/*

     dsh-evolve  Framework for evolutionary algorithms.

     Copyright (c) 2005-2012 held jointly by the individual authors.

     This library is free software; you can redistribute it and/or modify it

     under the terms of the GNU Lesser General Public License as published

     by the Free Software Foundation; either version 3 of the License, or (at

     your option) any later version.

     This library is distributed in the hope that it will be useful, but WITHOUT

     ANY WARRANTY; with out even the implied warranty of MERCHANTABILITY or

     FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public

     License for more details.

     You should have received a copy of the GNU Lesser General Public License

     along with this library;  if not, write to the Free Software Foundation,

     Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA.

     > http://www.fsf.org/licensing/licenses/lgpl.html

     > http://www.opensource.org/licenses/lgpl-license.php

 */

 package org.dishevelled.evolve.mutate;

 import java.util.ArrayList;

 import java.util.Collection;

 import org.dishevelled.weighted.WeightedMap;

 import org.dishevelled.weighted.HashWeightedMap;

 import org.dishevelled.evolve.Mutation;

 /**

  * Proportional mutation function.

  *

  * @param <I> individual type

  * @author  Michael Heuer

  * @version $Revision: 1059 $ $Date: 2012-01-03 14:03:02 -0600 (Tue, 03 Jan 2012) $

  */

 public final class ProportionalMutation<I>

     implements Mutation<I>

 {

     /** Weighted map of individual-wise mutation functions. */

     private WeightedMap<IndividualWiseMutation<I>> mutations;

     /** Default null individual-wise mutation function, in case the map is empty. */

     private final IndividualWiseMutation<I> nullMutation = new NullIndividualWiseMutation<I>();

     /**

      * Create a new proportional mutation function.

      */

     public ProportionalMutation()

     {

         mutations = new HashWeightedMap<IndividualWiseMutation<I>>();

     }

     /**

      * Add the specified individual-wise mutation function to this

      * proportional mutation function at the specified weight.

      *

      * @param mutation individual-wise mutation function, must not be null

      * @param weight weight

      */

     public void add(final IndividualWiseMutation<I> mutation, final double weight)

     {

         if (mutation == null)

         {

             throw new IllegalArgumentException("mutation must not be null");

         }

         mutations.put(mutation, Double.valueOf(weight));

     }

     /** {@inheritDoc} */

     public Collection<I> mutate(final Collection<I> recombined)

     {

         Collection<I> mutated = new ArrayList<I>(recombined.size());

         for (I i : recombined)

         {

             IndividualWiseMutation<I> mutation = mutations.sample();

             if (mutation == null)

             {

                 mutation = nullMutation;

             }

             mutated.add(mutation.mutate(i));

         }

         return mutated;

     }

 }