source: branches/HeuristicLab.EvolutionTracking/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Tracking/SymbolicDataAnalysisExpressionBeforeManipulatorOperator.cs @ 11387

#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2014 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab 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.
 *
 * HeuristicLab 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 HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using System.Linq;
using HeuristicLab.Core;
using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
using HeuristicLab.EvolutionTracking;

namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
  public class SymbolicDataAnalysisExpressionBeforeManipulatorOperator : BeforeManipulatorOperator<ISymbolicExpressionTree> {
    public override IOperation Apply() {
      // the call below does the following things:
      // 1) creates a clone of the individual to be manipulated, and adds it in the genealogy graph with rank = currentRank - 0.5.
      //    the cloning will also clone the vertex data object, therefore reference comparison of node lists will not work
      // 2) replaces the parent of the current individual with the clone, and alters graph connections accordingly
      //    therefore, vChild will be the vertex of the child, and vClone the vertex of the cloned parent
      var result = base.Apply();
      var vChild = GenealogyGraph.GetByContent(ChildParameter.ActualValue);
      var vClone = vChild.Parents.Last();

      var fragment = (IFragment<ISymbolicExpressionTreeNode>)vClone.InArcs.Last().Data;
      if (fragment != null) {
        // this step must be performed because the fragment root actually references the original child (not the clone). 
        // when mutation occurs the fragment root would point to the mutated subtree in the child instead of the original one in the clone
        fragment.Root = vClone.Data.IterateNodesPrefix().ElementAt(fragment.Index1);
      }

      return result;
    }
  }
}