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 <__utility/convert_to_integral.h>
23#include <__utility/pair.h>
24#include <type_traits>  // __convert_to_integral
25
26#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
27#  pragma GCC system_header
28#endif
29
30_LIBCPP_BEGIN_NAMESPACE_STD
31
32template <class _AlgPolicy, class _Pred, class _Iter, class _Sent, class _SizeT, class _Type, class _Proj>
33_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
34pair<_Iter, _Iter> __search_n_forward_impl(_Iter __first, _Sent __last,
35                                           _SizeT __count,
36                                           const _Type& __value,
37                                           _Pred& __pred,
38                                           _Proj& __proj) {
39  if (__count <= 0)
40    return std::make_pair(__first, __first);
41  while (true) {
42    // Find first element in sequence that matchs __value, with a mininum of loop checks
43    while (true) {
44      if (__first == __last) { // return __last if no element matches __value
45        _IterOps<_AlgPolicy>::__advance_to(__first, __last);
46        return std::make_pair(__first, __first);
47      }
48      if (std::__invoke(__pred, std::__invoke(__proj, *__first), __value))
49        break;
50      ++__first;
51    }
52    // *__first matches __value, now match elements after here
53    _Iter __m = __first;
54    _SizeT __c(0);
55    while (true) {
56      if (++__c == __count) // If pattern exhausted, __first is the answer (works for 1 element pattern)
57        return std::make_pair(__first, ++__m);
58      if (++__m == __last) { // Otherwise if source exhaused, pattern not found
59        _IterOps<_AlgPolicy>::__advance_to(__first, __last);
60        return std::make_pair(__first, __first);
61      }
62
63      // if there is a mismatch, restart with a new __first
64      if (!std::__invoke(__pred, std::__invoke(__proj, *__m), __value))
65      {
66        __first = __m;
67        ++__first;
68        break;
69      } // else there is a match, check next elements
70    }
71  }
72}
73
74template <class _AlgPolicy, class _Pred, class _Iter, class _Sent, class _SizeT, class _Type, class _Proj, class _DiffT>
75_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
76std::pair<_Iter, _Iter> __search_n_random_access_impl(_Iter __first, _Sent __last,
77                                                      _SizeT __count,
78                                                      const _Type& __value,
79                                                      _Pred& __pred,
80                                                      _Proj& __proj,
81                                                      _DiffT __size1) {
82  using difference_type = typename iterator_traits<_Iter>::difference_type;
83  if (__count == 0)
84    return std::make_pair(__first, __first);
85  if (__size1 < static_cast<_DiffT>(__count)) {
86    _IterOps<_AlgPolicy>::__advance_to(__first, __last);
87    return std::make_pair(__first, __first);
88  }
89
90  const auto __s = __first + __size1 - difference_type(__count - 1); // Start of pattern match can't go beyond here
91  while (true) {
92    // Find first element in sequence that matchs __value, with a mininum of loop checks
93    while (true) {
94      if (__first >= __s) { // return __last if no element matches __value
95        _IterOps<_AlgPolicy>::__advance_to(__first, __last);
96        return std::make_pair(__first, __first);
97      }
98      if (std::__invoke(__pred, std::__invoke(__proj, *__first), __value))
99        break;
100      ++__first;
101    }
102    // *__first matches __value_, now match elements after here
103    auto __m = __first;
104    _SizeT __c(0);
105    while (true) {
106      if (++__c == __count) // If pattern exhausted, __first is the answer (works for 1 element pattern)
107        return std::make_pair(__first, __first + _DiffT(__count));
108      ++__m; // no need to check range on __m because __s guarantees we have enough source
109
110      // if there is a mismatch, restart with a new __first
111      if (!std::__invoke(__pred, std::__invoke(__proj, *__m), __value))
112      {
113        __first = __m;
114        ++__first;
115        break;
116      } // else there is a match, check next elements
117    }
118  }
119}
120
121template <class _Iter, class _Sent,
122          class _DiffT,
123          class _Type,
124          class _Pred,
125          class _Proj>
126_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
127pair<_Iter, _Iter> __search_n_impl(_Iter __first, _Sent __last,
128                                   _DiffT __count,
129                                   const _Type& __value,
130                                   _Pred& __pred,
131                                   _Proj& __proj,
132                                   __enable_if_t<__is_cpp17_random_access_iterator<_Iter>::value>* = nullptr) {
133  return std::__search_n_random_access_impl<_ClassicAlgPolicy>(__first, __last,
134                                                               __count,
135                                                               __value,
136                                                               __pred,
137                                                               __proj,
138                                                               __last - __first);
139}
140
141template <class _Iter1, class _Sent1,
142          class _DiffT,
143          class _Type,
144          class _Pred,
145          class _Proj>
146_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
147pair<_Iter1, _Iter1> __search_n_impl(_Iter1 __first, _Sent1 __last,
148                                     _DiffT __count,
149                                     const _Type& __value,
150                                     _Pred& __pred,
151                                     _Proj& __proj,
152                                     __enable_if_t<__is_cpp17_forward_iterator<_Iter1>::value
153                                               && !__is_cpp17_random_access_iterator<_Iter1>::value>* = nullptr) {
154  return std::__search_n_forward_impl<_ClassicAlgPolicy>(__first, __last,
155                                                         __count,
156                                                         __value,
157                                                         __pred,
158                                                         __proj);
159}
160
161template <class _ForwardIterator, class _Size, class _Tp, class _BinaryPredicate>
162_LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
163_ForwardIterator search_n(_ForwardIterator __first, _ForwardIterator __last,
164                          _Size __count,
165                          const _Tp& __value,
166                          _BinaryPredicate __pred) {
167  static_assert(__is_callable<_BinaryPredicate, decltype(*__first), const _Tp&>::value,
168                "BinaryPredicate has to be callable");
169  auto __proj = __identity();
170  return std::__search_n_impl(__first, __last, std::__convert_to_integral(__count), __value, __pred, __proj).first;
171}
172
173template <class _ForwardIterator, class _Size, class _Tp>
174_LIBCPP_NODISCARD_EXT inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
175_ForwardIterator search_n(_ForwardIterator __first, _ForwardIterator __last, _Size __count, const _Tp& __value) {
176  return std::search_n(__first, __last, std::__convert_to_integral(__count), __value, __equal_to());
177}
178
179_LIBCPP_END_NAMESPACE_STD
180
181#endif // _LIBCPP___ALGORITHM_SEARCH_N_H
182