master
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___ITERATOR_CONCEPTS_H
11#define _LIBCPP___ITERATOR_CONCEPTS_H
12
13#include <__concepts/arithmetic.h>
14#include <__concepts/assignable.h>
15#include <__concepts/common_reference_with.h>
16#include <__concepts/constructible.h>
17#include <__concepts/copyable.h>
18#include <__concepts/derived_from.h>
19#include <__concepts/equality_comparable.h>
20#include <__concepts/invocable.h>
21#include <__concepts/movable.h>
22#include <__concepts/predicate.h>
23#include <__concepts/regular.h>
24#include <__concepts/relation.h>
25#include <__concepts/same_as.h>
26#include <__concepts/semiregular.h>
27#include <__concepts/totally_ordered.h>
28#include <__config>
29#include <__iterator/incrementable_traits.h>
30#include <__iterator/iter_move.h>
31#include <__iterator/iterator_traits.h>
32#include <__memory/pointer_traits.h>
33#include <__type_traits/add_pointer.h>
34#include <__type_traits/common_reference.h>
35#include <__type_traits/conditional.h>
36#include <__type_traits/disjunction.h>
37#include <__type_traits/enable_if.h>
38#include <__type_traits/integral_constant.h>
39#include <__type_traits/invoke.h>
40#include <__type_traits/is_pointer.h>
41#include <__type_traits/is_primary_template.h>
42#include <__type_traits/is_reference.h>
43#include <__type_traits/is_referenceable.h>
44#include <__type_traits/is_valid_expansion.h>
45#include <__type_traits/remove_cv.h>
46#include <__type_traits/remove_cvref.h>
47#include <__utility/forward.h>
48
49#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
50# pragma GCC system_header
51#endif
52
53_LIBCPP_BEGIN_NAMESPACE_STD
54
55#if _LIBCPP_STD_VER >= 20
56
57// [iterator.concept.readable]
58template <class _In>
59concept __indirectly_readable_impl =
60 requires(const _In __i) {
61 typename iter_value_t<_In>;
62 typename iter_reference_t<_In>;
63 typename iter_rvalue_reference_t<_In>;
64 { *__i } -> same_as<iter_reference_t<_In>>;
65 { ranges::iter_move(__i) } -> same_as<iter_rvalue_reference_t<_In>>;
66 } && common_reference_with<iter_reference_t<_In>&&, iter_value_t<_In>&> &&
67 common_reference_with<iter_reference_t<_In>&&, iter_rvalue_reference_t<_In>&&> &&
68 common_reference_with<iter_rvalue_reference_t<_In>&&, const iter_value_t<_In>&>;
69
70template <class _In>
71concept indirectly_readable = __indirectly_readable_impl<remove_cvref_t<_In>>;
72
73template <class _Tp>
74using __projected_iterator_t _LIBCPP_NODEBUG = typename _Tp::__projected_iterator;
75
76template <class _Tp>
77using __projected_projection_t _LIBCPP_NODEBUG = typename _Tp::__projected_projection;
78
79template <class _Tp>
80concept __specialization_of_projected = requires {
81 typename __projected_iterator_t<_Tp>;
82 typename __projected_projection_t<_Tp>;
83} && __is_primary_template<_Tp>::value;
84
85template <class _Tp>
86struct __indirect_value_t_impl {
87 using type _LIBCPP_NODEBUG = iter_value_t<_Tp>&;
88};
89template <__specialization_of_projected _Tp>
90struct __indirect_value_t_impl<_Tp> {
91 using type _LIBCPP_NODEBUG =
92 invoke_result_t<__projected_projection_t<_Tp>&,
93 typename __indirect_value_t_impl<__projected_iterator_t<_Tp>>::type>;
94};
95
96template <indirectly_readable _Tp>
97using __indirect_value_t _LIBCPP_NODEBUG = typename __indirect_value_t_impl<_Tp>::type;
98
99template <indirectly_readable _Tp>
100using iter_common_reference_t = common_reference_t<iter_reference_t<_Tp>, __indirect_value_t<_Tp>>;
101
102// [iterator.concept.writable]
103template <class _Out, class _Tp>
104concept indirectly_writable = requires(_Out&& __o, _Tp&& __t) {
105 *__o = std::forward<_Tp>(__t); // not required to be equality-preserving
106 *std::forward<_Out>(__o) = std::forward<_Tp>(__t); // not required to be equality-preserving
107 const_cast<const iter_reference_t<_Out>&&>(*__o) = std::forward<_Tp>(__t); // not required to be equality-preserving
108 const_cast<const iter_reference_t<_Out>&&>(*std::forward<_Out>(__o)) =
109 std::forward<_Tp>(__t); // not required to be equality-preserving
110};
111
112// [iterator.concept.winc]
113template <class _Tp>
114concept __integer_like = integral<_Tp> && !same_as<_Tp, bool>;
115
116template <class _Tp>
117concept __signed_integer_like = signed_integral<_Tp>;
118
119template <class _Ip>
120concept weakly_incrementable =
121 // TODO: remove this once the clang bug is fixed (bugs.llvm.org/PR48173).
122 !same_as<_Ip, bool> && // Currently, clang does not handle bool correctly.
123 movable<_Ip> && requires(_Ip __i) {
124 typename iter_difference_t<_Ip>;
125 requires __signed_integer_like<iter_difference_t<_Ip>>;
126 { ++__i } -> same_as<_Ip&>; // not required to be equality-preserving
127 __i++; // not required to be equality-preserving
128 };
129
130// [iterator.concept.inc]
131template <class _Ip>
132concept incrementable = regular<_Ip> && weakly_incrementable<_Ip> && requires(_Ip __i) {
133 { __i++ } -> same_as<_Ip>;
134};
135
136// [iterator.concept.iterator]
137template <class _Ip>
138concept input_or_output_iterator = requires(_Ip __i) {
139 { *__i } -> __referenceable;
140} && weakly_incrementable<_Ip>;
141
142// [iterator.concept.sentinel]
143template <class _Sp, class _Ip>
144concept sentinel_for = semiregular<_Sp> && input_or_output_iterator<_Ip> && __weakly_equality_comparable_with<_Sp, _Ip>;
145
146template <class, class>
147inline constexpr bool disable_sized_sentinel_for = false;
148
149template <class _Sp, class _Ip>
150concept sized_sentinel_for =
151 sentinel_for<_Sp, _Ip> && !disable_sized_sentinel_for<remove_cv_t<_Sp>, remove_cv_t<_Ip>> &&
152 requires(const _Ip& __i, const _Sp& __s) {
153 { __s - __i } -> same_as<iter_difference_t<_Ip>>;
154 { __i - __s } -> same_as<iter_difference_t<_Ip>>;
155 };
156
157template <class _Iter>
158struct __iter_traits_cache {
159 using type _LIBCPP_NODEBUG =
160 _If<__is_primary_template<iterator_traits<_Iter> >::value, _Iter, iterator_traits<_Iter> >;
161};
162template <class _Iter>
163using _ITER_TRAITS _LIBCPP_NODEBUG = typename __iter_traits_cache<_Iter>::type;
164
165struct __iter_concept_concept_test {
166 template <class _Iter>
167 using _Apply _LIBCPP_NODEBUG = typename _ITER_TRAITS<_Iter>::iterator_concept;
168};
169struct __iter_concept_category_test {
170 template <class _Iter>
171 using _Apply _LIBCPP_NODEBUG = typename _ITER_TRAITS<_Iter>::iterator_category;
172};
173struct __iter_concept_random_fallback {
174 template <class _Iter>
175 using _Apply _LIBCPP_NODEBUG =
176 __enable_if_t<__is_primary_template<iterator_traits<_Iter> >::value, random_access_iterator_tag>;
177};
178
179template <class _Iter, class _Tester>
180struct __test_iter_concept : _IsValidExpansion<_Tester::template _Apply, _Iter>, _Tester {};
181
182template <class _Iter>
183struct __iter_concept_cache {
184 using type _LIBCPP_NODEBUG =
185 _Or<__test_iter_concept<_Iter, __iter_concept_concept_test>,
186 __test_iter_concept<_Iter, __iter_concept_category_test>,
187 __test_iter_concept<_Iter, __iter_concept_random_fallback> >;
188};
189
190template <class _Iter>
191using _ITER_CONCEPT _LIBCPP_NODEBUG = typename __iter_concept_cache<_Iter>::type::template _Apply<_Iter>;
192
193// [iterator.concept.input]
194template <class _Ip>
195concept input_iterator = input_or_output_iterator<_Ip> && indirectly_readable<_Ip> && requires {
196 typename _ITER_CONCEPT<_Ip>;
197} && derived_from<_ITER_CONCEPT<_Ip>, input_iterator_tag>;
198
199// [iterator.concept.output]
200template <class _Ip, class _Tp>
201concept output_iterator =
202 input_or_output_iterator<_Ip> && indirectly_writable<_Ip, _Tp> && requires(_Ip __it, _Tp&& __t) {
203 *__it++ = std::forward<_Tp>(__t); // not required to be equality-preserving
204 };
205
206// [iterator.concept.forward]
207template <class _Ip>
208concept forward_iterator =
209 input_iterator<_Ip> && derived_from<_ITER_CONCEPT<_Ip>, forward_iterator_tag> && incrementable<_Ip> &&
210 sentinel_for<_Ip, _Ip>;
211
212// [iterator.concept.bidir]
213template <class _Ip>
214concept bidirectional_iterator =
215 forward_iterator<_Ip> && derived_from<_ITER_CONCEPT<_Ip>, bidirectional_iterator_tag> && requires(_Ip __i) {
216 { --__i } -> same_as<_Ip&>;
217 { __i-- } -> same_as<_Ip>;
218 };
219
220template <class _Ip>
221concept random_access_iterator =
222 bidirectional_iterator<_Ip> && derived_from<_ITER_CONCEPT<_Ip>, random_access_iterator_tag> &&
223 totally_ordered<_Ip> && sized_sentinel_for<_Ip, _Ip> &&
224 requires(_Ip __i, const _Ip __j, const iter_difference_t<_Ip> __n) {
225 { __i += __n } -> same_as<_Ip&>;
226 { __j + __n } -> same_as<_Ip>;
227 { __n + __j } -> same_as<_Ip>;
228 { __i -= __n } -> same_as<_Ip&>;
229 { __j - __n } -> same_as<_Ip>;
230 { __j[__n] } -> same_as<iter_reference_t<_Ip>>;
231 };
232
233template <class _Ip>
234concept contiguous_iterator =
235 random_access_iterator<_Ip> && derived_from<_ITER_CONCEPT<_Ip>, contiguous_iterator_tag> &&
236 is_lvalue_reference_v<iter_reference_t<_Ip>> && same_as<iter_value_t<_Ip>, remove_cvref_t<iter_reference_t<_Ip>>> &&
237 requires(const _Ip& __i) {
238 { std::to_address(__i) } -> same_as<add_pointer_t<iter_reference_t<_Ip>>>;
239 };
240
241template <class _Ip>
242concept __has_arrow = input_iterator<_Ip> && (is_pointer_v<_Ip> || requires(_Ip __i) { __i.operator->(); });
243
244// [indirectcallable.indirectinvocable]
245template <class _Fp, class _It>
246concept indirectly_unary_invocable =
247 indirectly_readable<_It> && copy_constructible<_Fp> && invocable<_Fp&, __indirect_value_t<_It>> &&
248 invocable<_Fp&, iter_reference_t<_It>> &&
249 common_reference_with< invoke_result_t<_Fp&, __indirect_value_t<_It>>,
250 invoke_result_t<_Fp&, iter_reference_t<_It>>>;
251
252template <class _Fp, class _It>
253concept indirectly_regular_unary_invocable =
254 indirectly_readable<_It> && copy_constructible<_Fp> && regular_invocable<_Fp&, __indirect_value_t<_It>> &&
255 regular_invocable<_Fp&, iter_reference_t<_It>> &&
256 common_reference_with< invoke_result_t<_Fp&, __indirect_value_t<_It>>,
257 invoke_result_t<_Fp&, iter_reference_t<_It>>>;
258
259template <class _Fp, class _It>
260concept indirect_unary_predicate =
261 indirectly_readable<_It> && copy_constructible<_Fp> && predicate<_Fp&, __indirect_value_t<_It>> &&
262 predicate<_Fp&, iter_reference_t<_It>>;
263
264template <class _Fp, class _It1, class _It2>
265concept indirect_binary_predicate =
266 indirectly_readable<_It1> && indirectly_readable<_It2> && copy_constructible<_Fp> &&
267 predicate<_Fp&, __indirect_value_t<_It1>, __indirect_value_t<_It2>> &&
268 predicate<_Fp&, __indirect_value_t<_It1>, iter_reference_t<_It2>> &&
269 predicate<_Fp&, iter_reference_t<_It1>, __indirect_value_t<_It2>> &&
270 predicate<_Fp&, iter_reference_t<_It1>, iter_reference_t<_It2>>;
271
272template <class _Fp, class _It1, class _It2 = _It1>
273concept indirect_equivalence_relation =
274 indirectly_readable<_It1> && indirectly_readable<_It2> && copy_constructible<_Fp> &&
275 equivalence_relation<_Fp&, __indirect_value_t<_It1>, __indirect_value_t<_It2>> &&
276 equivalence_relation<_Fp&, __indirect_value_t<_It1>, iter_reference_t<_It2>> &&
277 equivalence_relation<_Fp&, iter_reference_t<_It1>, __indirect_value_t<_It2>> &&
278 equivalence_relation<_Fp&, iter_reference_t<_It1>, iter_reference_t<_It2>>;
279
280template <class _Fp, class _It1, class _It2 = _It1>
281concept indirect_strict_weak_order =
282 indirectly_readable<_It1> && indirectly_readable<_It2> && copy_constructible<_Fp> &&
283 strict_weak_order<_Fp&, __indirect_value_t<_It1>, __indirect_value_t<_It2>> &&
284 strict_weak_order<_Fp&, __indirect_value_t<_It1>, iter_reference_t<_It2>> &&
285 strict_weak_order<_Fp&, iter_reference_t<_It1>, __indirect_value_t<_It2>> &&
286 strict_weak_order<_Fp&, iter_reference_t<_It1>, iter_reference_t<_It2>>;
287
288template <class _Fp, class... _Its>
289 requires(indirectly_readable<_Its> && ...) && invocable<_Fp, iter_reference_t<_Its>...>
290using indirect_result_t = invoke_result_t<_Fp, iter_reference_t<_Its>...>;
291
292template <class _In, class _Out>
293concept indirectly_movable = indirectly_readable<_In> && indirectly_writable<_Out, iter_rvalue_reference_t<_In>>;
294
295template <class _In, class _Out>
296concept indirectly_movable_storable =
297 indirectly_movable<_In, _Out> && indirectly_writable<_Out, iter_value_t<_In>> && movable<iter_value_t<_In>> &&
298 constructible_from<iter_value_t<_In>, iter_rvalue_reference_t<_In>> &&
299 assignable_from<iter_value_t<_In>&, iter_rvalue_reference_t<_In>>;
300
301template <class _In, class _Out>
302concept indirectly_copyable = indirectly_readable<_In> && indirectly_writable<_Out, iter_reference_t<_In>>;
303
304template <class _In, class _Out>
305concept indirectly_copyable_storable =
306 indirectly_copyable<_In, _Out> && indirectly_writable<_Out, iter_value_t<_In>&> &&
307 indirectly_writable<_Out, const iter_value_t<_In>&> && indirectly_writable<_Out, iter_value_t<_In>&&> &&
308 indirectly_writable<_Out, const iter_value_t<_In>&&> && copyable<iter_value_t<_In>> &&
309 constructible_from<iter_value_t<_In>, iter_reference_t<_In>> &&
310 assignable_from<iter_value_t<_In>&, iter_reference_t<_In>>;
311
312// Note: indirectly_swappable is located in iter_swap.h to prevent a dependency cycle
313// (both iter_swap and indirectly_swappable require indirectly_readable).
314
315#endif // _LIBCPP_STD_VER >= 20
316
317template <class _Tp>
318using __has_random_access_iterator_category_or_concept _LIBCPP_NODEBUG
319#if _LIBCPP_STD_VER >= 20
320 = integral_constant<bool, random_access_iterator<_Tp>>;
321#else // _LIBCPP_STD_VER < 20
322 = __has_random_access_iterator_category<_Tp>;
323#endif // _LIBCPP_STD_VER
324
325_LIBCPP_END_NAMESPACE_STD
326
327#endif // _LIBCPP___ITERATOR_CONCEPTS_H