libcxx/include/__algorithm/is_permutation.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_IS_PERMUTATION_H
  11 #define _LIBCPP___ALGORITHM_IS_PERMUTATION_H
  12
  13 #include <__algorithm/comp.h>
  14 #include <__algorithm/iterator_operations.h>
  15 #include <__config>
  16 #include <__functional/identity.h>
  17 #include <__iterator/concepts.h>
  18 #include <__iterator/distance.h>
  19 #include <__iterator/iterator_traits.h>
  20 #include <__iterator/next.h>
  21 #include <__type_traits/enable_if.h>
  22 #include <__type_traits/invoke.h>
  23 #include <__type_traits/is_callable.h>
  24 #include <__type_traits/is_same.h>
  25 #include <__utility/move.h>
  26
  27 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  28 #  pragma GCC system_header
  29 #endif
  30
  31 _LIBCPP_PUSH_MACROS
  32 #include <__undef_macros>
  33
  34 _LIBCPP_BEGIN_NAMESPACE_STD
  35
  36 template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class = void>
  37 struct _ConstTimeDistance : false_type {};
  38
  39 #if _LIBCPP_STD_VER >= 20
  40
  41 template <class _Iter1, class _Sent1, class _Iter2, class _Sent2>
  42 struct _ConstTimeDistance<_Iter1,
  43                           _Sent1,
  44                           _Iter2,
  45                           _Sent2,
  46                           __enable_if_t< sized_sentinel_for<_Sent1, _Iter1> && sized_sentinel_for<_Sent2, _Iter2> >>
  47     : true_type {};
  48
  49 #else
  50
  51 template <class _Iter1, class _Iter2>
  52 struct _ConstTimeDistance<
  53     _Iter1,
  54     _Iter1,
  55     _Iter2,
  56     _Iter2,
  57     __enable_if_t< is_same<typename iterator_traits<_Iter1>::iterator_category, random_access_iterator_tag>::value &&
  58                    is_same<typename iterator_traits<_Iter2>::iterator_category, random_access_iterator_tag>::value > >
  59     : true_type {};
  60
  61 #endif // _LIBCPP_STD_VER >= 20
  62
  63 // Internal functions
  64
  65 // For each element in [f1, l1) see if there are the same number of equal elements in [f2, l2)
  66 template <class _AlgPolicy,
  67           class _Iter1,
  68           class _Sent1,
  69           class _Iter2,
  70           class _Sent2,
  71           class _Proj1,
  72           class _Proj2,
  73           class _Pred>
  74 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation_impl(
  75     _Iter1 __first1,
  76     _Sent1 __last1,
  77     _Iter2 __first2,
  78     _Sent2 __last2,
  79     _Pred&& __pred,
  80     _Proj1&& __proj1,
  81     _Proj2&& __proj2) {
  82   using _D1 = __iter_diff_t<_Iter1>;
  83
  84   for (auto __i = __first1; __i != __last1; ++__i) {
  85     //  Have we already counted the number of *__i in [f1, l1)?
  86     auto __match = __first1;
  87     for (; __match != __i; ++__match) {
  88       if (std::__invoke(__pred, std::__invoke(__proj1, *__match), std::__invoke(__proj1, *__i)))
  89         break;
  90     }
  91
  92     if (__match == __i) {
  93       // Count number of *__i in [f2, l2)
  94       _D1 __c2 = 0;
  95       for (auto __j = __first2; __j != __last2; ++__j) {
  96         if (std::__invoke(__pred, std::__invoke(__proj1, *__i), std::__invoke(__proj2, *__j)))
  97           ++__c2;
  98       }
  99       if (__c2 == 0)
 100         return false;
 101
 102       // Count number of *__i in [__i, l1) (we can start with 1)
 103       _D1 __c1 = 1;
 104       for (auto __j = _IterOps<_AlgPolicy>::next(__i); __j != __last1; ++__j) {
 105         if (std::__invoke(__pred, std::__invoke(__proj1, *__i), std::__invoke(__proj1, *__j)))
 106           ++__c1;
 107       }
 108       if (__c1 != __c2)
 109         return false;
 110     }
 111   }
 112
 113   return true;
 114 }
 115
 116 // 2+1 iterators, predicate. Not used by range algorithms.
 117 template <class _AlgPolicy, class _ForwardIterator1, class _Sentinel1, class _ForwardIterator2, class _BinaryPredicate>
 118 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation(
 119     _ForwardIterator1 __first1, _Sentinel1 __last1, _ForwardIterator2 __first2, _BinaryPredicate&& __pred) {
 120   // Shorten sequences as much as possible by lopping of any equal prefix.
 121   for (; __first1 != __last1; ++__first1, (void)++__first2) {
 122     if (!__pred(*__first1, *__first2))
 123       break;
 124   }
 125
 126   if (__first1 == __last1)
 127     return true;
 128
 129   //  __first1 != __last1 && *__first1 != *__first2
 130   using _D1 = __iter_diff_t<_ForwardIterator1>;
 131   _D1 __l1  = _IterOps<_AlgPolicy>::distance(__first1, __last1);
 132   if (__l1 == _D1(1))
 133     return false;
 134   auto __last2 = _IterOps<_AlgPolicy>::next(__first2, __l1);
 135
 136   return std::__is_permutation_impl<_AlgPolicy>(
 137       std::move(__first1),
 138       std::move(__last1),
 139       std::move(__first2),
 140       std::move(__last2),
 141       __pred,
 142       __identity(),
 143       __identity());
 144 }
 145
 146 // 2+2 iterators, predicate, non-constant time `distance`.
 147 template <class _AlgPolicy,
 148           class _Iter1,
 149           class _Sent1,
 150           class _Iter2,
 151           class _Sent2,
 152           class _Proj1,
 153           class _Proj2,
 154           class _Pred>
 155 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation(
 156     _Iter1 __first1,
 157     _Sent1 __last1,
 158     _Iter2 __first2,
 159     _Sent2 __last2,
 160     _Pred&& __pred,
 161     _Proj1&& __proj1,
 162     _Proj2&& __proj2,
 163     /*_ConstTimeDistance=*/false_type) {
 164   // Shorten sequences as much as possible by lopping of any equal prefix.
 165   while (__first1 != __last1 && __first2 != __last2) {
 166     if (!std::__invoke(__pred, std::__invoke(__proj1, *__first1), std::__invoke(__proj2, *__first2)))
 167       break;
 168     ++__first1;
 169     ++__first2;
 170   }
 171
 172   if (__first1 == __last1)
 173     return __first2 == __last2;
 174   if (__first2 == __last2) // Second range is shorter
 175     return false;
 176
 177   using _D1 = __iter_diff_t<_Iter1>;
 178   _D1 __l1  = _IterOps<_AlgPolicy>::distance(__first1, __last1);
 179
 180   using _D2 = __iter_diff_t<_Iter2>;
 181   _D2 __l2  = _IterOps<_AlgPolicy>::distance(__first2, __last2);
 182   if (__l1 != __l2)
 183     return false;
 184
 185   return std::__is_permutation_impl<_AlgPolicy>(
 186       std::move(__first1), std::move(__last1), std::move(__first2), std::move(__last2), __pred, __proj1, __proj2);
 187 }
 188
 189 // 2+2 iterators, predicate, specialization for constant-time `distance` call.
 190 template <class _AlgPolicy,
 191           class _Iter1,
 192           class _Sent1,
 193           class _Iter2,
 194           class _Sent2,
 195           class _Proj1,
 196           class _Proj2,
 197           class _Pred>
 198 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation(
 199     _Iter1 __first1,
 200     _Sent1 __last1,
 201     _Iter2 __first2,
 202     _Sent2 __last2,
 203     _Pred&& __pred,
 204     _Proj1&& __proj1,
 205     _Proj2&& __proj2,
 206     /*_ConstTimeDistance=*/true_type) {
 207   if (std::distance(__first1, __last1) != std::distance(__first2, __last2))
 208     return false;
 209   return std::__is_permutation<_AlgPolicy>(
 210       std::move(__first1),
 211       std::move(__last1),
 212       std::move(__first2),
 213       std::move(__last2),
 214       __pred,
 215       __proj1,
 216       __proj2,
 217       /*_ConstTimeDistance=*/false_type());
 218 }
 219
 220 // 2+2 iterators, predicate
 221 template <class _AlgPolicy,
 222           class _Iter1,
 223           class _Sent1,
 224           class _Iter2,
 225           class _Sent2,
 226           class _Proj1,
 227           class _Proj2,
 228           class _Pred>
 229 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation(
 230     _Iter1 __first1,
 231     _Sent1 __last1,
 232     _Iter2 __first2,
 233     _Sent2 __last2,
 234     _Pred&& __pred,
 235     _Proj1&& __proj1,
 236     _Proj2&& __proj2) {
 237   return std::__is_permutation<_AlgPolicy>(
 238       std::move(__first1),
 239       std::move(__last1),
 240       std::move(__first2),
 241       std::move(__last2),
 242       __pred,
 243       __proj1,
 244       __proj2,
 245       _ConstTimeDistance<_Iter1, _Sent1, _Iter2, _Sent2>());
 246 }
 247
 248 // Public interface
 249
 250 // 2+1 iterators, predicate
 251 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
 252 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool is_permutation(
 253     _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _BinaryPredicate __pred) {
 254   static_assert(__is_callable<_BinaryPredicate&, decltype(*__first1), decltype(*__first2)>::value,
 255                 "The comparator has to be callable");
 256
 257   return std::__is_permutation<_ClassicAlgPolicy>(std::move(__first1), std::move(__last1), std::move(__first2), __pred);
 258 }
 259
 260 // 2+1 iterators
 261 template <class _ForwardIterator1, class _ForwardIterator2>
 262 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
 263 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2) {
 264   return std::is_permutation(__first1, __last1, __first2, __equal_to());
 265 }
 266
 267 #if _LIBCPP_STD_VER >= 14
 268
 269 // 2+2 iterators
 270 template <class _ForwardIterator1, class _ForwardIterator2>
 271 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool is_permutation(
 272     _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2) {
 273   return std::__is_permutation<_ClassicAlgPolicy>(
 274       std::move(__first1),
 275       std::move(__last1),
 276       std::move(__first2),
 277       std::move(__last2),
 278       __equal_to(),
 279       __identity(),
 280       __identity());
 281 }
 282
 283 // 2+2 iterators, predicate
 284 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
 285 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool is_permutation(
 286     _ForwardIterator1 __first1,
 287     _ForwardIterator1 __last1,
 288     _ForwardIterator2 __first2,
 289     _ForwardIterator2 __last2,
 290     _BinaryPredicate __pred) {
 291   static_assert(__is_callable<_BinaryPredicate&, decltype(*__first1), decltype(*__first2)>::value,
 292                 "The comparator has to be callable");
 293
 294   return std::__is_permutation<_ClassicAlgPolicy>(
 295       std::move(__first1),
 296       std::move(__last1),
 297       std::move(__first2),
 298       std::move(__last2),
 299       __pred,
 300       __identity(),
 301       __identity());
 302 }
 303
 304 #endif // _LIBCPP_STD_VER >= 14
 305
 306 _LIBCPP_END_NAMESPACE_STD
 307
 308 _LIBCPP_POP_MACROS
 309
 310 #endif // _LIBCPP___ALGORITHM_IS_PERMUTATION_H