libcxx/include/__algorithm/find_end.h

   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 <__algorithm/comp.h>
  14 #include <__algorithm/iterator_operations.h>
  15 #include <__algorithm/search.h>
  16 #include <__config>
  17 #include <__functional/identity.h>
  18 #include <__functional/invoke.h>
  19 #include <__iterator/advance.h>
  20 #include <__iterator/iterator_traits.h>
  21 #include <__iterator/next.h>
  22 #include <__iterator/reverse_iterator.h>
  23 #include <__utility/pair.h>
  24
  25 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  26 #  pragma GCC system_header
  27 #endif
  28
  29 _LIBCPP_BEGIN_NAMESPACE_STD
  30
  31 template < class _AlgPolicy,
  32            class _Iter1,
  33            class _Sent1,
  34            class _Iter2,
  35            class _Sent2,
  36            class _Pred,
  37            class _Proj1,
  38            class _Proj2>
  39 _LIBCPP_HIDE_FROM_ABI inline _LIBCPP_CONSTEXPR_SINCE_CXX14 pair<_Iter1, _Iter1> __find_end_impl(
  40     _Iter1 __first1,
  41     _Sent1 __last1,
  42     _Iter2 __first2,
  43     _Sent2 __last2,
  44     _Pred& __pred,
  45     _Proj1& __proj1,
  46     _Proj2& __proj2,
  47     forward_iterator_tag,
  48     forward_iterator_tag) {
  49   // modeled after search algorithm
  50   _Iter1 __match_first = _IterOps<_AlgPolicy>::next(__first1, __last1); // __last1 is the "default" answer
  51   _Iter1 __match_last  = __match_first;
  52   if (__first2 == __last2)
  53     return pair<_Iter1, _Iter1>(__match_last, __match_last);
  54   while (true) {
  55     while (true) {
  56       if (__first1 == __last1) // if source exhausted return last correct answer (or __last1 if never found)
  57         return pair<_Iter1, _Iter1>(__match_first, __match_last);
  58       if (std::__invoke(__pred, std::__invoke(__proj1, *__first1), std::__invoke(__proj2, *__first2)))
  59         break;
  60       ++__first1;
  61     }
  62     // *__first1 matches *__first2, now match elements after here
  63     _Iter1 __m1 = __first1;
  64     _Iter2 __m2 = __first2;
  65     while (true) {
  66       if (++__m2 == __last2) { // Pattern exhaused, record answer and search for another one
  67         __match_first = __first1;
  68         __match_last  = ++__m1;
  69         ++__first1;
  70         break;
  71       }
  72       if (++__m1 == __last1) // Source exhausted, return last answer
  73         return pair<_Iter1, _Iter1>(__match_first, __match_last);
  74       // mismatch, restart with a new __first
  75       if (!std::__invoke(__pred, std::__invoke(__proj1, *__m1), std::__invoke(__proj2, *__m2))) {
  76         ++__first1;
  77         break;
  78       } // else there is a match, check next elements
  79     }
  80   }
  81 }
  82
  83 template < class _IterOps,
  84            class _Pred,
  85            class _Iter1,
  86            class _Sent1,
  87            class _Iter2,
  88            class _Sent2,
  89            class _Proj1,
  90            class _Proj2>
  91 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Iter1 __find_end(
  92     _Iter1 __first1,
  93     _Sent1 __sent1,
  94     _Iter2 __first2,
  95     _Sent2 __sent2,
  96     _Pred& __pred,
  97     _Proj1& __proj1,
  98     _Proj2& __proj2,
  99     bidirectional_iterator_tag,
 100     bidirectional_iterator_tag) {
 101   auto __last1 = _IterOps::next(__first1, __sent1);
 102   auto __last2 = _IterOps::next(__first2, __sent2);
 103   // modeled after search algorithm (in reverse)
 104   if (__first2 == __last2)
 105     return __last1; // Everything matches an empty sequence
 106   _Iter1 __l1 = __last1;
 107   _Iter2 __l2 = __last2;
 108   --__l2;
 109   while (true) {
 110     // Find last element in sequence 1 that matchs *(__last2-1), with a mininum of loop checks
 111     while (true) {
 112       if (__first1 == __l1) // return __last1 if no element matches *__first2
 113         return __last1;
 114       if (std::__invoke(__pred, std::__invoke(__proj1, *--__l1), std::__invoke(__proj2, *__l2)))
 115         break;
 116     }
 117     // *__l1 matches *__l2, now match elements before here
 118     _Iter1 __m1 = __l1;
 119     _Iter2 __m2 = __l2;
 120     while (true) {
 121       if (__m2 == __first2) // If pattern exhausted, __m1 is the answer (works for 1 element pattern)
 122         return __m1;
 123       if (__m1 == __first1) // Otherwise if source exhaused, pattern not found
 124         return __last1;
 125
 126       // if there is a mismatch, restart with a new __l1
 127       if (!std::__invoke(__pred, std::__invoke(__proj1, *--__m1), std::__invoke(__proj2, *--__m2))) {
 128         break;
 129       } // else there is a match, check next elements
 130     }
 131   }
 132 }
 133
 134 template < class _AlgPolicy,
 135            class _Pred,
 136            class _Iter1,
 137            class _Sent1,
 138            class _Iter2,
 139            class _Sent2,
 140            class _Proj1,
 141            class _Proj2>
 142 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iter1 __find_end(
 143     _Iter1 __first1,
 144     _Sent1 __sent1,
 145     _Iter2 __first2,
 146     _Sent2 __sent2,
 147     _Pred& __pred,
 148     _Proj1& __proj1,
 149     _Proj2& __proj2,
 150     random_access_iterator_tag,
 151     random_access_iterator_tag) {
 152   typedef typename iterator_traits<_Iter1>::difference_type _D1;
 153   auto __last1 = _IterOps<_AlgPolicy>::next(__first1, __sent1);
 154   auto __last2 = _IterOps<_AlgPolicy>::next(__first2, __sent2);
 155   // Take advantage of knowing source and pattern lengths.  Stop short when source is smaller than pattern
 156   auto __len2 = __last2 - __first2;
 157   if (__len2 == 0)
 158     return __last1;
 159   auto __len1 = __last1 - __first1;
 160   if (__len1 < __len2)
 161     return __last1;
 162   const _Iter1 __s = __first1 + _D1(__len2 - 1); // End of pattern match can't go before here
 163   _Iter1 __l1      = __last1;
 164   _Iter2 __l2      = __last2;
 165   --__l2;
 166   while (true) {
 167     while (true) {
 168       if (__s == __l1)
 169         return __last1;
 170       if (std::__invoke(__pred, std::__invoke(__proj1, *--__l1), std::__invoke(__proj2, *__l2)))
 171         break;
 172     }
 173     _Iter1 __m1 = __l1;
 174     _Iter2 __m2 = __l2;
 175     while (true) {
 176       if (__m2 == __first2)
 177         return __m1;
 178       // no need to check range on __m1 because __s guarantees we have enough source
 179       if (!std::__invoke(__pred, std::__invoke(__proj1, *--__m1), std::__invoke(*--__m2))) {
 180         break;
 181       }
 182     }
 183   }
 184 }
 185
 186 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
 187 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _ForwardIterator1 __find_end_classic(
 188     _ForwardIterator1 __first1,
 189     _ForwardIterator1 __last1,
 190     _ForwardIterator2 __first2,
 191     _ForwardIterator2 __last2,
 192     _BinaryPredicate& __pred) {
 193   auto __proj = __identity();
 194   return std::__find_end_impl<_ClassicAlgPolicy>(
 195              __first1,
 196              __last1,
 197              __first2,
 198              __last2,
 199              __pred,
 200              __proj,
 201              __proj,
 202              typename iterator_traits<_ForwardIterator1>::iterator_category(),
 203              typename iterator_traits<_ForwardIterator2>::iterator_category())
 204       .first;
 205 }
 206
 207 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
 208 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator1 find_end(
 209     _ForwardIterator1 __first1,
 210     _ForwardIterator1 __last1,
 211     _ForwardIterator2 __first2,
 212     _ForwardIterator2 __last2,
 213     _BinaryPredicate __pred) {
 214   return std::__find_end_classic(__first1, __last1, __first2, __last2, __pred);
 215 }
 216
 217 template <class _ForwardIterator1, class _ForwardIterator2>
 218 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator1
 219 find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2) {
 220   return std::find_end(__first1, __last1, __first2, __last2, __equal_to());
 221 }
 222
 223 _LIBCPP_END_NAMESPACE_STD
 224
 225 #endif // _LIBCPP___ALGORITHM_FIND_END_OF_H