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