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  1. // -*- C++ -*-
  2.  
  3. // Copyright (C) 2005-2015 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.  
  41. namespace __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.