1// -*- C++ -*-
2
3// Copyright (C) 2005, 2006 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 terms
7// of the GNU General Public License as published by the Free Software
8// Foundation; either version 2, or (at your option) any later
9// version.
10
11// This library is distributed in the hope that it will be useful, but
12// WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14// General Public License for more details.
15
16// You should have received a copy of the GNU General Public License
17// along with this library; see the file COPYING.  If not, write to
18// the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
19// MA 02111-1307, USA.
20
21// As a special exception, you may use this file as part of a free
22// software library without restriction.  Specifically, if other files
23// instantiate templates or use macros or inline functions from this
24// file, or you compile this file and link it with other files to
25// produce an executable, this file does not by itself cause the
26// resulting executable to be covered by the GNU General Public
27// License.  This exception does not however invalidate any other
28// reasons why the executable file might be covered by the GNU General
29// Public License.
30
31// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
32
33// Permission to use, copy, modify, sell, and distribute this software
34// is hereby granted without fee, provided that the above copyright
35// notice appears in all copies, and that both that copyright notice
36// and this permission notice appear in supporting documentation. None
37// of the above authors, nor IBM Haifa Research Laboratories, make any
38// representation about the suitability of this software for any
39// purpose. It is provided "as is" without express or implied
40// warranty.
41
42/**
43 * @file counter_lu_metadata.hpp
44 * Contains implementation of a lu counter policy's metadata.
45 */
46
47namespace pb_ds
48{
49  namespace detail
50  {
51    template<typename Size_Type>
52    class counter_lu_policy_base;
53
54    // A list-update metadata type that moves elements to the front of
55    // the list based on the counter algorithm.
56    template<typename Size_Type = size_t>
57    class counter_lu_metadata
58    {
59    public:
60      typedef Size_Type size_type;
61
62    private:
63      counter_lu_metadata(size_type init_count) : m_count(init_count)
64      { }
65
66      friend class counter_lu_policy_base<size_type>;
67
68      mutable size_type m_count;
69    };
70
71    template<typename Size_Type>
72    class counter_lu_policy_base
73    {
74    protected:
75      typedef Size_Type size_type;
76
77      counter_lu_metadata<size_type>
78      operator()(size_type max_size) const
79      { return counter_lu_metadata<Size_Type>(rand() % max_size); }
80
81      template<typename Metadata_Reference>
82      bool
83      operator()(Metadata_Reference r_data, size_type m_max_count) const
84      {
85	if (++r_data.m_count != m_max_count)
86	  return false;
87	r_data.m_count = 0;
88	return true;
89      }
90    };
91  } // namespace detail
92} // namespace pb_ds
93