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 <__config> 14 #include <__iterator/iterator_traits.h> 15 #include <__iterator/next.h> 16 #include <iterator> // FIXME: replace with <__iterator/distance.h> when it lands 17 18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 19 #pragma GCC system_header 20 #endif 21 22 _LIBCPP_PUSH_MACROS 23 #include <__undef_macros> 24 25 _LIBCPP_BEGIN_NAMESPACE_STD 26 27 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate> 28 _LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 29 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, 30 _BinaryPredicate __pred) { 31 // shorten sequences as much as possible by lopping of any equal prefix 32 for (; __first1 != __last1; ++__first1, (void)++__first2) 33 if (!__pred(*__first1, *__first2)) 34 break; 35 if (__first1 == __last1) 36 return true; 37 38 // __first1 != __last1 && *__first1 != *__first2 39 typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1; 40 _D1 __l1 = _VSTD::distance(__first1, __last1); 41 if (__l1 == _D1(1)) 42 return false; 43 _ForwardIterator2 __last2 = _VSTD::next(__first2, __l1); 44 // For each element in [f1, l1) see if there are the same number of 45 // equal elements in [f2, l2) 46 for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i) { 47 // Have we already counted the number of *__i in [f1, l1)? 48 _ForwardIterator1 __match = __first1; 49 for (; __match != __i; ++__match) 50 if (__pred(*__match, *__i)) 51 break; 52 if (__match == __i) { 53 // Count number of *__i in [f2, l2) 54 _D1 __c2 = 0; 55 for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j) 56 if (__pred(*__i, *__j)) 57 ++__c2; 58 if (__c2 == 0) 59 return false; 60 // Count number of *__i in [__i, l1) (we can start with 1) 61 _D1 __c1 = 1; 62 for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j) 63 if (__pred(*__i, *__j)) 64 ++__c1; 65 if (__c1 != __c2) 66 return false; 67 } 68 } 69 return true; 70 } 71 72 template <class _ForwardIterator1, class _ForwardIterator2> 73 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 74 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2) { 75 typedef typename iterator_traits<_ForwardIterator1>::value_type __v1; 76 typedef typename iterator_traits<_ForwardIterator2>::value_type __v2; 77 return _VSTD::is_permutation(__first1, __last1, __first2, __equal_to<__v1, __v2>()); 78 } 79 80 #if _LIBCPP_STD_VER > 11 81 template <class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2> 82 _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 83 __is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, 84 _ForwardIterator2 __last2, _BinaryPredicate __pred, forward_iterator_tag, forward_iterator_tag) { 85 // shorten sequences as much as possible by lopping of any equal prefix 86 for (; __first1 != __last1 && __first2 != __last2; ++__first1, (void)++__first2) 87 if (!__pred(*__first1, *__first2)) 88 break; 89 if (__first1 == __last1) 90 return __first2 == __last2; 91 else if (__first2 == __last2) 92 return false; 93 94 typedef typename iterator_traits<_ForwardIterator1>::difference_type _D1; 95 _D1 __l1 = _VSTD::distance(__first1, __last1); 96 97 typedef typename iterator_traits<_ForwardIterator2>::difference_type _D2; 98 _D2 __l2 = _VSTD::distance(__first2, __last2); 99 if (__l1 != __l2) 100 return false; 101 102 // For each element in [f1, l1) see if there are the same number of 103 // equal elements in [f2, l2) 104 for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i) { 105 // Have we already counted the number of *__i in [f1, l1)? 106 _ForwardIterator1 __match = __first1; 107 for (; __match != __i; ++__match) 108 if (__pred(*__match, *__i)) 109 break; 110 if (__match == __i) { 111 // Count number of *__i in [f2, l2) 112 _D1 __c2 = 0; 113 for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j) 114 if (__pred(*__i, *__j)) 115 ++__c2; 116 if (__c2 == 0) 117 return false; 118 // Count number of *__i in [__i, l1) (we can start with 1) 119 _D1 __c1 = 1; 120 for (_ForwardIterator1 __j = _VSTD::next(__i); __j != __last1; ++__j) 121 if (__pred(*__i, *__j)) 122 ++__c1; 123 if (__c1 != __c2) 124 return false; 125 } 126 } 127 return true; 128 } 129 130 template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2> 131 _LIBCPP_CONSTEXPR_AFTER_CXX17 bool __is_permutation(_RandomAccessIterator1 __first1, _RandomAccessIterator2 __last1, 132 _RandomAccessIterator1 __first2, _RandomAccessIterator2 __last2, 133 _BinaryPredicate __pred, random_access_iterator_tag, 134 random_access_iterator_tag) { 135 if (_VSTD::distance(__first1, __last1) != _VSTD::distance(__first2, __last2)) 136 return false; 137 return _VSTD::is_permutation<_RandomAccessIterator1, _RandomAccessIterator2, 138 typename add_lvalue_reference<_BinaryPredicate>::type>(__first1, __last1, __first2, 139 __pred); 140 } 141 142 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate> 143 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 144 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, 145 _ForwardIterator2 __last2, _BinaryPredicate __pred) { 146 return _VSTD::__is_permutation<typename add_lvalue_reference<_BinaryPredicate>::type>( 147 __first1, __last1, __first2, __last2, __pred, typename iterator_traits<_ForwardIterator1>::iterator_category(), 148 typename iterator_traits<_ForwardIterator2>::iterator_category()); 149 } 150 151 template <class _ForwardIterator1, class _ForwardIterator2> 152 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 bool 153 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, 154 _ForwardIterator2 __last2) { 155 typedef typename iterator_traits<_ForwardIterator1>::value_type __v1; 156 typedef typename iterator_traits<_ForwardIterator2>::value_type __v2; 157 return _VSTD::__is_permutation(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>(), 158 typename iterator_traits<_ForwardIterator1>::iterator_category(), 159 typename iterator_traits<_ForwardIterator2>::iterator_category()); 160 } 161 #endif 162 163 _LIBCPP_END_NAMESPACE_STD 164 165 _LIBCPP_POP_MACROS 166 167 #endif // _LIBCPP___ALGORITHM_IS_PERMUTATION_H 168