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 <__config> 15 #include <__iterator/distance.h> 16 #include <__iterator/iterator_traits.h> 17 #include <__iterator/next.h> 18 19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 20 # pragma GCC system_header 21 # pragma clang include_instead(<algorithm>) 22 #endif 23 24 _LIBCPP_BEGIN_NAMESPACE_STD 25 26 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate> 27 _LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 28 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, 29 _BinaryPredicate __pred) { 30 // shorten sequences as much as possible by lopping of any equal prefix 31 for (; __first1 != __last1; ++__first1, (void)++__first2) 32 if (!__pred(*__first1, *__first2)) 33 break; 34 if (__first1 == __last1) 35 return true; 36 37 // __first1 != __last1 && *__first1 != *__first2 38 typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1; 39 _D1 __l1 = _VSTD::distance(__first1, __last1); 40 if (__l1 == _D1(1)) 41 return false; 42 _ForwardIterator2 __last2 = _VSTD::next(__first2, __l1); 43 // For each element in [f1, l1) see if there are the same number of 44 // equal elements in [f2, l2) 45 for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i) { 46 // Have we already counted the number of *__i in [f1, l1)? 47 _ForwardIterator1 __match = __first1; 48 for (; __match != __i; ++__match) 49 if (__pred(*__match, *__i)) 50 break; 51 if (__match == __i) { 52 // Count number of *__i in [f2, l2) 53 _D1 __c2 = 0; 54 for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j) 55 if (__pred(*__i, *__j)) 56 ++__c2; 57 if (__c2 == 0) 58 return false; 59 // Count number of *__i in [__i, l1) (we can start with 1) 60 _D1 __c1 = 1; 61 for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j) 62 if (__pred(*__i, *__j)) 63 ++__c1; 64 if (__c1 != __c2) 65 return false; 66 } 67 } 68 return true; 69 } 70 71 template <class _ForwardIterator1, class _ForwardIterator2> 72 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 73 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2) { 74 typedef typename iterator_traits<_ForwardIterator1>::value_type __v1; 75 typedef typename iterator_traits<_ForwardIterator2>::value_type __v2; 76 return _VSTD::is_permutation(__first1, __last1, __first2, __equal_to<__v1, __v2>()); 77 } 78 79 #if _LIBCPP_STD_VER > 11 80 template <class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2> 81 _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 82 __is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, 83 _ForwardIterator2 __last2, _BinaryPredicate __pred, forward_iterator_tag, forward_iterator_tag) { 84 // shorten sequences as much as possible by lopping of any equal prefix 85 for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void)++__first2) 86 if (!__pred(*__first1, *__first2)) 87 break; 88 if (__first1 == __last1) 89 return __first2 == __last2; 90 else if (__first2 == __last2) 91 return false; 92 93 typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1; 94 _D1 __l1 = _VSTD::distance(__first1, __last1); 95 96 typedef typename iterator_traits<_ForwardIterator2>::difference_type _D2; 97 _D2 __l2 = _VSTD::distance(__first2, __last2); 98 if (__l1 != __l2) 99 return false; 100 101 // For each element in [f1, l1) see if there are the same number of 102 // equal elements in [f2, l2) 103 for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i) { 104 // Have we already counted the number of *__i in [f1, l1)? 105 _ForwardIterator1 __match = __first1; 106 for (; __match != __i; ++__match) 107 if (__pred(*__match, *__i)) 108 break; 109 if (__match == __i) { 110 // Count number of *__i in [f2, l2) 111 _D1 __c2 = 0; 112 for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j) 113 if (__pred(*__i, *__j)) 114 ++__c2; 115 if (__c2 == 0) 116 return false; 117 // Count number of *__i in [__i, l1) (we can start with 1) 118 _D1 __c1 = 1; 119 for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j) 120 if (__pred(*__i, *__j)) 121 ++__c1; 122 if (__c1 != __c2) 123 return false; 124 } 125 } 126 return true; 127 } 128 129 template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2> 130 _LIBCPP_CONSTEXPR_AFTER_CXX17 bool __is_permutation(_RandomAccessIterator1 __first1, _RandomAccessIterator2 __last1, 131 _RandomAccessIterator1 __first2, _RandomAccessIterator2 __last2, 132 _BinaryPredicate __pred, random_access_iterator_tag, 133 random_access_iterator_tag) { 134 if (_VSTD::distance(__first1, __last1) != _VSTD::distance(__first2, __last2)) 135 return false; 136 return _VSTD::is_permutation<_RandomAccessIterator1, _RandomAccessIterator2, 137 _BinaryPredicate&>(__first1, __last1, __first2, __pred); 138 } 139 140 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate> 141 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 142 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, 143 _ForwardIterator2 __last2, _BinaryPredicate __pred) { 144 return _VSTD::__is_permutation<_BinaryPredicate&>( 145 __first1, __last1, __first2, __last2, __pred, typename iterator_traits<_ForwardIterator1>::iterator_category(), 146 typename iterator_traits<_ForwardIterator2>::iterator_category()); 147 } 148 149 template <class _ForwardIterator1, class _ForwardIterator2> 150 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 151 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, 152 _ForwardIterator2 __last2) { 153 typedef typename iterator_traits<_ForwardIterator1>::value_type __v1; 154 typedef typename iterator_traits<_ForwardIterator2>::value_type __v2; 155 return _VSTD::__is_permutation(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>(), 156 typename iterator_traits<_ForwardIterator1>::iterator_category(), 157 typename iterator_traits<_ForwardIterator2>::iterator_category()); 158 } 159 #endif 160 161 _LIBCPP_END_NAMESPACE_STD 162 163 #endif // _LIBCPP___ALGORITHM_IS_PERMUTATION_H 164