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___ALGORITHM_IS_PERMUTATION_H
11#define _LIBCPP___ALGORITHM_IS_PERMUTATION_H
12
13#include <__algorithm/comp.h>
14#include <__algorithm/iterator_operations.h>
15#include <__config>
16#include <__functional/identity.h>
17#include <__iterator/concepts.h>
18#include <__iterator/distance.h>
19#include <__iterator/iterator_traits.h>
20#include <__type_traits/enable_if.h>
21#include <__type_traits/invoke.h>
22#include <__type_traits/is_callable.h>
23#include <__type_traits/is_same.h>
24#include <__utility/move.h>
25
26#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
27# pragma GCC system_header
28#endif
29
30_LIBCPP_PUSH_MACROS
31#include <__undef_macros>
32
33_LIBCPP_BEGIN_NAMESPACE_STD
34
35template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class = void>
36struct _ConstTimeDistance : false_type {};
37
38#if _LIBCPP_STD_VER >= 20
39
40template <class _Iter1, class _Sent1, class _Iter2, class _Sent2>
41struct _ConstTimeDistance<_Iter1,
42 _Sent1,
43 _Iter2,
44 _Sent2,
45 __enable_if_t< sized_sentinel_for<_Sent1, _Iter1> && sized_sentinel_for<_Sent2, _Iter2> >>
46 : true_type {};
47
48#else
49
50template <class _Iter1, class _Iter2>
51struct _ConstTimeDistance<
52 _Iter1,
53 _Iter1,
54 _Iter2,
55 _Iter2,
56 __enable_if_t< is_same<typename iterator_traits<_Iter1>::iterator_category, random_access_iterator_tag>::value &&
57 is_same<typename iterator_traits<_Iter2>::iterator_category, random_access_iterator_tag>::value > >
58 : true_type {};
59
60#endif // _LIBCPP_STD_VER >= 20
61
62// Internal functions
63
64// For each element in [f1, l1) see if there are the same number of equal elements in [f2, l2)
65template <class _AlgPolicy,
66 class _Iter1,
67 class _Sent1,
68 class _Iter2,
69 class _Sent2,
70 class _Proj1,
71 class _Proj2,
72 class _Pred>
73_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation_impl(
74 _Iter1 __first1,
75 _Sent1 __last1,
76 _Iter2 __first2,
77 _Sent2 __last2,
78 _Pred&& __pred,
79 _Proj1&& __proj1,
80 _Proj2&& __proj2) {
81 using _D1 = __iter_diff_t<_Iter1>;
82
83 for (auto __i = __first1; __i != __last1; ++__i) {
84 // Have we already counted the number of *__i in [f1, l1)?
85 auto __match = __first1;
86 for (; __match != __i; ++__match) {
87 if (std::__invoke(__pred, std::__invoke(__proj1, *__match), std::__invoke(__proj1, *__i)))
88 break;
89 }
90
91 if (__match == __i) {
92 // Count number of *__i in [f2, l2)
93 _D1 __c2 = 0;
94 for (auto __j = __first2; __j != __last2; ++__j) {
95 if (std::__invoke(__pred, std::__invoke(__proj1, *__i), std::__invoke(__proj2, *__j)))
96 ++__c2;
97 }
98 if (__c2 == 0)
99 return false;
100
101 // Count number of *__i in [__i, l1) (we can start with 1)
102 _D1 __c1 = 1;
103 for (auto __j = _IterOps<_AlgPolicy>::next(__i); __j != __last1; ++__j) {
104 if (std::__invoke(__pred, std::__invoke(__proj1, *__i), std::__invoke(__proj1, *__j)))
105 ++__c1;
106 }
107 if (__c1 != __c2)
108 return false;
109 }
110 }
111
112 return true;
113}
114
115// 2+1 iterators, predicate. Not used by range algorithms.
116template <class _AlgPolicy, class _ForwardIterator1, class _Sentinel1, class _ForwardIterator2, class _BinaryPredicate>
117[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation(
118 _ForwardIterator1 __first1, _Sentinel1 __last1, _ForwardIterator2 __first2, _BinaryPredicate&& __pred) {
119 // Shorten sequences as much as possible by lopping of any equal prefix.
120 for (; __first1 != __last1; ++__first1, (void)++__first2) {
121 if (!__pred(*__first1, *__first2))
122 break;
123 }
124
125 if (__first1 == __last1)
126 return true;
127
128 // __first1 != __last1 && *__first1 != *__first2
129 using _D1 = __iter_diff_t<_ForwardIterator1>;
130 _D1 __l1 = _IterOps<_AlgPolicy>::distance(__first1, __last1);
131 if (__l1 == _D1(1))
132 return false;
133 auto __last2 = _IterOps<_AlgPolicy>::next(__first2, __l1);
134
135 return std::__is_permutation_impl<_AlgPolicy>(
136 std::move(__first1),
137 std::move(__last1),
138 std::move(__first2),
139 std::move(__last2),
140 __pred,
141 __identity(),
142 __identity());
143}
144
145// 2+2 iterators, predicate, non-constant time `distance`.
146template <class _AlgPolicy,
147 class _Iter1,
148 class _Sent1,
149 class _Iter2,
150 class _Sent2,
151 class _Proj1,
152 class _Proj2,
153 class _Pred>
154_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation(
155 _Iter1 __first1,
156 _Sent1 __last1,
157 _Iter2 __first2,
158 _Sent2 __last2,
159 _Pred&& __pred,
160 _Proj1&& __proj1,
161 _Proj2&& __proj2,
162 /*_ConstTimeDistance=*/false_type) {
163 // Shorten sequences as much as possible by lopping of any equal prefix.
164 while (__first1 != __last1 && __first2 != __last2) {
165 if (!std::__invoke(__pred, std::__invoke(__proj1, *__first1), std::__invoke(__proj2, *__first2)))
166 break;
167 ++__first1;
168 ++__first2;
169 }
170
171 if (__first1 == __last1)
172 return __first2 == __last2;
173 if (__first2 == __last2) // Second range is shorter
174 return false;
175
176 using _D1 = __iter_diff_t<_Iter1>;
177 _D1 __l1 = _IterOps<_AlgPolicy>::distance(__first1, __last1);
178
179 using _D2 = __iter_diff_t<_Iter2>;
180 _D2 __l2 = _IterOps<_AlgPolicy>::distance(__first2, __last2);
181 if (__l1 != __l2)
182 return false;
183
184 return std::__is_permutation_impl<_AlgPolicy>(
185 std::move(__first1), std::move(__last1), std::move(__first2), std::move(__last2), __pred, __proj1, __proj2);
186}
187
188// 2+2 iterators, predicate, specialization for constant-time `distance` call.
189template <class _AlgPolicy,
190 class _Iter1,
191 class _Sent1,
192 class _Iter2,
193 class _Sent2,
194 class _Proj1,
195 class _Proj2,
196 class _Pred>
197_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation(
198 _Iter1 __first1,
199 _Sent1 __last1,
200 _Iter2 __first2,
201 _Sent2 __last2,
202 _Pred&& __pred,
203 _Proj1&& __proj1,
204 _Proj2&& __proj2,
205 /*_ConstTimeDistance=*/true_type) {
206 if (std::distance(__first1, __last1) != std::distance(__first2, __last2))
207 return false;
208 return std::__is_permutation<_AlgPolicy>(
209 std::move(__first1),
210 std::move(__last1),
211 std::move(__first2),
212 std::move(__last2),
213 __pred,
214 __proj1,
215 __proj2,
216 /*_ConstTimeDistance=*/false_type());
217}
218
219// 2+2 iterators, predicate
220template <class _AlgPolicy,
221 class _Iter1,
222 class _Sent1,
223 class _Iter2,
224 class _Sent2,
225 class _Proj1,
226 class _Proj2,
227 class _Pred>
228_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation(
229 _Iter1 __first1,
230 _Sent1 __last1,
231 _Iter2 __first2,
232 _Sent2 __last2,
233 _Pred&& __pred,
234 _Proj1&& __proj1,
235 _Proj2&& __proj2) {
236 return std::__is_permutation<_AlgPolicy>(
237 std::move(__first1),
238 std::move(__last1),
239 std::move(__first2),
240 std::move(__last2),
241 __pred,
242 __proj1,
243 __proj2,
244 _ConstTimeDistance<_Iter1, _Sent1, _Iter2, _Sent2>());
245}
246
247// Public interface
248
249// 2+1 iterators, predicate
250template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
251[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool is_permutation(
252 _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _BinaryPredicate __pred) {
253 static_assert(__is_callable<_BinaryPredicate&, decltype(*__first1), decltype(*__first2)>::value,
254 "The comparator has to be callable");
255
256 return std::__is_permutation<_ClassicAlgPolicy>(std::move(__first1), std::move(__last1), std::move(__first2), __pred);
257}
258
259// 2+1 iterators
260template <class _ForwardIterator1, class _ForwardIterator2>
261[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
262is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2) {
263 return std::is_permutation(__first1, __last1, __first2, __equal_to());
264}
265
266#if _LIBCPP_STD_VER >= 14
267
268// 2+2 iterators
269template <class _ForwardIterator1, class _ForwardIterator2>
270[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool is_permutation(
271 _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2) {
272 return std::__is_permutation<_ClassicAlgPolicy>(
273 std::move(__first1),
274 std::move(__last1),
275 std::move(__first2),
276 std::move(__last2),
277 __equal_to(),
278 __identity(),
279 __identity());
280}
281
282// 2+2 iterators, predicate
283template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
284[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool is_permutation(
285 _ForwardIterator1 __first1,
286 _ForwardIterator1 __last1,
287 _ForwardIterator2 __first2,
288 _ForwardIterator2 __last2,
289 _BinaryPredicate __pred) {
290 static_assert(__is_callable<_BinaryPredicate&, decltype(*__first1), decltype(*__first2)>::value,
291 "The comparator has to be callable");
292
293 return std::__is_permutation<_ClassicAlgPolicy>(
294 std::move(__first1),
295 std::move(__last1),
296 std::move(__first2),
297 std::move(__last2),
298 __pred,
299 __identity(),
300 __identity());
301}
302
303#endif // _LIBCPP_STD_VER >= 14
304
305_LIBCPP_END_NAMESPACE_STD
306
307_LIBCPP_POP_MACROS
308
309#endif // _LIBCPP___ALGORITHM_IS_PERMUTATION_H