// Copyright 2008, 2009 Brady J. Garvin

// This file is part of Covering Arrays by Simulated Annealing (CASA).

// CASA 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.

// CASA 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 CASA.  If not, see <http://www.gnu.org/licenses/>.


#ifndef FILTER_H
#define FILTER_H

#include <set>

#include "search/Heuristic.H"
#include "search/Goal.H"

// Controls which children (immediately reachable neighbors) are explored by a
// search. The filtering happens after children are enumerated; limitations that
// apply to the enumeration process itself (such as only computing a fixed
// number of random children) are better managed by the parameters in a
// SearchConfiguration, which are passed to the getChildren() method of the
// StateSpace.

template<class STATE, class COST>class Filter {
public:
  typedef Heuristic<STATE,COST>		HeuristicT;
  typedef Goal<STATE>			GoalT;

  virtual ~Filter() {}

  // Mutates the children set; the heuristic and goal may guide the mutation.
  virtual void operator()
    (std::set<STATE>&children, const HeuristicT&heuristic, const GoalT&goal)
    const {}

  // Just as the other operator(), but, at the filter's option, the parent may
  // be considered to be its own child.  This is useful, for example, when the
  // SearchConfiguration is sampling a random subset of the children and the
  // filter would prefer a different pool to choose from.
  virtual void operator()
    (std::set<STATE>&children,
     const STATE&parent,
     const HeuristicT&heuristic,
     const GoalT&goal) const {
    children.insert(parent);
    operator()(children, heuristic, goal);
  }
};

#endif