libstdc++-v3/testsuite/23_containers/unordered_set/hash_policy/rehash.cc

   1 // Copyright (C) 2011-2023 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8 //
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17 //
  18 // { dg-do run { target c++11 } }
  19
  20 #include <unordered_set>
  21
  22 #include <testsuite_hooks.h>
  23
  24 template<typename _USet>
  25   void test()
  26   {
  27     _USet us;
  28     typedef typename _USet::size_type size_type;
  29     bool rehashed = false;
  30     for (int i = 0; i != 100000; ++i)
  31       {
  32         size_type bkt_count = us.bucket_count();
  33         us.insert(i);
  34         if (bkt_count != us.bucket_count())
  35           {
  36             // Container has been rehashed, lets check that it won't be rehash
  37             // again if we remove and restore the last 2 inserted elements:
  38             rehashed = true;
  39             bkt_count = us.bucket_count();
  40             VERIFY( us.erase(i) == 1 );
  41             VERIFY( bkt_count == us.bucket_count() );
  42             if (i > 0)
  43               {
  44                 VERIFY( us.erase(i - 1) == 1 );
  45                 VERIFY( bkt_count == us.bucket_count() );
  46
  47                 VERIFY( us.insert(i - 1).second );
  48                 VERIFY( bkt_count == us.bucket_count() );
  49               }
  50             VERIFY( us.insert(i).second );
  51             VERIFY( bkt_count == us.bucket_count() );
  52           }
  53       }
  54
  55     // At lest we check a rehash once:
  56     VERIFY( rehashed );
  57   }
  58
  59 template<typename _Value>
  60   using unordered_set_power2_rehash =
  61   std::_Hashtable<_Value, _Value, std::allocator<_Value>,
  62                   std::__detail::_Identity,
  63                   std::equal_to<_Value>,
  64                   std::hash<_Value>,
  65                   std::__detail::_Mask_range_hashing,
  66                   std::__detail::_Default_ranged_hash,
  67                   std::__detail::_Power2_rehash_policy,
  68                   std::__detail::_Hashtable_traits<false, true, true>>;
  69
  70 int main()
  71 {
  72   test<std::unordered_set<int>>();
  73   test<unordered_set_power2_rehash<int>>();
  74   return 0;
  75 }