1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP___RANGES_IOTA_VIEW_H
11#define _LIBCPP___RANGES_IOTA_VIEW_H
12
13#include <__assert>
14#include <__compare/three_way_comparable.h>
15#include <__concepts/arithmetic.h>
16#include <__concepts/constructible.h>
17#include <__concepts/convertible_to.h>
18#include <__concepts/copyable.h>
19#include <__concepts/equality_comparable.h>
20#include <__concepts/invocable.h>
21#include <__concepts/same_as.h>
22#include <__concepts/semiregular.h>
23#include <__concepts/totally_ordered.h>
24#include <__config>
25#include <__iterator/concepts.h>
26#include <__iterator/incrementable_traits.h>
27#include <__iterator/iterator_traits.h>
28#include <__iterator/unreachable_sentinel.h>
29#include <__ranges/enable_borrowed_range.h>
30#include <__ranges/movable_box.h>
31#include <__ranges/view_interface.h>
32#include <__type_traits/conditional.h>
33#include <__type_traits/is_nothrow_constructible.h>
34#include <__type_traits/make_unsigned.h>
35#include <__type_traits/type_identity.h>
36#include <__utility/forward.h>
37#include <__utility/move.h>
38
39#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
40# pragma GCC system_header
41#endif
42
43_LIBCPP_PUSH_MACROS
44#include <__undef_macros>
45
46_LIBCPP_BEGIN_NAMESPACE_STD
47
48#if _LIBCPP_STD_VER >= 20
49
50namespace ranges {
51template <class _Int>
52struct __get_wider_signed {
53 consteval static auto __call() {
54 if constexpr (sizeof(_Int) < sizeof(short))
55 return type_identity<short>{};
56 else if constexpr (sizeof(_Int) < sizeof(int))
57 return type_identity<int>{};
58 else if constexpr (sizeof(_Int) < sizeof(long))
59 return type_identity<long>{};
60 else
61 return type_identity<long long>{};
62
63 static_assert(
64 sizeof(_Int) <= sizeof(long long), "Found integer-like type that is bigger than largest integer like type.");
65 }
66
67 using type = typename decltype(__call())::type;
68};
69
70template <class _Start>
71using _IotaDiffT _LIBCPP_NODEBUG =
72 typename _If< (!integral<_Start> || sizeof(iter_difference_t<_Start>) > sizeof(_Start)),
73 type_identity<iter_difference_t<_Start>>,
74 __get_wider_signed<_Start> >::type;
75
76template <class _Iter>
77concept __decrementable = incrementable<_Iter> && requires(_Iter __i) {
78 { --__i } -> same_as<_Iter&>;
79 { __i-- } -> same_as<_Iter>;
80};
81
82template <class _Iter>
83concept __advanceable =
84 __decrementable<_Iter> && totally_ordered<_Iter> &&
85 requires(_Iter __i, const _Iter __j, const _IotaDiffT<_Iter> __n) {
86 { __i += __n } -> same_as<_Iter&>;
87 { __i -= __n } -> same_as<_Iter&>;
88 _Iter(__j + __n);
89 _Iter(__n + __j);
90 _Iter(__j - __n);
91 { __j - __j } -> convertible_to<_IotaDiffT<_Iter>>;
92 };
93
94template <class>
95struct __iota_iterator_category {};
96
97template <incrementable _Tp>
98struct __iota_iterator_category<_Tp> {
99 using iterator_category = input_iterator_tag;
100};
101
102template <weakly_incrementable _Start, semiregular _BoundSentinel = unreachable_sentinel_t>
103 requires __weakly_equality_comparable_with<_Start, _BoundSentinel> && copyable<_Start>
104class iota_view : public view_interface<iota_view<_Start, _BoundSentinel>> {
105 struct __iterator : public __iota_iterator_category<_Start> {
106 friend class iota_view;
107
108 using iterator_concept =
109 _If<__advanceable<_Start>,
110 random_access_iterator_tag,
111 _If<__decrementable<_Start>,
112 bidirectional_iterator_tag,
113 _If<incrementable<_Start>,
114 forward_iterator_tag,
115 /*Else*/ input_iterator_tag>>>;
116
117 using value_type = _Start;
118 using difference_type = _IotaDiffT<_Start>;
119
120 _Start __value_ = _Start();
121
122 _LIBCPP_HIDE_FROM_ABI __iterator()
123 requires default_initializable<_Start>
124 = default;
125
126 _LIBCPP_HIDE_FROM_ABI constexpr explicit __iterator(_Start __value) : __value_(std::move(__value)) {}
127
128 _LIBCPP_HIDE_FROM_ABI constexpr _Start operator*() const noexcept(is_nothrow_copy_constructible_v<_Start>) {
129 return __value_;
130 }
131
132 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() {
133 ++__value_;
134 return *this;
135 }
136
137 _LIBCPP_HIDE_FROM_ABI constexpr void operator++(int) { ++*this; }
138
139 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator++(int)
140 requires incrementable<_Start>
141 {
142 auto __tmp = *this;
143 ++*this;
144 return __tmp;
145 }
146
147 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator--()
148 requires __decrementable<_Start>
149 {
150 --__value_;
151 return *this;
152 }
153
154 _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator--(int)
155 requires __decrementable<_Start>
156 {
157 auto __tmp = *this;
158 --*this;
159 return __tmp;
160 }
161
162 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator+=(difference_type __n)
163 requires __advanceable<_Start>
164 {
165 if constexpr (__integer_like<_Start> && !__signed_integer_like<_Start>) {
166 if (__n >= difference_type(0)) {
167 __value_ += static_cast<_Start>(__n);
168 } else {
169 __value_ -= static_cast<_Start>(-__n);
170 }
171 } else {
172 __value_ += __n;
173 }
174 return *this;
175 }
176
177 _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator-=(difference_type __n)
178 requires __advanceable<_Start>
179 {
180 if constexpr (__integer_like<_Start> && !__signed_integer_like<_Start>) {
181 if (__n >= difference_type(0)) {
182 __value_ -= static_cast<_Start>(__n);
183 } else {
184 __value_ += static_cast<_Start>(-__n);
185 }
186 } else {
187 __value_ -= __n;
188 }
189 return *this;
190 }
191
192 _LIBCPP_HIDE_FROM_ABI constexpr _Start operator[](difference_type __n) const
193 requires __advanceable<_Start>
194 {
195 return _Start(__value_ + __n);
196 }
197
198 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, const __iterator& __y)
199 requires equality_comparable<_Start>
200 {
201 return __x.__value_ == __y.__value_;
202 }
203
204 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<(const __iterator& __x, const __iterator& __y)
205 requires totally_ordered<_Start>
206 {
207 return __x.__value_ < __y.__value_;
208 }
209
210 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>(const __iterator& __x, const __iterator& __y)
211 requires totally_ordered<_Start>
212 {
213 return __y < __x;
214 }
215
216 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y)
217 requires totally_ordered<_Start>
218 {
219 return !(__y < __x);
220 }
221
222 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>=(const __iterator& __x, const __iterator& __y)
223 requires totally_ordered<_Start>
224 {
225 return !(__x < __y);
226 }
227
228 _LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y)
229 requires totally_ordered<_Start> && three_way_comparable<_Start>
230 {
231 return __x.__value_ <=> __y.__value_;
232 }
233
234 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(__iterator __i, difference_type __n)
235 requires __advanceable<_Start>
236 {
237 __i += __n;
238 return __i;
239 }
240
241 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator+(difference_type __n, __iterator __i)
242 requires __advanceable<_Start>
243 {
244 return __i + __n;
245 }
246
247 _LIBCPP_HIDE_FROM_ABI friend constexpr __iterator operator-(__iterator __i, difference_type __n)
248 requires __advanceable<_Start>
249 {
250 __i -= __n;
251 return __i;
252 }
253
254 _LIBCPP_HIDE_FROM_ABI friend constexpr difference_type operator-(const __iterator& __x, const __iterator& __y)
255 requires __advanceable<_Start>
256 {
257 if constexpr (__integer_like<_Start>) {
258 if constexpr (__signed_integer_like<_Start>) {
259 return difference_type(difference_type(__x.__value_) - difference_type(__y.__value_));
260 }
261 if (__y.__value_ > __x.__value_) {
262 return difference_type(-difference_type(__y.__value_ - __x.__value_));
263 }
264 return difference_type(__x.__value_ - __y.__value_);
265 }
266 return __x.__value_ - __y.__value_;
267 }
268 };
269
270 struct __sentinel {
271 friend class iota_view;
272
273 private:
274 _BoundSentinel __bound_sentinel_ = _BoundSentinel();
275
276 public:
277 _LIBCPP_HIDE_FROM_ABI __sentinel() = default;
278 _LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(_BoundSentinel __bound_sentinel)
279 : __bound_sentinel_(std::move(__bound_sentinel)) {}
280
281 _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, const __sentinel& __y) {
282 return __x.__value_ == __y.__bound_sentinel_;
283 }
284
285 _LIBCPP_HIDE_FROM_ABI friend constexpr iter_difference_t<_Start>
286 operator-(const __iterator& __x, const __sentinel& __y)
287 requires sized_sentinel_for<_BoundSentinel, _Start>
288 {
289 return __x.__value_ - __y.__bound_sentinel_;
290 }
291
292 _LIBCPP_HIDE_FROM_ABI friend constexpr iter_difference_t<_Start>
293 operator-(const __sentinel& __x, const __iterator& __y)
294 requires sized_sentinel_for<_BoundSentinel, _Start>
295 {
296 return -(__y - __x);
297 }
298 };
299
300 _Start __value_ = _Start();
301 _BoundSentinel __bound_sentinel_ = _BoundSentinel();
302
303public:
304 _LIBCPP_HIDE_FROM_ABI iota_view()
305 requires default_initializable<_Start>
306 = default;
307
308 _LIBCPP_HIDE_FROM_ABI constexpr explicit iota_view(_Start __value) : __value_(std::move(__value)) {}
309
310 _LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23
311 iota_view(type_identity_t<_Start> __value, type_identity_t<_BoundSentinel> __bound_sentinel)
312 : __value_(std::move(__value)), __bound_sentinel_(std::move(__bound_sentinel)) {
313 // Validate the precondition if possible.
314 if constexpr (totally_ordered_with<_Start, _BoundSentinel>) {
315 _LIBCPP_ASSERT_VALID_INPUT_RANGE(
316 bool(__value_ <= __bound_sentinel_), "iota_view: bound must be reachable from value");
317 }
318 }
319
320 _LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23 iota_view(__iterator __first, __iterator __last)
321 requires same_as<_Start, _BoundSentinel>
322 : iota_view(std::move(__first.__value_), std::move(__last.__value_)) {}
323
324 _LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23 iota_view(__iterator __first, _BoundSentinel __last)
325 requires same_as<_BoundSentinel, unreachable_sentinel_t>
326 : iota_view(std::move(__first.__value_), std::move(__last)) {}
327
328 _LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23 iota_view(__iterator __first, __sentinel __last)
329 requires(!same_as<_Start, _BoundSentinel> && !same_as<_BoundSentinel, unreachable_sentinel_t>)
330 : iota_view(std::move(__first.__value_), std::move(__last.__bound_sentinel_)) {}
331
332 _LIBCPP_HIDE_FROM_ABI constexpr __iterator begin() const { return __iterator{__value_}; }
333
334 _LIBCPP_HIDE_FROM_ABI constexpr auto end() const {
335 if constexpr (same_as<_BoundSentinel, unreachable_sentinel_t>)
336 return unreachable_sentinel;
337 else
338 return __sentinel{__bound_sentinel_};
339 }
340
341 _LIBCPP_HIDE_FROM_ABI constexpr __iterator end() const
342 requires same_as<_Start, _BoundSentinel>
343 {
344 return __iterator{__bound_sentinel_};
345 }
346
347 _LIBCPP_HIDE_FROM_ABI constexpr bool empty() const { return __value_ == __bound_sentinel_; }
348
349 _LIBCPP_HIDE_FROM_ABI constexpr auto size() const
350 requires(same_as<_Start, _BoundSentinel> && __advanceable<_Start>) ||
351 (integral<_Start> && integral<_BoundSentinel>) || sized_sentinel_for<_BoundSentinel, _Start>
352 {
353 if constexpr (__integer_like<_Start> && __integer_like<_BoundSentinel>) {
354 return (__value_ < 0)
355 ? ((__bound_sentinel_ < 0)
356 ? std::__to_unsigned_like(-__value_) - std::__to_unsigned_like(-__bound_sentinel_)
357 : std::__to_unsigned_like(__bound_sentinel_) + std::__to_unsigned_like(-__value_))
358 : std::__to_unsigned_like(__bound_sentinel_) - std::__to_unsigned_like(__value_);
359 } else {
360 return std::__to_unsigned_like(__bound_sentinel_ - __value_);
361 }
362 }
363};
364
365template <class _Start, class _BoundSentinel>
366 requires(!__integer_like<_Start> || !__integer_like<_BoundSentinel> ||
367 (__signed_integer_like<_Start> == __signed_integer_like<_BoundSentinel>))
368iota_view(_Start, _BoundSentinel) -> iota_view<_Start, _BoundSentinel>;
369
370template <class _Start, class _BoundSentinel>
371inline constexpr bool enable_borrowed_range<iota_view<_Start, _BoundSentinel>> = true;
372
373namespace views {
374namespace __iota {
375struct __fn {
376 template <class _Start>
377 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Start&& __start) const
378 noexcept(noexcept(ranges::iota_view(std::forward<_Start>(__start))))
379 -> decltype(ranges::iota_view(std::forward<_Start>(__start))) {
380 return ranges::iota_view(std::forward<_Start>(__start));
381 }
382
383 template <class _Start, class _BoundSentinel>
384 _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Start&& __start, _BoundSentinel&& __bound_sentinel) const noexcept(
385 noexcept(ranges::iota_view(std::forward<_Start>(__start), std::forward<_BoundSentinel>(__bound_sentinel))))
386 -> decltype(ranges::iota_view(std::forward<_Start>(__start), std::forward<_BoundSentinel>(__bound_sentinel))) {
387 return ranges::iota_view(std::forward<_Start>(__start), std::forward<_BoundSentinel>(__bound_sentinel));
388 }
389};
390} // namespace __iota
391
392inline namespace __cpo {
393inline constexpr auto iota = __iota::__fn{};
394} // namespace __cpo
395} // namespace views
396} // namespace ranges
397
398#endif // _LIBCPP_STD_VER >= 20
399
400_LIBCPP_END_NAMESPACE_STD
401
402_LIBCPP_POP_MACROS
403
404#endif // _LIBCPP___RANGES_IOTA_VIEW_H
405