libstdc++
lu_counter_metadata.hpp
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1 // -*- C++ -*-
2 
3 // Copyright (C) 2005, 2006, 2007, 2009, 2010, 2011
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12 // This library is distributed in the hope that it will be useful, but
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17 // Under Section 7 of GPL version 3, you are granted additional
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26 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
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36 
37 /**
38  * @file lu_counter_metadata.hpp
39  * Contains implementation of a lu counter policy's metadata.
40  */
41 
42 namespace __gnu_pbds
43 {
44  namespace detail
45  {
46  template<typename Size_Type>
47  class lu_counter_policy_base;
48 
49  /// A list-update metadata type that moves elements to the front of
50  /// the list based on the counter algorithm.
51  template<typename Size_Type = std::size_t>
53  {
54  public:
55  typedef Size_Type size_type;
56 
57  private:
58  lu_counter_metadata(size_type init_count) : m_count(init_count)
59  { }
60 
61  friend class lu_counter_policy_base<size_type>;
62 
63  mutable size_type m_count;
64  };
65 
66  /// Base class for list-update counter policy.
67  template<typename Size_Type>
69  {
70  protected:
71  typedef Size_Type size_type;
72 
74  operator()(size_type max_size) const
75  { return lu_counter_metadata<Size_Type>(std::rand() % max_size); }
76 
77  template<typename Metadata_Reference>
78  bool
79  operator()(Metadata_Reference r_data, size_type m_max_count) const
80  {
81  if (++r_data.m_count != m_max_count)
82  return false;
83  r_data.m_count = 0;
84  return true;
85  }
86  };
87  } // namespace detail
88 } // namespace __gnu_pbds