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 34 template <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 71 template <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 } 111 112 template <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 } 124 125 template <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 } 138 139 template <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 } 147 148 template <class _ForwardIterator, class _Size, class _Tp> 149 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator 150 search_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 157