1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2010 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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4 | *
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5 | * This file is part of HeuristicLab.
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6 | *
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7 | * HeuristicLab is free software: you can redistribute it and/or modify
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8 | * it under the terms of the GNU General Public License as published by
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9 | * the Free Software Foundation, either version 3 of the License, or
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10 | * (at your option) any later version.
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11 | *
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12 | * HeuristicLab is distributed in the hope that it will be useful,
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 | * GNU General Public License for more details.
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16 | *
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17 | * You should have received a copy of the GNU General Public License
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18 | * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
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19 | */
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20 | #endregion
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21 |
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22 | using System;
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23 | using System.Collections.Generic;
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24 | using System.Linq;
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25 | using System.Text;
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26 | using System.IO;
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27 | using System.Diagnostics;
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28 | using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding.Symbols;
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29 | using HeuristicLab.Problems.DataAnalysis.Symbolic.Symbols;
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30 | using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
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31 |
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32 | namespace HeuristicLab.Problems.DataAnalysis.Tests {
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33 | internal class SymbolicExpressionImporter {
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34 | private const string VARSTART = "var";
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35 | private Dictionary<string, Symbol> knownSymbols = new Dictionary<string, Symbol>()
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36 | {
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37 | {"+", new Addition()},
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38 | {"/", new Division()},
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39 | {"*", new Multiplication()},
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40 | {"-", new Subtraction()},
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41 |
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42 | };
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43 | Constant constant = new Constant();
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44 | Variable variable = new Variable();
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45 | ProgramRootSymbol programRootSymbol = new ProgramRootSymbol();
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46 | StartSymbol startSymbol = new StartSymbol();
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47 |
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48 | public SymbolicExpressionImporter() {
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49 | }
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50 |
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51 | internal SymbolicExpressionTree Import(string str) {
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52 | str = str.Replace("(", " ( ").Replace(")", " ) ");
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53 | SymbolicExpressionTreeNode root = programRootSymbol.CreateTreeNode();
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54 | SymbolicExpressionTreeNode start = startSymbol.CreateTreeNode();
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55 | SymbolicExpressionTreeNode mainBranch = ParseSexp(new Queue<Token>(GetTokenStream(str)));
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56 | root.AddSubTree(start);
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57 | start.AddSubTree(mainBranch);
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58 | return new SymbolicExpressionTree(root);
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59 | }
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60 |
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61 | private IEnumerable<Token> GetTokenStream(string str) {
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62 | return
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63 | from strToken in str.Split(new string[] { " " }, StringSplitOptions.RemoveEmptyEntries).AsEnumerable()
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64 | let t = Token.Parse(strToken)
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65 | where t != null
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66 | select t;
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67 | }
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68 |
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69 | private SymbolicExpressionTreeNode ParseSexp(Queue<Token> tokens) {
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70 | if (tokens.Peek().Symbol == TokenSymbol.LPAR) {
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71 | SymbolicExpressionTreeNode tree;
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72 | Expect(Token.LPAR, tokens);
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73 | if (tokens.Peek().StringValue.StartsWith(VARSTART)) {
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74 | tree = ParseVariable(tokens);
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75 | } else {
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76 | Token curToken = tokens.Dequeue();
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77 | tree = CreateTree(curToken);
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78 | while (!tokens.Peek().Equals(Token.RPAR)) {
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79 | tree.AddSubTree(ParseSexp(tokens));
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80 | }
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81 | }
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82 | Expect(Token.RPAR, tokens);
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83 | return tree;
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84 | } else if (tokens.Peek().Symbol == TokenSymbol.NUMBER) {
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85 | ConstantTreeNode t = (ConstantTreeNode)constant.CreateTreeNode();
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86 | t.Value = tokens.Dequeue().DoubleValue;
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87 | return t;
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88 | } else throw new FormatException("Expected function or constant symbol");
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89 | }
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90 |
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91 | private SymbolicExpressionTreeNode ParseVariable(Queue<Token> tokens) {
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92 | Token varTok = tokens.Dequeue();
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93 | Debug.Assert(varTok.StringValue == "variable");
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94 | VariableTreeNode t = (VariableTreeNode)variable.CreateTreeNode();
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95 | t.Weight = tokens.Dequeue().DoubleValue;
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96 | t.VariableName = tokens.Dequeue().StringValue;
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97 | return t;
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98 | }
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99 |
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100 | private SymbolicExpressionTreeNode CreateTree(Token token) {
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101 | if (token.Symbol != TokenSymbol.SYMB) throw new FormatException("Expected function symbol, but got: " + token.StringValue);
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102 | return knownSymbols[token.StringValue].CreateTreeNode();
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103 | }
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104 |
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105 | private void Expect(Token token, Queue<Token> tokens) {
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106 | Token cur = tokens.Dequeue();
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107 | if (!token.Equals(cur)) throw new FormatException("Expected: " + token.StringValue + ", but got: " + cur.StringValue);
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108 | }
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109 | }
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110 | }
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