1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2016 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.Globalization;
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25 | using System.Linq;
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26 | using System.Text;
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27 | using HeuristicLab.Collections;
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28 | using HeuristicLab.Common;
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29 | using HeuristicLab.Encodings.SymbolicExpressionTreeEncoding;
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30 |
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31 | namespace HeuristicLab.Problems.DataAnalysis.Symbolic {
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32 | /// <summary>
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33 | /// Parses mathematical expressions in infix form. E.g. x1 * (3.0 * x2 + x3)
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34 | /// Identifier format (functions or variables): '_' | letter { '_' | letter | digit }
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35 | /// Variables names and variable values can be set under quotes "" or '' because variable names might contain spaces.
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36 | /// Variable = ident | " ident " | ' ident '
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37 | /// It is also possible to use functions e.g. log("x1") or real-valued constants e.g. 3.1415 .
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38 | /// Variable names are case sensitive. Function names are not case sensitive.
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39 | ///
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40 | ///
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41 | /// S = Expr EOF
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42 | /// Expr = ['-' | '+'] Term { '+' Term | '-' Term }
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43 | /// Term = Fact { '*' Fact | '/' Fact }
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44 | /// Fact = '(' Expr ')'
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45 | /// | 'LAG' '(' varId ',' ['+' | '-' ] number ')'
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46 | /// | funcId '(' ArgList ')'
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47 | /// | VarExpr | number
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48 | /// ArgList = Expr { ',' Expr }
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49 | /// VarExpr = varId OptFactorPart
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50 | /// OptFactorPart = [ ('=' varVal | '[' number {',' number } ']' ) ]
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51 | /// varId = ident | ' ident ' | " ident "
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52 | /// varVal = ident | ' ident ' | " ident "
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53 | /// ident = '_' | letter { '_' | letter | digit }
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54 | /// </summary>
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55 | public sealed class InfixExpressionParser {
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56 | private enum TokenType { Operator, Identifier, Number, LeftPar, RightPar, LeftBracket, RightBracket, Comma, Eq, End, NA };
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57 | private class Token {
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58 | internal double doubleVal;
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59 | internal string strVal;
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60 | internal TokenType TokenType;
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61 | }
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62 |
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63 | private class SymbolNameComparer : IEqualityComparer<ISymbol>, IComparer<ISymbol> {
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64 | public int Compare(ISymbol x, ISymbol y) {
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65 | return x.Name.CompareTo(y.Name);
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66 | }
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67 |
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68 | public bool Equals(ISymbol x, ISymbol y) {
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69 | return Compare(x, y) == 0;
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70 | }
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71 |
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72 | public int GetHashCode(ISymbol obj) {
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73 | return obj.Name.GetHashCode();
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74 | }
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75 | }
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76 | // format name <-> symbol
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77 | // the lookup table is also used in the corresponding formatter
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78 | internal static readonly BidirectionalLookup<string, ISymbol>
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79 | knownSymbols = new BidirectionalLookup<string, ISymbol>(StringComparer.InvariantCulture, new SymbolNameComparer());
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80 |
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81 | private Constant constant = new Constant();
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82 | private Variable variable = new Variable();
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83 | private BinaryFactorVariable binaryFactorVar = new BinaryFactorVariable();
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84 | private FactorVariable factorVar = new FactorVariable();
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85 |
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86 | private ProgramRootSymbol programRootSymbol = new ProgramRootSymbol();
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87 | private StartSymbol startSymbol = new StartSymbol();
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88 |
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89 | static InfixExpressionParser() {
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90 | // populate bidirectional lookup
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91 | var dict = new Dictionary<string, ISymbol>
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92 | {
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93 | { "+", new Addition()},
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94 | { "/", new Division()},
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95 | { "*", new Multiplication()},
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96 | { "-", new Subtraction()},
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97 | { "EXP", new Exponential()},
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98 | { "LOG", new Logarithm()},
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99 | { "POW", new Power()},
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100 | { "ROOT", new Root()},
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101 | { "SQR", new Square() },
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102 | { "SQRT", new SquareRoot() },
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103 | { "SIN",new Sine()},
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104 | { "COS", new Cosine()},
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105 | { "TAN", new Tangent()},
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106 | { "AIRYA", new AiryA()},
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107 | { "AIRYB", new AiryB()},
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108 | { "BESSEL", new Bessel()},
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109 | { "COSINT", new CosineIntegral()},
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110 | { "SININT", new SineIntegral()},
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111 | { "HYPCOSINT", new HyperbolicCosineIntegral()},
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112 | { "HYPSININT", new HyperbolicSineIntegral()},
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113 | { "FRESNELSININT", new FresnelSineIntegral()},
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114 | { "FRESNELCOSINT", new FresnelCosineIntegral()},
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115 | { "NORM", new Norm()},
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116 | { "ERF", new Erf()},
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117 | { "GAMMA", new Gamma()},
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118 | { "PSI", new Psi()},
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119 | { "DAWSON", new Dawson()},
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120 | { "EXPINT", new ExponentialIntegralEi()},
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121 | { "MEAN", new Average()},
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122 | { "IF", new IfThenElse()},
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123 | { "GT", new GreaterThan()},
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124 | { "LT", new LessThan()},
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125 | { "AND", new And()},
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126 | { "OR", new Or()},
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127 | { "NOT", new Not()},
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128 | { "XOR", new Xor()},
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129 | { "DIFF", new Derivative()},
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130 | { "LAG", new LaggedVariable() },
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131 | };
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132 |
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133 |
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134 | foreach(var kvp in dict) {
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135 | knownSymbols.Add(kvp.Key, kvp.Value);
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136 | }
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137 | }
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138 |
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139 | public ISymbolicExpressionTree Parse(string str) {
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140 | ISymbolicExpressionTreeNode root = programRootSymbol.CreateTreeNode();
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141 | ISymbolicExpressionTreeNode start = startSymbol.CreateTreeNode();
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142 | var allTokens = GetAllTokens(str).ToArray();
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143 | ISymbolicExpressionTreeNode mainBranch = ParseS(new Queue<Token>(allTokens));
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144 |
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145 | // only a main branch was given => insert the main branch into the default tree template
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146 | root.AddSubtree(start);
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147 | start.AddSubtree(mainBranch);
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148 | return new SymbolicExpressionTree(root);
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149 | }
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150 |
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151 | private IEnumerable<Token> GetAllTokens(string str) {
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152 | int pos = 0;
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153 | while(true) {
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154 | while(pos < str.Length && Char.IsWhiteSpace(str[pos])) pos++;
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155 | if(pos >= str.Length) {
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156 | yield return new Token { TokenType = TokenType.End, strVal = "" };
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157 | yield break;
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158 | }
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159 | if(char.IsDigit(str[pos])) {
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160 | // read number (=> read until white space or operator or comma)
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161 | var sb = new StringBuilder();
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162 | sb.Append(str[pos]);
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163 | pos++;
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164 | while(pos < str.Length && !char.IsWhiteSpace(str[pos])
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165 | && (str[pos] != '+' || str[pos - 1] == 'e' || str[pos - 1] == 'E') // continue reading exponents
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166 | && (str[pos] != '-' || str[pos - 1] == 'e' || str[pos - 1] == 'E')
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167 | && str[pos] != '*'
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168 | && str[pos] != '/'
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169 | && str[pos] != ')'
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170 | && str[pos] != ']'
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171 | && str[pos] != ',') {
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172 | sb.Append(str[pos]);
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173 | pos++;
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174 | }
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175 | double dblVal;
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176 | if(double.TryParse(sb.ToString(), NumberStyles.Float, CultureInfo.InvariantCulture, out dblVal))
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177 | yield return new Token { TokenType = TokenType.Number, strVal = sb.ToString(), doubleVal = dblVal };
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178 | else yield return new Token { TokenType = TokenType.NA, strVal = sb.ToString() };
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179 | } else if(char.IsLetter(str[pos]) || str[pos] == '_') {
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180 | // read ident
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181 | var sb = new StringBuilder();
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182 | sb.Append(str[pos]);
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183 | pos++;
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184 | while(pos < str.Length &&
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185 | (char.IsLetter(str[pos]) || str[pos] == '_' || char.IsDigit(str[pos]))) {
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186 | sb.Append(str[pos]);
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187 | pos++;
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188 | }
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189 | yield return new Token { TokenType = TokenType.Identifier, strVal = sb.ToString() };
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190 | } else if(str[pos] == '"') {
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191 | // read to next "
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192 | pos++;
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193 | var sb = new StringBuilder();
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194 | while(pos < str.Length && str[pos] != '"') {
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195 | sb.Append(str[pos]);
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196 | pos++;
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197 | }
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198 | if(pos < str.Length && str[pos] == '"') {
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199 | pos++; // skip "
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200 | yield return new Token { TokenType = TokenType.Identifier, strVal = sb.ToString() };
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201 | } else
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202 | yield return new Token { TokenType = TokenType.NA };
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203 |
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204 | } else if(str[pos] == '\'') {
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205 | // read to next '
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206 | pos++;
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207 | var sb = new StringBuilder();
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208 | while(pos < str.Length && str[pos] != '\'') {
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209 | sb.Append(str[pos]);
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210 | pos++;
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211 | }
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212 | if(pos < str.Length && str[pos] == '\'') {
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213 | pos++; // skip '
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214 | yield return new Token { TokenType = TokenType.Identifier, strVal = sb.ToString() };
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215 | } else
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216 | yield return new Token { TokenType = TokenType.NA };
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217 | } else if(str[pos] == '+') {
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218 | pos++;
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219 | yield return new Token { TokenType = TokenType.Operator, strVal = "+" };
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220 | } else if(str[pos] == '-') {
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221 | pos++;
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222 | yield return new Token { TokenType = TokenType.Operator, strVal = "-" };
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223 | } else if(str[pos] == '/') {
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224 | pos++;
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225 | yield return new Token { TokenType = TokenType.Operator, strVal = "/" };
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226 | } else if(str[pos] == '*') {
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227 | pos++;
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228 | yield return new Token { TokenType = TokenType.Operator, strVal = "*" };
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229 | } else if(str[pos] == '(') {
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230 | pos++;
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231 | yield return new Token { TokenType = TokenType.LeftPar, strVal = "(" };
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232 | } else if(str[pos] == ')') {
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233 | pos++;
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234 | yield return new Token { TokenType = TokenType.RightPar, strVal = ")" };
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235 | } else if(str[pos] == '[') {
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236 | pos++;
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237 | yield return new Token { TokenType = TokenType.LeftBracket, strVal = "[" };
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238 | } else if(str[pos] == ']') {
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239 | pos++;
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240 | yield return new Token { TokenType = TokenType.RightBracket, strVal = "]" };
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241 | } else if(str[pos] == '=') {
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242 | pos++;
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243 | yield return new Token { TokenType = TokenType.Eq, strVal = "=" };
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244 | } else if(str[pos] == ',') {
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245 | pos++;
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246 | yield return new Token { TokenType = TokenType.Comma, strVal = "," };
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247 | } else {
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248 | throw new ArgumentException("Invalid character: " + str[pos]);
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249 | }
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250 | }
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251 | }
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252 | /// S = Expr EOF
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253 | private ISymbolicExpressionTreeNode ParseS(Queue<Token> tokens) {
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254 | var expr = ParseExpr(tokens);
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255 |
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256 | var endTok = tokens.Dequeue();
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257 | if(endTok.TokenType != TokenType.End)
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258 | throw new ArgumentException(string.Format("Expected end of expression (got {0})", endTok.strVal));
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259 |
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260 | return expr;
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261 | }
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262 |
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263 | /// Expr = ['-' | '+'] Term { '+' Term | '-' Term }
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264 | private ISymbolicExpressionTreeNode ParseExpr(Queue<Token> tokens) {
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265 | var next = tokens.Peek();
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266 | var posTerms = new List<ISymbolicExpressionTreeNode>();
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267 | var negTerms = new List<ISymbolicExpressionTreeNode>();
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268 | bool negateFirstTerm = false;
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269 | if(next.TokenType == TokenType.Operator && (next.strVal == "+" || next.strVal == "-")) {
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270 | tokens.Dequeue();
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271 | if(next.strVal == "-")
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272 | negateFirstTerm = true;
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273 | }
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274 | var t = ParseTerm(tokens);
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275 | if(negateFirstTerm) negTerms.Add(t);
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276 | else posTerms.Add(t);
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277 |
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278 | next = tokens.Peek();
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279 | while(next.strVal == "+" || next.strVal == "-") {
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280 | switch(next.strVal) {
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281 | case "+": {
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282 | tokens.Dequeue();
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283 | var term = ParseTerm(tokens);
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284 | posTerms.Add(term);
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285 | break;
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286 | }
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287 | case "-": {
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288 | tokens.Dequeue();
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289 | var term = ParseTerm(tokens);
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290 | negTerms.Add(term);
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291 | break;
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292 | }
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293 | }
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294 | next = tokens.Peek();
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295 | }
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296 |
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297 | var sum = GetSymbol("+").CreateTreeNode();
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298 | foreach(var posTerm in posTerms) sum.AddSubtree(posTerm);
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299 | if(negTerms.Any()) {
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300 | if(negTerms.Count == 1) {
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301 | var sub = GetSymbol("-").CreateTreeNode();
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302 | sub.AddSubtree(negTerms.Single());
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303 | sum.AddSubtree(sub);
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304 | } else {
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305 | var sumNeg = GetSymbol("+").CreateTreeNode();
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306 | foreach(var negTerm in negTerms) sumNeg.AddSubtree(negTerm);
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307 |
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308 | var constNode = (ConstantTreeNode)constant.CreateTreeNode();
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309 | constNode.Value = -1.0;
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310 | var prod = GetSymbol("*").CreateTreeNode();
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311 | prod.AddSubtree(constNode);
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312 | prod.AddSubtree(sumNeg);
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313 |
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314 | sum.AddSubtree(prod);
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315 | }
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316 | }
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317 | if(sum.SubtreeCount == 1) return sum.Subtrees.First();
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318 | else return sum;
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319 | }
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320 |
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321 | private ISymbol GetSymbol(string tok) {
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322 | var symb = knownSymbols.GetByFirst(tok).FirstOrDefault();
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323 | if(symb == null) throw new ArgumentException(string.Format("Unknown token {0} found.", tok));
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324 | return symb;
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325 | }
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326 |
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327 | /// Term = Fact { '*' Fact | '/' Fact }
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328 | private ISymbolicExpressionTreeNode ParseTerm(Queue<Token> tokens) {
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329 | var factors = new List<ISymbolicExpressionTreeNode>();
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330 | var firstFactor = ParseFact(tokens);
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331 | factors.Add(firstFactor);
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332 |
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333 | var next = tokens.Peek();
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334 | while(next.strVal == "*" || next.strVal == "/") {
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335 | switch(next.strVal) {
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336 | case "*": {
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337 | tokens.Dequeue();
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338 | var fact = ParseFact(tokens);
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339 | factors.Add(fact);
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340 | break;
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341 | }
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342 | case "/": {
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343 | tokens.Dequeue();
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344 | var invFact = ParseFact(tokens);
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345 | var divNode = GetSymbol("/").CreateTreeNode(); // 1/x
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346 | divNode.AddSubtree(invFact);
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347 | factors.Add(divNode);
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348 | break;
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349 | }
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350 | }
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351 |
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352 | next = tokens.Peek();
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353 | }
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354 | if(factors.Count == 1) return factors.First();
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355 | else {
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356 | var prod = GetSymbol("*").CreateTreeNode();
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357 | foreach(var f in factors) prod.AddSubtree(f);
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358 | return prod;
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359 | }
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360 | }
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361 |
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362 | /// Fact = '(' Expr ')'
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363 | /// | 'LAG' '(' varId ',' ['+' | '-' ] number ')'
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364 | /// | funcId '(' ArgList ')'
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365 | /// | VarExpr | number
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366 | /// ArgList = Expr { ',' Expr }
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367 | /// VarExpr = varId OptFactorPart
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368 | /// OptFactorPart = [ ('=' varVal | '[' number {',' number } ']' ) ]
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369 | /// varId = ident | ' ident ' | " ident "
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370 | /// varVal = ident | ' ident ' | " ident "
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371 | /// ident = '_' | letter { '_' | letter | digit }
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372 | private ISymbolicExpressionTreeNode ParseFact(Queue<Token> tokens) {
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373 | var next = tokens.Peek();
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374 | if(next.TokenType == TokenType.LeftPar) {
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375 | tokens.Dequeue();
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376 | var expr = ParseExpr(tokens);
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377 | var rPar = tokens.Dequeue();
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378 | if(rPar.TokenType != TokenType.RightPar)
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379 | throw new ArgumentException("expected )");
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380 | return expr;
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381 | } else if(next.TokenType == TokenType.Identifier) {
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382 | var idTok = tokens.Dequeue();
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383 | if(tokens.Peek().TokenType == TokenType.LeftPar) {
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384 | // function identifier or LAG
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385 | var funcId = idTok.strVal.ToUpperInvariant();
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386 |
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387 | var funcNode = GetSymbol(funcId).CreateTreeNode();
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388 | var lPar = tokens.Dequeue();
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389 | if(lPar.TokenType != TokenType.LeftPar)
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390 | throw new ArgumentException("expected (");
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391 |
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392 | // handle 'lag' specifically
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393 | if(funcNode.Symbol is LaggedVariable) {
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394 | var varId = tokens.Dequeue();
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395 | if(varId.TokenType != TokenType.Identifier) throw new ArgumentException("Identifier expected. Format for lagged variables: \"lag(x, -1)\"");
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396 | var comma = tokens.Dequeue();
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397 | if(comma.TokenType != TokenType.Comma) throw new ArgumentException("',' expected, Format for lagged variables: \"lag(x, -1)\"");
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398 | double sign = 1.0;
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399 | if(tokens.Peek().strVal == "+" || tokens.Peek().strVal == "-") {
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400 | // read sign
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401 | var signTok = tokens.Dequeue();
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402 | if(signTok.strVal == "-") sign = -1.0;
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403 | }
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404 | var lagToken = tokens.Dequeue();
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405 | if(lagToken.TokenType != TokenType.Number) throw new ArgumentException("Number expected, Format for lagged variables: \"lag(x, -1)\"");
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406 | if(!lagToken.doubleVal.IsAlmost(Math.Round(lagToken.doubleVal)))
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407 | throw new ArgumentException("Time lags must be integer values");
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408 | var laggedVarNode = funcNode as LaggedVariableTreeNode;
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409 | laggedVarNode.VariableName = varId.strVal;
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410 | laggedVarNode.Lag = (int)Math.Round(sign * lagToken.doubleVal);
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411 | laggedVarNode.Weight = 1.0;
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412 | } else {
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413 | // functions
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414 | var args = ParseArgList(tokens);
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415 | // check number of arguments
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416 | if(funcNode.Symbol.MinimumArity > args.Length || funcNode.Symbol.MaximumArity < args.Length) {
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417 | throw new ArgumentException(string.Format("Symbol {0} requires between {1} and {2} arguments.", funcId,
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418 | funcNode.Symbol.MinimumArity, funcNode.Symbol.MaximumArity));
|
---|
419 | }
|
---|
420 | foreach(var arg in args) funcNode.AddSubtree(arg);
|
---|
421 | }
|
---|
422 |
|
---|
423 | var rPar = tokens.Dequeue();
|
---|
424 | if(rPar.TokenType != TokenType.RightPar)
|
---|
425 | throw new ArgumentException("expected )");
|
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426 |
|
---|
427 | return funcNode;
|
---|
428 | } else {
|
---|
429 | // variable
|
---|
430 | if(tokens.Peek().TokenType == TokenType.Eq) {
|
---|
431 | // binary factor
|
---|
432 | tokens.Dequeue(); // skip Eq
|
---|
433 | var valTok = tokens.Dequeue();
|
---|
434 | if(valTok.TokenType != TokenType.Identifier) throw new ArgumentException("expected identifier");
|
---|
435 | var binFactorNode = (BinaryFactorVariableTreeNode)binaryFactorVar.CreateTreeNode();
|
---|
436 | binFactorNode.Weight = 1.0;
|
---|
437 | binFactorNode.VariableName = idTok.strVal;
|
---|
438 | binFactorNode.VariableValue = valTok.strVal;
|
---|
439 | return binFactorNode;
|
---|
440 | } else if(tokens.Peek().TokenType == TokenType.LeftBracket) {
|
---|
441 | // factor variable
|
---|
442 | var factorVariableNode = (FactorVariableTreeNode) factorVar.CreateTreeNode();
|
---|
443 | factorVariableNode.VariableName = idTok.strVal;
|
---|
444 |
|
---|
445 | tokens.Dequeue(); // skip [
|
---|
446 | var weights = new List<double>();
|
---|
447 | // at least one weight is necessary
|
---|
448 | if(tokens.Peek().TokenType != TokenType.Number) throw new ArgumentException("number expected");
|
---|
449 | var weightTok = tokens.Dequeue();
|
---|
450 | weights.Add(weightTok.doubleVal);
|
---|
451 | while(tokens.Peek().TokenType == TokenType.Comma) {
|
---|
452 | // skip comma
|
---|
453 | tokens.Dequeue();
|
---|
454 | weightTok = tokens.Dequeue();
|
---|
455 | if(weightTok.TokenType != TokenType.Number) throw new ArgumentException("number expected");
|
---|
456 | weights.Add(weightTok.doubleVal);
|
---|
457 | }
|
---|
458 | var rightBracketToken = tokens.Dequeue();
|
---|
459 | if(rightBracketToken.TokenType != TokenType.RightBracket) throw new ArgumentException("closing bracket ] expected");
|
---|
460 | factorVariableNode.Weights = weights.ToArray();
|
---|
461 | return factorVariableNode;
|
---|
462 | } else {
|
---|
463 | // variable
|
---|
464 | var varNode = (VariableTreeNode)variable.CreateTreeNode();
|
---|
465 | varNode.Weight = 1.0;
|
---|
466 | varNode.VariableName = idTok.strVal;
|
---|
467 | return varNode;
|
---|
468 | }
|
---|
469 | }
|
---|
470 | } else if(next.TokenType == TokenType.Number) {
|
---|
471 | var numTok = tokens.Dequeue();
|
---|
472 | var constNode = (ConstantTreeNode)constant.CreateTreeNode();
|
---|
473 | constNode.Value = numTok.doubleVal;
|
---|
474 | return constNode;
|
---|
475 | } else {
|
---|
476 | throw new ArgumentException(string.Format("unexpected token in expression {0}", next.strVal));
|
---|
477 | }
|
---|
478 | }
|
---|
479 |
|
---|
480 | // ArgList = Expr { ',' Expr }
|
---|
481 | private ISymbolicExpressionTreeNode[] ParseArgList(Queue<Token> tokens) {
|
---|
482 | var exprList = new List<ISymbolicExpressionTreeNode>();
|
---|
483 | exprList.Add(ParseExpr(tokens));
|
---|
484 | while(tokens.Peek().TokenType != TokenType.RightPar) {
|
---|
485 | var comma = tokens.Dequeue();
|
---|
486 | if(comma.TokenType != TokenType.Comma) throw new ArgumentException("expected ',' ");
|
---|
487 | exprList.Add(ParseExpr(tokens));
|
---|
488 | }
|
---|
489 | return exprList.ToArray();
|
---|
490 | }
|
---|
491 | }
|
---|
492 | }
|
---|