utils/trie/counting-policy.hpp

/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
 * Copyright (c) 2011-2015  Regents of the University of California.
 *
 * This file is part of ndnSIM. See AUTHORS for complete list of ndnSIM authors and
 * contributors.
 *
 * ndnSIM 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 of the License, or (at your option) any later version.
 *
 * ndnSIM 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
 * ndnSIM, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
 **/

#ifndef COUNTING_POLICY_H_
#define COUNTING_POLICY_H_

/// @cond include_hidden

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

namespace ns3 {
namespace ndn {
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 {
  /// @brief Name that can be used to identify the policy (for NS-3 object model and logging)
  static std::string
  GetName()
  {
    return "Counting";
  }

  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
} // ndn
} // ns3

/// @endcond

#endif // COUNTING_POLICY_H_