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 <__utility/move.h> 23 #include <type_traits> 24 25 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 26 # pragma GCC system_header 27 #endif 28 29 _LIBCPP_BEGIN_NAMESPACE_STD 30 31 template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class = void> 32 struct _ConstTimeDistance : false_type {}; 33 34 #if _LIBCPP_STD_VER > 17 35 36 template <class _Iter1, class _Sent1, class _Iter2, class _Sent2> 37 struct _ConstTimeDistance<_Iter1, _Sent1, _Iter2, _Sent2, __enable_if_t< 38 sized_sentinel_for<_Sent1, _Iter1> && 39 sized_sentinel_for<_Sent2, _Iter2> 40 >> : true_type {}; 41 42 #else 43 44 template <class _Iter1, class _Iter2> 45 struct _ConstTimeDistance<_Iter1, _Iter1, _Iter2, _Iter2, __enable_if_t< 46 is_same<typename iterator_traits<_Iter1>::iterator_category, random_access_iterator_tag>::value && 47 is_same<typename iterator_traits<_Iter2>::iterator_category, random_access_iterator_tag>::value 48 > > : true_type {}; 49 50 #endif // _LIBCPP_STD_VER > 17 51 52 // Internal functions 53 54 // For each element in [f1, l1) see if there are the same number of equal elements in [f2, l2) 55 template <class _AlgPolicy, 56 class _Iter1, class _Sent1, class _Iter2, class _Sent2, 57 class _Proj1, class _Proj2, class _Pred> 58 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool 59 __is_permutation_impl(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2, 60 _Pred&& __pred, _Proj1&& __proj1, _Proj2&& __proj2) { 61 using _D1 = __iter_diff_t<_Iter1>; 62 63 for (auto __i = __first1; __i != __last1; ++__i) { 64 // Have we already counted the number of *__i in [f1, l1)? 65 auto __match = __first1; 66 for (; __match != __i; ++__match) { 67 if (std::__invoke(__pred, std::__invoke(__proj1, *__match), std::__invoke(__proj1, *__i))) 68 break; 69 } 70 71 if (__match == __i) { 72 // Count number of *__i in [f2, l2) 73 _D1 __c2 = 0; 74 for (auto __j = __first2; __j != __last2; ++__j) { 75 if (std::__invoke(__pred, std::__invoke(__proj1, *__i), std::__invoke(__proj2, *__j))) 76 ++__c2; 77 } 78 if (__c2 == 0) 79 return false; 80 81 // Count number of *__i in [__i, l1) (we can start with 1) 82 _D1 __c1 = 1; 83 for (auto __j = _IterOps<_AlgPolicy>::next(__i); __j != __last1; ++__j) { 84 if (std::__invoke(__pred, std::__invoke(__proj1, *__i), std::__invoke(__proj1, *__j))) 85 ++__c1; 86 } 87 if (__c1 != __c2) 88 return false; 89 } 90 } 91 92 return true; 93 } 94 95 // 2+1 iterators, predicate. Not used by range algorithms. 96 template <class _AlgPolicy, class _ForwardIterator1, class _Sentinel1, class _ForwardIterator2, class _BinaryPredicate> 97 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool 98 __is_permutation(_ForwardIterator1 __first1, _Sentinel1 __last1, _ForwardIterator2 __first2, 99 _BinaryPredicate&& __pred) { 100 // Shorten sequences as much as possible by lopping of any equal prefix. 101 for (; __first1 != __last1; ++__first1, (void)++__first2) { 102 if (!__pred(*__first1, *__first2)) 103 break; 104 } 105 106 if (__first1 == __last1) 107 return true; 108 109 // __first1 != __last1 && *__first1 != *__first2 110 using _D1 = __iter_diff_t<_ForwardIterator1>; 111 _D1 __l1 = _IterOps<_AlgPolicy>::distance(__first1, __last1); 112 if (__l1 == _D1(1)) 113 return false; 114 auto __last2 = _IterOps<_AlgPolicy>::next(__first2, __l1); 115 116 return std::__is_permutation_impl<_AlgPolicy>( 117 std::move(__first1), std::move(__last1), std::move(__first2), std::move(__last2), 118 __pred, __identity(), __identity()); 119 } 120 121 // 2+2 iterators, predicate, non-constant time `distance`. 122 template <class _AlgPolicy, 123 class _Iter1, class _Sent1, class _Iter2, class _Sent2, 124 class _Proj1, class _Proj2, class _Pred> 125 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool 126 __is_permutation(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2, 127 _Pred&& __pred, _Proj1&& __proj1, _Proj2&& __proj2, 128 /*_ConstTimeDistance=*/false_type) { 129 // Shorten sequences as much as possible by lopping of any equal prefix. 130 while (__first1 != __last1 && __first2 != __last2) { 131 if (!std::__invoke(__pred, std::__invoke(__proj1, *__first1), std::__invoke(__proj2, *__first2))) 132 break; 133 ++__first1; 134 ++__first2; 135 } 136 137 if (__first1 == __last1) 138 return __first2 == __last2; 139 if (__first2 == __last2) // Second range is shorter 140 return false; 141 142 using _D1 = __iter_diff_t<_Iter1>; 143 _D1 __l1 = _IterOps<_AlgPolicy>::distance(__first1, __last1); 144 145 using _D2 = __iter_diff_t<_Iter2>; 146 _D2 __l2 = _IterOps<_AlgPolicy>::distance(__first2, __last2); 147 if (__l1 != __l2) 148 return false; 149 150 return std::__is_permutation_impl<_AlgPolicy>( 151 std::move(__first1), std::move(__last1), std::move(__first2), std::move(__last2), 152 __pred, __proj1, __proj2); 153 } 154 155 // 2+2 iterators, predicate, specialization for constant-time `distance` call. 156 template <class _AlgPolicy, 157 class _Iter1, class _Sent1, class _Iter2, class _Sent2, 158 class _Proj1, class _Proj2, class _Pred> 159 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool 160 __is_permutation(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2, 161 _Pred&& __pred, _Proj1&& __proj1, _Proj2&& __proj2, 162 /*_ConstTimeDistance=*/true_type) { 163 if (std::distance(__first1, __last1) != std::distance(__first2, __last2)) 164 return false; 165 return std::__is_permutation<_AlgPolicy>( 166 std::move(__first1), std::move(__last1), std::move(__first2), std::move(__last2), 167 __pred, __proj1, __proj2, 168 /*_ConstTimeDistance=*/false_type()); 169 } 170 171 // 2+2 iterators, predicate 172 template <class _AlgPolicy, 173 class _Iter1, class _Sent1, class _Iter2, class _Sent2, 174 class _Proj1, class _Proj2, class _Pred> 175 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool 176 __is_permutation(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2, 177 _Pred&& __pred, _Proj1&& __proj1, _Proj2&& __proj2) { 178 return std::__is_permutation<_AlgPolicy>( 179 std::move(__first1), std::move(__last1), std::move(__first2), std::move(__last2), 180 __pred, __proj1, __proj2, 181 _ConstTimeDistance<_Iter1, _Sent1, _Iter2, _Sent2>()); 182 } 183 184 // Public interface 185 186 // 2+1 iterators, predicate 187 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate> 188 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool 189 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, 190 _BinaryPredicate __pred) { 191 static_assert(__is_callable<_BinaryPredicate, decltype(*__first1), decltype(*__first2)>::value, 192 "The predicate has to be callable"); 193 194 return std::__is_permutation<_ClassicAlgPolicy>( 195 std::move(__first1), std::move(__last1), std::move(__first2), __pred); 196 } 197 198 // 2+1 iterators 199 template <class _ForwardIterator1, class _ForwardIterator2> 200 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool 201 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2) { 202 return std::is_permutation(__first1, __last1, __first2, __equal_to()); 203 } 204 205 #if _LIBCPP_STD_VER > 11 206 207 // 2+2 iterators 208 template <class _ForwardIterator1, class _ForwardIterator2> 209 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool is_permutation( 210 _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2) { 211 return std::__is_permutation<_ClassicAlgPolicy>( 212 std::move(__first1), 213 std::move(__last1), 214 std::move(__first2), 215 std::move(__last2), 216 __equal_to(), 217 __identity(), 218 __identity()); 219 } 220 221 // 2+2 iterators, predicate 222 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate> 223 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool 224 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, 225 _ForwardIterator2 __last2, _BinaryPredicate __pred) { 226 static_assert(__is_callable<_BinaryPredicate, decltype(*__first1), decltype(*__first2)>::value, 227 "The predicate has to be callable"); 228 229 return std::__is_permutation<_ClassicAlgPolicy>( 230 std::move(__first1), std::move(__last1), std::move(__first2), std::move(__last2), 231 __pred, __identity(), __identity()); 232 } 233 234 #endif // _LIBCPP_STD_VER > 11 235 236 _LIBCPP_END_NAMESPACE_STD 237 238 #endif // _LIBCPP___ALGORITHM_IS_PERMUTATION_H 239