/*
 * ZeroInstanceInitializer.hpp
 *
 *  Created on: Jun 12, 2016
 *      Author: heber
 */


#ifndef ZEROINSTANCEINITIALIZER_HPP_
#define ZEROINSTANCEINITIALIZER_HPP_

// include config.h
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <map>
#include <vector>

#include "Fragmentation/Summation/ZeroInstance.hpp"

/** This struct initializes zero instances for Summation and OrthogonalSummation
 * to use as default set of base values.
 *
 * Template MapType gives us a boost::fusion::map of types that we iterate over to
 * fill.
 */
template <typename MapType>
struct ZeroInstanceInitializer
{
  /** Constructor of class ZeroInstanceInitializer.
   *
   */
  ZeroInstanceInitializer(
       MapType &_ZeroInstances) :
        ZeroInstances(_ZeroInstances)
  {}

  /** Operator that fills the specific type \a MapValue to \a MapKey in its given
   * maps and vectors with false and the default ZeroInstance<T>.
   *
   */
  template <typename MapKey>
  void operator()(MapKey &) {
    // We retrieve the type of the member variable from the boost::fusion::map.
    typedef typename boost::fusion::result_of::value_at_key<MapType, MapKey>::type MapValue;

    // fill vector with default value
    const MapValue value = ZeroInstance<MapValue>();
    boost::fusion::at_key<MapKey>(ZeroInstances) = value;
  }

  //!> vector of all zero instance, to be filled by operator()
  MapType &ZeroInstances;
};


#endif /* ZEROINSTANCEINITIALIZER_HPP_ */