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