libstdc++-v3/testsuite/ext/pb_ds/example/hash_illegal_resize.cc

   1 // { dg-timeout-factor 2.0 }
   2
   3 // -*- C++ -*-
   4
   5 // Copyright (C) 2005-2023 Free Software Foundation, Inc.
   6 //
   7 // This file is part of the GNU ISO C++ Library.  This library is free
   8 // software; you can redistribute it and/or modify it under the terms
   9 // of the GNU General Public License as published by the Free Software
  10 // Foundation; either version 3, or (at your option) any later
  11 // version.
  12
  13 // This library is distributed in the hope that it will be useful, but
  14 // WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 // General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this library; see the file COPYING3.  If not see
  20 // <http://www.gnu.org/licenses/>.
  21
  22
  23 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
  24
  25 // Permission to use, copy, modify, sell, and distribute this software
  26 // is hereby granted without fee, provided that the above copyright
  27 // notice appears in all copies, and that both that copyright notice
  28 // and this permission notice appear in supporting documentation. None
  29 // of the above authors, nor IBM Haifa Research Laboratories, make any
  30 // representation about the suitability of this software for any
  31 // purpose. It is provided "as is" without express or implied
  32 // warranty.
  33
  34 /**
  35  * @file hash_illegal_resize_example.cpp
  36  * An example of illegally externally resizing a hash-based container object.
  37  */
  38
  39 /**
  40  * This example shows the case where a hash-based container object is
  41  * resized to a value which it cannot accommodate at runtime. Illegal
  42  * runtime resizes cause an exception.
  43  */
  44
  45 #include <ext/pb_ds/assoc_container.hpp>
  46 #include <ext/pb_ds/hash_policy.hpp>
  47 #include <ext/pb_ds/exception.hpp>
  48 #include <cassert>
  49
  50 // size of test containers
  51 #ifdef _GLIBCXX_DEBUG
  52 # define SIZE 100
  53 # define RESIZE 20
  54 #else
  55 # define SIZE 1000
  56 # define RESIZE 200
  57 #endif
  58
  59 using namespace std;
  60 using namespace __gnu_pbds;
  61
  62 // A simple hash functor.
  63 // hash could serve instead of this functor, but it is not yet
  64 // standard everywhere.
  65 struct int_hash
  66 {
  67   size_t
  68   operator()(const int& r_i) const
  69   { return r_i; }
  70 };
  71
  72
  73 int main()
  74 {
  75   // A probing hash table mapping ints to chars.
  76   typedef
  77     gp_hash_table<
  78     int,
  79     int,
  80     int_hash,
  81     equal_to<int>,
  82     // Combining function.
  83     direct_mod_range_hashing<>,
  84     // Probe function.
  85     quadratic_probe_fn<>,
  86     // Resize policy.
  87     hash_standard_resize_policy<
  88     hash_prime_size_policy,
  89     hash_load_check_resize_trigger<>,
  90     /* Allow external access to size.
  91      *     Without setting this to true, external resizing
  92      *     is not possible.
  93      */
  94     true> >
  95     map_t;
  96
  97   map_t g;
  98
  99   // Insert some elements.
 100   int i;
 101
 102   for (i = 0; i < SIZE; ++i)
 103     g[i] = 2*  i;
 104
 105   // Check all ok.
 106   assert(g.size() == SIZE);
 107   for (i = 0; i < SIZE; ++i)
 108     assert(g.find(i) != g.end() && g.find(i)->second == 2 * i);
 109
 110   // Now attempt to resize the table to 200 (impossible).
 111   bool ex_thrown = false;
 112
 113   try
 114     {
 115       g.resize(RESIZE);
 116     }
 117   catch(__gnu_pbds::resize_error& )
 118     {
 119       ex_thrown = true;
 120     }
 121
 122   // Assert an exception was thrown. A probing table cannot contain
 123   // 1000 entries in less than 1000 places.
 124   assert(ex_thrown);
 125
 126   // Irrespective of the fact that the resize was not successful, the
 127   // container object should still be in a valid state; the following
 128   // checks this.
 129   // Check all ok.
 130   assert(g.size() == SIZE);
 131   for (i = 0; i < SIZE; ++i)
 132     assert(g.find(i) != g.end() && g.find(i)->second == 2 * i);
 133
 134   return 0;
 135 }