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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___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
31template <class _AlgPolicy, class _Pred, class _Iter, class _Sent, class _SizeT, class _Type, class _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
68template <class _AlgPolicy, class _Pred, class _Iter, class _Sent, class _SizeT, class _Type, class _Proj, class _DiffT>
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
109template <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>
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
122template <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>
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
136template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
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
145template <class _ForwardIterator, class _Size, class _Tp>
146_LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _ForwardIterator
147search_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

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source code of libcxx/include/__cxx03/__algorithm/search_n.h