1 | using System;
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2 | using System.Collections.Generic;
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3 | using System.Diagnostics;
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4 | using System.Linq;
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5 | using HeuristicLab.Algorithms.DataAnalysis.SymRegGrammarEnumeration.GrammarEnumeration;
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6 | using HeuristicLab.Common;
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7 | using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
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8 | using HeuristicLab.Problems.DataAnalysis.Symbolic;
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9 |
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10 | namespace HeuristicLab.Algorithms.DataAnalysis.SymRegGrammarEnumeration {
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11 | public class Grammar {
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12 |
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13 | public Symbol StartSymbol;
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14 |
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15 | #region Symbols
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16 |
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17 | public VariableSymbol Var;
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18 |
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19 | public NonterminalSymbol Expr;
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20 | public NonterminalSymbol Term;
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21 | public NonterminalSymbol Factor;
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22 |
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23 | public TerminalSymbol Addition;
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24 | public TerminalSymbol Multiplication;
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25 |
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26 | #endregion
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27 |
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28 |
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29 | #region HL Symbols for Parsing ExpressionTrees
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30 |
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31 | private TypeCoherentExpressionGrammar symbolicExpressionGrammar;
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32 |
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33 | private ISymbol constSy;
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34 | private ISymbol varSy;
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35 |
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36 | private ISymbol addSy;
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37 | private ISymbol mulSy;
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38 | private ISymbol logSy;
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39 | private ISymbol expSy;
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40 | private ISymbol divSy;
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41 |
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42 | private ISymbol rootSy;
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43 | private ISymbol startSy;
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44 |
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45 | #endregion
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46 |
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47 | public Grammar(string[] variables) {
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48 | #region Define Symbols
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49 | Var = new VariableSymbol("var", variables);
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50 |
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51 | Expr = new NonterminalSymbol("Expr");
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52 | Term = new NonterminalSymbol("Term");
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53 | Factor = new NonterminalSymbol("Factor");
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54 |
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55 | Addition = new TerminalSymbol("+");
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56 | Multiplication = new TerminalSymbol("*");
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57 | #endregion
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58 |
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59 |
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60 | #region Production rules
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61 | // order of production is important, since they are accessed via index
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62 | // in memoization.
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63 | StartSymbol = Expr;
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64 |
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65 | Expr.AddProduction(Term, Expr, Addition);
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66 | Expr.AddProduction(Term);
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67 |
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68 | Term.AddProduction(Factor, Term, Multiplication);
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69 | Term.AddProduction(Factor);
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70 |
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71 | Factor.AddProduction(Var);
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72 | #endregion
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73 |
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74 | #region Parsing to SymbolicExpressionTree
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75 | symbolicExpressionGrammar = new TypeCoherentExpressionGrammar();
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76 | symbolicExpressionGrammar.ConfigureAsDefaultRegressionGrammar();
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77 |
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78 | constSy = symbolicExpressionGrammar.Symbols.OfType<Constant>().First();
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79 | varSy = symbolicExpressionGrammar.Symbols.OfType<Variable>().First();
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80 | addSy = symbolicExpressionGrammar.AllowedSymbols.OfType<Addition>().First();
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81 | mulSy = symbolicExpressionGrammar.AllowedSymbols.OfType<Multiplication>().First();
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82 | logSy = symbolicExpressionGrammar.AllowedSymbols.OfType<Logarithm>().First();
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83 | expSy = symbolicExpressionGrammar.AllowedSymbols.OfType<Exponential>().First();
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84 | divSy = symbolicExpressionGrammar.AllowedSymbols.OfType<Division>().First();
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85 |
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86 | rootSy = symbolicExpressionGrammar.AllowedSymbols.OfType<ProgramRootSymbol>().First();
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87 | startSy = symbolicExpressionGrammar.AllowedSymbols.OfType<StartSymbol>().First();
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88 |
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89 | #endregion
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90 | }
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91 |
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92 | #region Hashing
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93 | public int CalcHashCode(SymbolString sentence) {
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94 | Debug.Assert(sentence.Any(), "Trying to evaluate empty sentence!");
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95 | // Debug.Assert(sentence.All(s => s is TerminalSymbol), "Trying to evaluate symbol sequence with nonterminalsymbols!");
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96 |
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97 | Stack<Symbol> parseStack = new Stack<Symbol>(sentence);
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98 |
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99 | Symbol peek = parseStack.Peek();
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100 | int[] subtreeHashes = GetSubtreeHashes(parseStack);
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101 | return AggregateHashes(peek, subtreeHashes);
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102 | }
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103 |
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104 | private int[] GetSubtreeHashes(Stack<Symbol> parseStack) {
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105 | Symbol currentSymbol = parseStack.Pop();
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106 |
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107 | // VARIABLE
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108 | // if (Var.VariableTerminalSymbols.Contains(currentSymbol)) {
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109 | // return currentSymbol.StringRepresentation.GetHashCode().ToEnumerable().ToArray();
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110 | // }
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111 |
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112 | // MULTIPLICATION
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113 | if (ReferenceEquals(currentSymbol, Multiplication)) {
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114 | List<int> childHashes = new List<int>();
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115 |
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116 | // First subtree
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117 | if (ReferenceEquals(parseStack.Peek(), Multiplication)) {
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118 | childHashes.AddRange(GetSubtreeHashes(parseStack));
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119 | } else {
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120 | childHashes.Add(AggregateHashes(parseStack.Peek(), GetSubtreeHashes(parseStack)));
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121 | }
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122 | // Second subtree
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123 | if (ReferenceEquals(parseStack.Peek(), Multiplication)) {
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124 | childHashes.AddRange(GetSubtreeHashes(parseStack));
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125 | } else {
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126 | childHashes.Add(AggregateHashes(parseStack.Peek(), GetSubtreeHashes(parseStack)));
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127 | }
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128 |
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129 | // Sort due to commutativity
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130 | childHashes.Sort();
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131 | return childHashes.ToArray();
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132 | }
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133 |
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134 | // ADDITION
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135 | if (ReferenceEquals(currentSymbol, Addition)) {
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136 | HashSet<int> uniqueChildHashes = new HashSet<int>();
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137 |
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138 | // First subtree
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139 | if (ReferenceEquals(parseStack.Peek(), Addition)) {
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140 | uniqueChildHashes.UnionWith(GetSubtreeHashes(parseStack));
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141 | } else {
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142 | var peek = parseStack.Peek();
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143 | uniqueChildHashes.Add(AggregateHashes(peek, GetSubtreeHashes(parseStack)));
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144 | }
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145 | // Second subtree
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146 | if (ReferenceEquals(parseStack.Peek(), Addition)) {
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147 | uniqueChildHashes.UnionWith(GetSubtreeHashes(parseStack));
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148 | } else {
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149 | var peek = parseStack.Peek();
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150 | uniqueChildHashes.Add(AggregateHashes(peek, GetSubtreeHashes(parseStack)));
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151 | }
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152 |
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153 | var result = uniqueChildHashes.ToList();
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154 | result.Sort();
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155 | return result.ToArray();
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156 | }
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157 |
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158 | // var or nonterminal symbol
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159 | return currentSymbol.StringRepresentation.GetHashCode().ToEnumerable().ToArray();
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160 | }
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161 |
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162 | private int AggregateHashes(Symbol operatorSym, IEnumerable<int> hashes) {
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163 | // If multiple subtrees are "merged" (e.g. added, multiplied, etc.), consider the executed operation
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164 | var hashesArray = hashes.ToArray();
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165 | int start = hashesArray.Length > 1 ? operatorSym.StringRepresentation.GetHashCode() : 0;
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166 | return hashesArray.Aggregate(start, (result, ti) => ((result << 5) + result) ^ ti.GetHashCode());
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167 | }
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168 | #endregion
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169 |
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170 | #region Parse to SymbolicExpressionTree
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171 | public SymbolicExpressionTree ParseSymbolicExpressionTree(SymbolString sentence) {
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172 | Debug.Assert(sentence.Any(), "Trying to evaluate empty sentence!");
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173 | Debug.Assert(sentence.All(s => s is TerminalSymbol), "Trying to evaluate symbol sequence with nonterminalsymbols!");
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174 |
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175 | symbolicExpressionGrammar.ConfigureAsDefaultRegressionGrammar();
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176 |
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177 | var rootNode = rootSy.CreateTreeNode();
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178 | var startNode = startSy.CreateTreeNode();
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179 | rootNode.AddSubtree(startNode);
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180 |
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181 | Stack<TerminalSymbol> parseStack = new Stack<TerminalSymbol>(sentence.OfType<TerminalSymbol>());
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182 | startNode.AddSubtree(ParseSymbolicExpressionTree(parseStack));
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183 |
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184 | return new SymbolicExpressionTree(rootNode);
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185 | }
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186 |
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187 | public ISymbolicExpressionTreeNode ParseSymbolicExpressionTree(Stack<TerminalSymbol> parseStack) {
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188 | TerminalSymbol currentSymbol = parseStack.Pop();
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189 |
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190 | ISymbolicExpressionTreeNode parsedSubTree = null;
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191 |
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192 | if (ReferenceEquals(currentSymbol, Addition)) {
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193 | parsedSubTree = addSy.CreateTreeNode();
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194 | parsedSubTree.AddSubtree(ParseSymbolicExpressionTree(parseStack)); // left part
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195 | parsedSubTree.AddSubtree(ParseSymbolicExpressionTree(parseStack)); // right part
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196 |
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197 | } else if (ReferenceEquals(currentSymbol, Multiplication)) {
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198 | parsedSubTree = mulSy.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 (Var.VariableTerminalSymbols.Contains(currentSymbol)) {
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203 | VariableTreeNode varNode = (VariableTreeNode)varSy.CreateTreeNode();
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204 | varNode.Weight = 1.0;
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205 | varNode.VariableName = currentSymbol.StringRepresentation;
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206 | parsedSubTree = varNode;
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207 | }
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208 |
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209 | Debug.Assert(parsedSubTree != null);
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210 | return parsedSubTree;
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211 | }
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212 | #endregion
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213 |
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214 | #region Parse to Infix string
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215 |
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216 | public SymbolString PostfixToInfixParser(SymbolString phrase) {
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217 | Stack<Symbol> parseStack = new Stack<Symbol>(phrase);
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218 |
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219 | return PostfixToInfixSubtreeParser(parseStack);
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220 | }
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221 |
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222 | private SymbolString PostfixToInfixSubtreeParser(Stack<Symbol> parseStack) {
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223 | Symbol head = parseStack.Pop();
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224 |
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225 | SymbolString result = new SymbolString();
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226 |
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227 | if (ReferenceEquals(head, Addition) || ReferenceEquals(head, Multiplication)) {
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228 | // right part
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229 | SymbolString rightPart = PostfixToInfixSubtreeParser(parseStack);
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230 | SymbolString leftPart = PostfixToInfixSubtreeParser(parseStack);
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231 |
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232 | result.AddRange(leftPart);
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233 | result.Add(head);
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234 | result.AddRange(rightPart);
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235 | } else {
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236 | result.Add(head);
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237 | }
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238 | return result;
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239 | }
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240 |
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241 | #endregion
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242 | }
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243 | }
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