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
is_permutation(_ForwardIterator1 __first1,_ForwardIterator1 __last1,_ForwardIterator2 __first2,_BinaryPredicate __pred)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
is_permutation(_ForwardIterator1 __first1,_ForwardIterator1 __last1,_ForwardIterator2 __first2)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
__is_permutation(_ForwardIterator1 __first1,_ForwardIterator1 __last1,_ForwardIterator2 __first2,_ForwardIterator2 __last2,_BinaryPredicate __pred,forward_iterator_tag,forward_iterator_tag)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>
__is_permutation(_RandomAccessIterator1 __first1,_RandomAccessIterator2 __last1,_RandomAccessIterator1 __first2,_RandomAccessIterator2 __last2,_BinaryPredicate __pred,random_access_iterator_tag,random_access_iterator_tag)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
is_permutation(_ForwardIterator1 __first1,_ForwardIterator1 __last1,_ForwardIterator2 __first2,_ForwardIterator2 __last2,_BinaryPredicate __pred)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
is_permutation(_ForwardIterator1 __first1,_ForwardIterator1 __last1,_ForwardIterator2 __first2,_ForwardIterator2 __last2)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