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_H 11 #define _LIBCPP___ALGORITHM_SEARCH_H 12 13 #include <__algorithm/comp.h> 14 #include <__config> 15 #include <__iterator/iterator_traits.h> 16 #include <__utility/pair.h> 17 18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 19 # pragma GCC system_header 20 # pragma clang include_instead(<algorithm>) 21 #endif 22 23 _LIBCPP_BEGIN_NAMESPACE_STD 24 25 template <class _BinaryPredicate, class _ForwardIterator1, class _ForwardIterator2> 26 pair<_ForwardIterator1, _ForwardIterator1> 27 _LIBCPP_CONSTEXPR_AFTER_CXX11 __search(_ForwardIterator1 __first1, _ForwardIterator1 __last1, 28 _ForwardIterator2 __first2, _ForwardIterator2 __last2, 29 _BinaryPredicate __pred, forward_iterator_tag, forward_iterator_tag) { 30 if (__first2 == __last2) 31 return _VSTD::make_pair(__first1, __first1); // Everything matches an empty sequence 32 while (true) { 33 // Find first element in sequence 1 that matchs *__first2, with a mininum of loop checks 34 while (true) { 35 if (__first1 == __last1) // return __last1 if no element matches *__first2 36 return _VSTD::make_pair(__last1, __last1); 37 if (__pred(*__first1, *__first2)) 38 break; 39 ++__first1; 40 } 41 // *__first1 matches *__first2, now match elements after here 42 _ForwardIterator1 __m1 = __first1; 43 _ForwardIterator2 __m2 = __first2; 44 while (true) { 45 if (++__m2 == __last2) // If pattern exhausted, __first1 is the answer (works for 1 element pattern) 46 return _VSTD::make_pair(__first1, __m1); 47 if (++__m1 == __last1) // Otherwise if source exhaused, pattern not found 48 return _VSTD::make_pair(__last1, __last1); 49 if (!__pred(*__m1, *__m2)) // if there is a mismatch, restart with a new __first1 50 { 51 ++__first1; 52 break; 53 } // else there is a match, check next elements 54 } 55 } 56 } 57 58 template <class _BinaryPredicate, class _RandomAccessIterator1, class _RandomAccessIterator2> 59 _LIBCPP_CONSTEXPR_AFTER_CXX11 pair<_RandomAccessIterator1, _RandomAccessIterator1> 60 __search(_RandomAccessIterator1 __first1, _RandomAccessIterator1 __last1, _RandomAccessIterator2 __first2, 61 _RandomAccessIterator2 __last2, _BinaryPredicate __pred, random_access_iterator_tag, 62 random_access_iterator_tag) { 63 typedef typename iterator_traits<_RandomAccessIterator1>::difference_type _D1; 64 typedef typename iterator_traits<_RandomAccessIterator2>::difference_type _D2; 65 // Take advantage of knowing source and pattern lengths. Stop short when source is smaller than pattern 66 const _D2 __len2 = __last2 - __first2; 67 if (__len2 == 0) 68 return _VSTD::make_pair(__first1, __first1); 69 const _D1 __len1 = __last1 - __first1; 70 if (__len1 < __len2) 71 return _VSTD::make_pair(__last1, __last1); 72 const _RandomAccessIterator1 __s = __last1 - _D1(__len2 - 1); // Start of pattern match can't go beyond here 73 74 while (true) { 75 while (true) { 76 if (__first1 == __s) 77 return _VSTD::make_pair(__last1, __last1); 78 if (__pred(*__first1, *__first2)) 79 break; 80 ++__first1; 81 } 82 83 _RandomAccessIterator1 __m1 = __first1; 84 _RandomAccessIterator2 __m2 = __first2; 85 while (true) { 86 if (++__m2 == __last2) 87 return _VSTD::make_pair(__first1, __first1 + _D1(__len2)); 88 ++__m1; // no need to check range on __m1 because __s guarantees we have enough source 89 if (!__pred(*__m1, *__m2)) { 90 ++__first1; 91 break; 92 } 93 } 94 } 95 } 96 97 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate> 98 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1 99 search(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2, 100 _BinaryPredicate __pred) { 101 return _VSTD::__search<_BinaryPredicate&>( 102 __first1, __last1, __first2, __last2, __pred, 103 typename iterator_traits<_ForwardIterator1>::iterator_category(), 104 typename iterator_traits<_ForwardIterator2>::iterator_category()).first; 105 } 106 107 template <class _ForwardIterator1, class _ForwardIterator2> 108 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator1 109 search(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2) { 110 typedef typename iterator_traits<_ForwardIterator1>::value_type __v1; 111 typedef typename iterator_traits<_ForwardIterator2>::value_type __v2; 112 return _VSTD::search(__first1, __last1, __first2, __last2, __equal_to<__v1, __v2>()); 113 } 114 115 #if _LIBCPP_STD_VER > 14 116 template <class _ForwardIterator, class _Searcher> 117 _LIBCPP_NODISCARD_EXT _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator 118 search(_ForwardIterator __f, _ForwardIterator __l, const _Searcher& __s) { 119 return __s(__f, __l).first; 120 } 121 122 #endif 123 124 _LIBCPP_END_NAMESPACE_STD 125 126 #endif // _LIBCPP___ALGORITHM_SEARCH_H 127