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_FIND_END_OF_H 11 #define _LIBCPP___ALGORITHM_FIND_END_OF_H 12 13 #include <__config> 14 #include <__algorithm/comp.h> 15 #include <__iterator/iterator_traits.h> 16 17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 18 #pragma GCC system_header 19 #endif 20 21 _LIBCPP_PUSH_MACROS 22 #include <__undef_macros> 23 24 _LIBCPP_BEGIN_NAMESPACE_STD 25 26 template <class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2> 27 _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1 __find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1, 28 _ForwardIterator2 __first2, _ForwardIterator2 __last2, 29 _BinaryPredicate __pred, forward_iterator_tag, 30 forward_iterator_tag) { 31 // modeled after search algorithm 32 _ForwardIterator1 __r = __last1; // __last1 is the "default" answer 33 if (__first2 == __last2) 34 return __r; 35 while (true) { 36 while (true) { 37 if (__first1 == __last1) // if source exhausted return last correct answer 38 return __r; // (or __last1 if never found) 39 if (__pred(*__first1, *__first2)) 40 break; 41 ++__first1; 42 } 43 // *__first1 matches *__first2, now match elements after here 44 _ForwardIterator1 __m1 = __first1; 45 _ForwardIterator2 __m2 = __first2; 46 while (true) { 47 if (++__m2 == __last2) { // Pattern exhaused, record answer and search for another one 48 __r = __first1; 49 ++__first1; 50 break; 51 } 52 if (++__m1 == __last1) // Source exhausted, return last answer 53 return __r; 54 if (!__pred(*__m1, *__m2)) // mismatch, restart with a new __first 55 { 56 ++__first1; 57 break; 58 } // else there is a match, check next elements 59 } 60 } 61 } 62 63 template <class _BinaryPredicate, class _BidirectionalIterator1, class _BidirectionalIterator2> 64 _LIBCPP_CONSTEXPR_AFTER_CXX17 _BidirectionalIterator1 __find_end( 65 _BidirectionalIterator1 __first1, _BidirectionalIterator1 __last1, _BidirectionalIterator2 __first2, 66 _BidirectionalIterator2 __last2, _BinaryPredicate __pred, bidirectional_iterator_tag, bidirectional_iterator_tag) { 67 // modeled after search algorithm (in reverse) 68 if (__first2 == __last2) 69 return __last1; // Everything matches an empty sequence 70 _BidirectionalIterator1 __l1 = __last1; 71 _BidirectionalIterator2 __l2 = __last2; 72 --__l2; 73 while (true) { 74 // Find last element in sequence 1 that matchs *(__last2-1), with a mininum of loop checks 75 while (true) { 76 if (__first1 == __l1) // return __last1 if no element matches *__first2 77 return __last1; 78 if (__pred(*--__l1, *__l2)) 79 break; 80 } 81 // *__l1 matches *__l2, now match elements before here 82 _BidirectionalIterator1 __m1 = __l1; 83 _BidirectionalIterator2 __m2 = __l2; 84 while (true) { 85 if (__m2 == __first2) // If pattern exhausted, __m1 is the answer (works for 1 element pattern) 86 return __m1; 87 if (__m1 == __first1) // Otherwise if source exhaused, pattern not found 88 return __last1; 89 if (!__pred(*--__m1, *--__m2)) // if there is a mismatch, restart with a new __l1 90 { 91 break; 92 } // else there is a match, check next elements 93 } 94 } 95 } 96 97 template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2> 98 _LIBCPP_CONSTEXPR_AFTER_CXX11 _RandomAccessIterator1 __find_end( 99 _RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1, _RandomAccessIterator2 __first2, 100 _RandomAccessIterator2 __last2, _BinaryPredicate __pred, random_access_iterator_tag, random_access_iterator_tag) { 101 // Take advantage of knowing source and pattern lengths. Stop short when source is smaller than pattern 102 typename iterator_traits<_RandomAccessIterator2>::difference_type __len2 = __last2 - __first2; 103 if (__len2 == 0) 104 return __last1; 105 typename iterator_traits<_RandomAccessIterator1>::difference_type __len1 = __last1 - __first1; 106 if (__len1 < __len2) 107 return __last1; 108 const _RandomAccessIterator1 __s = __first1 + (__len2 - 1); // End of pattern match can't go before here 109 _RandomAccessIterator1 __l1 = __last1; 110 _RandomAccessIterator2 __l2 = __last2; 111 --__l2; 112 while (true) { 113 while (true) { 114 if (__s == __l1) 115 return __last1; 116 if (__pred(*--__l1, *__l2)) 117 break; 118 } 119 _RandomAccessIterator1 __m1 = __l1; 120 _RandomAccessIterator2 __m2 = __l2; 121 while (true) { 122 if (__m2 == __first2) 123 return __m1; 124 // no need to check range on __m1 because __s guarantees we have enough source 125 if (!__pred(*--__m1, *--__m2)) { 126 break; 127 } 128 } 129 } 130 } 131 132 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate> 133 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1 134 find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2, 135 _BinaryPredicate __pred) { 136 return _VSTD::__find_end<_BinaryPredicate&>( 137 __first1, __last1, __first2, __last2, __pred, typename iterator_traits<_ForwardIterator1>::iterator_category(), 138 typename iterator_traits<_ForwardIterator2>::iterator_category()); 139 } 140 141 template <class _ForwardIterator1, class _ForwardIterator2> 142 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1 143 find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2) { 144 typedef typename iterator_traits<_ForwardIterator1>::value_type __v1; 145 typedef typename iterator_traits<_ForwardIterator2>::value_type __v2; 146 return _VSTD::find_end(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>()); 147 } 148 149 _LIBCPP_END_NAMESPACE_STD 150 151 _LIBCPP_POP_MACROS 152 153 #endif // _LIBCPP___ALGORITHM_FIND_END_OF_H 154