libstdc++
lu_counter_metadata.hpp
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1 // -*- C++ -*-
2 
3 // Copyright (C) 2005-2018 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
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24 
25 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
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28 // is hereby granted without fee, provided that the above copyright
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35 
36 /**
37  * @file lu_counter_metadata.hpp
38  * Contains implementation of a lu counter policy's metadata.
39  */
40 
41 namespace __gnu_pbds
42 {
43  namespace detail
44  {
45  template<typename Size_Type>
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>
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>
68  {
69  protected:
70  typedef Size_Type size_type;
71 
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
Base class for list-update counter policy.
GNU extensions for policy-based data structures for public use.
A list-update metadata type that moves elements to the front of the list based on the counter algorit...