1 | using System.Collections;
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2 | using System.Collections.Generic;
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3 | using System.ComponentModel;
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4 | using System.Diagnostics;
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5 | using System.Linq;
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6 | using HeuristicLab.Algorithms.DataAnalysis.SymRegGrammarEnumeration.GrammarEnumeration;
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7 | using HeuristicLab.Common;
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8 | using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
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9 | using HeuristicLab.Problems.DataAnalysis.Symbolic;
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10 |
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11 | namespace HeuristicLab.Algorithms.DataAnalysis.SymRegGrammarEnumeration {
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12 | public class Grammar {
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13 |
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14 | public Symbol StartSymbol;
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15 |
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16 | #region Symbols
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17 |
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18 | public VariableSymbol Var;
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19 |
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20 | public NonterminalSymbol Expr;
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21 | public NonterminalSymbol Term;
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22 | public NonterminalSymbol Factor;
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23 |
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24 | public TerminalSymbol Addition;
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25 | public TerminalSymbol Multiplication;
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26 |
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27 | #endregion
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28 |
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29 |
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30 | #region HL Symbols for Parsing ExpressionTrees
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31 |
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32 | private TypeCoherentExpressionGrammar symbolicExpressionGrammar;
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33 |
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34 | private ISymbol constSy;
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35 | private ISymbol varSy;
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36 |
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37 | private ISymbol addSy;
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38 | private ISymbol mulSy;
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39 | private ISymbol logSy;
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40 | private ISymbol expSy;
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41 | private ISymbol divSy;
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42 |
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43 | private ISymbol rootSy;
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44 | private ISymbol startSy;
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45 |
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46 | #endregion
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47 |
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48 | public Grammar(string[] variables) {
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49 | #region Define Symbols
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50 | Var = new VariableSymbol("var", variables);
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51 |
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52 | Expr = new NonterminalSymbol("Expr");
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53 | Term = new NonterminalSymbol("Term");
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54 | Factor = new NonterminalSymbol("Factor");
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55 |
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56 | Addition = new TerminalSymbol("+");
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57 | Multiplication = new TerminalSymbol("*");
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58 | #endregion
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59 |
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60 |
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61 | #region Production ruless
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62 | StartSymbol = Expr;
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63 |
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64 | Expr.AddProduction(Term, Expr, Addition);
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65 | Expr.AddProduction(Term);
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66 |
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67 | Term.AddProduction(Factor, Term, Multiplication);
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68 | Term.AddProduction(Factor);
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69 |
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70 | Factor.AddProduction(Var);
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71 | #endregion
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72 |
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73 | #region Parsing to SymbolicExpressionTree
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74 | symbolicExpressionGrammar = new TypeCoherentExpressionGrammar();
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75 | symbolicExpressionGrammar.ConfigureAsDefaultRegressionGrammar();
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76 |
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77 | constSy = symbolicExpressionGrammar.Symbols.OfType<Constant>().First();
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78 | varSy = symbolicExpressionGrammar.Symbols.OfType<Variable>().First();
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79 | addSy = symbolicExpressionGrammar.AllowedSymbols.OfType<Addition>().First();
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80 | mulSy = symbolicExpressionGrammar.AllowedSymbols.OfType<Multiplication>().First();
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81 | logSy = symbolicExpressionGrammar.AllowedSymbols.OfType<Logarithm>().First();
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82 | expSy = symbolicExpressionGrammar.AllowedSymbols.OfType<Exponential>().First();
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83 | divSy = symbolicExpressionGrammar.AllowedSymbols.OfType<Division>().First();
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84 |
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85 | rootSy = symbolicExpressionGrammar.AllowedSymbols.OfType<ProgramRootSymbol>().First();
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86 | startSy = symbolicExpressionGrammar.AllowedSymbols.OfType<StartSymbol>().First();
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87 |
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88 | #endregion
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89 | }
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90 |
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91 | public int CalcHashCode(SymbolString sentence) {
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92 | Debug.Assert(sentence.Any(), "Trying to evaluate empty sentence!");
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93 | Debug.Assert(sentence.All(s => s is TerminalSymbol), "Trying to evaluate symbol sequence with nonterminalsymbols!");
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94 |
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95 | Stack<TerminalSymbol> parseStack = new Stack<TerminalSymbol>(sentence.OfType<TerminalSymbol>());
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96 |
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97 | int[] subtreeHashes = GetSubtreeHashes(parseStack.Pop(), parseStack);
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98 | return AggregateHashes(subtreeHashes);
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99 | }
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100 |
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101 | #region Hashing
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102 | private int[] GetSubtreeHashes(TerminalSymbol currentSymbol, Stack<TerminalSymbol> parseStack) {
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103 | List<int> childHashes = null;
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104 |
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105 | if (Var.VariableTerminalSymbols.Contains(currentSymbol)) {
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106 | childHashes = currentSymbol.StringRepresentation.GetHashCode().ToEnumerable().ToList();
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107 |
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108 | } else if (ReferenceEquals(currentSymbol, Multiplication)) {
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109 | // MULTIPLICATION
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110 | childHashes = new List<int>();
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111 |
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112 | // First subtree
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113 | TerminalSymbol firstSubtreeRoot = parseStack.Pop();
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114 | int[] firstSubtreeHashes = GetSubtreeHashes(firstSubtreeRoot, parseStack);
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115 |
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116 | if (ReferenceEquals(firstSubtreeRoot, Multiplication)) {
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117 | childHashes.AddRange(firstSubtreeHashes);
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118 | } else {
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119 | childHashes.Add(AggregateHashes(firstSubtreeHashes));
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120 | }
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121 |
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122 | // Second subtree
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123 | TerminalSymbol secondSubtreeRoot = parseStack.Pop();
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124 | int[] secondSubtreeHashes = GetSubtreeHashes(secondSubtreeRoot, parseStack);
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125 |
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126 | if (ReferenceEquals(secondSubtreeRoot, Multiplication)) {
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127 | childHashes.AddRange(secondSubtreeHashes);
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128 | } else {
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129 | childHashes.Add(AggregateHashes(secondSubtreeHashes));
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130 | }
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131 |
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132 | // Sort due to commutativity
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133 | childHashes.Sort();
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134 |
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135 |
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136 |
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137 | } else if (ReferenceEquals(currentSymbol, Addition)) {
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138 | // ADDITION
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139 | HashSet<int> uniqueChildHashes = new HashSet<int>();
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140 |
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141 | TerminalSymbol firstSubtreeRoot = parseStack.Pop();
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142 | int[] firstSubtreeHashes = GetSubtreeHashes(firstSubtreeRoot, parseStack);
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143 |
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144 | // First subtree
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145 | if (ReferenceEquals(firstSubtreeRoot, Addition)) {
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146 | uniqueChildHashes.UnionWith(firstSubtreeHashes);
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147 | } else {
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148 | uniqueChildHashes.Add(AggregateHashes(firstSubtreeHashes));
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149 | }
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150 |
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151 | // Second subtree
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152 | TerminalSymbol secondSubtreeRoot = parseStack.Pop();
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153 | int[] secondSubtreeHashes = GetSubtreeHashes(secondSubtreeRoot, parseStack);
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154 |
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155 | if (ReferenceEquals(secondSubtreeRoot, Addition)) {
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156 | uniqueChildHashes.UnionWith(secondSubtreeHashes);
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157 | } else {
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158 | uniqueChildHashes.Add(AggregateHashes(secondSubtreeHashes));
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159 | }
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160 |
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161 | childHashes = uniqueChildHashes.ToList();
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162 | childHashes.Sort();
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163 | }
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164 |
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165 | Debug.Assert(childHashes != null, "Sentence not hashable!");
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166 | return childHashes.ToArray();
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167 | }
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168 |
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169 |
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170 | private int AggregateHashes(IEnumerable<int> hashes) {
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171 | return hashes.Aggregate(0, (result, ti) => ((result << 5) + result) ^ ti.GetHashCode());
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172 | }
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173 | #endregion
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174 |
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175 | #region Parse to SymbolicExpressionTree
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176 | public SymbolicExpressionTree ParseSymbolicExpressionTree(SymbolString sentence) {
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177 | Debug.Assert(sentence.Any(), "Trying to evaluate empty sentence!");
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178 | Debug.Assert(sentence.All(s => s is TerminalSymbol), "Trying to evaluate symbol sequence with nonterminalsymbols!");
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179 |
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180 | symbolicExpressionGrammar.ConfigureAsDefaultRegressionGrammar();
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181 |
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182 | var rootNode = rootSy.CreateTreeNode();
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183 | var startNode = startSy.CreateTreeNode();
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184 | rootNode.AddSubtree(startNode);
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185 |
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186 | Stack<TerminalSymbol> parseStack = new Stack<TerminalSymbol>(sentence.OfType<TerminalSymbol>());
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187 | startNode.AddSubtree(ParseSymbolicExpressionTree(parseStack));
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188 |
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189 | return new SymbolicExpressionTree(rootNode);
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190 | }
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191 |
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192 | public ISymbolicExpressionTreeNode ParseSymbolicExpressionTree(Stack<TerminalSymbol> parseStack) {
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193 | TerminalSymbol currentSymbol = parseStack.Pop();
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194 |
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195 | ISymbolicExpressionTreeNode parsedSubTree = null;
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196 |
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197 | if (ReferenceEquals(currentSymbol, Addition)) {
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198 | parsedSubTree = addSy.CreateTreeNode();
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199 | parsedSubTree.AddSubtree(ParseSymbolicExpressionTree(parseStack)); // left part
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200 | parsedSubTree.AddSubtree(ParseSymbolicExpressionTree(parseStack)); // right part
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201 |
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202 | } else if (ReferenceEquals(currentSymbol, Multiplication)) {
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203 | parsedSubTree = mulSy.CreateTreeNode();
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204 | parsedSubTree.AddSubtree(ParseSymbolicExpressionTree(parseStack)); // left part
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205 | parsedSubTree.AddSubtree(ParseSymbolicExpressionTree(parseStack)); // right part
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206 |
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207 | } else if (Var.VariableTerminalSymbols.Contains(currentSymbol)) {
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208 | VariableTreeNode varNode = (VariableTreeNode)varSy.CreateTreeNode();
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209 | varNode.Weight = 1.0;
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210 | varNode.VariableName = currentSymbol.StringRepresentation;
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211 | parsedSubTree = varNode;
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212 | }
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213 |
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214 | Debug.Assert(parsedSubTree != null);
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215 | return parsedSubTree;
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216 | }
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217 | #endregion
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218 | }
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219 | }
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