bidirectional_iterator _Iter2>
468 requires indirectly_movable<_Iter1, _Iter2>
469 constexpr move_backward_result<_Iter1, _Iter2>
470 operator()(_Iter1 __first, _Sent1 __last, _Iter2 __result) const
471 {
472 return ranges::__copy_or_move_backward<true>(std::move(__first),
473 std::move(__last),
474 std::move(__result));
475 }
476
477 template<bidirectional_range _Range, bidirectional_iterator _Iter>
478 requires indirectly_movable<iterator_t<_Range>, _Iter>
479 constexpr move_backward_result<borrowed_iterator_t<_Range>, _Iter>
480 operator()(_Range&& __r, _Iter __result) const
481 {
482 return (*this)(ranges::begin(__r), ranges::end(__r),
483 std::move(__result));
484 }
485 };
486
487 inline constexpr __move_backward_fn move_backward{};
488
489 template<typename _Iter, typename _Out>
490 using copy_n_result = in_out_result<_Iter, _Out>;
491
492 struct __copy_n_fn
493 {
494 template<input_iterator _Iter, weakly_incrementable _Out>
495 requires indirectly_copyable<_Iter, _Out>
496 constexpr copy_n_result<_Iter, _Out>
497 operator()(_Iter __first, iter_difference_t<_Iter> __n,
498 _Out __result) const
499 {
500 if constexpr (random_access_iterator<_Iter>)
501 {
502 if (__n > 0)
503 return ranges::copy(__first, __first + __n, std::move(__result));
504 }
505 else
506 {
507 for (; __n > 0; --__n, (void)++__result, (void)++__first)
508 *__result = *__first;
509 }
510 return {std::move(__first), std::move(__result)};
511 }
512 };
513
514 inline constexpr __copy_n_fn copy_n{};
515
516 struct __fill_n_fn
517 {
518 template<typename _Tp, output_iterator<const _Tp&> _Out>
519 constexpr _Out
520 operator()(_Out __first, iter_difference_t<_Out> __n,
521 const _Tp& __value) const
522 {
523 // TODO: implement more specializations to be at least on par with
524 // std::fill_n
525 if (__n <= 0)
526 return __first;
527
528 // TODO: Generalize this optimization to contiguous iterators.
529 if constexpr (is_pointer_v<_Out>
530 // Note that __is_byte already implies !is_volatile.
531 && __is_byte<remove_pointer_t<_Out>>::__value
532 && integral<_Tp>)
533 {
534 __builtin_memset(__first, static_cast<unsigned char>(__value), __n);
535 return __first + __n;
536 }
537 else if constexpr (is_scalar_v<_Tp>)
538 {
539 const auto __tmp = __value;
540 for (; __n > 0; --__n, (void)++__first)
541 *__first = __tmp;
542 return __first;
543 }
544 else
545 {
546 for (; __n > 0; --__n, (void)++__first)
547 *__first = __value;
548 return __first;
549 }
550 }
551 };
552
553 inline constexpr __fill_n_fn fill_n{};
554
555 struct __fill_fn
556 {
557 template<typename _Tp,
558 output_iterator<const _Tp&> _Out, sentinel_for<_Out> _Sent>
559 constexpr _Out
560 operator()(_Out __first, _Sent __last, const _Tp& __value) const
561 {
562 // TODO: implement more specializations to be at least on par with
563 // std::fill
564 if constexpr (sized_sentinel_for<_Sent, _Out>)
565 {
566 const auto __len = __last - __first;
567 return ranges::fill_n(__first, __len, __value);
568 }
569 else if constexpr (is_scalar_v<_Tp>)
570 {
571 const auto __tmp = __value;
572 for (; __first != __last; ++__first)
573 *__first = __tmp;
574 return __first;
575 }
576 else
577 {
578 for (; __first != __last; ++__first)
579 *__first = __value;
580 return __first;
581 }
582 }
583
584 template<typename _Tp, output_range<const _Tp&> _Range>
585 constexpr borrowed_iterator_t<_Range>
586 operator()(_Range&& __r, const _Tp& __value) const
587 {
588 return (*this)(ranges::begin(__r), ranges::end(__r), __value);
589 }
590 };
591
592 inline constexpr __fill_fn fill{};
593 }
594 _GLIBCXX_END_NAMESPACE_VERSION
595 } // namespace std
596 #endif // concepts
597 #endif // C++20
598 #endif // _RANGES_ALGOBASE_H
599