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 <__iterator/next.h> 21 #include <__type_traits/enable_if.h> 22 #include <__type_traits/invoke.h> 23 #include <__type_traits/is_callable.h> 24 #include <__type_traits/is_same.h> 25 #include <__utility/move.h> 26 27 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 28 # pragma GCC system_header 29 #endif 30 31 _LIBCPP_PUSH_MACROS 32 #include <__undef_macros> 33 34 _LIBCPP_BEGIN_NAMESPACE_STD 35 36 template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class = void> 37 struct _ConstTimeDistance : false_type {}; 38 39 #if _LIBCPP_STD_VER >= 20 40 41 template <class _Iter1, class _Sent1, class _Iter2, class _Sent2> 42 struct _ConstTimeDistance<_Iter1, 43 _Sent1, 44 _Iter2, 45 _Sent2, 46 __enable_if_t< sized_sentinel_for<_Sent1, _Iter1> && sized_sentinel_for<_Sent2, _Iter2> >> 47 : true_type {}; 48 49 #else 50 51 template <class _Iter1, class _Iter2> 52 struct _ConstTimeDistance< 53 _Iter1, 54 _Iter1, 55 _Iter2, 56 _Iter2, 57 __enable_if_t< is_same<typename iterator_traits<_Iter1>::iterator_category, random_access_iterator_tag>::value && 58 is_same<typename iterator_traits<_Iter2>::iterator_category, random_access_iterator_tag>::value > > 59 : true_type {}; 60 61 #endif // _LIBCPP_STD_VER >= 20 62 63 // Internal functions 64 65 // For each element in [f1, l1) see if there are the same number of equal elements in [f2, l2) 66 template <class _AlgPolicy, 67 class _Iter1, 68 class _Sent1, 69 class _Iter2, 70 class _Sent2, 71 class _Proj1, 72 class _Proj2, 73 class _Pred> 74 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation_impl( 75 _Iter1 __first1, 76 _Sent1 __last1, 77 _Iter2 __first2, 78 _Sent2 __last2, 79 _Pred&& __pred, 80 _Proj1&& __proj1, 81 _Proj2&& __proj2) { 82 using _D1 = __iter_diff_t<_Iter1>; 83 84 for (auto __i = __first1; __i != __last1; ++__i) { 85 // Have we already counted the number of *__i in [f1, l1)? 86 auto __match = __first1; 87 for (; __match != __i; ++__match) { 88 if (std::__invoke(__pred, std::__invoke(__proj1, *__match), std::__invoke(__proj1, *__i))) 89 break; 90 } 91 92 if (__match == __i) { 93 // Count number of *__i in [f2, l2) 94 _D1 __c2 = 0; 95 for (auto __j = __first2; __j != __last2; ++__j) { 96 if (std::__invoke(__pred, std::__invoke(__proj1, *__i), std::__invoke(__proj2, *__j))) 97 ++__c2; 98 } 99 if (__c2 == 0) 100 return false; 101 102 // Count number of *__i in [__i, l1) (we can start with 1) 103 _D1 __c1 = 1; 104 for (auto __j = _IterOps<_AlgPolicy>::next(__i); __j != __last1; ++__j) { 105 if (std::__invoke(__pred, std::__invoke(__proj1, *__i), std::__invoke(__proj1, *__j))) 106 ++__c1; 107 } 108 if (__c1 != __c2) 109 return false; 110 } 111 } 112 113 return true; 114 } 115 116 // 2+1 iterators, predicate. Not used by range algorithms. 117 template <class _AlgPolicy, class _ForwardIterator1, class _Sentinel1, class _ForwardIterator2, class _BinaryPredicate> 118 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation( 119 _ForwardIterator1 __first1, _Sentinel1 __last1, _ForwardIterator2 __first2, _BinaryPredicate&& __pred) { 120 // Shorten sequences as much as possible by lopping of any equal prefix. 121 for (; __first1 != __last1; ++__first1, (void)++__first2) { 122 if (!__pred(*__first1, *__first2)) 123 break; 124 } 125 126 if (__first1 == __last1) 127 return true; 128 129 // __first1 != __last1 && *__first1 != *__first2 130 using _D1 = __iter_diff_t<_ForwardIterator1>; 131 _D1 __l1 = _IterOps<_AlgPolicy>::distance(__first1, __last1); 132 if (__l1 == _D1(1)) 133 return false; 134 auto __last2 = _IterOps<_AlgPolicy>::next(__first2, __l1); 135 136 return std::__is_permutation_impl<_AlgPolicy>( 137 std::move(__first1), 138 std::move(__last1), 139 std::move(__first2), 140 std::move(__last2), 141 __pred, 142 __identity(), 143 __identity()); 144 } 145 146 // 2+2 iterators, predicate, non-constant time `distance`. 147 template <class _AlgPolicy, 148 class _Iter1, 149 class _Sent1, 150 class _Iter2, 151 class _Sent2, 152 class _Proj1, 153 class _Proj2, 154 class _Pred> 155 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation( 156 _Iter1 __first1, 157 _Sent1 __last1, 158 _Iter2 __first2, 159 _Sent2 __last2, 160 _Pred&& __pred, 161 _Proj1&& __proj1, 162 _Proj2&& __proj2, 163 /*_ConstTimeDistance=*/false_type) { 164 // Shorten sequences as much as possible by lopping of any equal prefix. 165 while (__first1 != __last1 && __first2 != __last2) { 166 if (!std::__invoke(__pred, std::__invoke(__proj1, *__first1), std::__invoke(__proj2, *__first2))) 167 break; 168 ++__first1; 169 ++__first2; 170 } 171 172 if (__first1 == __last1) 173 return __first2 == __last2; 174 if (__first2 == __last2) // Second range is shorter 175 return false; 176 177 using _D1 = __iter_diff_t<_Iter1>; 178 _D1 __l1 = _IterOps<_AlgPolicy>::distance(__first1, __last1); 179 180 using _D2 = __iter_diff_t<_Iter2>; 181 _D2 __l2 = _IterOps<_AlgPolicy>::distance(__first2, __last2); 182 if (__l1 != __l2) 183 return false; 184 185 return std::__is_permutation_impl<_AlgPolicy>( 186 std::move(__first1), std::move(__last1), std::move(__first2), std::move(__last2), __pred, __proj1, __proj2); 187 } 188 189 // 2+2 iterators, predicate, specialization for constant-time `distance` call. 190 template <class _AlgPolicy, 191 class _Iter1, 192 class _Sent1, 193 class _Iter2, 194 class _Sent2, 195 class _Proj1, 196 class _Proj2, 197 class _Pred> 198 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation( 199 _Iter1 __first1, 200 _Sent1 __last1, 201 _Iter2 __first2, 202 _Sent2 __last2, 203 _Pred&& __pred, 204 _Proj1&& __proj1, 205 _Proj2&& __proj2, 206 /*_ConstTimeDistance=*/true_type) { 207 if (std::distance(__first1, __last1) != std::distance(__first2, __last2)) 208 return false; 209 return std::__is_permutation<_AlgPolicy>( 210 std::move(__first1), 211 std::move(__last1), 212 std::move(__first2), 213 std::move(__last2), 214 __pred, 215 __proj1, 216 __proj2, 217 /*_ConstTimeDistance=*/false_type()); 218 } 219 220 // 2+2 iterators, predicate 221 template <class _AlgPolicy, 222 class _Iter1, 223 class _Sent1, 224 class _Iter2, 225 class _Sent2, 226 class _Proj1, 227 class _Proj2, 228 class _Pred> 229 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation( 230 _Iter1 __first1, 231 _Sent1 __last1, 232 _Iter2 __first2, 233 _Sent2 __last2, 234 _Pred&& __pred, 235 _Proj1&& __proj1, 236 _Proj2&& __proj2) { 237 return std::__is_permutation<_AlgPolicy>( 238 std::move(__first1), 239 std::move(__last1), 240 std::move(__first2), 241 std::move(__last2), 242 __pred, 243 __proj1, 244 __proj2, 245 _ConstTimeDistance<_Iter1, _Sent1, _Iter2, _Sent2>()); 246 } 247 248 // Public interface 249 250 // 2+1 iterators, predicate 251 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate> 252 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool is_permutation( 253 _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _BinaryPredicate __pred) { 254 static_assert(__is_callable<_BinaryPredicate&, decltype(*__first1), decltype(*__first2)>::value, 255 "The comparator has to be callable"); 256 257 return std::__is_permutation<_ClassicAlgPolicy>(std::move(__first1), std::move(__last1), std::move(__first2), __pred); 258 } 259 260 // 2+1 iterators 261 template <class _ForwardIterator1, class _ForwardIterator2> 262 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool 263 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2) { 264 return std::is_permutation(__first1, __last1, __first2, __equal_to()); 265 } 266 267 #if _LIBCPP_STD_VER >= 14 268 269 // 2+2 iterators 270 template <class _ForwardIterator1, class _ForwardIterator2> 271 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool is_permutation( 272 _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2) { 273 return std::__is_permutation<_ClassicAlgPolicy>( 274 std::move(__first1), 275 std::move(__last1), 276 std::move(__first2), 277 std::move(__last2), 278 __equal_to(), 279 __identity(), 280 __identity()); 281 } 282 283 // 2+2 iterators, predicate 284 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate> 285 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool is_permutation( 286 _ForwardIterator1 __first1, 287 _ForwardIterator1 __last1, 288 _ForwardIterator2 __first2, 289 _ForwardIterator2 __last2, 290 _BinaryPredicate __pred) { 291 static_assert(__is_callable<_BinaryPredicate&, decltype(*__first1), decltype(*__first2)>::value, 292 "The comparator has to be callable"); 293 294 return std::__is_permutation<_ClassicAlgPolicy>( 295 std::move(__first1), 296 std::move(__last1), 297 std::move(__first2), 298 std::move(__last2), 299 __pred, 300 __identity(), 301 __identity()); 302 } 303 304 #endif // _LIBCPP_STD_VER >= 14 305 306 _LIBCPP_END_NAMESPACE_STD 307 308 _LIBCPP_POP_MACROS 309 310 #endif // _LIBCPP___ALGORITHM_IS_PERMUTATION_H 311