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 <__config>
14 #include <__algorithm/comp.h>
15 #include <__iterator/iterator_traits.h>
16 #include <type_traits>
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 _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2>
__find_end(_ForwardIterator1 __first1,_ForwardIterator1 __last1,_ForwardIterator2 __first2,_ForwardIterator2 __last2,_BinaryPredicate __pred,forward_iterator_tag,forward_iterator_tag)28 _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1 __find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
29 _ForwardIterator2 __first2, _ForwardIterator2 __last2,
30 _BinaryPredicate __pred, forward_iterator_tag,
31 forward_iterator_tag) {
32 // modeled after search algorithm
33 _ForwardIterator1 __r = __last1; // __last1 is the "default" answer
34 if (__first2 == __last2)
35 return __r;
36 while (true) {
37 while (true) {
38 if (__first1 == __last1) // if source exhausted return last correct answer
39 return __r; // (or __last1 if never found)
40 if (__pred(*__first1, *__first2))
41 break;
42 ++__first1;
43 }
44 // *__first1 matches *__first2, now match elements after here
45 _ForwardIterator1 __m1 = __first1;
46 _ForwardIterator2 __m2 = __first2;
47 while (true) {
48 if (++__m2 == __last2) { // Pattern exhaused, record answer and search for another one
49 __r = __first1;
50 ++__first1;
51 break;
52 }
53 if (++__m1 == __last1) // Source exhausted, return last answer
54 return __r;
55 if (!__pred(*__m1, *__m2)) // mismatch, restart with a new __first
56 {
57 ++__first1;
58 break;
59 } // else there is a match, check next elements
60 }
61 }
62 }
63
64 template <class _BinaryPredicate, class _BidirectionalIterator1, class _BidirectionalIterator2>
__find_end(_BidirectionalIterator1 __first1,_BidirectionalIterator1 __last1,_BidirectionalIterator2 __first2,_BidirectionalIterator2 __last2,_BinaryPredicate __pred,bidirectional_iterator_tag,bidirectional_iterator_tag)65 _LIBCPP_CONSTEXPR_AFTER_CXX17 _BidirectionalIterator1 __find_end(
66 _BidirectionalIterator1 __first1, _BidirectionalIterator1 __last1, _BidirectionalIterator2 __first2,
67 _BidirectionalIterator2 __last2, _BinaryPredicate __pred, bidirectional_iterator_tag, bidirectional_iterator_tag) {
68 // modeled after search algorithm (in reverse)
69 if (__first2 == __last2)
70 return __last1; // Everything matches an empty sequence
71 _BidirectionalIterator1 __l1 = __last1;
72 _BidirectionalIterator2 __l2 = __last2;
73 --__l2;
74 while (true) {
75 // Find last element in sequence 1 that matchs *(__last2-1), with a mininum of loop checks
76 while (true) {
77 if (__first1 == __l1) // return __last1 if no element matches *__first2
78 return __last1;
79 if (__pred(*--__l1, *__l2))
80 break;
81 }
82 // *__l1 matches *__l2, now match elements before here
83 _BidirectionalIterator1 __m1 = __l1;
84 _BidirectionalIterator2 __m2 = __l2;
85 while (true) {
86 if (__m2 == __first2) // If pattern exhausted, __m1 is the answer (works for 1 element pattern)
87 return __m1;
88 if (__m1 == __first1) // Otherwise if source exhaused, pattern not found
89 return __last1;
90 if (!__pred(*--__m1, *--__m2)) // if there is a mismatch, restart with a new __l1
91 {
92 break;
93 } // else there is a match, check next elements
94 }
95 }
96 }
97
98 template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2>
__find_end(_RandomAccessIterator1 __first1,_RandomAccessIterator1 __last1,_RandomAccessIterator2 __first2,_RandomAccessIterator2 __last2,_BinaryPredicate __pred,random_access_iterator_tag,random_access_iterator_tag)99 _LIBCPP_CONSTEXPR_AFTER_CXX11 _RandomAccessIterator1 __find_end(
100 _RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1, _RandomAccessIterator2 __first2,
101 _RandomAccessIterator2 __last2, _BinaryPredicate __pred, random_access_iterator_tag, random_access_iterator_tag) {
102 // Take advantage of knowing source and pattern lengths. Stop short when source is smaller than pattern
103 typename iterator_traits<_RandomAccessIterator2>::difference_type __len2 = __last2 - __first2;
104 if (__len2 == 0)
105 return __last1;
106 typename iterator_traits<_RandomAccessIterator1>::difference_type __len1 = __last1 - __first1;
107 if (__len1 < __len2)
108 return __last1;
109 const _RandomAccessIterator1 __s = __first1 + (__len2 - 1); // End of pattern match can't go before here
110 _RandomAccessIterator1 __l1 = __last1;
111 _RandomAccessIterator2 __l2 = __last2;
112 --__l2;
113 while (true) {
114 while (true) {
115 if (__s == __l1)
116 return __last1;
117 if (__pred(*--__l1, *__l2))
118 break;
119 }
120 _RandomAccessIterator1 __m1 = __l1;
121 _RandomAccessIterator2 __m2 = __l2;
122 while (true) {
123 if (__m2 == __first2)
124 return __m1;
125 // no need to check range on __m1 because __s guarantees we have enough source
126 if (!__pred(*--__m1, *--__m2)) {
127 break;
128 }
129 }
130 }
131 }
132
133 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
134 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1
find_end(_ForwardIterator1 __first1,_ForwardIterator1 __last1,_ForwardIterator2 __first2,_ForwardIterator2 __last2,_BinaryPredicate __pred)135 find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2,
136 _BinaryPredicate __pred) {
137 return _VSTD::__find_end<typename add_lvalue_reference<_BinaryPredicate>::type>(
138 __first1, __last1, __first2, __last2, __pred, typename iterator_traits<_ForwardIterator1>::iterator_category(),
139 typename iterator_traits<_ForwardIterator2>::iterator_category());
140 }
141
142 template <class _ForwardIterator1, class _ForwardIterator2>
143 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1
find_end(_ForwardIterator1 __first1,_ForwardIterator1 __last1,_ForwardIterator2 __first2,_ForwardIterator2 __last2)144 find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2) {
145 typedef typename iterator_traits<_ForwardIterator1>::value_type __v1;
146 typedef typename iterator_traits<_ForwardIterator2>::value_type __v2;
147 return _VSTD::find_end(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>());
148 }
149
150 _LIBCPP_END_NAMESPACE_STD
151
152 _LIBCPP_POP_MACROS
153
154 #endif // _LIBCPP___ALGORITHM_FIND_END_OF_H
155