libcxx/include/__cxx03/__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 <__cxx03/__algorithm/comp.h>
  14 #include <__cxx03/__algorithm/iterator_operations.h>
  15 #include <__cxx03/__config>
  16 #include <__cxx03/__functional/identity.h>
  17 #include <__cxx03/__functional/invoke.h>
  18 #include <__cxx03/__iterator/concepts.h>
  19 #include <__cxx03/__iterator/distance.h>
  20 #include <__cxx03/__iterator/iterator_traits.h>
  21 #include <__cxx03/__iterator/next.h>
  22 #include <__cxx03/__type_traits/is_callable.h>
  23 #include <__cxx03/__utility/move.h>
  24
  25 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  26 #  pragma GCC system_header
  27 #endif
  28
  29 _LIBCPP_PUSH_MACROS
  30 #include <__cxx03/__undef_macros>
  31
  32 _LIBCPP_BEGIN_NAMESPACE_STD
  33
  34 template <class _Iter1, class _Sent1, class _Iter2, class _Sent2, class = void>
  35 struct _ConstTimeDistance : false_type {};
  36
  37 #if _LIBCPP_STD_VER >= 20
  38
  39 template <class _Iter1, class _Sent1, class _Iter2, class _Sent2>
  40 struct _ConstTimeDistance<_Iter1,
  41                           _Sent1,
  42                           _Iter2,
  43                           _Sent2,
  44                           __enable_if_t< sized_sentinel_for<_Sent1, _Iter1> && sized_sentinel_for<_Sent2, _Iter2> >>
  45     : true_type {};
  46
  47 #else
  48
  49 template <class _Iter1, class _Iter2>
  50 struct _ConstTimeDistance<
  51     _Iter1,
  52     _Iter1,
  53     _Iter2,
  54     _Iter2,
  55     __enable_if_t< is_same<typename iterator_traits<_Iter1>::iterator_category, random_access_iterator_tag>::value &&
  56                    is_same<typename iterator_traits<_Iter2>::iterator_category, random_access_iterator_tag>::value > >
  57     : true_type {};
  58
  59 #endif // _LIBCPP_STD_VER >= 20
  60
  61 // Internal functions
  62
  63 // For each element in [f1, l1) see if there are the same number of equal elements in [f2, l2)
  64 template <class _AlgPolicy,
  65           class _Iter1,
  66           class _Sent1,
  67           class _Iter2,
  68           class _Sent2,
  69           class _Proj1,
  70           class _Proj2,
  71           class _Pred>
  72 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation_impl(
  73     _Iter1 __first1,
  74     _Sent1 __last1,
  75     _Iter2 __first2,
  76     _Sent2 __last2,
  77     _Pred&& __pred,
  78     _Proj1&& __proj1,
  79     _Proj2&& __proj2) {
  80   using _D1 = __iter_diff_t<_Iter1>;
  81
  82   for (auto __i = __first1; __i != __last1; ++__i) {
  83     //  Have we already counted the number of *__i in [f1, l1)?
  84     auto __match = __first1;
  85     for (; __match != __i; ++__match) {
  86       if (std::__invoke(__pred, std::__invoke(__proj1, *__match), std::__invoke(__proj1, *__i)))
  87         break;
  88     }
  89
  90     if (__match == __i) {
  91       // Count number of *__i in [f2, l2)
  92       _D1 __c2 = 0;
  93       for (auto __j = __first2; __j != __last2; ++__j) {
  94         if (std::__invoke(__pred, std::__invoke(__proj1, *__i), std::__invoke(__proj2, *__j)))
  95           ++__c2;
  96       }
  97       if (__c2 == 0)
  98         return false;
  99
 100       // Count number of *__i in [__i, l1) (we can start with 1)
 101       _D1 __c1 = 1;
 102       for (auto __j = _IterOps<_AlgPolicy>::next(__i); __j != __last1; ++__j) {
 103         if (std::__invoke(__pred, std::__invoke(__proj1, *__i), std::__invoke(__proj1, *__j)))
 104           ++__c1;
 105       }
 106       if (__c1 != __c2)
 107         return false;
 108     }
 109   }
 110
 111   return true;
 112 }
 113
 114 // 2+1 iterators, predicate. Not used by range algorithms.
 115 template <class _AlgPolicy, class _ForwardIterator1, class _Sentinel1, class _ForwardIterator2, class _BinaryPredicate>
 116 _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation(
 117     _ForwardIterator1 __first1, _Sentinel1 __last1, _ForwardIterator2 __first2, _BinaryPredicate&& __pred) {
 118   // Shorten sequences as much as possible by lopping of any equal prefix.
 119   for (; __first1 != __last1; ++__first1, (void)++__first2) {
 120     if (!__pred(*__first1, *__first2))
 121       break;
 122   }
 123
 124   if (__first1 == __last1)
 125     return true;
 126
 127   //  __first1 != __last1 && *__first1 != *__first2
 128   using _D1 = __iter_diff_t<_ForwardIterator1>;
 129   _D1 __l1  = _IterOps<_AlgPolicy>::distance(__first1, __last1);
 130   if (__l1 == _D1(1))
 131     return false;
 132   auto __last2 = _IterOps<_AlgPolicy>::next(__first2, __l1);
 133
 134   return std::__is_permutation_impl<_AlgPolicy>(
 135       std::move(__first1),
 136       std::move(__last1),
 137       std::move(__first2),
 138       std::move(__last2),
 139       __pred,
 140       __identity(),
 141       __identity());
 142 }
 143
 144 // 2+2 iterators, predicate, non-constant time `distance`.
 145 template <class _AlgPolicy,
 146           class _Iter1,
 147           class _Sent1,
 148           class _Iter2,
 149           class _Sent2,
 150           class _Proj1,
 151           class _Proj2,
 152           class _Pred>
 153 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation(
 154     _Iter1 __first1,
 155     _Sent1 __last1,
 156     _Iter2 __first2,
 157     _Sent2 __last2,
 158     _Pred&& __pred,
 159     _Proj1&& __proj1,
 160     _Proj2&& __proj2,
 161     /*_ConstTimeDistance=*/false_type) {
 162   // Shorten sequences as much as possible by lopping of any equal prefix.
 163   while (__first1 != __last1 && __first2 != __last2) {
 164     if (!std::__invoke(__pred, std::__invoke(__proj1, *__first1), std::__invoke(__proj2, *__first2)))
 165       break;
 166     ++__first1;
 167     ++__first2;
 168   }
 169
 170   if (__first1 == __last1)
 171     return __first2 == __last2;
 172   if (__first2 == __last2) // Second range is shorter
 173     return false;
 174
 175   using _D1 = __iter_diff_t<_Iter1>;
 176   _D1 __l1  = _IterOps<_AlgPolicy>::distance(__first1, __last1);
 177
 178   using _D2 = __iter_diff_t<_Iter2>;
 179   _D2 __l2  = _IterOps<_AlgPolicy>::distance(__first2, __last2);
 180   if (__l1 != __l2)
 181     return false;
 182
 183   return std::__is_permutation_impl<_AlgPolicy>(
 184       std::move(__first1), std::move(__last1), std::move(__first2), std::move(__last2), __pred, __proj1, __proj2);
 185 }
 186
 187 // 2+2 iterators, predicate, specialization for constant-time `distance` call.
 188 template <class _AlgPolicy,
 189           class _Iter1,
 190           class _Sent1,
 191           class _Iter2,
 192           class _Sent2,
 193           class _Proj1,
 194           class _Proj2,
 195           class _Pred>
 196 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation(
 197     _Iter1 __first1,
 198     _Sent1 __last1,
 199     _Iter2 __first2,
 200     _Sent2 __last2,
 201     _Pred&& __pred,
 202     _Proj1&& __proj1,
 203     _Proj2&& __proj2,
 204     /*_ConstTimeDistance=*/true_type) {
 205   if (std::distance(__first1, __last1) != std::distance(__first2, __last2))
 206     return false;
 207   return std::__is_permutation<_AlgPolicy>(
 208       std::move(__first1),
 209       std::move(__last1),
 210       std::move(__first2),
 211       std::move(__last2),
 212       __pred,
 213       __proj1,
 214       __proj2,
 215       /*_ConstTimeDistance=*/false_type());
 216 }
 217
 218 // 2+2 iterators, predicate
 219 template <class _AlgPolicy,
 220           class _Iter1,
 221           class _Sent1,
 222           class _Iter2,
 223           class _Sent2,
 224           class _Proj1,
 225           class _Proj2,
 226           class _Pred>
 227 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __is_permutation(
 228     _Iter1 __first1,
 229     _Sent1 __last1,
 230     _Iter2 __first2,
 231     _Sent2 __last2,
 232     _Pred&& __pred,
 233     _Proj1&& __proj1,
 234     _Proj2&& __proj2) {
 235   return std::__is_permutation<_AlgPolicy>(
 236       std::move(__first1),
 237       std::move(__last1),
 238       std::move(__first2),
 239       std::move(__last2),
 240       __pred,
 241       __proj1,
 242       __proj2,
 243       _ConstTimeDistance<_Iter1, _Sent1, _Iter2, _Sent2>());
 244 }
 245
 246 // Public interface
 247
 248 // 2+1 iterators, predicate
 249 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
 250 _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool is_permutation(
 251     _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _BinaryPredicate __pred) {
 252   static_assert(__is_callable<_BinaryPredicate, decltype(*__first1), decltype(*__first2)>::value,
 253                 "The predicate has to be callable");
 254
 255   return std::__is_permutation<_ClassicAlgPolicy>(std::move(__first1), std::move(__last1), std::move(__first2), __pred);
 256 }
 257
 258 // 2+1 iterators
 259 template <class _ForwardIterator1, class _ForwardIterator2>
 260 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool
 261 is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2) {
 262   return std::is_permutation(__first1, __last1, __first2, __equal_to());
 263 }
 264
 265 #if _LIBCPP_STD_VER >= 14
 266
 267 // 2+2 iterators
 268 template <class _ForwardIterator1, class _ForwardIterator2>
 269 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool is_permutation(
 270     _ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2, _ForwardIterator2 __last2) {
 271   return std::__is_permutation<_ClassicAlgPolicy>(
 272       std::move(__first1),
 273       std::move(__last1),
 274       std::move(__first2),
 275       std::move(__last2),
 276       __equal_to(),
 277       __identity(),
 278       __identity());
 279 }
 280
 281 // 2+2 iterators, predicate
 282 template <class _ForwardIterator1, class _ForwardIterator2, class _BinaryPredicate>
 283 _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool is_permutation(
 284     _ForwardIterator1 __first1,
 285     _ForwardIterator1 __last1,
 286     _ForwardIterator2 __first2,
 287     _ForwardIterator2 __last2,
 288     _BinaryPredicate __pred) {
 289   static_assert(__is_callable<_BinaryPredicate, decltype(*__first1), decltype(*__first2)>::value,
 290                 "The predicate has to be callable");
 291
 292   return std::__is_permutation<_ClassicAlgPolicy>(
 293       std::move(__first1),
 294       std::move(__last1),
 295       std::move(__first2),
 296       std::move(__last2),
 297       __pred,
 298       __identity(),
 299       __identity());
 300 }
 301
 302 #endif // _LIBCPP_STD_VER >= 14
 303
 304 _LIBCPP_END_NAMESPACE_STD
 305
 306 _LIBCPP_POP_MACROS
 307
 308 #endif // _LIBCPP___ALGORITHM_IS_PERMUTATION_H