1// -*- C++ -*-
2
3// Copyright (C) 2005 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 2, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14// GNU General Public License for more details.
15
16// You should have received a copy of the GNU General Public License along
17// with this library; see the file COPYING.  If not, write to the Free
18// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
19// USA.
20
21// As a special exception, you may use this file as part of a free software
22// library without restriction.  Specifically, if other files instantiate
23// templates or use macros or inline functions from this file, or you compile
24// this file and link it with other files to produce an executable, this
25// file does not by itself cause the resulting executable to be covered by
26// the GNU General Public License.  This exception does not however
27// invalidate any other reasons why the executable file might be covered by
28// the GNU General Public License.
29
30// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
31
32// Permission to use, copy, modify, sell, and distribute this software
33// is hereby granted without fee, provided that the above copyright
34// notice appears in all copies, and that both that copyright notice and
35// this permission notice appear in supporting documentation. None of
36// the above authors, nor IBM Haifa Research Laboratories, make any
37// representation about the suitability of this software for any
38// purpose. It is provided "as is" without express or implied warranty.
39
40/**
41 * @file hash_illegal_resize_example.cpp
42 * An example of externally resizing a hash-based container object.
43 */
44
45// For gp_hash_assoc_cntnr
46#include <ext/pb_assoc/assoc_cntnr.hpp>
47// For hash-related policies.
48#include <ext/pb_assoc/hash_policy.hpp>
49// For cannot_resize
50#include <ext/pb_assoc/exception.hpp>
51// For assert
52#include <cassert>
53
54/*
55 * A simple hash functor.
56 *	std::hash could serve instead of this functor,
57 *	but it is not yet standard everywhere.
58 */
59struct int_hash : public std::unary_function<
60  int,
61	     size_t>
62{
63  inline size_t
64  operator()(const int& r_i) const
65  {
66    return (r_i);
67  }
68};
69
70int
71main()
72{
73  /*
74   * A probing hash table mapping ints to chars.
75   */
76  typedef
77    pb_assoc::gp_hash_assoc_cntnr<
78    int,
79    int,
80    int_hash,
81    std::equal_to<
82    int>,
83    // Combining function.
84    pb_assoc::direct_mod_range_hashing<>,
85    // Probe function.
86    pb_assoc::quadratic_probe_fn<
87    const int& >,
88    // Resize policy.
89    pb_assoc::hash_standard_resize_policy<
90    pb_assoc::hash_prime_size_policy,
91    pb_assoc::hash_load_check_resize_trigger<>,
92    /* Allow external access to size.
93     *	Without setting this to true, external resizing
94     *	is not possible.
95     */
96    true> >
97    map_t;
98
99  map_t g;
100
101  /*
102   * Check the actual size of the container object.
103   *	This should be at least
104   *	the initial size given by the size policy object.
105   **/
106  assert(g.get_actual_size() > 8);
107
108  // Insert some elements.
109
110  int i;
111
112  for (i = 0; i < 1000; ++i)
113    g[i] = 2*  i;
114
115  // Check all ok.
116
117  assert(g.size() == 1000);
118
119  for (i = 0; i < 1000; ++i)
120    assert(g.find(i) != g.end()&&  g.find(i)->second == 2*  i);
121
122  // Now attempt to resize the table to 200 (impossible).
123
124  bool ex_thrown = false;
125
126  try
127    {
128      g.resize(200);
129    }
130  catch(pb_assoc::cannot_resize& )
131    {
132      ex_thrown = true;
133    }
134
135  /*
136   * Assert an exception was thrown. A probing table cannot contain
137   *	1000 entries in less than 1000 places.
138   */
139  assert(ex_thrown);
140
141  // Check all ok.
142
143  assert(g.size() == 1000);
144
145  for (i = 0; i < 1000; ++i)
146    assert(g.find(i) != g.end()&&  g.find(i)->second == 2*  i);
147}
148
149