source: branches/HeuristicLab.EvolutionaryTracking/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.4/Manipulators/TracingSymbolicExpressionTreeManipulator.cs @ 8213

#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2012 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;
using System.Linq;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.EvolutionaryTracking;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

using CloneMapType = HeuristicLab.Core.ItemDictionary<HeuristicLab.Core.IItem, HeuristicLab.Core.IItem>;
using TraceMapType = HeuristicLab.Core.ItemDictionary<HeuristicLab.Core.IItem, HeuristicLab.Core.IItemList<HeuristicLab.Core.IItem>>;

namespace HeuristicLab.Encodings.SymbolicExpressionTreeEncoding {
  /// <summary>
  /// A base class for operators that manipulate real-valued vectors.
  /// </summary>
  [Item("TracingSymbolicExpressionTreeManipulator", "A base class for operators that manipulate symbolic expression trees.")]
  [StorableClass]
  public abstract class TracingSymbolicExpressionTreeManipulator : SymbolicExpressionTreeOperator, ISymbolicExpressionTreeManipulator {
    private const string SymbolicExpressionTreeParameterName = "SymbolicExpressionTree";
    private const string GlobalTraceMapParameterName = "GlobalTraceMap";
    private const string GlobalCloneMapParameterName = "GlobalCloneMap";
    private const string GlobalFragmentMapParameterName = "GlobalFragmentMap";

    #region Parameter Properties
    public ILookupParameter<ISymbolicExpressionTree> SymbolicExpressionTreeParameter {
      get { return (ILookupParameter<ISymbolicExpressionTree>)Parameters[SymbolicExpressionTreeParameterName]; }
    }
    public LookupParameter<CloneMapType> GlobalCloneMapParameter {
      get { return (LookupParameter<CloneMapType>)Parameters[GlobalCloneMapParameterName]; }
    }
    public LookupParameter<TraceMapType> GlobalTraceMapParameter {
      get { return (LookupParameter<TraceMapType>)Parameters[GlobalTraceMapParameterName]; }
    }
    public LookupParameter<CloneMapType> GlobalFragmentMapParameter {
      get { return (LookupParameter<CloneMapType>)Parameters[GlobalFragmentMapParameterName]; }
    }
    #endregion

    #region Properties
    public ISymbolicExpressionTree SymbolicExpressionTree {
      get { return SymbolicExpressionTreeParameter.ActualValue; }
    }
    public CloneMapType GlobalCloneMap {
      get { return GlobalCloneMapParameter.ActualValue; }
    }
    public TraceMapType GlobalTraceMap {
      get { return GlobalTraceMapParameter.ActualValue; }
    }
    public CloneMapType GlobalFragmentMap {
      get { return GlobalFragmentMapParameter.ActualValue; }
    }
    #endregion

    [StorableConstructor]
    protected TracingSymbolicExpressionTreeManipulator(bool deserializing) : base(deserializing) { }
    protected TracingSymbolicExpressionTreeManipulator(TracingSymbolicExpressionTreeManipulator original, Cloner cloner) : base(original, cloner) { }
    public TracingSymbolicExpressionTreeManipulator()
      : base() {
      Parameters.Add(new LookupParameter<ISymbolicExpressionTree>(SymbolicExpressionTreeParameterName, "The symbolic expression tree on which the operator should be applied."));
      Parameters.Add(new LookupParameter<CloneMapType>(GlobalCloneMapParameterName, "A global map keeping track of trees and their clones (made during selection)."));
      Parameters.Add(new LookupParameter<TraceMapType>(GlobalTraceMapParameterName, "A global cache containing tracing info."));
      Parameters.Add(new LookupParameter<CloneMapType>(GlobalFragmentMapParameterName, "A global map keeping track of tree fragments received via crossover."));
    }

    public sealed override IOperation Apply() {
      ISymbolicExpressionTree tree = SymbolicExpressionTreeParameter.ActualValue;

      var gScope = ExecutionContext.Scope;
      while (gScope.Parent != null)
        gScope = gScope.Parent;

      if (GlobalTraceMap == null)
        gScope.Variables.Add(new Variable(GlobalTraceMapParameterName, new TraceMapType()));
      if (GlobalFragmentMap == null)
        gScope.Variables.Add(new Variable(GlobalFragmentMapParameterName, new CloneMapType()));

      int i = 0;
      if (GlobalTraceMap.ContainsKey(tree)) {
        // tree was affected by crossover before mutation
        // if the tree to be manipulated is already a product of crossover (in the current reproduction phase), 
        // then there exists no relationship with the original "parent". 
        // In order to preserve information, a tree clone is created before mutation and added to the trace map.
        var clone = (IItem)tree.Clone();
        GlobalTraceMap[clone] = GlobalTraceMap[tree]; // clone gets parents of tree
        GlobalTraceMap[tree] = new ItemList<IItem> { clone }; // tree gets clone as parent
        var nodes = tree.IterateNodesBreadth().ToList();
        for (i = 0; i != nodes.Count; ++i) {
          if ((GlobalFragmentMap[tree] as GenericWrapper<SymbolicExpressionTreeNode>).Content == nodes[i]) break;
        }
        var fragment = (SymbolicExpressionTreeNode)(((SymbolicExpressionTree)clone).IterateNodesBreadth().ElementAt(i));
        GlobalFragmentMap[clone] = new GenericWrapper<SymbolicExpressionTreeNode>(fragment);
      } else {
        var original = GlobalCloneMap[tree];
        GlobalTraceMap[tree] = new ItemList<IItem> { original };
      }
      var nodes0 = tree.IterateNodesBreadth().ToList();
      Manipulate(RandomParameter.ActualValue, tree);
      var nodes1 = tree.IterateNodesBreadth().ToList();
      int min = Math.Min(nodes0.Count, nodes1.Count);
      for (i = 0; i != min; ++i)
        if (nodes0[i] != nodes1[i]) break;
      GlobalFragmentMap[tree] = new GenericWrapper<SymbolicExpressionTreeNode>(i == min ? null : (SymbolicExpressionTreeNode)nodes1[i]);
      return base.Apply();
    }

    protected abstract void Manipulate(IRandom random, ISymbolicExpressionTree symbolicExpressionTree);
  }
}