source: branches/HeuristicLab.Problems.GPDL/HeuristicLab.Problems.GPDL/3.4/ProblemGenerator.cs @ 9872

#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2013 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.CodeDom.Compiler;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using HeuristicLab.Optimization;
using Microsoft.CSharp;

public class ProblemGenerator {
  #region templates

  private string usings = @"
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Data;
using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using HeuristicLab.Random;
using HeuristicLab.PluginInfrastructure;
using HeuristicLab.Optimization;
using HeuristicLab.Optimization.Operators;
using HeuristicLab.Operators;
using HeuristicLab.Parameters;
using System.Collections.Generic;
using System.Linq;
using System;
using System.Threading;
using HeuristicLab.Algorithms.OffspringSelectionGeneticAlgorithm;
using HeuristicLab.SequentialEngine;
using HeuristicLab.Selection;
";

  private string problemClassTemplate = @"
namespace ?PROBLEMNAME? {
  [StorableClass]
  [Item(""?IDENT?Problem"", """")]
  public sealed class ?IDENT?Problem : SingleObjectiveHeuristicOptimizationProblem<?IDENT?Evaluator, ISymbolicExpressionTreeCreator> {
    public new ?IDENT?Evaluator Evaluator { 
      get { return (?IDENT?Evaluator)base.Evaluator; }
      set { base.Evaluator = value; }
    }
    public IValueParameter<ISymbolicExpressionGrammar> GrammarParameter { 
      get { return (IValueParameter<ISymbolicExpressionGrammar>)Parameters[""SymbolicExpressionTreeGrammar""]; }
    }

    [Storable]
    public ISymbolicExpressionGrammar Grammar { get { return GrammarParameter.Value; } }

    [StorableConstructor]
    private ?IDENT?Problem(bool deserializing) : base(deserializing) { 
       Initialize();
    }
    private ?IDENT?Problem(?IDENT?Problem original, Cloner cloner) : base(original, cloner) {
      Initialize();
    }
    public ?IDENT?Problem() { 
      Parameters.Add(new ValueParameter<ISymbolicExpressionGrammar>(""SymbolicExpressionTreeGrammar"", new ?IDENT?Grammar(this)));
      Parameters.Add(new FixedValueParameter<IntValue>(""MaximumSymbolicExpressionTreeDepth"", new IntValue(15)));
      Parameters.Add(new FixedValueParameter<IntValue>(""MaximumSymbolicExpressionTreeLength"", new IntValue(100)));
      Parameters.Add(new FixedValueParameter<IntValue>(""MaximumFunctionDefinitions"", new IntValue(0)));
      Parameters.Add(new FixedValueParameter<IntValue>(""MaximumFunctionArguments"", new IntValue(0)));
      Parameters[""MaximumFunctionDefinitions""].Hidden = true;
      Parameters[""MaximumFunctionArguments""].Hidden = true;
      Initialize();

      Evaluator = new ?IDENT?Evaluator(this);
      SolutionCreator = new ProbabilisticTreeCreator();

 
      Maximization.Value = Evaluator.Maximization;
      MaximizationParameter.Hidden = true;
    
      InitializeOperators();
    }    

    private void Initialize() {
      ?INITCODE?
    }

    private void InitializeOperators() {
      Operators.AddRange(ApplicationManager.Manager.GetInstances<ISymbolicExpressionTreeOperator>());
      Operators.Add(new SymbolicExpressionSymbolFrequencyAnalyzer());
      Operators.Add(new MinAverageMaxSymbolicExpressionTreeLengthAnalyzer());
      Operators.Add(new SymbolicExpressionTreeLengthAnalyzer());
      Operators.Add(new BestSymbolicExpressionTreeAnalyzer());
      ParameterizeOperators();
    }
    private void ParameterizeOperators() {
      var operators = Parameters.OfType<IValueParameter>().Select(p => p.Value).OfType<IOperator>().Union(Operators).ToList();

      foreach (var op in operators.OfType<ISymbolicExpressionTreeGrammarBasedOperator>()) {
        op.SymbolicExpressionTreeGrammarParameter.ActualName = GrammarParameter.Name;
      }
      foreach (var op in operators.OfType<ISymbolicExpressionTreeSizeConstraintOperator>()) {
        op.MaximumSymbolicExpressionTreeDepthParameter.ActualName = ""MaximumSymbolicExpressionTreeDepth"";
        op.MaximumSymbolicExpressionTreeLengthParameter.ActualName = ""MaximumSymbolicExpressionTreeLength"";
      }
      foreach (var op in operators.OfType<ISymbolicExpressionTreeArchitectureAlteringOperator>()) {
        op.MaximumFunctionArgumentsParameter.ActualName = ""MaximumFunctionArguments"";
        op.MaximumFunctionDefinitionsParameter.ActualName = ""MaximumFunctionDefinitions"";
      }
      foreach (var op in operators.OfType<ISymbolicExpressionTreeCrossover>()) {
        op.ParentsParameter.ActualName = SolutionCreator.SymbolicExpressionTreeParameter.ActualName;
        op.ChildParameter.ActualName = SolutionCreator.SymbolicExpressionTreeParameter.ActualName;
      }
      foreach (var op in operators.OfType<ISymbolicExpressionTreeManipulator>()) {
        op.SymbolicExpressionTreeParameter.ActualName = SolutionCreator.SymbolicExpressionTreeParameter.ActualName;
      }
      foreach (var op in operators.OfType<ISymbolicExpressionTreeAnalyzer>()) {
        op.SymbolicExpressionTreeParameter.ActualName = SolutionCreator.SymbolicExpressionTreeParameter.ActualName;
      }
      foreach(var op in operators.OfType<BestSymbolicExpressionTreeAnalyzer>()) {
        op.QualityParameter.ActualName = Evaluator.QualityParameter.Name;
      }
    }


    public override IDeepCloneable Clone(Cloner cloner) {
      return new ?IDENT?Problem(this, cloner);
    }

    public double Calculate(ISymbolicExpressionTree solution) {
      InitSymbolStream(solution);
      try {
      ?FITNESSFUNCTION?
      } catch(Exception e) {
        var formatter = new SymbolicExpressionTreeStringFormatter();
        Console.WriteLine(formatter.Format(solution));
        throw;
      }
    }

    ?ADDITIONALCODE?

    private ISymbolicExpressionTreeNode rootNode;
    private void InitSymbolStream(ISymbolicExpressionTree solution) {    
      this.rootNode =  solution.Root.GetSubtree(0).GetSubtree(0);
    }

    ?INTERPRETERSOURCE?

    ?CONSTRAINTSSOURCE?
  }
}";

  private string symbolClassTemplate = @"
namespace ?PROBLEMNAME? {
  [StorableClass]
  [Item(""?IDENT?"", """")]
  public sealed class ?IDENT? : Symbol {
    public override int MinimumArity {
      get { return 0; }
    }
    public override int MaximumArity {
      get { return byte.MaxValue; }
    }

    internal ?PROBLEMNAME?Problem problem;

    [StorableConstructor]
    private ?IDENT?(bool deserializing) : base(deserializing) { }
    private ?IDENT?(?IDENT? original, Cloner cloner) : base(original, cloner) { 
      this.problem = original.problem;
    }
    public override IDeepCloneable Clone(Cloner cloner) {
      return new ?IDENT?(this, cloner);
    }
    public ?IDENT?(?PROBLEMNAME?Problem problem) : base(""?IDENT?"", string.Empty) { 
      this.problem = problem;
    }
  }
}";

  private string terminalSymbolClassTemplate = @"
namespace ?PROBLEMNAME? {
  [StorableClass]
  [Item(""?IDENT?"", """")]
  public sealed class ?IDENT? : Symbol {
    public override int MinimumArity {
      get { return 0; }
    }
    public override int MaximumArity {
      get { return 0; }
    }

    internal ?PROBLEMNAME?Problem problem;

    [StorableConstructor]
    private ?IDENT?(bool deserializing) : base(deserializing) { }
    private ?IDENT?(?IDENT? original, Cloner cloner) : base(original, cloner) { 
      this.problem = original.problem;
    }
    public override IDeepCloneable Clone(Cloner cloner) {
      return new ?IDENT?(this, cloner);
    }
    public ?IDENT?(?PROBLEMNAME?Problem problem) : base(""?IDENT?"", string.Empty) { 
      this.problem = problem;
    }
    public override ISymbolicExpressionTreeNode CreateTreeNode() {
      return new ?IDENT?TreeNode(this);
    }
  }
}";

  private string treeNodeClassTemplate = @"
namespace ?PROBLEMNAME? {
  [StorableClass]
  public sealed class ?IDENT?TreeNode : SymbolicExpressionTreeTerminalNode {
    public new ?IDENT? Symbol {
      get { return (?IDENT?)base.Symbol; }
    }

    ?FIELDS?

    [StorableConstructor]
    private ?IDENT?TreeNode(bool deserializing) : base(deserializing) { }
    private ?IDENT?TreeNode(?IDENT?TreeNode original, Cloner cloner)
      : base(original, cloner) {
      ?CLONECODE? 
    }
    public ?IDENT?TreeNode(?IDENT? symbol) : base(symbol) { }

    public override bool HasLocalParameters {
      get { return true; }
    }

    public override void ResetLocalParameters(IRandom random) {
      base.ResetLocalParameters(random);
      ?RESETFIELDSCODE?
    }

    public override void ShakeLocalParameters(IRandom random, double shakingFactor) {
      base.ShakeLocalParameters(random, shakingFactor);
      ?SHAKEFIELDSCODE?
    }

    public override IDeepCloneable Clone(Cloner cloner) {
      return new ?IDENT?TreeNode(this, cloner);
    }    
  }
}";

  private string grammarClassTemplate = @"
namespace ?PROBLEMNAME? {
  [NonDiscoverableType]
  [StorableClass]
  [Item(""?IDENT?Grammar"", """")]
  public class ?IDENT?Grammar : SymbolicExpressionGrammar {
    [StorableConstructor]
    protected ?IDENT?Grammar(bool deserializing) : base(deserializing) { }
    protected ?IDENT?Grammar(?IDENT?Grammar original, Cloner cloner) : base(original, cloner) { }
    public ?IDENT?Grammar(?IDENT?Problem problem)
      : base(ItemAttribute.GetName(typeof(?IDENT?Grammar)), ItemAttribute.GetDescription(typeof(?IDENT?Grammar))) {
      Initialize(problem);
    }
    public override IDeepCloneable Clone(Cloner cloner) {
      return new ?IDENT?Grammar(this, cloner);
    }

    private void Initialize(?IDENT?Problem problem) {
      ?CREATESYMBOLS?
      var rootSymbol = ?ROOTSYMBOL?;

      ?SETSUBTREECOUNTS?

      // set start symbol
      AddAllowedChildSymbol(StartSymbol, rootSymbol);

      ?SETALLOWEDSUBTREECOUNTS?
    }
  }
}
";
  private string evaluatorClassTemplate = @"
namespace ?PROBLEMNAME? {
  [StorableClass]
  [Item(""?IDENT?Evaluator"", """")]  
  public class ?IDENT?Evaluator : SingleSuccessorOperator, ISingleObjectiveEvaluator {
    private const string SymbolicExpressionTreeParameterName = ""SymbolicExpressionTree"";
    private const string QualityParameterName = ""Quality"";

    public override bool CanChangeName { get { return false; } }

    #region parameter properties
    public ILookupParameter<ISymbolicExpressionTree> SymbolicExpressionTreeParameter {
      get { return (ILookupParameter<ISymbolicExpressionTree>)Parameters[SymbolicExpressionTreeParameterName]; }
    }
    public ILookupParameter<DoubleValue> QualityParameter {
      get { return (ILookupParameter<DoubleValue>)Parameters[QualityParameterName]; }
    }
    #endregion
    public bool Maximization { get { return ?MAXIMIZATION?; }  }

    public ?IDENT?Problem problem;

    [StorableConstructor]
    protected ?IDENT?Evaluator(bool deserializing) : base(deserializing) { }
    protected ?IDENT?Evaluator(?IDENT?Evaluator original, Cloner cloner)
      : base(original, cloner) {
      this.problem = original.problem;
    }
    public ?IDENT?Evaluator(?IDENT?Problem problem)
      : base() {
      Parameters.Add(new LookupParameter<ISymbolicExpressionTree>(SymbolicExpressionTreeParameterName));
      Parameters.Add(new LookupParameter<DoubleValue>(QualityParameterName));
      this.problem = problem;
    }
    [StorableHook(HookType.AfterDeserialization)]
    private void AfterDeserialization() {
    }
    public override IDeepCloneable Clone(Cloner cloner) {
      return new ?IDENT?Evaluator(this, cloner);
    }

    public override IOperation Apply() {
      var solution = SymbolicExpressionTreeParameter.ActualValue;
      double quality = problem.Calculate(solution);
      QualityParameter.ActualValue = new DoubleValue(quality);
      return base.Apply();
    }
  }
}
";
  #endregion

  private StringBuilder problemSourceCode;

  public ProblemGenerator() {
    problemSourceCode = new StringBuilder();
  }

  public ISingleObjectiveHeuristicOptimizationProblem GenerateFromAst(GPDefNode definition) {
    problemSourceCode.AppendLine(usings);

    GenerateSymbols(definition.NonTerminals);
    GenerateSymbols(definition.Terminals);

    GenerateTreeNodes(definition.Terminals);
    GenerateGrammar(definition);

    GenerateEvaluator(definition);
    GenerateProblem(definition);

    problemSourceCode.Replace("?PROBLEMNAME?", definition.Name);

    // write to a file for debugging
    using (var stream = new StreamWriter(definition.Name + ".cs")) {
      stream.WriteLine(problemSourceCode.ToString());
    }

    // compile generated source
    using (var csc = new CSharpCodeProvider(new Dictionary<string, string>() { { "CompilerVersion", "v4.0" } })) {
      var parameters = new CompilerParameters(new[] { "mscorlib.dll", "System.Core.dll", "System.dll", "System.Drawing.dll" }, Path.ChangeExtension(Path.GetRandomFileName(), ".dll"), true);
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Common-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Common.Resources-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Core-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Data-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Encodings.SymbolicExpressionTreeEncoding-3.4.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Random-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Persistence-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.PluginInfrastructure-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Optimization-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Optimization.Operators-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Operators-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Collections-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Parameters-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Problems.DataAnalysis-3.4.dll");
      parameters.ReferencedAssemblies.Add(@"ALGLIB-3.7.0.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Problems.Instances-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Problems.Instances.DataAnalysis-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.SequentialEngine-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.ParallelEngine-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Algorithms.GeneticAlgorithm-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Algorithms.OffspringSelectionGeneticAlgorithm-3.3.dll");
      parameters.ReferencedAssemblies.Add(@"HeuristicLab.Selection-3.3.dll");

      CompilerResults results = csc.CompileAssemblyFromSource(parameters, problemSourceCode.ToString());
      results.Errors.Cast<CompilerError>()
        .ToList()
        .ForEach(error => Console.WriteLine(error.Line + " " + error.ErrorText));

      // load the assembly, and create an instance from the generate problem class
      var asm = results.CompiledAssembly;
      AppDomain.CurrentDomain.Load(asm.GetName());
      var problem = Activator.CreateInstance(asm.FullName, definition.Name + "." + definition.Name + "Problem").Unwrap();
      return (ISingleObjectiveHeuristicOptimizationProblem)problem;
    }
  }



  private void GenerateEvaluator(GPDefNode definition) {
    var evaluatorClassCode =
      evaluatorClassTemplate
        .Replace("?IDENT?", definition.Name)
        .Replace("?MAXIMIZATION?", definition.FitnessFunctionNode.Maximization ? "true" : "false");
    problemSourceCode.AppendLine(evaluatorClassCode).AppendLine();
  }

  private void GenerateProblem(GPDefNode definition) {
    var problemClassCode =
      problemClassTemplate
        .Replace("?IDENT?", definition.Name)
        .Replace("?FITNESSFUNCTION?", definition.FitnessFunctionNode.SrcCode)
        .Replace("?INTERPRETERSOURCE?", GenerateInterpreterSource(definition))
        .Replace("?INITCODE?", definition.InitCodeNode.SrcCode)
        .Replace("?ADDITIONALCODE?", definition.ClassCodeNode.SrcCode)
        .Replace("?CONSTRAINTSSOURCE?", GenerateConstraintMethods(definition.Terminals));

    problemSourceCode.AppendLine(problemClassCode).AppendLine();
  }

  private string GenerateConstraintMethods(List<SymbolNode> symbols) {
    var sb = new StringBuilder();
    var terminals = symbols.OfType<TerminalNode>();
    foreach (var t in terminals) {
      sb.AppendLine(GenerateConstraintMethods(t));
    }
    return sb.ToString();
  }

  private string GenerateConstraintMethods(TerminalNode t) {
    var sb = new StringBuilder();
    foreach (var c in t.Constraints) {
      var fieldType = t.FieldDefinitions.First(d => d.Identifier == c.Ident).Type;
      if (c.Type == ConstraintNodeType.Range) {
        sb.AppendFormat("public {0} GetMax{1}_{2}() {{ return {3}; }}", fieldType, t.Ident, c.Ident, c.RangeMaxExpression).AppendLine();
        sb.AppendFormat("public {0} GetMin{1}_{2}() {{ return {3}; }}", fieldType, t.Ident, c.Ident, c.RangeMinExpression).AppendLine();
      } else if (c.Type == ConstraintNodeType.Set) {
        sb.AppendFormat("public IEnumerable<{0}> GetAllowed{1}_{2}() {{ return {3}; }}", fieldType, t.Ident, c.Ident, c.SetExpression).AppendLine();
      }
    }
    return sb.ToString();
  }

  private string GenerateInterpreterSource(GPDefNode definition) {
    var sb = new StringBuilder();
    var g = new Grammar(definition.NonTerminals, definition.Terminals, definition.Rules);
    string formalParameter = definition.NonTerminals.Single(nt => nt.Ident == g.RootSymbol).FormalParameters;
    var actualParameterEnumerable =
      Util.ExtractFormalParameters(formalParameter).Select(e => e.RefOrOut + " " + e.Identifier);
    string actualParameter = string.Empty;
    if (actualParameterEnumerable.Any()) {
      foreach (var e in actualParameterEnumerable) {
        actualParameter += ", " + e;
      }
    }
    sb.AppendFormat("void {0}({1}) {{ {0}(rootNode {2}); }}", g.RootSymbol, formalParameter, actualParameter).AppendLine();

    foreach (var s in definition.NonTerminals) {
      sb.AppendLine(GenerateInterpreterMethod(g, s));
    }
    foreach (var s in definition.Terminals) {
      sb.AppendLine(GenerateTerminalInterpreterMethod((TerminalNode)s));
    }
    return sb.ToString();
  }

  private string GenerateTerminalInterpreterMethod(TerminalNode s) {
    var sb = new StringBuilder();
    if (!s.FormalParameters.Any())
      sb.AppendFormat("private void {0}(ISymbolicExpressionTreeNode tree) {{", s.Ident);
    else
      sb.AppendFormat("private void {0}(ISymbolicExpressionTreeNode tree, {1}) {{", s.Ident, s.FormalParameters);
    sb.AppendFormat("if (tree.Symbol == null || tree.Symbol.Name != \"{0}\") throw new InvalidOperationException();", s.Ident).AppendLine();
    sb.AppendFormat("var cur = ({0}TreeNode)tree;", s.Ident).AppendLine();
    foreach (var element in s.FieldDefinitions) {
      sb.AppendFormat("{0} = cur.{0}", element.Identifier).AppendLine(";");
    }
    sb.AppendLine("}");
    return sb.ToString();
  }

  private string GenerateInterpreterMethod(Grammar g, SymbolNode s) {
    var sb = new StringBuilder();
    if (!s.FormalParameters.Any())
      sb.AppendFormat("private void {0}(ISymbolicExpressionTreeNode tree) {{", s.Ident);
    else
      sb.AppendFormat("private void {0}(ISymbolicExpressionTreeNode tree, {1}) {{", s.Ident, s.FormalParameters);
    sb.AppendLine(g.GetLocalDefinitions(s.Ident));
    sb.AppendFormat("ISymbolicExpressionTreeNode subtree = null;").AppendLine();
    sb.AppendFormat("if (tree.Symbol== null || tree.Symbol.Name != \"{0}\") throw new InvalidOperationException();", s.Ident).AppendLine();
    var alts = g.GetAlternatives(s.Ident);
    var lookahead = alts.Select(seq => seq.First());
    if (lookahead.Count() > 1) {
      sb.AppendLine("System.Diagnostics.Debug.Assert(tree.SubtreeCount == 1);");
      sb.AppendLine("subtree = tree.GetSubtree(0);");
      int i = 0;
      sb.AppendFormat("if(subtree.Symbol.Name == \"{0}\") {{ ", lookahead.First()).AppendLine();
      foreach (var e in g.GetSequenceWithSemanticActions(s.Ident, i++)) {
        sb.AppendLine(GenerateSourceForAction(e));
      }
      foreach (var l in lookahead.Skip(1)) {
        sb.AppendFormat("}} else if(subtree.Symbol.Name == \"{0}\") {{ ", l).AppendLine();
        foreach (var e in g.GetSequenceWithSemanticActions(s.Ident, i++)) {
          sb.AppendLine(GenerateSourceForAction(e));
        }
      }
      sb.AppendFormat("}} else throw new System.InvalidOperationException(\"In {0} found symbol \"+tree.Symbol.Name+\". Expected one of: {1}\");", s.Ident, lookahead.Aggregate("", (acc, l) => acc + l + " ")).AppendLine();
    } else {
      int eIdx = 0;
      foreach (var e in g.GetSequenceWithSemanticActions(s.Ident, 0)) {
        if (e is CallSymbolNode) {
          sb.AppendFormat("subtree = tree.GetSubtree({0});", eIdx++);
        }
        sb.AppendLine(GenerateSourceForAction(e));
      }
    }
    sb.AppendLine("}");
    return sb.ToString();
  }

  private string GenerateSourceForAction(RuleExprNode e) {
    var action = e as RuleActionNode;
    var call = e as CallSymbolNode;
    if (action != null) {
      return action.SrcCode + ";";
    } else if (call != null) {
      if (!call.ActualParameter.Any())
        return string.Format("{0}(subtree);", call.Ident);
      else
        return string.Format("{0}(subtree, {1});", call.Ident, call.ActualParameter);
    } else {
      throw new ArgumentException();
    }
  }

  private void GenerateGrammar(GPDefNode definition) {
    IEnumerable<SymbolNode> ntSymbols = definition.NonTerminals;
    IEnumerable<SymbolNode> tSymbols = definition.Terminals;
    List<RuleNode> ruleNodes = definition.Rules;
    var g = new Grammar(ntSymbols, tSymbols, ruleNodes);
    Console.WriteLine(g);

    var grammarClassCode =
      grammarClassTemplate
        .Replace("?IDENT?", definition.Name)
        .Replace("?CREATESYMBOLS?", GenerateGrammarSymbolDefinitionSource(g))
        .Replace("?ROOTSYMBOL?", "_" + g.RootSymbol)
        .Replace("?SETSUBTREECOUNTS?", GenerateGrammarSubtreeCountDefinitionSource(g))
        .Replace("?SETALLOWEDSUBTREECOUNTS?", GenerateGrammarAllowedSubtreeDefinitionSource(g));


    problemSourceCode.AppendLine(grammarClassCode).AppendLine();
  }

  private string GenerateGrammarSymbolDefinitionSource(Grammar g) {
    StringBuilder sb = new StringBuilder();
    foreach (var sy in g.Symbols) {
      sb.AppendFormat("var _{0} = new {0}(problem); AddSymbol(_{0});", sy).AppendLine();
    }
    return sb.ToString();
  }

  private string GenerateGrammarSubtreeCountDefinitionSource(Grammar g) {
    StringBuilder sb = new StringBuilder();
    foreach (var sy in g.Symbols) {
      var alt = g.GetAlternatives(sy);
      if (alt.Count() > 0) {
        var minSeqLength = alt.Min(seq => seq.Count);
        var maxSeqLength = alt.Max(seq => seq.Count);
        sb.AppendFormat("SetSubtreeCount(_{0}, {1}, {2});", sy, maxSeqLength, minSeqLength).AppendLine();
      } else {
        sb.AppendFormat("SetSubtreeCount(_{0}, {1}, {2});", sy, 0, 0).AppendLine();
      }
    }
    return sb.ToString();
  }

  private string GenerateGrammarAllowedSubtreeDefinitionSource(Grammar g) {
    StringBuilder sb = new StringBuilder();
    foreach (var sy in g.Symbols) {
      foreach (var seq in g.GetAlternatives(sy)) {
        for (int argIdx = 0; argIdx < seq.Count; argIdx++) {
          var childSy = seq[argIdx];
          sb.AppendFormat("AddAllowedChildSymbol(_{0}, _{1}, {2});", sy, childSy, argIdx).AppendLine();
        }
      }
    }
    return sb.ToString();
  }

  private void GenerateTreeNodes(IEnumerable<SymbolNode> symbols) {
    foreach (var s in symbols.OfType<TerminalNode>()) {
      var classCode = treeNodeClassTemplate
        .Replace("?IDENT?", s.Ident)
        .Replace("?RESETFIELDSCODE?", GenerateNodeInitSourceCode(s))
        .Replace("?SHAKEFIELDSCODE?", GenerateNodeUpdateSourceCode(s))
        ;

      StringBuilder fieldSource = new StringBuilder();
      StringBuilder cloningSource = new StringBuilder();
      foreach (var par in s.FieldDefinitions) {
        fieldSource.AppendLine("[Storable]");
        fieldSource.Append("internal ").Append(par.Type).Append(" ").Append(par.Identifier).AppendLine(";");

        cloningSource.Append("this.").Append(par.Identifier)
          .Append("=").Append("(").Append(par.Type).Append(")")
          .Append("original.").Append(par.Identifier).AppendLine(";");

      }

      classCode = classCode.Replace("?FIELDS?", fieldSource.ToString());
      classCode = classCode.Replace("?CLONECODE?", cloningSource.ToString());

      problemSourceCode
        .AppendLine(classCode)
        .AppendLine();
    }
  }

  private string GenerateNodeInitSourceCode(TerminalNode s) {
    var sb = new StringBuilder();
    sb.AppendLine("var problem = Symbol.problem;");
    foreach (var f in s.FieldDefinitions) {
      var cType = GetConstraintTypeFor(f.Identifier, s.Constraints);
      if (cType == ConstraintNodeType.Range) {
        sb.AppendFormat("var max_{1} = problem.GetMax{0}_{1}();", s.Ident, f.Identifier).AppendLine();
        sb.AppendFormat("var min_{1} = problem.GetMin{0}_{1}();", s.Ident, f.Identifier).AppendLine();
        sb.AppendFormat("{0} = min_{0} + random.NextDouble() * (max_{0} - min_{0});", f.Identifier).AppendLine();
      } else if (cType == ConstraintNodeType.Set) {
        sb.AppendFormat("var set_{1} = problem.GetAllowed{0}_{1}().ToList();", s.Ident, f.Identifier).AppendLine();
        sb.AppendFormat("{0} = set_{0}[random.Next(set_{0}.Count())];", f.Identifier).AppendLine();
      }
    }
    return sb.ToString();
  }

  private string GenerateNodeUpdateSourceCode(TerminalNode s) {
    var sb = new StringBuilder();
    sb.AppendLine("var problem = Symbol.problem;");
    foreach (var f in s.FieldDefinitions) {
      var cType = GetConstraintTypeFor(f.Identifier, s.Constraints);
      if (cType == ConstraintNodeType.Range) {
        sb.AppendFormat("var max_{1} = problem.GetMax{0}_{1}();", s.Ident, f.Identifier).AppendLine();
        sb.AppendFormat("var min_{1} = problem.GetMin{0}_{1}();", s.Ident, f.Identifier).AppendLine();
        sb.AppendFormat("{0} = min_{0} + random.NextDouble() * (max_{0} - min_{0});", f.Identifier).AppendLine();
      } else if (cType == ConstraintNodeType.Set) {
        sb.AppendFormat("var set_{1} = problem.GetAllowed{0}_{1}().ToList();", s.Ident, f.Identifier).AppendLine();
        sb.AppendFormat("{0} = set_{0}[random.Next(set_{0}.Count())];", f.Identifier).AppendLine();
      }
    }
    return sb.ToString();
  }

  private ConstraintNodeType GetConstraintTypeFor(string id, IEnumerable<ConstraintNode> contraints) {
    return contraints.Single(c => c.Ident == id).Type;
  }

  private void GenerateSymbols(List<SymbolNode> symbols) {
    foreach (var s in symbols.OfType<NonTerminalNode>()) {
      problemSourceCode
        .AppendLine(symbolClassTemplate.Replace("?IDENT?", s.Ident))
        .AppendLine();
    }
    foreach (var s in symbols.OfType<TerminalNode>()) {
      problemSourceCode
        .AppendLine(terminalSymbolClassTemplate.Replace("?IDENT?", s.Ident))
        .AppendLine();
    }
  }
}