source: branches/HeuristicLab.EvolutionTracking/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Matching/SymbolicExpressionTreeEqualityComparer.cs @ 10650

using System;
using System.Collections.Generic;
using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;

namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
  public class SymbolicExpressionTreeEqualityComparer : IEqualityComparer<ISymbolicExpressionTree> {
    public SymbolicExpressionTreeNodeSimilarityComparer SimilarityComparer { get; set; }

    public bool Equals(ISymbolicExpressionTree a, ISymbolicExpressionTree b) {
      if (SimilarityComparer == null) throw new Exception("SimilarityComparer needs to be initialized first.");
      return a.Length == b.Length &&
             SymbolicExpressionTreeMatching.Match(a.Root, b.Root, SimilarityComparer) == Math.Min(a.Length, b.Length);
    }

    public int GetHashCode(ISymbolicExpressionTree tree) {
      return (tree.Length << 8) % 12345;
    }
  }
}