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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_SEARCH_N_H
11#define _LIBCPP___ALGORITHM_SEARCH_N_H
12
13#include <__algorithm/comp.h>
14#include <__algorithm/iterator_operations.h>
15#include <__config>
16#include <__functional/identity.h>
17#include <__iterator/advance.h>
18#include <__iterator/concepts.h>
19#include <__iterator/distance.h>
20#include <__iterator/iterator_traits.h>
21#include <__ranges/concepts.h>
22#include <__type_traits/enable_if.h>
23#include <__type_traits/invoke.h>
24#include <__type_traits/is_callable.h>
25#include <__utility/convert_to_integral.h>
26#include <__utility/pair.h>
27
28#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
29# pragma GCC system_header
30#endif
31
32_LIBCPP_BEGIN_NAMESPACE_STD
33
34template <class _AlgPolicy, class _Pred, class _Iter, class _Sent, class _SizeT, class _Type, class _Proj>
35_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_Iter, _Iter> __search_n_forward_impl(
36 _Iter __first, _Sent __last, _SizeT __count, const _Type& __value, _Pred& __pred, _Proj& __proj) {
37 if (__count <= 0)
38 return std::make_pair(__first, __first);
39 while (true) {
40 // Find first element in sequence that matchs __value, with a mininum of loop checks
41 while (true) {
42 if (__first == __last) { // return __last if no element matches __value
43 _IterOps<_AlgPolicy>::__advance_to(__first, __last);
44 return std::make_pair(__first, __first);
45 }
46 if (std::__invoke(__pred, std::__invoke(__proj, *__first), __value))
47 break;
48 ++__first;
49 }
50 // *__first matches __value, now match elements after here
51 _Iter __m = __first;
52 _SizeT __c(0);
53 while (true) {
54 if (++__c == __count) // If pattern exhausted, __first is the answer (works for 1 element pattern)
55 return std::make_pair(__first, ++__m);
56 if (++__m == __last) { // Otherwise if source exhaused, pattern not found
57 _IterOps<_AlgPolicy>::__advance_to(__first, __last);
58 return std::make_pair(__first, __first);
59 }
60
61 // if there is a mismatch, restart with a new __first
62 if (!std::__invoke(__pred, std::__invoke(__proj, *__m), __value)) {
63 __first = __m;
64 ++__first;
65 break;
66 } // else there is a match, check next elements
67 }
68 }
69}
70
71template <class _AlgPolicy, class _Pred, class _Iter, class _Sent, class _SizeT, class _Type, class _Proj, class _DiffT>
72_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 std::pair<_Iter, _Iter> __search_n_random_access_impl(
73 _Iter __first, _Sent __last, _SizeT __count, const _Type& __value, _Pred& __pred, _Proj& __proj, _DiffT __size1) {
74 using difference_type = typename iterator_traits<_Iter>::difference_type;
75 if (__count == 0)
76 return std::make_pair(__first, __first);
77 if (__size1 < static_cast<_DiffT>(__count)) {
78 _IterOps<_AlgPolicy>::__advance_to(__first, __last);
79 return std::make_pair(__first, __first);
80 }
81
82 const auto __s = __first + __size1 - difference_type(__count - 1); // Start of pattern match can't go beyond here
83 while (true) {
84 // Find first element in sequence that matchs __value, with a mininum of loop checks
85 while (true) {
86 if (__first >= __s) { // return __last if no element matches __value
87 _IterOps<_AlgPolicy>::__advance_to(__first, __last);
88 return std::make_pair(__first, __first);
89 }
90 if (std::__invoke(__pred, std::__invoke(__proj, *__first), __value))
91 break;
92 ++__first;
93 }
94 // *__first matches __value_, now match elements after here
95 auto __m = __first;
96 _SizeT __c(0);
97 while (true) {
98 if (++__c == __count) // If pattern exhausted, __first is the answer (works for 1 element pattern)
99 return std::make_pair(__first, __first + _DiffT(__count));
100 ++__m; // no need to check range on __m because __s guarantees we have enough source
101
102 // if there is a mismatch, restart with a new __first
103 if (!std::__invoke(__pred, std::__invoke(__proj, *__m), __value)) {
104 __first = __m;
105 ++__first;
106 break;
107 } // else there is a match, check next elements
108 }
109 }
110}
111
112template <class _Iter,
113 class _Sent,
114 class _DiffT,
115 class _Type,
116 class _Pred,
117 class _Proj,
118 __enable_if_t<__has_random_access_iterator_category<_Iter>::value, int> = 0>
119_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_Iter, _Iter>
120__search_n_impl(_Iter __first, _Sent __last, _DiffT __count, const _Type& __value, _Pred& __pred, _Proj& __proj) {
121 return std::__search_n_random_access_impl<_ClassicAlgPolicy>(
122 __first, __last, __count, __value, __pred, __proj, __last - __first);
123}
124
125template <class _Iter1,
126 class _Sent1,
127 class _DiffT,
128 class _Type,
129 class _Pred,
130 class _Proj,
131 __enable_if_t<__has_forward_iterator_category<_Iter1>::value &&
132 !__has_random_access_iterator_category<_Iter1>::value,
133 int> = 0>
134_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_Iter1, _Iter1>
135__search_n_impl(_Iter1 __first, _Sent1 __last, _DiffT __count, const _Type& __value, _Pred& __pred, _Proj& __proj) {
136 return std::__search_n_forward_impl<_ClassicAlgPolicy>(__first, __last, __count, __value, __pred, __proj);
137}
138
139template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
140[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator search_n(
141 _ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value, _BinaryPredicate __pred) {
142 static_assert(
143 __is_callable<_BinaryPredicate&, decltype(*__first), const _Tp&>::value, "The comparator has to be callable");
144 auto __proj = __identity();
145 return std::__search_n_impl(__first, __last, std::__convert_to_integral(__count), __value, __pred, __proj).first;
146}
147
148template <class _ForwardIterator, class _Size, class _Tp>
149[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator
150search_n(_ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value) {
151 return std::search_n(__first, __last, std::__convert_to_integral(__count), __value, __equal_to());
152}
153
154_LIBCPP_END_NAMESPACE_STD
155
156#endif // _LIBCPP___ALGORITHM_SEARCH_N_H