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