paradiseo/mo/src/explorer/moVNSexplorer.h

/*
  <moVNSexplorer.h>
  Copyright (C) DOLPHIN Project-Team, INRIA Lille - Nord Europe, 2006-2010

  Sebastien Verel, Arnaud Liefooghe, Jeremie Humeau

  This software is governed by the CeCILL license under French law and
  abiding by the rules of distribution of free software.  You can  ue,
  modify and/ or redistribute the software under the terms of the CeCILL
  license as circulated by CEA, CNRS and INRIA at the following URL
  "http://www.cecill.info".

  In this respect, the user's attention is drawn to the risks associated
  with loading,  using,  modifying and/or developing or reproducing the
  software by the user in light of its specific status of free software,
  that may mean  that it is complicated to manipulate,  and  that  also
  therefore means  that it is reserved for developers  and  experienced
  professionals having in-depth computer knowledge. Users are therefore
  encouraged to load and test the software's suitability as regards their
  requirements in conditions enabling the security of their systems and/or
  data to be ensured and,  more generally, to use and operate it in the
  same conditions as regards security.
  The fact that you are presently reading this means that you have had
  knowledge of the CeCILL license and that you accept its terms.

  ParadisEO WebSite : http://paradiseo.gforge.inria.fr
  Contact: paradiseo-help@lists.gforge.inria.fr
*/

#ifndef _moVNSexplorer_h
#define _moVNSexplorer_h

#include <explorer/moNeighborhoodExplorer.h>
#include <neighborhood/moVariableNeighborhoodSelection.h>
#include <eoOp.h>
#include <acceptCrit/moAcceptanceCriterion.h>

/**
 * Explorer for the "Variable Neighborhood Search" metaheuristic
 */
template< class Neighbor>
class moVNSexplorer : public moNeighborhoodExplorer< Neighbor >
{
public:

  typedef typename Neighbor::EOT EOT;

  /**
   * Default constructor
   */

  moVNSexplorer() {}

  /**
   * Constructor
   * @param _selection selection the "neighborhood" search heuristics during the search
   * @param _acceptCrit acceptance criteria which compare and accept or not the two solutions
   */
  moVNSexplorer(moVariableNeighborhoodSelection<EOT> & _selection,
		moAcceptanceCriterion<Neighbor>& _acceptCrit):
    moNeighborhoodExplorer<Neighbor>(), selection(_selection), acceptCrit(_acceptCrit), stop(false), first(true)
  {}

  /**
   * Empty destructor
   */
  ~moVNSexplorer() {
  }

  /**
   * Initialization on the initial search opeartors based on the "first" neighborhood
   * @param _solution the current solution
   */
  virtual void initParam(EOT& _solution) {
    // the best solution found 
    bestSoFar = _solution;
    // initialization of the LS
    selection.init(_solution);
    // for the first ls, the solution will be improved, so the next ls must be applied
    first = true;
  }

  /**
   * Change the search operators on the next neighborhood search.
   * @param _solution the current solution
   */
  virtual void updateParam(EOT & _solution) {
    if (!first && (*this).moveApplied()) {
      first = false;
      selection.init(_solution);
    } else 
      if (selection.cont(currentSol)) {
	selection.next(_solution);
      } else
	stop = true;
  }

  /**
   * terminate: return the best solution found
   */
  virtual void terminate(EOT & _solution) {
    _solution = bestSoFar;
  }

  /**
   * Explore the neighborhood of a solution by the "neighborhood" search heuristics
   * @param _solution the current solution
   */
  virtual void operator()(EOT & _solution) {
    eoMonOp<EOT> & shake = selection.getShake();
    eoMonOp<EOT> & ls    = selection.getLocalSearch();

    currentSol = _solution;
    shake(currentSol);
    ls(currentSol);

    // update the best solution found
    if (bestSoFar.fitness() < currentSol.fitness())
      bestSoFar = currentSol;
  }

  /**
   * continue if a move is accepted
   * @param _solution the solution
   * @return true if an ameliorated neighbor was be found
   */
  virtual bool isContinue(EOT & /*_solution*/) {
    return !stop;
  };

  /**
   * move the solution with to current accepted solution
   * @param _solution the solution to move
   */
  virtual void move(EOT & _solution) {
    _solution = currentSol;
  };

  /**
   * accept test if an amelirated neighbor was be found according to acceptance criteria
   * @param _solution the solution
   * @return true if the neighbor ameliorate the fitness
   */
  virtual bool accept(EOT & _solution) {
    return acceptCrit(_solution, currentSol);
  };

  /**
   * Return the class id.
   * @return the class name as a std::string
   */
  virtual std::string className() const {
    return "moVNSexplorer";
  }

private:  
  /** the set of LS and shake operators to applied */
  moVariableNeighborhoodSelection<EOT>& selection;
  /** Acceptance criterium between two LS */
  moAcceptanceCriterion<Neighbor>& acceptCrit;
  /** stopping criterium flag */
  bool stop;
  /** the current solution */
  EOT currentSol;
  /** Best solution found during the search */
  EOT bestSoFar;
  /** first LS flag */
  bool first;
};


#endif