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1 | // Utilities for representing and manipulating ranges -*- C++ -*- |
2 | ||
99dee823 | 3 | // Copyright (C) 2019-2021 Free Software Foundation, Inc. |
160061ac JW |
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_util.h | |
26 | * This is an internal header file, included by other library headers. | |
27 | * Do not attempt to use it directly. @headername{ranges} | |
28 | */ | |
29 | ||
30 | #ifndef _RANGES_UTIL_H | |
31 | #define _RANGES_UTIL_H 1 | |
32 | ||
33 | #if __cplusplus > 201703L | |
34 | # include <bits/ranges_base.h> | |
35 | ||
36 | #ifdef __cpp_lib_ranges | |
37 | namespace std _GLIBCXX_VISIBILITY(default) | |
38 | { | |
39 | _GLIBCXX_BEGIN_NAMESPACE_VERSION | |
40 | namespace ranges | |
41 | { | |
42 | // C++20 24.5 [range.utility] Range utilities | |
43 | ||
44 | namespace __detail | |
45 | { | |
46 | template<typename _Range> | |
47 | concept __simple_view = view<_Range> && range<const _Range> | |
48 | && same_as<iterator_t<_Range>, iterator_t<const _Range>> | |
49 | && same_as<sentinel_t<_Range>, sentinel_t<const _Range>>; | |
50 | ||
51 | template<typename _It> | |
52 | concept __has_arrow = input_iterator<_It> | |
53 | && (is_pointer_v<_It> || requires(_It __it) { __it.operator->(); }); | |
54 | ||
55 | template<typename _Tp, typename _Up> | |
56 | concept __not_same_as | |
57 | = !same_as<remove_cvref_t<_Tp>, remove_cvref_t<_Up>>; | |
58 | } // namespace __detail | |
59 | ||
60 | /// The ranges::view_interface class template | |
61 | template<typename _Derived> | |
62 | requires is_class_v<_Derived> && same_as<_Derived, remove_cv_t<_Derived>> | |
63 | class view_interface : public view_base | |
64 | { | |
65 | private: | |
66 | constexpr _Derived& _M_derived() noexcept | |
67 | { | |
68 | static_assert(derived_from<_Derived, view_interface<_Derived>>); | |
69 | static_assert(view<_Derived>); | |
70 | return static_cast<_Derived&>(*this); | |
71 | } | |
72 | ||
73 | constexpr const _Derived& _M_derived() const noexcept | |
74 | { | |
75 | static_assert(derived_from<_Derived, view_interface<_Derived>>); | |
76 | static_assert(view<_Derived>); | |
77 | return static_cast<const _Derived&>(*this); | |
78 | } | |
79 | ||
80 | public: | |
81 | constexpr bool | |
82 | empty() requires forward_range<_Derived> | |
83 | { return ranges::begin(_M_derived()) == ranges::end(_M_derived()); } | |
84 | ||
85 | constexpr bool | |
86 | empty() const requires forward_range<const _Derived> | |
87 | { return ranges::begin(_M_derived()) == ranges::end(_M_derived()); } | |
88 | ||
89 | constexpr explicit | |
90 | operator bool() requires requires { ranges::empty(_M_derived()); } | |
91 | { return !ranges::empty(_M_derived()); } | |
92 | ||
93 | constexpr explicit | |
94 | operator bool() const requires requires { ranges::empty(_M_derived()); } | |
95 | { return !ranges::empty(_M_derived()); } | |
96 | ||
97 | constexpr auto | |
98 | data() requires contiguous_iterator<iterator_t<_Derived>> | |
99 | { return to_address(ranges::begin(_M_derived())); } | |
100 | ||
101 | constexpr auto | |
102 | data() const | |
103 | requires range<const _Derived> | |
104 | && contiguous_iterator<iterator_t<const _Derived>> | |
105 | { return to_address(ranges::begin(_M_derived())); } | |
106 | ||
107 | constexpr auto | |
108 | size() | |
109 | requires forward_range<_Derived> | |
110 | && sized_sentinel_for<sentinel_t<_Derived>, iterator_t<_Derived>> | |
111 | { return ranges::end(_M_derived()) - ranges::begin(_M_derived()); } | |
112 | ||
113 | constexpr auto | |
114 | size() const | |
115 | requires forward_range<const _Derived> | |
116 | && sized_sentinel_for<sentinel_t<const _Derived>, | |
117 | iterator_t<const _Derived>> | |
118 | { return ranges::end(_M_derived()) - ranges::begin(_M_derived()); } | |
119 | ||
120 | constexpr decltype(auto) | |
121 | front() requires forward_range<_Derived> | |
122 | { | |
123 | __glibcxx_assert(!empty()); | |
124 | return *ranges::begin(_M_derived()); | |
125 | } | |
126 | ||
127 | constexpr decltype(auto) | |
128 | front() const requires forward_range<const _Derived> | |
129 | { | |
130 | __glibcxx_assert(!empty()); | |
131 | return *ranges::begin(_M_derived()); | |
132 | } | |
133 | ||
134 | constexpr decltype(auto) | |
135 | back() | |
136 | requires bidirectional_range<_Derived> && common_range<_Derived> | |
137 | { | |
138 | __glibcxx_assert(!empty()); | |
139 | return *ranges::prev(ranges::end(_M_derived())); | |
140 | } | |
141 | ||
142 | constexpr decltype(auto) | |
143 | back() const | |
144 | requires bidirectional_range<const _Derived> | |
145 | && common_range<const _Derived> | |
146 | { | |
147 | __glibcxx_assert(!empty()); | |
148 | return *ranges::prev(ranges::end(_M_derived())); | |
149 | } | |
150 | ||
151 | template<random_access_range _Range = _Derived> | |
152 | constexpr decltype(auto) | |
153 | operator[](range_difference_t<_Range> __n) | |
154 | { return ranges::begin(_M_derived())[__n]; } | |
155 | ||
156 | template<random_access_range _Range = const _Derived> | |
157 | constexpr decltype(auto) | |
158 | operator[](range_difference_t<_Range> __n) const | |
159 | { return ranges::begin(_M_derived())[__n]; } | |
160 | }; | |
161 | ||
162 | namespace __detail | |
163 | { | |
164 | template<class _From, class _To> | |
165 | concept __convertible_to_non_slicing = convertible_to<_From, _To> | |
166 | && !(is_pointer_v<decay_t<_From>> && is_pointer_v<decay_t<_To>> | |
167 | && __not_same_as<remove_pointer_t<decay_t<_From>>, | |
168 | remove_pointer_t<decay_t<_To>>>); | |
169 | ||
170 | template<typename _Tp> | |
171 | concept __pair_like | |
172 | = !is_reference_v<_Tp> && requires(_Tp __t) | |
173 | { | |
174 | typename tuple_size<_Tp>::type; | |
175 | requires derived_from<tuple_size<_Tp>, integral_constant<size_t, 2>>; | |
176 | typename tuple_element_t<0, remove_const_t<_Tp>>; | |
177 | typename tuple_element_t<1, remove_const_t<_Tp>>; | |
178 | { get<0>(__t) } -> convertible_to<const tuple_element_t<0, _Tp>&>; | |
179 | { get<1>(__t) } -> convertible_to<const tuple_element_t<1, _Tp>&>; | |
180 | }; | |
181 | ||
182 | template<typename _Tp, typename _Up, typename _Vp> | |
183 | concept __pair_like_convertible_from | |
184 | = !range<_Tp> && __pair_like<_Tp> | |
185 | && constructible_from<_Tp, _Up, _Vp> | |
186 | && __convertible_to_non_slicing<_Up, tuple_element_t<0, _Tp>> | |
187 | && convertible_to<_Vp, tuple_element_t<1, _Tp>>; | |
188 | ||
189 | template<typename _Tp> | |
190 | concept __iterator_sentinel_pair | |
191 | = !range<_Tp> && __pair_like<_Tp> | |
192 | && sentinel_for<tuple_element_t<1, _Tp>, tuple_element_t<0, _Tp>>; | |
193 | ||
194 | } // namespace __detail | |
195 | ||
196 | enum class subrange_kind : bool { unsized, sized }; | |
197 | ||
198 | /// The ranges::subrange class template | |
199 | template<input_or_output_iterator _It, sentinel_for<_It> _Sent = _It, | |
200 | subrange_kind _Kind = sized_sentinel_for<_Sent, _It> | |
201 | ? subrange_kind::sized : subrange_kind::unsized> | |
202 | requires (_Kind == subrange_kind::sized || !sized_sentinel_for<_Sent, _It>) | |
203 | class subrange : public view_interface<subrange<_It, _Sent, _Kind>> | |
204 | { | |
205 | private: | |
206 | // XXX: gcc complains when using constexpr here | |
207 | static const bool _S_store_size | |
208 | = _Kind == subrange_kind::sized && !sized_sentinel_for<_Sent, _It>; | |
209 | ||
210 | _It _M_begin = _It(); | |
620db4ca | 211 | [[no_unique_address]] _Sent _M_end = _Sent(); |
160061ac JW |
212 | |
213 | template<typename, bool = _S_store_size> | |
214 | struct _Size | |
215 | { }; | |
216 | ||
217 | template<typename _Tp> | |
218 | struct _Size<_Tp, true> | |
219 | { __detail::__make_unsigned_like_t<_Tp> _M_size; }; | |
220 | ||
221 | [[no_unique_address]] _Size<iter_difference_t<_It>> _M_size = {}; | |
222 | ||
223 | public: | |
224 | subrange() = default; | |
225 | ||
226 | constexpr | |
227 | subrange(__detail::__convertible_to_non_slicing<_It> auto __i, _Sent __s) | |
228 | requires (!_S_store_size) | |
229 | : _M_begin(std::move(__i)), _M_end(__s) | |
230 | { } | |
231 | ||
232 | constexpr | |
233 | subrange(__detail::__convertible_to_non_slicing<_It> auto __i, _Sent __s, | |
234 | __detail::__make_unsigned_like_t<iter_difference_t<_It>> __n) | |
235 | requires (_Kind == subrange_kind::sized) | |
236 | : _M_begin(std::move(__i)), _M_end(__s) | |
237 | { | |
238 | using __detail::__to_unsigned_like; | |
239 | __glibcxx_assert(__n == __to_unsigned_like(ranges::distance(__i, __s))); | |
240 | if constexpr (_S_store_size) | |
241 | _M_size._M_size = __n; | |
242 | } | |
243 | ||
244 | template<__detail::__not_same_as<subrange> _Rng> | |
245 | requires borrowed_range<_Rng> | |
246 | && __detail::__convertible_to_non_slicing<iterator_t<_Rng>, _It> | |
247 | && convertible_to<sentinel_t<_Rng>, _Sent> | |
248 | constexpr | |
249 | subrange(_Rng&& __r) requires _S_store_size && sized_range<_Rng> | |
a55cda89 | 250 | : subrange(__r, ranges::size(__r)) |
160061ac JW |
251 | { } |
252 | ||
253 | template<__detail::__not_same_as<subrange> _Rng> | |
254 | requires borrowed_range<_Rng> | |
255 | && __detail::__convertible_to_non_slicing<iterator_t<_Rng>, _It> | |
256 | && convertible_to<sentinel_t<_Rng>, _Sent> | |
257 | constexpr | |
258 | subrange(_Rng&& __r) requires (!_S_store_size) | |
259 | : subrange{ranges::begin(__r), ranges::end(__r)} | |
260 | { } | |
261 | ||
262 | template<borrowed_range _Rng> | |
263 | requires __detail::__convertible_to_non_slicing<iterator_t<_Rng>, _It> | |
264 | && convertible_to<sentinel_t<_Rng>, _Sent> | |
265 | constexpr | |
266 | subrange(_Rng&& __r, | |
267 | __detail::__make_unsigned_like_t<iter_difference_t<_It>> __n) | |
268 | requires (_Kind == subrange_kind::sized) | |
269 | : subrange{ranges::begin(__r), ranges::end(__r), __n} | |
270 | { } | |
271 | ||
272 | template<__detail::__not_same_as<subrange> _PairLike> | |
273 | requires __detail::__pair_like_convertible_from<_PairLike, const _It&, | |
274 | const _Sent&> | |
275 | constexpr | |
276 | operator _PairLike() const | |
277 | { return _PairLike(_M_begin, _M_end); } | |
278 | ||
279 | constexpr _It | |
280 | begin() const requires copyable<_It> | |
281 | { return _M_begin; } | |
282 | ||
283 | [[nodiscard]] constexpr _It | |
284 | begin() requires (!copyable<_It>) | |
285 | { return std::move(_M_begin); } | |
286 | ||
287 | constexpr _Sent end() const { return _M_end; } | |
288 | ||
289 | constexpr bool empty() const { return _M_begin == _M_end; } | |
290 | ||
291 | constexpr __detail::__make_unsigned_like_t<iter_difference_t<_It>> | |
292 | size() const requires (_Kind == subrange_kind::sized) | |
293 | { | |
294 | if constexpr (_S_store_size) | |
295 | return _M_size._M_size; | |
296 | else | |
297 | return __detail::__to_unsigned_like(_M_end - _M_begin); | |
298 | } | |
299 | ||
300 | [[nodiscard]] constexpr subrange | |
301 | next(iter_difference_t<_It> __n = 1) const & | |
302 | requires forward_iterator<_It> | |
303 | { | |
304 | auto __tmp = *this; | |
305 | __tmp.advance(__n); | |
306 | return __tmp; | |
307 | } | |
308 | ||
309 | [[nodiscard]] constexpr subrange | |
310 | next(iter_difference_t<_It> __n = 1) && | |
311 | { | |
312 | advance(__n); | |
313 | return std::move(*this); | |
314 | } | |
315 | ||
316 | [[nodiscard]] constexpr subrange | |
317 | prev(iter_difference_t<_It> __n = 1) const | |
318 | requires bidirectional_iterator<_It> | |
319 | { | |
320 | auto __tmp = *this; | |
321 | __tmp.advance(-__n); | |
322 | return __tmp; | |
323 | } | |
324 | ||
325 | constexpr subrange& | |
326 | advance(iter_difference_t<_It> __n) | |
327 | { | |
328 | // _GLIBCXX_RESOLVE_LIB_DEFECTS | |
329 | // 3433. subrange::advance(n) has UB when n < 0 | |
330 | if constexpr (bidirectional_iterator<_It>) | |
331 | if (__n < 0) | |
332 | { | |
333 | ranges::advance(_M_begin, __n); | |
334 | if constexpr (_S_store_size) | |
335 | _M_size._M_size += __detail::__to_unsigned_like(-__n); | |
336 | return *this; | |
337 | } | |
338 | ||
339 | __glibcxx_assert(__n >= 0); | |
340 | auto __d = __n - ranges::advance(_M_begin, __n, _M_end); | |
341 | if constexpr (_S_store_size) | |
342 | _M_size._M_size -= __detail::__to_unsigned_like(__d); | |
343 | return *this; | |
344 | } | |
345 | }; | |
346 | ||
347 | template<input_or_output_iterator _It, sentinel_for<_It> _Sent> | |
348 | subrange(_It, _Sent) -> subrange<_It, _Sent>; | |
349 | ||
350 | template<input_or_output_iterator _It, sentinel_for<_It> _Sent> | |
351 | subrange(_It, _Sent, | |
352 | __detail::__make_unsigned_like_t<iter_difference_t<_It>>) | |
353 | -> subrange<_It, _Sent, subrange_kind::sized>; | |
354 | ||
355 | template<__detail::__iterator_sentinel_pair _Pr> | |
356 | subrange(_Pr) | |
357 | -> subrange<tuple_element_t<0, _Pr>, tuple_element_t<1, _Pr>>; | |
358 | ||
359 | template<__detail::__iterator_sentinel_pair _Pr> | |
360 | subrange(_Pr, __detail::__make_unsigned_like_t<iter_difference_t< | |
361 | tuple_element_t<0, _Pr>>>) | |
362 | -> subrange<tuple_element_t<0, _Pr>, tuple_element_t<1, _Pr>, | |
363 | subrange_kind::sized>; | |
364 | ||
365 | template<borrowed_range _Rng> | |
366 | subrange(_Rng&&) | |
367 | -> subrange<iterator_t<_Rng>, sentinel_t<_Rng>, | |
368 | (sized_range<_Rng> | |
369 | || sized_sentinel_for<sentinel_t<_Rng>, iterator_t<_Rng>>) | |
370 | ? subrange_kind::sized : subrange_kind::unsized>; | |
371 | ||
372 | template<borrowed_range _Rng> | |
373 | subrange(_Rng&&, | |
374 | __detail::__make_unsigned_like_t<range_difference_t<_Rng>>) | |
375 | -> subrange<iterator_t<_Rng>, sentinel_t<_Rng>, subrange_kind::sized>; | |
376 | ||
377 | template<size_t _Num, class _It, class _Sent, subrange_kind _Kind> | |
378 | requires (_Num < 2) | |
379 | constexpr auto | |
380 | get(const subrange<_It, _Sent, _Kind>& __r) | |
381 | { | |
382 | if constexpr (_Num == 0) | |
383 | return __r.begin(); | |
384 | else | |
385 | return __r.end(); | |
386 | } | |
387 | ||
388 | template<size_t _Num, class _It, class _Sent, subrange_kind _Kind> | |
389 | requires (_Num < 2) | |
390 | constexpr auto | |
391 | get(subrange<_It, _Sent, _Kind>&& __r) | |
392 | { | |
393 | if constexpr (_Num == 0) | |
394 | return __r.begin(); | |
395 | else | |
396 | return __r.end(); | |
397 | } | |
398 | ||
399 | template<input_or_output_iterator _It, sentinel_for<_It> _Sent, | |
400 | subrange_kind _Kind> | |
401 | inline constexpr bool | |
402 | enable_borrowed_range<subrange<_It, _Sent, _Kind>> = true; | |
403 | ||
404 | template<range _Range> | |
405 | using borrowed_subrange_t = conditional_t<borrowed_range<_Range>, | |
406 | subrange<iterator_t<_Range>>, | |
407 | dangling>; | |
408 | ||
409 | } // namespace ranges | |
410 | ||
411 | using ranges::get; | |
412 | ||
a186ab67 JW |
413 | template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> |
414 | struct tuple_size<ranges::subrange<_Iter, _Sent, _Kind>> | |
415 | : integral_constant<size_t, 2> | |
416 | { }; | |
417 | ||
418 | template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> | |
419 | struct tuple_element<0, ranges::subrange<_Iter, _Sent, _Kind>> | |
420 | { using type = _Iter; }; | |
421 | ||
422 | template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> | |
423 | struct tuple_element<1, ranges::subrange<_Iter, _Sent, _Kind>> | |
424 | { using type = _Sent; }; | |
425 | ||
426 | template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> | |
427 | struct tuple_element<0, const ranges::subrange<_Iter, _Sent, _Kind>> | |
428 | { using type = _Iter; }; | |
429 | ||
430 | template<typename _Iter, typename _Sent, ranges::subrange_kind _Kind> | |
431 | struct tuple_element<1, const ranges::subrange<_Iter, _Sent, _Kind>> | |
432 | { using type = _Sent; }; | |
433 | ||
160061ac JW |
434 | _GLIBCXX_END_NAMESPACE_VERSION |
435 | } // namespace std | |
436 | #endif // library concepts | |
437 | #endif // C++20 | |
438 | #endif // _RANGES_UTIL_H |