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