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/iterator_traits.h> 16 #include <__iterator/next.h> 17 #include <iterator> // FIXME: replace with <__iterator/distance.h> when it lands 18 19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 20 #pragma GCC system_header 21 #endif 22 23 _LIBCPP_PUSH_MACROS 24 #include <__undef_macros> 25 26 _LIBCPP_BEGIN_NAMESPACE_STD 27 28 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate> 29 _LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 30 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, 31 _BinaryPredicate __pred) { 32 // shorten sequences as much as possible by lopping of any equal prefix 33 for (; __first1 != __last1; ++__first1, (void)++__first2) 34 if (!__pred(*__first1, *__first2)) 35 break; 36 if (__first1 == __last1) 37 return true; 38 39 // __first1 != __last1 && *__first1 != *__first2 40 typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1; 41 _D1 __l1 = _VSTD::distance(__first1, __last1); 42 if (__l1 == _D1(1)) 43 return false; 44 _ForwardIterator2 __last2 = _VSTD::next(__first2, __l1); 45 // For each element in [f1, l1) see if there are the same number of 46 // equal elements in [f2, l2) 47 for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i) { 48 // Have we already counted the number of *__i in [f1, l1)? 49 _ForwardIterator1 __match = __first1; 50 for (; __match != __i; ++__match) 51 if (__pred(*__match, *__i)) 52 break; 53 if (__match == __i) { 54 // Count number of *__i in [f2, l2) 55 _D1 __c2 = 0; 56 for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j) 57 if (__pred(*__i, *__j)) 58 ++__c2; 59 if (__c2 == 0) 60 return false; 61 // Count number of *__i in [__i, l1) (we can start with 1) 62 _D1 __c1 = 1; 63 for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j) 64 if (__pred(*__i, *__j)) 65 ++__c1; 66 if (__c1 != __c2) 67 return false; 68 } 69 } 70 return true; 71 } 72 73 template <class _ForwardIterator1, class _ForwardIterator2> 74 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 75 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2) { 76 typedef typename iterator_traits<_ForwardIterator1>::value_type __v1; 77 typedef typename iterator_traits<_ForwardIterator2>::value_type __v2; 78 return _VSTD::is_permutation(__first1, __last1, __first2, __equal_to<__v1, __v2>()); 79 } 80 81 #if _LIBCPP_STD_VER > 11 82 template <class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2> 83 _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 84 __is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, 85 _ForwardIterator2 __last2, _BinaryPredicate __pred, forward_iterator_tag, forward_iterator_tag) { 86 // shorten sequences as much as possible by lopping of any equal prefix 87 for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void)++__first2) 88 if (!__pred(*__first1, *__first2)) 89 break; 90 if (__first1 == __last1) 91 return __first2 == __last2; 92 else if (__first2 == __last2) 93 return false; 94 95 typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1; 96 _D1 __l1 = _VSTD::distance(__first1, __last1); 97 98 typedef typename iterator_traits<_ForwardIterator2>::difference_type _D2; 99 _D2 __l2 = _VSTD::distance(__first2, __last2); 100 if (__l1 != __l2) 101 return false; 102 103 // For each element in [f1, l1) see if there are the same number of 104 // equal elements in [f2, l2) 105 for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i) { 106 // Have we already counted the number of *__i in [f1, l1)? 107 _ForwardIterator1 __match = __first1; 108 for (; __match != __i; ++__match) 109 if (__pred(*__match, *__i)) 110 break; 111 if (__match == __i) { 112 // Count number of *__i in [f2, l2) 113 _D1 __c2 = 0; 114 for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j) 115 if (__pred(*__i, *__j)) 116 ++__c2; 117 if (__c2 == 0) 118 return false; 119 // Count number of *__i in [__i, l1) (we can start with 1) 120 _D1 __c1 = 1; 121 for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j) 122 if (__pred(*__i, *__j)) 123 ++__c1; 124 if (__c1 != __c2) 125 return false; 126 } 127 } 128 return true; 129 } 130 131 template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2> 132 _LIBCPP_CONSTEXPR_AFTER_CXX17 bool __is_permutation(_RandomAccessIterator1 __first1, _RandomAccessIterator2 __last1, 133 _RandomAccessIterator1 __first2, _RandomAccessIterator2 __last2, 134 _BinaryPredicate __pred, random_access_iterator_tag, 135 random_access_iterator_tag) { 136 if (_VSTD::distance(__first1, __last1) != _VSTD::distance(__first2, __last2)) 137 return false; 138 return _VSTD::is_permutation<_RandomAccessIterator1, _RandomAccessIterator2, 139 typename add_lvalue_reference<_BinaryPredicate>::type>(__first1, __last1, __first2, 140 __pred); 141 } 142 143 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate> 144 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 145 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, 146 _ForwardIterator2 __last2, _BinaryPredicate __pred) { 147 return _VSTD::__is_permutation<typename add_lvalue_reference<_BinaryPredicate>::type>( 148 __first1, __last1, __first2, __last2, __pred, typename iterator_traits<_ForwardIterator1>::iterator_category(), 149 typename iterator_traits<_ForwardIterator2>::iterator_category()); 150 } 151 152 template <class _ForwardIterator1, class _ForwardIterator2> 153 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 154 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, 155 _ForwardIterator2 __last2) { 156 typedef typename iterator_traits<_ForwardIterator1>::value_type __v1; 157 typedef typename iterator_traits<_ForwardIterator2>::value_type __v2; 158 return _VSTD::__is_permutation(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>(), 159 typename iterator_traits<_ForwardIterator1>::iterator_category(), 160 typename iterator_traits<_ForwardIterator2>::iterator_category()); 161 } 162 #endif 163 164 _LIBCPP_END_NAMESPACE_STD 165 166 _LIBCPP_POP_MACROS 167 168 #endif // _LIBCPP___ALGORITHM_IS_PERMUTATION_H 169