ndn-cpp/trie/policies/multi-policy.h

/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
/*
 * Copyright (c) 2013, Regents of the University of California
 *                     Alexander Afanasyev
 *
 * BSD license, See the LICENSE file for more information
 *
 * Author: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
 */

#ifndef MULTI_POLICY_H_
#define MULTI_POLICY_H_

#include "detail/multi-type-container.h"
#include "detail/multi-policy-container.h"
#include "detail/functor-hook.h"

#include <boost/mpl/size.hpp>
#include <boost/mpl/at.hpp>
#include <boost/mpl/range_c.hpp>
#include <boost/mpl/transform.hpp>
#include <boost/mpl/back_inserter.hpp>
#include <boost/mpl/vector.hpp>
#include <boost/mpl/for_each.hpp>

#include <boost/intrusive/options.hpp>

namespace ndn {
namespace trie {

template<typename Policies> // e.g., mpl::vector1< lru_policy_traits >
struct multi_policy_traits
{
  typedef Policies policy_traits;

  struct getHook { template<class Item> struct apply { typedef typename Item::policy_hook_type type; }; };
  typedef detail::multi_type_container< typename boost::mpl::transform1<policy_traits, getHook>::type > policy_hook_type;
  
  template<class Container>
  struct container_hook
  {
    typedef policy_hook_type type;
  };

  template<class Base,
           class Container,
           class Hook>
  struct policy 
  {
    typedef boost::mpl::range_c<int, 0, boost::mpl::size<policy_traits>::type::value> policies_range;

    struct getPolicy
    {
      template<class Number>
      struct apply
      {
        typedef
        typename boost::mpl::at_c<policy_traits, Number::value>::type::
        template policy<Base,
                        Container,
                        boost::intrusive::function_hook< detail::FunctorHook <Hook,
                                                                              Container,
                                                                              Number::value> > >::type
        type;
      };
    };
    
    typedef
    typename boost::mpl::transform1<policies_range,
                                    getPolicy,
                                    boost::mpl::back_inserter< boost::mpl::vector0<> > >::type policies;
                             
    
    typedef detail::multi_policy_container< Base, policies > policy_container;
    
    class type : public policy_container
    {
    public:
      typedef policy policy_base; // to get access to get_time methods from outside
      typedef Container parent_trie;

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

      inline void
      update (typename parent_trie::iterator item)
      {
        policy_container::update (item);
      }
  
      inline bool
      insert (typename parent_trie::iterator item)
      {
        return policy_container::insert (item);
      }
  
      inline void
      lookup (typename parent_trie::iterator item)
      {
        policy_container::lookup (item);
      }
  
      inline void
      erase (typename parent_trie::iterator item)
      {
        policy_container::erase (item);
      }
      
      inline void
      clear ()
      {
        policy_container::clear ();
      }

      struct max_size_setter
      {
        max_size_setter (policy_container &container, size_t size) : m_container (container), m_size (size) { }
        
        template< typename U > void operator() (U index)
        {
          m_container.template get<U::value> ().set_max_size (m_size);
        }

      private:
        policy_container &m_container;
        size_t m_size;
      };
      
      inline void
      set_max_size (size_t max_size)
      {
        boost::mpl::for_each< boost::mpl::range_c<int, 0, boost::mpl::size<policy_traits>::type::value> >
          (max_size_setter (*this, max_size));
      }

      inline size_t
      get_max_size () const
      {
        // as max size should be the same everywhere, get the value from the first available policy
        return policy_container::template get<0> ().get_max_size ();
      }
      
    };
  };


  struct name_getter
  {
    name_getter (std::string &name) : m_name (name) { }
    
    template< typename U > void operator() (U index)
    {
      if (!m_name.empty ())
        m_name += "::";
      m_name += boost::mpl::at_c< policy_traits, U::value >::type::GetName ();
    }

    std::string &m_name;
  };

  /// @brief Name that can be used to identify the policy (e.g., for logging)
  static std::string GetName ()
  {
    // combine names of all internal policies
    std::string name;
    boost::mpl::for_each< boost::mpl::range_c<int, 0, boost::mpl::size<policy_traits>::type::value> > (name_getter (name));
    
    return name;
  }
};

} // trie
} // ndn

#endif // MULTI_POLICY_H_