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 35 template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class = void> 36 struct _ConstTimeDistance : false_type {}; 37 38 #if _LIBCPP_STD_VER >= 20 39 40 template <class _Iter1, class _Sent1, class _Iter2, class _Sent2> 41 struct _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 50 template <class _Iter1, class _Iter2> 51 struct _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) 65 template <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. 116 template <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`. 146 template <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. 189 template <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 220 template <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 250 template <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 260 template <class _ForwardIterator1, class _ForwardIterator2> 261 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool 262 is_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 269 template <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 283 template <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 310