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___CXX03___ALGORITHM_SEARCH_N_H
11 #define _LIBCPP___CXX03___ALGORITHM_SEARCH_N_H
12
13 #include <__cxx03/__algorithm/comp.h>
14 #include <__cxx03/__algorithm/iterator_operations.h>
15 #include <__cxx03/__config>
16 #include <__cxx03/__functional/identity.h>
17 #include <__cxx03/__iterator/advance.h>
18 #include <__cxx03/__iterator/distance.h>
19 #include <__cxx03/__iterator/iterator_traits.h>
20 #include <__cxx03/__type_traits/invoke.h>
21 #include <__cxx03/__type_traits/is_callable.h>
22 #include <__cxx03/__utility/convert_to_integral.h>
23 #include <__cxx03/__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, class _Pred, class _Iter, class _Sent, class _SizeT, class _Type, class _Proj>
__search_n_forward_impl(_Iter __first,_Sent __last,_SizeT __count,const _Type & __value,_Pred & __pred,_Proj & __proj)32 _LIBCPP_HIDE_FROM_ABI pair<_Iter, _Iter> __search_n_forward_impl(
33 _Iter __first, _Sent __last, _SizeT __count, const _Type& __value, _Pred& __pred, _Proj& __proj) {
34 if (__count <= 0)
35 return std::make_pair(__first, __first);
36 while (true) {
37 // Find first element in sequence that matchs __value, with a mininum of loop checks
38 while (true) {
39 if (__first == __last) { // return __last if no element matches __value
40 _IterOps<_AlgPolicy>::__advance_to(__first, __last);
41 return std::make_pair(__first, __first);
42 }
43 if (std::__invoke(__pred, std::__invoke(__proj, *__first), __value))
44 break;
45 ++__first;
46 }
47 // *__first matches __value, now match elements after here
48 _Iter __m = __first;
49 _SizeT __c(0);
50 while (true) {
51 if (++__c == __count) // If pattern exhausted, __first is the answer (works for 1 element pattern)
52 return std::make_pair(__first, ++__m);
53 if (++__m == __last) { // Otherwise if source exhaused, pattern not found
54 _IterOps<_AlgPolicy>::__advance_to(__first, __last);
55 return std::make_pair(__first, __first);
56 }
57
58 // if there is a mismatch, restart with a new __first
59 if (!std::__invoke(__pred, std::__invoke(__proj, *__m), __value)) {
60 __first = __m;
61 ++__first;
62 break;
63 } // else there is a match, check next elements
64 }
65 }
66 }
67
68 template <class _AlgPolicy, class _Pred, class _Iter, class _Sent, class _SizeT, class _Type, class _Proj, class _DiffT>
__search_n_random_access_impl(_Iter __first,_Sent __last,_SizeT __count,const _Type & __value,_Pred & __pred,_Proj & __proj,_DiffT __size1)69 _LIBCPP_HIDE_FROM_ABI std::pair<_Iter, _Iter> __search_n_random_access_impl(
70 _Iter __first, _Sent __last, _SizeT __count, const _Type& __value, _Pred& __pred, _Proj& __proj, _DiffT __size1) {
71 using difference_type = typename iterator_traits<_Iter>::difference_type;
72 if (__count == 0)
73 return std::make_pair(__first, __first);
74 if (__size1 < static_cast<_DiffT>(__count)) {
75 _IterOps<_AlgPolicy>::__advance_to(__first, __last);
76 return std::make_pair(__first, __first);
77 }
78
79 const auto __s = __first + __size1 - difference_type(__count - 1); // Start of pattern match can't go beyond here
80 while (true) {
81 // Find first element in sequence that matchs __value, with a mininum of loop checks
82 while (true) {
83 if (__first >= __s) { // return __last if no element matches __value
84 _IterOps<_AlgPolicy>::__advance_to(__first, __last);
85 return std::make_pair(__first, __first);
86 }
87 if (std::__invoke(__pred, std::__invoke(__proj, *__first), __value))
88 break;
89 ++__first;
90 }
91 // *__first matches __value_, now match elements after here
92 auto __m = __first;
93 _SizeT __c(0);
94 while (true) {
95 if (++__c == __count) // If pattern exhausted, __first is the answer (works for 1 element pattern)
96 return std::make_pair(__first, __first + _DiffT(__count));
97 ++__m; // no need to check range on __m because __s guarantees we have enough source
98
99 // if there is a mismatch, restart with a new __first
100 if (!std::__invoke(__pred, std::__invoke(__proj, *__m), __value)) {
101 __first = __m;
102 ++__first;
103 break;
104 } // else there is a match, check next elements
105 }
106 }
107 }
108
109 template <class _Iter,
110 class _Sent,
111 class _DiffT,
112 class _Type,
113 class _Pred,
114 class _Proj,
115 __enable_if_t<__has_random_access_iterator_category<_Iter>::value, int> = 0>
116 _LIBCPP_HIDE_FROM_ABI pair<_Iter, _Iter>
__search_n_impl(_Iter __first,_Sent __last,_DiffT __count,const _Type & __value,_Pred & __pred,_Proj & __proj)117 __search_n_impl(_Iter __first, _Sent __last, _DiffT __count, const _Type& __value, _Pred& __pred, _Proj& __proj) {
118 return std::__search_n_random_access_impl<_ClassicAlgPolicy>(
119 __first, __last, __count, __value, __pred, __proj, __last - __first);
120 }
121
122 template <class _Iter1,
123 class _Sent1,
124 class _DiffT,
125 class _Type,
126 class _Pred,
127 class _Proj,
128 __enable_if_t<__has_forward_iterator_category<_Iter1>::value &&
129 !__has_random_access_iterator_category<_Iter1>::value,
130 int> = 0>
131 _LIBCPP_HIDE_FROM_ABI pair<_Iter1, _Iter1>
__search_n_impl(_Iter1 __first,_Sent1 __last,_DiffT __count,const _Type & __value,_Pred & __pred,_Proj & __proj)132 __search_n_impl(_Iter1 __first, _Sent1 __last, _DiffT __count, const _Type& __value, _Pred& __pred, _Proj& __proj) {
133 return std::__search_n_forward_impl<_ClassicAlgPolicy>(__first, __last, __count, __value, __pred, __proj);
134 }
135
136 template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
search_n(_ForwardIterator __first,_ForwardIterator __last,_Size __count,const _Tp & __value,_BinaryPredicate __pred)137 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _ForwardIterator search_n(
138 _ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value, _BinaryPredicate __pred) {
139 static_assert(
140 __is_callable<_BinaryPredicate, decltype(*__first), const _Tp&>::value, "BinaryPredicate has to be callable");
141 auto __proj = __identity();
142 return std::__search_n_impl(__first, __last, std::__convert_to_integral(__count), __value, __pred, __proj).first;
143 }
144
145 template <class _ForwardIterator, class _Size, class _Tp>
146 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _ForwardIterator
search_n(_ForwardIterator __first,_ForwardIterator __last,_Size __count,const _Tp & __value)147 search_n(_ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value) {
148 return std::search_n(__first, __last, std::__convert_to_integral(__count), __value, __equal_to());
149 }
150
151 _LIBCPP_END_NAMESPACE_STD
152
153 #endif // _LIBCPP___CXX03___ALGORITHM_SEARCH_N_H
154