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 34 template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class = void> 35 struct _ConstTimeDistance : false_type {}; 36 37 #if _LIBCPP_STD_VER >= 20 38 39 template <class _Iter1, class _Sent1, class _Iter2, class _Sent2> 40 struct _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 49 template <class _Iter1, class _Iter2> 50 struct _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) 64 template <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. 115 template <class _AlgPolicy, class _ForwardIterator1, class _Sentinel1, class _ForwardIterator2, class _BinaryPredicate> 116 _LIBCPP_NODISCARD_EXT _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`. 145 template <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. 188 template <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 219 template <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 249 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate> 250 _LIBCPP_NODISCARD_EXT _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 259 template <class _ForwardIterator1, class _ForwardIterator2> 260 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool 261 is_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 268 template <class _ForwardIterator1, class _ForwardIterator2> 269 _LIBCPP_NODISCARD_EXT 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 282 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate> 283 _LIBCPP_NODISCARD_EXT 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