libstdc++-v3/testsuite/23_containers/unordered_set/hash_policy/power2_rehash.cc

   1 // Copyright (C) 2016-2024 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 <limits>
  21 #include <unordered_set>
  22
  23 #include <testsuite_hooks.h>
  24
  25 void test01()
  26 {
  27   std::__detail::_Power2_rehash_policy policy;
  28   VERIFY( policy._M_next_bkt(1) == 2 );
  29   VERIFY( policy._M_next_bkt(2) == 2 );
  30   VERIFY( policy._M_next_bkt(3) == 4 );
  31   VERIFY( policy._M_next_bkt(5) == 8 );
  32   VERIFY( policy._M_next_bkt(16) == 16 );
  33   VERIFY( policy._M_next_bkt(33) == 64 );
  34   VERIFY( policy._M_next_bkt((std::size_t(1) << (sizeof(std::size_t) * 8 - 2)) + 1)
  35           == (std::size_t(1) << (sizeof(std::size_t) * 8 - 1)) );
  36 }
  37
  38 void test02()
  39 {
  40   std::__detail::_Power2_rehash_policy policy;
  41
  42   for (std::size_t i = 3;;)
  43     {
  44       auto nxt = policy._M_next_bkt(i);
  45
  46       if (nxt <= i)
  47         {
  48           // Lower or equal only when reaching max.
  49           constexpr auto mx = std::numeric_limits<std::size_t>::max();
  50           VERIFY( nxt == policy._M_next_bkt(mx) );
  51           break;
  52         }
  53
  54       VERIFY( nxt >= i );
  55       i = nxt + 1;
  56     }
  57 }
  58
  59 int main()
  60 {
  61   test01();
  62   test02();
  63   return 0;
  64 }