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