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 gp_ht_map_resize_example.cpp
42 * An example of setting an initial size for a 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 assert
50#include <cassert>
51
52/*
53 * A simple hash functor.
54 *	std::hash could serve instead of this functor,
55 *	but it is not yet standard everywhere.
56 */
57struct int_hash : public std::unary_function<
58  int,
59	     size_t>
60{
61  inline size_t
62  operator()(const int& r_i) const
63  {
64    return (r_i);
65  }
66};
67
68int
69main()
70{
71  // Resize policy type.
72  typedef
73    pb_assoc::hash_standard_resize_policy<
74    // Size-policy type.
75    pb_assoc::hash_exponential_size_policy<>,
76    // Trigger-policy type.
77    pb_assoc::hash_load_check_resize_trigger<>,
78    /* Allow external access to size.
79     *	This is just used in this example for using the
80     *	get_actual_size method (which won't be accessible without
81     *	this flag.
82     */
83    true>
84    resize_policy_t;
85
86  /*
87   * A collision-probing hash table mapping ints to chars.
88   */
89  typedef
90    pb_assoc::gp_hash_assoc_cntnr<
91    int,
92    char,
93    int_hash,
94    std::equal_to<
95    int>,
96    // Combining function.
97    pb_assoc::direct_mask_range_hashing<>,
98    // Probe function.
99    pb_assoc::linear_probe_fn<
100    const int& >,
101    // Resize policy.
102    resize_policy_t>
103    map_t;
104
105  // A resize-policy object with suggested initial size 256.
106  resize_policy_t res(pb_assoc::hash_exponential_size_policy<>(256));
107
108  map_t g(int_hash(),
109	  std::equal_to<int>(),
110	  pb_assoc::direct_mask_range_hashing<>(),
111	  pb_assoc::linear_probe_fn<const int& >(),
112	  res);
113
114  /*
115   * Check the actual size of the container object. In this case,
116   *	this should be the initial size given by the size policy object.
117   **/
118  assert(g.get_actual_size() >= 256);
119
120  assert(g.size() == 0);
121}
122
123