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_FIND_END_OF_H
11#define _LIBCPP___ALGORITHM_FIND_END_OF_H
12
13#include <__algorithm/comp.h>
14#include <__algorithm/iterator_operations.h>
15#include <__config>
16#include <__functional/identity.h>
17#include <__iterator/iterator_traits.h>
18#include <__type_traits/invoke.h>
19#include <__utility/pair.h>
20
21#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
22# pragma GCC system_header
23#endif
24
25_LIBCPP_BEGIN_NAMESPACE_STD
26
27template < class _AlgPolicy,
28 class _Iter1,
29 class _Sent1,
30 class _Iter2,
31 class _Sent2,
32 class _Pred,
33 class _Proj1,
34 class _Proj2>
35_LIBCPP_HIDE_FROM_ABI inline _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_Iter1, _Iter1> __find_end_impl(
36 _Iter1 __first1,
37 _Sent1 __last1,
38 _Iter2 __first2,
39 _Sent2 __last2,
40 _Pred& __pred,
41 _Proj1& __proj1,
42 _Proj2& __proj2,
43 forward_iterator_tag,
44 forward_iterator_tag) {
45 // modeled after search algorithm
46 _Iter1 __match_first = _IterOps<_AlgPolicy>::next(__first1, __last1); // __last1 is the "default" answer
47 _Iter1 __match_last = __match_first;
48 if (__first2 == __last2)
49 return pair<_Iter1, _Iter1>(__match_last, __match_last);
50 while (true) {
51 while (true) {
52 if (__first1 == __last1) // if source exhausted return last correct answer (or __last1 if never found)
53 return pair<_Iter1, _Iter1>(__match_first, __match_last);
54 if (std::__invoke(__pred, std::__invoke(__proj1, *__first1), std::__invoke(__proj2, *__first2)))
55 break;
56 ++__first1;
57 }
58 // *__first1 matches *__first2, now match elements after here
59 _Iter1 __m1 = __first1;
60 _Iter2 __m2 = __first2;
61 while (true) {
62 if (++__m2 == __last2) { // Pattern exhaused, record answer and search for another one
63 __match_first = __first1;
64 __match_last = ++__m1;
65 ++__first1;
66 break;
67 }
68 if (++__m1 == __last1) // Source exhausted, return last answer
69 return pair<_Iter1, _Iter1>(__match_first, __match_last);
70 // mismatch, restart with a new __first
71 if (!std::__invoke(__pred, std::__invoke(__proj1, *__m1), std::__invoke(__proj2, *__m2))) {
72 ++__first1;
73 break;
74 } // else there is a match, check next elements
75 }
76 }
77}
78
79template <class _AlgPolicy,
80 class _Pred,
81 class _Iter1,
82 class _Sent1,
83 class _Iter2,
84 class _Sent2,
85 class _Proj1,
86 class _Proj2>
87_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pair<_Iter1, _Iter1> __find_end_impl(
88 _Iter1 __first1,
89 _Sent1 __sent1,
90 _Iter2 __first2,
91 _Sent2 __sent2,
92 _Pred& __pred,
93 _Proj1& __proj1,
94 _Proj2& __proj2,
95 bidirectional_iterator_tag,
96 bidirectional_iterator_tag) {
97 auto __last1 = _IterOps<_AlgPolicy>::next(__first1, __sent1);
98 auto __last2 = _IterOps<_AlgPolicy>::next(__first2, __sent2);
99 // modeled after search algorithm (in reverse)
100 if (__first2 == __last2)
101 return std::make_pair(__last1, __last1); // Everything matches an empty sequence
102 _Iter1 __l1 = __last1;
103 _Iter2 __l2 = __last2;
104 --__l2;
105 while (true) {
106 // Find last element in sequence 1 that matches *(__last2-1), with a mininum of loop checks
107 while (true) {
108 if (__first1 == __l1) // return __last1 if no element matches *__first2
109 return std::make_pair(__last1, __last1);
110 if (std::__invoke(__pred, std::__invoke(__proj1, *--__l1), std::__invoke(__proj2, *__l2)))
111 break;
112 }
113 // *__l1 matches *__l2, now match elements before here
114 _Iter1 __match_last = __l1;
115 _Iter1 __m1 = __l1;
116 _Iter2 __m2 = __l2;
117 while (true) {
118 if (__m2 == __first2) // If pattern exhausted, __m1 is the answer (works for 1 element pattern)
119 return std::make_pair(__m1, ++__match_last);
120 if (__m1 == __first1) // Otherwise if source exhaused, pattern not found
121 return std::make_pair(__last1, __last1);
122
123 // if there is a mismatch, restart with a new __l1
124 if (!std::__invoke(__pred, std::__invoke(__proj1, *--__m1), std::__invoke(__proj2, *--__m2))) {
125 break;
126 } // else there is a match, check next elements
127 }
128 }
129}
130
131template <class _AlgPolicy,
132 class _Pred,
133 class _Iter1,
134 class _Sent1,
135 class _Iter2,
136 class _Sent2,
137 class _Proj1,
138 class _Proj2>
139_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_Iter1, _Iter1> __find_end_impl(
140 _Iter1 __first1,
141 _Sent1 __sent1,
142 _Iter2 __first2,
143 _Sent2 __sent2,
144 _Pred& __pred,
145 _Proj1& __proj1,
146 _Proj2& __proj2,
147 random_access_iterator_tag,
148 random_access_iterator_tag) {
149 typedef typename iterator_traits<_Iter1>::difference_type _D1;
150 auto __last1 = _IterOps<_AlgPolicy>::next(__first1, __sent1);
151 auto __last2 = _IterOps<_AlgPolicy>::next(__first2, __sent2);
152 // Take advantage of knowing source and pattern lengths. Stop short when source is smaller than pattern
153 auto __len2 = __last2 - __first2;
154 if (__len2 == 0)
155 return std::make_pair(__last1, __last1);
156 auto __len1 = __last1 - __first1;
157 if (__len1 < __len2)
158 return std::make_pair(__last1, __last1);
159 const _Iter1 __s = __first1 + _D1(__len2 - 1); // End of pattern match can't go before here
160 _Iter1 __l1 = __last1;
161 _Iter2 __l2 = __last2;
162 --__l2;
163 while (true) {
164 while (true) {
165 if (__s == __l1)
166 return std::make_pair(__last1, __last1);
167 if (std::__invoke(__pred, std::__invoke(__proj1, *--__l1), std::__invoke(__proj2, *__l2)))
168 break;
169 }
170 _Iter1 __last_match = __l1;
171 _Iter1 __m1 = __l1;
172 _Iter2 __m2 = __l2;
173 while (true) {
174 if (__m2 == __first2)
175 return std::make_pair(__m1, ++__last_match);
176 // no need to check range on __m1 because __s guarantees we have enough source
177 if (!std::__invoke(__pred, std::__invoke(__proj1, *--__m1), std::__invoke(__proj2, *--__m2))) {
178 break;
179 }
180 }
181 }
182}
183
184template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
185[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _ForwardIterator1 __find_end_classic(
186 _ForwardIterator1 __first1,
187 _ForwardIterator1 __last1,
188 _ForwardIterator2 __first2,
189 _ForwardIterator2 __last2,
190 _BinaryPredicate& __pred) {
191 auto __proj = __identity();
192 return std::__find_end_impl<_ClassicAlgPolicy>(
193 __first1,
194 __last1,
195 __first2,
196 __last2,
197 __pred,
198 __proj,
199 __proj,
200 typename iterator_traits<_ForwardIterator1>::iterator_category(),
201 typename iterator_traits<_ForwardIterator2>::iterator_category())
202 .first;
203}
204
205template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
206[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator1 find_end(
207 _ForwardIterator1 __first1,
208 _ForwardIterator1 __last1,
209 _ForwardIterator2 __first2,
210 _ForwardIterator2 __last2,
211 _BinaryPredicate __pred) {
212 return std::__find_end_classic(__first1, __last1, __first2, __last2, __pred);
213}
214
215template <class _ForwardIterator1, class _ForwardIterator2>
216[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator1
217find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2) {
218 return std::find_end(__first1, __last1, __first2, __last2, __equal_to());
219}
220
221_LIBCPP_END_NAMESPACE_STD
222
223#endif // _LIBCPP___ALGORITHM_FIND_END_OF_H
224