lu_counter_metadata.hpp
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// -*- C++ -*-
// Copyright (C) 2005-2013 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the terms
// of the GNU General Public License as published by the Free Software
// Foundation; either version 3, or (at your option) any later
// version.
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
// Permission to use, copy, modify, sell, and distribute this software
// is hereby granted without fee, provided that the above copyright
// notice appears in all copies, and that both that copyright notice
// and this permission notice appear in supporting documentation. None
// of the above authors, nor IBM Haifa Research Laboratories, make any
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// warranty.
/**
* @file lu_counter_metadata.hpp
* Contains implementation of a lu counter policy's metadata.
*/
namespace __gnu_pbds
{
namespace detail
{
template<typename Size_Type>
class lu_counter_policy_base;
/// A list-update metadata type that moves elements to the front of
/// the list based on the counter algorithm.
template<typename Size_Type = std::size_t>
class lu_counter_metadata
{
public:
typedef Size_Type size_type;
private:
lu_counter_metadata(size_type init_count) : m_count(init_count)
{ }
friend class lu_counter_policy_base<size_type>;
mutable size_type m_count;
};
/// Base class for list-update counter policy.
template<typename Size_Type>
class lu_counter_policy_base
{
protected:
typedef Size_Type size_type;
lu_counter_metadata<size_type>
operator()(size_type max_size) const
{ return lu_counter_metadata<Size_Type>(std::rand() % max_size); }
template<typename Metadata_Reference>
bool
operator()(Metadata_Reference r_data, size_type m_max_count) const
{
if (++r_data.m_count != m_max_count)
return false;
r_data.m_count = 0;
return true;
}
};
} // namespace detail
} // namespace __gnu_pbds