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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-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___ALGORITHM_SEARCH_N_H11#define _LIBCPP___ALGORITHM_SEARCH_N_H12 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_header30#endif31 32_LIBCPP_BEGIN_NAMESPACE_STD33 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 checks41 while (true) {42 if (__first == __last) { // return __last if no element matches __value43 _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 here51 _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 found57 _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 __first62 if (!std::__invoke(__pred, std::__invoke(__proj, *__m), __value)) {63 __first = __m;64 ++__first;65 break;66 } // else there is a match, check next elements67 }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 here83 while (true) {84 // Find first element in sequence that matchs __value, with a mininum of loop checks85 while (true) {86 if (__first >= __s) { // return __last if no element matches __value87 _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 here95 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 source101 102 // if there is a mismatch, restart with a new __first103 if (!std::__invoke(__pred, std::__invoke(__proj, *__m), __value)) {104 __first = __m;105 ++__first;106 break;107 } // else there is a match, check next elements108 }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 _ForwardIterator150search_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_STD155 156#endif // _LIBCPP___ALGORITHM_SEARCH_N_H157