1// -*- C++ -*-
2
3// Copyright (C) 2005-2020 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 3, 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// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.
24
25// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
26
27// Permission to use, copy, modify, sell, and distribute this software
28// is hereby granted without fee, provided that the above copyright
29// notice appears in all copies, and that both that copyright notice
30// and this permission notice appear in supporting documentation. None
31// of the above authors, nor IBM Haifa Research Laboratories, make any
32// representation about the suitability of this software for any
33// purpose. It is provided "as is" without express or implied
34// warranty.
35
36/**
37 * @file lu_counter_metadata.hpp
38 * Contains implementation of a lu counter policy's metadata.
39 */
40
41namespace __gnu_pbds
42{
43  namespace detail
44  {
45    template<typename Size_Type>
46      class lu_counter_policy_base;
47
48    /// A list-update metadata type that moves elements to the front of
49    /// the list based on the counter algorithm.
50    template<typename Size_Type = std::size_t>
51      class lu_counter_metadata
52      {
53      public:
54	typedef Size_Type 	size_type;
55
56      private:
57	lu_counter_metadata(size_type init_count) : m_count(init_count)
58	{ }
59
60	friend class lu_counter_policy_base<size_type>;
61
62	mutable size_type 	m_count;
63    };
64
65    /// Base class for list-update counter policy.
66    template<typename Size_Type>
67      class lu_counter_policy_base
68      {
69      protected:
70	typedef Size_Type 	size_type;
71
72	lu_counter_metadata<size_type>
73	operator()(size_type max_size) const
74	{ return lu_counter_metadata<Size_Type>(std::rand() % max_size); }
75
76	template<typename Metadata_Reference>
77	bool
78	operator()(Metadata_Reference r_data, size_type m_max_count) const
79	{
80	  if (++r_data.m_count != m_max_count)
81	    return false;
82	  r_data.m_count = 0;
83	  return true;
84	}
85      };
86  } // namespace detail
87} // namespace __gnu_pbds
88