libcxx/include/__algorithm/search.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_SEARCH_H
  11 #define _LIBCPP___ALGORITHM_SEARCH_H
  12
  13 #include <__algorithm/comp.h>
  14 #include <__algorithm/iterator_operations.h>
  15 #include <__config>
  16 #include <__functional/identity.h>
  17 #include <__functional/invoke.h>
  18 #include <__iterator/advance.h>
  19 #include <__iterator/concepts.h>
  20 #include <__iterator/iterator_traits.h>
  21 #include <__type_traits/enable_if.h>
  22 #include <__type_traits/is_callable.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, class _Sent1,
  33           class _Iter2, class _Sent2,
  34           class _Pred,
  35           class _Proj1,
  36           class _Proj2>
  37 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
  38 pair<_Iter1, _Iter1> __search_forward_impl(_Iter1 __first1, _Sent1 __last1,
  39                                            _Iter2 __first2, _Sent2 __last2,
  40                                            _Pred& __pred,
  41                                            _Proj1& __proj1,
  42                                            _Proj2& __proj2) {
  43   if (__first2 == __last2)
  44     return std::make_pair(__first1, __first1); // Everything matches an empty sequence
  45   while (true) {
  46     // Find first element in sequence 1 that matchs *__first2, with a mininum of loop checks
  47     while (true) {
  48       if (__first1 == __last1) { // return __last1 if no element matches *__first2
  49         _IterOps<_AlgPolicy>::__advance_to(__first1, __last1);
  50         return std::make_pair(__first1, __first1);
  51       }
  52       if (std::__invoke(__pred, std::__invoke(__proj1, *__first1), std::__invoke(__proj2, *__first2)))
  53         break;
  54       ++__first1;
  55     }
  56     // *__first1 matches *__first2, now match elements after here
  57     _Iter1 __m1 = __first1;
  58     _Iter2 __m2 = __first2;
  59     while (true) {
  60       if (++__m2 == __last2) // If pattern exhausted, __first1 is the answer (works for 1 element pattern)
  61         return std::make_pair(__first1, ++__m1);
  62       if (++__m1 == __last1) { // Otherwise if source exhaused, pattern not found
  63         return std::make_pair(__m1, __m1);
  64       }
  65
  66       // if there is a mismatch, restart with a new __first1
  67       if (!std::__invoke(__pred, std::__invoke(__proj1, *__m1), std::__invoke(__proj2, *__m2)))
  68       {
  69         ++__first1;
  70         break;
  71       } // else there is a match, check next elements
  72     }
  73   }
  74 }
  75
  76 template <class _AlgPolicy,
  77           class _Iter1, class _Sent1,
  78           class _Iter2, class _Sent2,
  79           class _Pred,
  80           class _Proj1,
  81           class _Proj2,
  82           class _DiffT1,
  83           class _DiffT2>
  84 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
  85 pair<_Iter1, _Iter1> __search_random_access_impl(_Iter1 __first1, _Sent1 __last1,
  86                                                  _Iter2 __first2, _Sent2 __last2,
  87                                                  _Pred& __pred,
  88                                                  _Proj1& __proj1,
  89                                                  _Proj2& __proj2,
  90                                                  _DiffT1 __size1,
  91                                                  _DiffT2 __size2) {
  92   const _Iter1 __s = __first1 + __size1 - _DiffT1(__size2 - 1); // Start of pattern match can't go beyond here
  93
  94   while (true) {
  95     while (true) {
  96       if (__first1 == __s) {
  97         _IterOps<_AlgPolicy>::__advance_to(__first1, __last1);
  98         return std::make_pair(__first1, __first1);
  99       }
 100       if (std::__invoke(__pred, std::__invoke(__proj1, *__first1), std::__invoke(__proj2, *__first2)))
 101         break;
 102       ++__first1;
 103     }
 104
 105     _Iter1 __m1 = __first1;
 106     _Iter2 __m2 = __first2;
 107     while (true) {
 108       if (++__m2 == __last2)
 109         return std::make_pair(__first1, __first1 + _DiffT1(__size2));
 110       ++__m1; // no need to check range on __m1 because __s guarantees we have enough source
 111       if (!std::__invoke(__pred, std::__invoke(__proj1, *__m1), std::__invoke(__proj2, *__m2))) {
 112         ++__first1;
 113         break;
 114       }
 115     }
 116   }
 117 }
 118
 119 template <class _Iter1, class _Sent1,
 120           class _Iter2, class _Sent2,
 121           class _Pred,
 122           class _Proj1,
 123           class _Proj2>
 124 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
 125 pair<_Iter1, _Iter1> __search_impl(_Iter1 __first1, _Sent1 __last1,
 126                                    _Iter2 __first2, _Sent2 __last2,
 127                                    _Pred& __pred,
 128                                    _Proj1& __proj1,
 129                                    _Proj2& __proj2,
 130                                    __enable_if_t<__has_random_access_iterator_category<_Iter1>::value
 131                                               && __has_random_access_iterator_category<_Iter2>::value>* = nullptr) {
 132
 133   auto __size2 = __last2 - __first2;
 134   if (__size2 == 0)
 135     return std::make_pair(__first1, __first1);
 136
 137   auto __size1 = __last1 - __first1;
 138   if (__size1 < __size2) {
 139     return std::make_pair(__last1, __last1);
 140   }
 141
 142   return std::__search_random_access_impl<_ClassicAlgPolicy>(__first1, __last1,
 143                                                              __first2, __last2,
 144                                                              __pred,
 145                                                              __proj1,
 146                                                              __proj2,
 147                                                              __size1,
 148                                                              __size2);
 149 }
 150
 151 template <class _Iter1, class _Sent1,
 152           class _Iter2, class _Sent2,
 153           class _Pred,
 154           class _Proj1,
 155           class _Proj2>
 156 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14
 157 pair<_Iter1, _Iter1> __search_impl(_Iter1 __first1, _Sent1 __last1,
 158                                    _Iter2 __first2, _Sent2 __last2,
 159                                    _Pred& __pred,
 160                                    _Proj1& __proj1,
 161                                    _Proj2& __proj2,
 162                                    __enable_if_t<__has_forward_iterator_category<_Iter1>::value
 163                                               && __has_forward_iterator_category<_Iter2>::value
 164                                               && !(__has_random_access_iterator_category<_Iter1>::value
 165                                                 && __has_random_access_iterator_category<_Iter2>::value)>* = nullptr) {
 166   return std::__search_forward_impl<_ClassicAlgPolicy>(__first1, __last1,
 167                                                        __first2, __last2,
 168                                                        __pred,
 169                                                        __proj1,
 170                                                        __proj2);
 171 }
 172
 173 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
 174 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
 175 _ForwardIterator1 search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
 176                          _ForwardIterator2 __first2, _ForwardIterator2 __last2,
 177                          _BinaryPredicate __pred) {
 178   static_assert(__is_callable<_BinaryPredicate, decltype(*__first1), decltype(*__first2)>::value,
 179                 "BinaryPredicate has to be callable");
 180   auto __proj = __identity();
 181   return std::__search_impl(__first1, __last1, __first2, __last2, __pred, __proj, __proj).first;
 182 }
 183
 184 template <class _ForwardIterator1, class _ForwardIterator2>
 185 _LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
 186 _ForwardIterator1 search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
 187                          _ForwardIterator2 __first2, _ForwardIterator2 __last2) {
 188   return std::search(__first1, __last1, __first2, __last2, __equal_to());
 189 }
 190
 191 #if _LIBCPP_STD_VER >= 17
 192 template <class _ForwardIterator, class _Searcher>
 193 _LIBCPP_NODISCARD_EXT _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator
 194 search(_ForwardIterator __f, _ForwardIterator __l, const _Searcher& __s) {
 195   return __s(__f, __l).first;
 196 }
 197
 198 #endif
 199
 200 _LIBCPP_END_NAMESPACE_STD
 201
 202 #endif // _LIBCPP___ALGORITHM_SEARCH_H