source: branches/HeuristicLab.EvolutionaryTracking/HeuristicLab.Encodings.SymbolicExpressionTreeEncoding/3.4/CutPoint.cs @ 7785

#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


namespace HeuristicLab.Encodings.SymbolicExpressionTreeEncoding {
  public class CutPoint {
    public ISymbolicExpressionTreeNode Parent { get; set; }
    public ISymbolicExpressionTreeNode Child { get; set; }
    private int childIndex;
    public int ChildIndex {
      get { return childIndex; }
    }
    public CutPoint(ISymbolicExpressionTreeNode parent, ISymbolicExpressionTreeNode child) {
      this.Parent = parent;
      this.Child = child;
      this.childIndex = parent.IndexOfSubtree(child);
    }
    public CutPoint(ISymbolicExpressionTreeNode parent, int childIndex) {
      this.Parent = parent;
      this.childIndex = childIndex;
      this.Child = null;
    }

    public bool IsMatchingPointType(ISymbolicExpressionTreeNode newChild) {
      var parent = this.Parent;
      if (newChild == null) {
        // make sure that one subtree can be removed and that only the last subtree is removed 
        return parent.Grammar.GetMinimumSubtreeCount(parent.Symbol) < parent.SubtreeCount &&
          this.ChildIndex == parent.SubtreeCount - 1;
      } else {
        // check syntax constraints of direct parent - child relation
        if (!parent.Grammar.ContainsSymbol(newChild.Symbol) ||
            !parent.Grammar.IsAllowedChildSymbol(parent.Symbol, newChild.Symbol, this.ChildIndex))
          return false;

        bool result = true;
        // check point type for the whole branch
        newChild.ForEachNodePostfix((n) => {
          result =
            result &&
            parent.Grammar.ContainsSymbol(n.Symbol) &&
            n.SubtreeCount >= parent.Grammar.GetMinimumSubtreeCount(n.Symbol) &&
            n.SubtreeCount <= parent.Grammar.GetMaximumSubtreeCount(n.Symbol);
        });
        return result;
      }
    }

    public static CutPoint GetCutPoint(ISymbolicExpressionTree parent, ISymbolicExpressionTree child) {
      return GetCutPoint(parent.Root, child.Root);
    }

    public static CutPoint GetCutPoint(ISymbolicExpressionTree parent, ISymbolicExpressionTreeNode child) {
      return GetCutPoint(parent.Root, child);
    }

    public static CutPoint GetCutPoint(ISymbolicExpressionTreeNode parent, ISymbolicExpressionTree child) {
      return GetCutPoint(parent, child.Root);
    }

    // child is the result of a genetic operation on parent
    // this method returns the index on which the two individuals start to differ
    public static CutPoint GetCutPoint(ISymbolicExpressionTreeNode parent, ISymbolicExpressionTreeNode child) {
      var e1 = parent.IterateNodesPostfix().GetEnumerator();
      var e2 = child.IterateNodesPostfix().GetEnumerator();
      int pos = -1;
      var comparer = new SymbolicExpressionTreeNodeComparer((int)SymbolicExpressionTreeMatching.SimilarityLevel.Exact);
      while (e1.MoveNext() && e2.MoveNext())
        if (comparer.Equals(e1.Current, e2.Current))
          ++pos;
      return pos == -1 ? null : new CutPoint(parent, pos);
    }
  }
}