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 <__algorithm/search.h>
16 #include <__config>
17 #include <__functional/identity.h>
18 #include <__iterator/advance.h>
19 #include <__iterator/iterator_traits.h>
20 #include <__iterator/next.h>
21 #include <__iterator/reverse_iterator.h>
22 #include <__utility/pair.h>
23 #include <type_traits>
24 
25 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
26 #  pragma GCC system_header
27 #endif
28 
29 _LIBCPP_BEGIN_NAMESPACE_STD
30 
31 template <
32     class _AlgPolicy,
33     class _Iter1,
34     class _Sent1,
35     class _Iter2,
36     class _Sent2,
37     class _Pred,
38     class _Proj1,
39     class _Proj2>
40 _LIBCPP_HIDE_FROM_ABI inline _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_Iter1, _Iter1> __find_end_impl(
41     _Iter1 __first1,
42     _Sent1 __last1,
43     _Iter2 __first2,
44     _Sent2 __last2,
45     _Pred& __pred,
46     _Proj1& __proj1,
47     _Proj2& __proj2,
48     forward_iterator_tag,
49     forward_iterator_tag) {
50   // modeled after search algorithm
51   _Iter1 __match_first = _IterOps<_AlgPolicy>::next(__first1, __last1); // __last1 is the "default" answer
52   _Iter1 __match_last = __match_first;
53   if (__first2 == __last2)
54     return pair<_Iter1, _Iter1>(__match_last, __match_last);
55   while (true) {
56     while (true) {
57       if (__first1 == __last1) // if source exhausted return last correct answer (or __last1 if never found)
58         return pair<_Iter1, _Iter1>(__match_first, __match_last);
59       if (std::__invoke(__pred, std::__invoke(__proj1, *__first1), std::__invoke(__proj2, *__first2)))
60         break;
61       ++__first1;
62     }
63     // *__first1 matches *__first2, now match elements after here
64     _Iter1 __m1 = __first1;
65     _Iter2 __m2 = __first2;
66     while (true) {
67       if (++__m2 == __last2) { // Pattern exhaused, record answer and search for another one
68         __match_first = __first1;
69         __match_last = ++__m1;
70         ++__first1;
71         break;
72       }
73       if (++__m1 == __last1) // Source exhausted, return last answer
74         return pair<_Iter1, _Iter1>(__match_first, __match_last);
75        // mismatch, restart with a new __first
76       if (!std::__invoke(__pred, std::__invoke(__proj1, *__m1), std::__invoke(__proj2, *__m2)))
77       {
78         ++__first1;
79         break;
80       } // else there is a match, check next elements
81     }
82   }
83 }
84 
85 template <
86     class _IterOps,
87     class _Pred,
88     class _Iter1,
89     class _Sent1,
90     class _Iter2,
91     class _Sent2,
92     class _Proj1,
93     class _Proj2>
94 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Iter1 __find_end(
95     _Iter1 __first1,
96     _Sent1 __sent1,
97     _Iter2 __first2,
98     _Sent2 __sent2,
99     _Pred& __pred,
100     _Proj1& __proj1,
101     _Proj2& __proj2,
102     bidirectional_iterator_tag,
103     bidirectional_iterator_tag) {
104   auto __last1 = _IterOps::next(__first1, __sent1);
105   auto __last2 = _IterOps::next(__first2, __sent2);
106   // modeled after search algorithm (in reverse)
107   if (__first2 == __last2)
108     return __last1; // Everything matches an empty sequence
109   _Iter1 __l1 = __last1;
110   _Iter2 __l2 = __last2;
111   --__l2;
112   while (true) {
113     // Find last element in sequence 1 that matchs *(__last2-1), with a mininum of loop checks
114     while (true) {
115       if (__first1 == __l1) // return __last1 if no element matches *__first2
116         return __last1;
117       if (std::__invoke(__pred, std::__invoke(__proj1, *--__l1), std::__invoke(__proj2, *__l2)))
118         break;
119     }
120     // *__l1 matches *__l2, now match elements before here
121     _Iter1 __m1 = __l1;
122     _Iter2 __m2 = __l2;
123     while (true) {
124       if (__m2 == __first2) // If pattern exhausted, __m1 is the answer (works for 1 element pattern)
125         return __m1;
126       if (__m1 == __first1) // Otherwise if source exhaused, pattern not found
127         return __last1;
128 
129       // if there is a mismatch, restart with a new __l1
130       if (!std::__invoke(__pred, std::__invoke(__proj1, *--__m1), std::__invoke(__proj2, *--__m2)))
131       {
132         break;
133       } // else there is a match, check next elements
134     }
135   }
136 }
137 
138 template <
139     class _AlgPolicy,
140     class _Pred,
141     class _Iter1,
142     class _Sent1,
143     class _Iter2,
144     class _Sent2,
145     class _Proj1,
146     class _Proj2>
147 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter1 __find_end(
148     _Iter1 __first1,
149     _Sent1 __sent1,
150     _Iter2 __first2,
151     _Sent2 __sent2,
152     _Pred& __pred,
153     _Proj1& __proj1,
154     _Proj2& __proj2,
155     random_access_iterator_tag,
156     random_access_iterator_tag) {
157   typedef typename iterator_traits<_Iter1>::difference_type _D1;
158   auto __last1 = _IterOps<_AlgPolicy>::next(__first1, __sent1);
159   auto __last2 = _IterOps<_AlgPolicy>::next(__first2, __sent2);
160   // Take advantage of knowing source and pattern lengths.  Stop short when source is smaller than pattern
161   auto __len2 = __last2 - __first2;
162   if (__len2 == 0)
163     return __last1;
164   auto __len1 = __last1 - __first1;
165   if (__len1 < __len2)
166     return __last1;
167   const _Iter1 __s = __first1 + _D1(__len2 - 1); // End of pattern match can't go before here
168   _Iter1 __l1 = __last1;
169   _Iter2 __l2 = __last2;
170   --__l2;
171   while (true) {
172     while (true) {
173       if (__s == __l1)
174         return __last1;
175       if (std::__invoke(__pred, std::__invoke(__proj1, *--__l1), std::__invoke(__proj2, *__l2)))
176         break;
177     }
178     _Iter1 __m1 = __l1;
179     _Iter2 __m2 = __l2;
180     while (true) {
181       if (__m2 == __first2)
182         return __m1;
183       // no need to check range on __m1 because __s guarantees we have enough source
184       if (!std::__invoke(__pred, std::__invoke(__proj1, *--__m1), std::__invoke(*--__m2))) {
185         break;
186       }
187     }
188   }
189 }
190 
191 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
192 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
193 _ForwardIterator1 __find_end_classic(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
194                                      _ForwardIterator2 __first2, _ForwardIterator2 __last2,
195                                      _BinaryPredicate& __pred) {
196   auto __proj = __identity();
197   return std::__find_end_impl<_ClassicAlgPolicy>(
198              __first1,
199              __last1,
200              __first2,
201              __last2,
202              __pred,
203              __proj,
204              __proj,
205              typename iterator_traits<_ForwardIterator1>::iterator_category(),
206              typename iterator_traits<_ForwardIterator2>::iterator_category())
207       .first;
208 }
209 
210 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
211 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
212 _ForwardIterator1 find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
213                            _ForwardIterator2 __first2, _ForwardIterator2 __last2,
214                            _BinaryPredicate __pred) {
215   return std::__find_end_classic(__first1, __last1, __first2, __last2, __pred);
216 }
217 
218 template <class _ForwardIterator1, class _ForwardIterator2>
219 _LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
220 _ForwardIterator1 find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
221                            _ForwardIterator2 __first2, _ForwardIterator2 __last2) {
222   return std::find_end(__first1, __last1, __first2, __last2, __equal_to());
223 }
224 
225 _LIBCPP_END_NAMESPACE_STD
226 
227 #endif // _LIBCPP___ALGORITHM_FIND_END_OF_H
228