utils/counting-policy.h

/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2011 University of California, Los Angeles
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * This program 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
 */

#ifndef COUNTING_POLICY_H_
#define COUNTING_POLICY_H_

#include <boost/intrusive/options.hpp>
#include <boost/intrusive/list.hpp>

namespace ndnSIM
{

/**
 * @brief Traits for policy that just keeps track of number of elements
 * It's doing a rather expensive job, but just in case it needs to be extended later
 */
struct counting_policy_traits
{
  struct policy_hook_type : public boost::intrusive::list_member_hook<> {};

  template<class Container>
  struct container_hook
  {
    // could be class/struct implementation
    typedef boost::intrusive::member_hook< Container,
                             policy_hook_type,
                             &Container::policy_hook_ > type;
  };

  template<class Base,
           class Container,
           class Hook>
  struct policy 
  {
    typedef typename boost::intrusive::list< Container, Hook > policy_container;
    
    // could be just typedef
    class type : public policy_container
    {
    public:
      typedef Container parent_trie;

      type (Base &base)
        : base_ (base)
      {
      }

      inline void
      update (typename parent_trie::iterator item)
      {
        // do nothing
      }
  
      inline bool
      insert (typename parent_trie::iterator item)
      {
        policy_container::push_back (*item);
        return true;
      }
  
      inline void
      lookup (typename parent_trie::iterator item)
      {
        // do nothing
      }
  
      inline void
      erase (typename parent_trie::iterator item)
      {
        policy_container::erase (policy_container::s_iterator_to (*item));
      }

      inline void
      clear ()
      {
        policy_container::clear ();
      }

    private:
      type () : base_(*((Base*)0)) { };

    private:
      Base &base_;
    };
  };
};

} // ndnSIM

#endif // COUNTING_POLICY_H_