[13645] | 1 | #region License Information
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| 2 | /* HeuristicLab
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[14185] | 3 | * Copyright (C) 2002-2016 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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[13645] | 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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[15410] | 24 | using System.Diagnostics;
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[13645] | 25 | using System.IO;
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[15410] | 26 | using System.Linq;
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[13645] | 27 |
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| 28 | namespace HeuristicLab.Algorithms.DataAnalysis.MctsSymbolicRegression {
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| 29 | // this is the core class for generating expressions.
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[13651] | 30 | // it represents a finite state automaton, each state transition can be associated with an action (e.g. to produce code).
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| 31 | // the automaton determines the possible structures for expressions.
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| 32 | //
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| 33 | // to understand this code it is worthwile to generate a graphical visualization of the automaton (see PrintAutomaton).
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| 34 | // If the code is compiled in debug mode the automaton produces a Graphviz file into the folder of the application
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| 35 | // whenever an instance of the automaton is constructed.
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| 36 | //
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| 37 | // This class relies on two other classes:
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| 38 | // - CodeGenerator to produce code for a stack-based evaluator and
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| 39 | // - ConstraintHandler to restrict the allowed set of expressions.
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| 40 | //
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| 41 | // The ConstraintHandler extends the automaton and adds semantic restrictions for expressions produced by the automaton.
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| 42 | //
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| 43 | //
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[13645] | 44 | internal class Automaton {
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[15410] | 45 | // TODO: refactor so that State is an enumerable type
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| 46 |
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| 47 | // there is a single final state (ExprEnd)
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| 48 | // states with lower values are closer to the final state
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| 49 | // (this is helpful when we try to navigate to the final state)
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| 50 | public const int StateExprEnd = 1;
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| 51 | public const int StateTermEnd = 2;
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| 52 | public const int StateFactorEnd = 3;
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| 53 |
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| 54 | public const int StateVariableFactorEnd = 4;
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| 55 | public const int StateExpFactorEnd = 5;
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| 56 | public const int StateLogFactorEnd = 6;
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| 57 | public const int StateInvFactorEnd = 7;
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| 58 |
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| 59 | public const int StateExpFEnd = 8;
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| 60 | public const int StateLogTEnd = 9;
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| 61 | public const int StateInvTEnd = 10;
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| 62 |
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| 63 | public const int StateLogTFEnd = 11;
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| 64 | public const int StateInvTFEnd = 12;
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| 65 |
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| 66 | public const int StateLogTFStart = 13;
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| 67 | public const int StateInvTFStart = 14;
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| 68 |
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[13645] | 69 | public const int StateExpFStart = 15;
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[15410] | 70 | public const int StateLogTStart = 16;
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| 71 | public const int StateInvTStart = 17;
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| 72 |
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| 73 | public const int StateVariableFactorStart = 18;
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| 74 | public const int StateExpFactorStart = 19;
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| 75 | public const int StateLogFactorStart = 20;
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| 76 | public const int StateInvFactorStart = 21;
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| 77 |
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| 78 | public const int StateFactorStart = 22;
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| 79 | public const int StateTermStart = 23;
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| 80 | public const int StateExpr = 24;
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[13651] | 81 | public const int FirstDynamicState = 25;
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| 82 | // more states for individual variables are created dynamically
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[13645] | 83 |
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| 84 | private const int StartState = StateExpr;
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| 85 | public int CurrentState { get; private set; }
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| 86 |
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| 87 | public readonly List<string> stateNames;
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| 88 | private List<int>[] followStates;
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| 89 | private List<Action>[,] actions; // not every follow state is possible but this representation should be efficient
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| 90 | private List<string>[,] actionStrings; // just for printing
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| 91 | private readonly CodeGenerator codeGenerator;
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[15410] | 92 | private IConstraintHandler constraintHandler;
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[13645] | 93 |
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[15410] | 94 | public Automaton(double[][] vars, IConstraintHandler constraintHandler,
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[13645] | 95 | bool allowProdOfVars = true,
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| 96 | bool allowExp = true,
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| 97 | bool allowLog = true,
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| 98 | bool allowInv = true,
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| 99 | bool allowMultipleTerms = false) {
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| 100 | int nVars = vars.Length;
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| 101 | stateNames = new List<string>() { string.Empty, "Expr", "ExprEnd", "TermStart", "TermEnd", "FactorStart", "FactorEnd", "VarFactorStart", "VarFactorEnd", "ExpFactorStart", "ExpFactorEnd", "LogFactorStart", "LogFactorEnd", "InvFactorStart", "InvFactorEnd", "ExpFStart", "ExpFEnd", "LogTStart", "LogTEnd", "LogTFStart", "LogTFEnd", "InvTStart", "InvTEnd", "InvTFStart", "InvTFEnd" };
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| 102 | codeGenerator = new CodeGenerator();
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[15410] | 103 | this.constraintHandler = constraintHandler;
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[13645] | 104 | BuildAutomaton(nVars, allowProdOfVars, allowExp, allowLog, allowInv, allowMultipleTerms);
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| 105 |
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| 106 | Reset();
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| 107 | #if DEBUG
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| 108 | PrintAutomaton();
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| 109 | #endif
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| 110 | }
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| 111 |
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[15410] | 112 | // postfix notation
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[15403] | 113 | // Expr -> 0 Term { '+' Term } '+' 'exit'
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[13645] | 114 | // Term -> c Fact { '*' Fact } '*'
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| 115 | // Fact -> VarFact | ExpFact | LogFact | InvFact
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| 116 | // VarFact -> var_1 ... var_n
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| 117 | // ExpFact -> 1 ExpF { '*' ExpF } '*' c '*' 'exp' // c must be at end to allow scaling in evaluator
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| 118 | // ExpF -> var_1 ... var_n
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| 119 | // LogFact -> 0 LogT { '+' LogT } '+' c '+' 'log' // c must be at end to allow scaling in evaluator
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| 120 | // LogT -> c LogTF { '*' LogTF } '*'
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| 121 | // LogTF -> var_1 ... var_n
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| 122 | // InvFact -> 1 InvT { '+' InvT } '+' 'inv'
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| 123 | // InvT -> (var_1 ... var_n) c '*'
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| 124 | private void BuildAutomaton(int nVars,
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| 125 | bool allowProdOfVars = true,
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| 126 | bool allowExp = true,
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| 127 | bool allowLog = true,
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| 128 | bool allowInv = true,
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| 129 | bool allowMultipleTerms = false) {
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| 130 |
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| 131 | int nStates = FirstDynamicState + 4 * nVars;
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| 132 | followStates = new List<int>[nStates];
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| 133 | actions = new List<Action>[nStates, nStates];
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| 134 | actionStrings = new List<string>[nStates, nStates];
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| 135 |
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[15403] | 136 | // Expr -> 0 Term { '+' Term } '+' 'exit'
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[13645] | 137 | AddTransition(StateExpr, StateTermStart, () => {
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| 138 | codeGenerator.Reset();
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| 139 | codeGenerator.Emit1(OpCodes.LoadConst0);
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| 140 | constraintHandler.Reset();
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[15403] | 141 | }, "0, Reset");
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[13645] | 142 | AddTransition(StateTermEnd, StateExprEnd, () => {
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| 143 | codeGenerator.Emit1(OpCodes.Add);
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| 144 | codeGenerator.Emit1(OpCodes.Exit);
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[15403] | 145 | }, "+ exit");
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[13645] | 146 | if (allowMultipleTerms)
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| 147 | AddTransition(StateTermEnd, StateTermStart, () => {
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| 148 | codeGenerator.Emit1(OpCodes.Add);
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| 149 | }, "+");
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| 150 |
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| 151 | // Term -> c Fact { '*' Fact } '*'
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| 152 | AddTransition(StateTermStart, StateFactorStart,
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| 153 | () => {
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| 154 | codeGenerator.Emit1(OpCodes.LoadParamN);
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| 155 | constraintHandler.StartTerm();
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| 156 | },
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| 157 | "c, StartTerm");
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| 158 | AddTransition(StateFactorEnd, StateTermEnd,
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| 159 | () => {
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| 160 | codeGenerator.Emit1(OpCodes.Mul);
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| 161 | constraintHandler.EndTerm();
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| 162 | },
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| 163 | "*, EndTerm");
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| 164 |
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| 165 | AddTransition(StateFactorEnd, StateFactorStart,
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| 166 | () => { codeGenerator.Emit1(OpCodes.Mul); },
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| 167 | "*");
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| 168 |
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| 169 |
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| 170 | // Fact -> VarFact | ExpFact | LogFact | InvFact
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| 171 | if (allowProdOfVars)
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| 172 | AddTransition(StateFactorStart, StateVariableFactorStart, () => {
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| 173 | constraintHandler.StartFactor(StateVariableFactorStart);
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| 174 | }, "StartFactor");
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| 175 | if (allowExp)
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| 176 | AddTransition(StateFactorStart, StateExpFactorStart, () => {
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| 177 | constraintHandler.StartFactor(StateExpFactorStart);
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| 178 | }, "StartFactor");
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| 179 | if (allowLog)
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| 180 | AddTransition(StateFactorStart, StateLogFactorStart, () => {
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| 181 | constraintHandler.StartFactor(StateLogFactorStart);
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| 182 | }, "StartFactor");
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| 183 | if (allowInv)
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| 184 | AddTransition(StateFactorStart, StateInvFactorStart, () => {
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| 185 | constraintHandler.StartFactor(StateInvFactorStart);
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| 186 | }, "StartFactor");
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| 187 | AddTransition(StateVariableFactorEnd, StateFactorEnd, () => { constraintHandler.EndFactor(); }, "EndFactor");
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| 188 | AddTransition(StateExpFactorEnd, StateFactorEnd, () => { constraintHandler.EndFactor(); }, "EndFactor");
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| 189 | AddTransition(StateLogFactorEnd, StateFactorEnd, () => { constraintHandler.EndFactor(); }, "EndFactor");
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| 190 | AddTransition(StateInvFactorEnd, StateFactorEnd, () => { constraintHandler.EndFactor(); }, "EndFactor");
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| 191 |
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| 192 | // VarFact -> var_1 ... var_n
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| 193 | // add dynamic states for each variable
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| 194 | int curDynVarState = FirstDynamicState;
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| 195 | for (int i = 0; i < nVars; i++) {
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| 196 | short varIdx = (short)i;
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| 197 | var varState = curDynVarState;
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| 198 | stateNames.Add("var_1");
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| 199 | AddTransition(StateVariableFactorStart, curDynVarState,
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| 200 | () => {
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| 201 | codeGenerator.Emit2(OpCodes.LoadVar, varIdx);
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| 202 | constraintHandler.AddVarToCurrentFactor(varState);
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| 203 | },
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| 204 | "var_" + varIdx + ", AddVar");
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| 205 | AddTransition(curDynVarState, StateVariableFactorEnd);
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| 206 | curDynVarState++;
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| 207 | }
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| 208 |
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| 209 | // ExpFact -> 1 ExpF { '*' ExpF } '*' c '*' 'exp'
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| 210 | AddTransition(StateExpFactorStart, StateExpFStart,
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| 211 | () => {
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| 212 | codeGenerator.Emit1(OpCodes.LoadConst1);
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| 213 | },
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| 214 | "1");
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| 215 | AddTransition(StateExpFEnd, StateExpFactorEnd,
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| 216 | () => {
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| 217 | codeGenerator.Emit1(OpCodes.LoadParamN);
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| 218 | codeGenerator.Emit1(OpCodes.Mul);
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| 219 | codeGenerator.Emit1(OpCodes.Exp);
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| 220 | },
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[15410] | 221 | "c*exp");
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[13645] | 222 | AddTransition(StateExpFEnd, StateExpFStart,
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[15410] | 223 | () => { },
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| 224 | "");
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[13645] | 225 |
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| 226 | // ExpF -> var_1 ... var_n
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| 227 | for (int i = 0; i < nVars; i++) {
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| 228 | short varIdx = (short)i;
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| 229 | int varState = curDynVarState;
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| 230 | stateNames.Add("var_2");
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| 231 | AddTransition(StateExpFStart, curDynVarState,
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| 232 | () => {
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| 233 | codeGenerator.Emit2(OpCodes.LoadVar, varIdx);
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| 234 | constraintHandler.AddVarToCurrentFactor(varState);
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| 235 | },
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| 236 | "var_" + varIdx + ", AddVar");
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[15410] | 237 | AddTransition(curDynVarState, StateExpFEnd,
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| 238 | () => {
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| 239 | codeGenerator.Emit1(OpCodes.Mul);
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| 240 | }, "*");
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[13645] | 241 | curDynVarState++;
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| 242 | }
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| 243 |
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| 244 | // must have c at end because of adjustment of c in evaluator
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| 245 | // LogFact -> 0 LogT { '+' LogT } '+' c '+' 'log'
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| 246 | AddTransition(StateLogFactorStart, StateLogTStart,
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| 247 | () => {
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| 248 | codeGenerator.Emit1(OpCodes.LoadConst0);
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[13651] | 249 | constraintHandler.StartNewTermInPoly();
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[13645] | 250 | },
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[13651] | 251 | "0, StartTermInPoly");
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[13645] | 252 | AddTransition(StateLogTEnd, StateLogFactorEnd,
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| 253 | () => {
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| 254 | codeGenerator.Emit1(OpCodes.Add);
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| 255 | codeGenerator.Emit1(OpCodes.LoadParamN);
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| 256 | codeGenerator.Emit1(OpCodes.Add);
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| 257 | codeGenerator.Emit1(OpCodes.Log);
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| 258 | },
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| 259 | "+c+log");
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| 260 | AddTransition(StateLogTEnd, StateLogTStart,
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| 261 | () => { codeGenerator.Emit1(OpCodes.Add); },
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| 262 | "+");
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| 263 |
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| 264 | // LogT -> c LogTF { '*' LogTF } '*'
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| 265 | AddTransition(StateLogTStart, StateLogTFStart,
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| 266 | () => {
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| 267 | codeGenerator.Emit1(OpCodes.LoadParamN);
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| 268 | },
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| 269 | "c");
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| 270 | AddTransition(StateLogTFEnd, StateLogTEnd,
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| 271 | () => {
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| 272 | codeGenerator.Emit1(OpCodes.Mul);
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| 273 | },
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| 274 | "*");
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| 275 | AddTransition(StateLogTFEnd, StateLogTFStart,
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| 276 | () => {
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| 277 | codeGenerator.Emit1(OpCodes.Mul);
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| 278 | },
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| 279 | "*");
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| 280 |
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| 281 | // LogTF -> var_1 ... var_n
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| 282 | for (int i = 0; i < nVars; i++) {
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| 283 | short varIdx = (short)i;
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| 284 | int varState = curDynVarState;
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| 285 | stateNames.Add("var_3");
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| 286 | AddTransition(StateLogTFStart, curDynVarState,
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| 287 | () => {
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| 288 | codeGenerator.Emit2(OpCodes.LoadVar, varIdx);
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| 289 | constraintHandler.AddVarToCurrentFactor(varState);
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| 290 | },
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| 291 | "var_" + varIdx + ", AddVar");
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| 292 | AddTransition(curDynVarState, StateLogTFEnd);
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| 293 | curDynVarState++;
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| 294 | }
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| 295 |
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| 296 | // InvFact -> 1 InvT { '+' InvT } '+' 'inv'
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| 297 | AddTransition(StateInvFactorStart, StateInvTStart,
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| 298 | () => {
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| 299 | codeGenerator.Emit1(OpCodes.LoadConst1);
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[13651] | 300 | constraintHandler.StartNewTermInPoly();
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[13645] | 301 | },
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[13651] | 302 | "c, StartTermInPoly");
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[13645] | 303 | AddTransition(StateInvTEnd, StateInvFactorEnd,
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| 304 | () => {
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| 305 | codeGenerator.Emit1(OpCodes.Add);
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| 306 | codeGenerator.Emit1(OpCodes.Inv);
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| 307 | },
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| 308 | "+inv");
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| 309 | AddTransition(StateInvTEnd, StateInvTStart,
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| 310 | () => { codeGenerator.Emit1(OpCodes.Add); },
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| 311 | "+");
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| 312 |
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| 313 | // InvT -> c InvTF { '*' InvTF } '*'
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| 314 | AddTransition(StateInvTStart, StateInvTFStart,
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| 315 | () => {
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| 316 | codeGenerator.Emit1(OpCodes.LoadParamN);
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| 317 | },
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| 318 | "c");
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| 319 | AddTransition(StateInvTFEnd, StateInvTEnd,
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| 320 | () => {
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| 321 | codeGenerator.Emit1(OpCodes.Mul);
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| 322 | },
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| 323 | "*");
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| 324 | AddTransition(StateInvTFEnd, StateInvTFStart,
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| 325 | () => {
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| 326 | codeGenerator.Emit1(OpCodes.Mul);
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| 327 | },
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| 328 | "*");
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| 329 |
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| 330 | // InvTF -> (var_1 ... var_n) c '*'
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| 331 | for (int i = 0; i < nVars; i++) {
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| 332 | short varIdx = (short)i;
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| 333 | int varState = curDynVarState;
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| 334 | stateNames.Add("var_4");
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| 335 | AddTransition(StateInvTFStart, curDynVarState,
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| 336 | () => {
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| 337 | codeGenerator.Emit2(OpCodes.LoadVar, varIdx);
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| 338 | constraintHandler.AddVarToCurrentFactor(varState);
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| 339 | },
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| 340 | "var_" + varIdx + ", AddVar");
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| 341 | AddTransition(curDynVarState, StateInvTFEnd);
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| 342 | curDynVarState++;
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| 343 | }
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| 344 |
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| 345 | followStates[StateExprEnd] = new List<int>(); // no follow states
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[15410] | 346 |
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| 347 | // order all followstates (the first follow state leads to the final state)
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| 348 | foreach (var list in followStates) {
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| 349 | if (list != null)
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| 350 | list.Sort();
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| 351 | }
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[13645] | 352 | }
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| 353 |
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| 354 | private void AddTransition(int fromState, int toState) {
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| 355 | if (followStates[fromState] == null) followStates[fromState] = new List<int>();
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| 356 | followStates[fromState].Add(toState);
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| 357 | }
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| 358 | private void AddTransition(int fromState, int toState, Action action, string str) {
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| 359 | if (followStates[fromState] == null) followStates[fromState] = new List<int>();
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| 360 | followStates[fromState].Add(toState);
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| 361 |
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| 362 | if (actions[fromState, toState] == null) {
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| 363 | actions[fromState, toState] = new List<Action>();
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| 364 | actionStrings[fromState, toState] = new List<string>();
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| 365 | }
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| 366 |
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| 367 | actions[fromState, toState].Add(action);
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| 368 | actionStrings[fromState, toState].Add(str);
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| 369 | }
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| 370 |
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| 371 | private readonly int[] followStatesBuf = new int[1000];
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| 372 | public void FollowStates(int state, out int[] buf, out int nElements) {
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| 373 | var fs = followStates[state];
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| 374 | int j = 0;
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| 375 | for (int i = 0; i < fs.Count; i++) {
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| 376 | var s = fs[i];
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| 377 | if (constraintHandler.IsAllowedFollowState(state, s)) {
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| 378 | followStatesBuf[j++] = s;
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| 379 | }
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| 380 | }
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| 381 | buf = followStatesBuf;
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| 382 | nElements = j;
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| 383 | }
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| 384 |
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| 385 |
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| 386 | public void Goto(int targetState) {
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| 387 | if (actions[CurrentState, targetState] != null)
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| 388 | actions[CurrentState, targetState].ForEach(a => a()); // execute all actions
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| 389 | CurrentState = targetState;
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| 390 | }
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| 391 |
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| 392 | public bool IsFinalState(int s) {
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[13651] | 393 | return s == StateExprEnd && !constraintHandler.IsInvalidExpression;
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[13645] | 394 | }
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| 395 |
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[15410] | 396 | public bool IsEvalState(int v) {
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| 397 | return v == StateFactorEnd ||
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| 398 | v == StateLogTFEnd ||
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| 399 | v == StateInvTFEnd ||
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[15414] | 400 | v == StateExpFEnd
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| 401 | ;
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[15410] | 402 | }
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| 403 |
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| 404 |
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| 405 | // Always returns valid code.
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| 406 | // If the method is called in an intermediate state the expression is completed by
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| 407 | // taking the shortest route to the final state.
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| 408 | // After that state of the automaton is restored to the current state.
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[13645] | 409 | public void GetCode(out byte[] code, out int nParams) {
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[15410] | 410 | IConstraintHandler storedConstraintHandler = null;
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| 411 | int storedState = CurrentState;
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| 412 | int storedPC = codeGenerator.ProgramCounter;
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| 413 |
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| 414 | if (!IsFinalState(CurrentState)) {
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| 415 | // save state and code,
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| 416 | // constraints are ignored while completing the expression
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| 417 | storedConstraintHandler = constraintHandler;
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| 418 | constraintHandler = new EmptyConstraintHandler();
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| 419 | storedState = CurrentState;
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| 420 | storedPC = codeGenerator.ProgramCounter;
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| 421 |
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| 422 | // take shortest route to final state (smaller state values are closer to the final state)
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| 423 | while (!IsFinalState(CurrentState)) {
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| 424 | Debug.Assert(followStates[CurrentState][0] == followStates[CurrentState].Min());
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| 425 | var nextState = followStates[CurrentState][0];
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| 426 | Goto(nextState);
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| 427 | }
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| 428 | }
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| 429 |
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[13645] | 430 | codeGenerator.GetCode(out code, out nParams);
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[15410] | 431 |
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| 432 | // restore
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| 433 | if (storedConstraintHandler != null) {
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| 434 | constraintHandler = storedConstraintHandler;
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| 435 | CurrentState = storedState;
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| 436 | codeGenerator.ProgramCounter = storedPC;
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| 437 | }
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[13645] | 438 | }
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| 439 |
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| 440 | public void Reset() {
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| 441 | CurrentState = StartState;
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| 442 | codeGenerator.Reset();
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| 443 | constraintHandler.Reset();
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| 444 | }
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| 445 |
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| 446 | #if DEBUG
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| 447 | public void PrintAutomaton() {
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| 448 | using (var writer = new StreamWriter("automaton.gv")) {
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| 449 | writer.WriteLine("digraph {");
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| 450 | // writer.WriteLine("rankdir=LR");
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| 451 | for (int s = StartState; s < stateNames.Count; s++) {
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| 452 | for (int i = 0; i < followStates[s].Count; i++) {
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| 453 | if (followStates[s][i] <= 0) continue;
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| 454 | var followS = followStates[s][i];
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| 455 | var label = actionStrings[s, followS] != null ? string.Join(" , ", actionStrings[s, followS]) : "";
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| 456 | writer.WriteLine("{0} -> {1} [ label = \"{2}\" ];", stateNames[s], stateNames[followS], label);
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| 457 | }
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| 458 | }
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| 459 | writer.WriteLine("}");
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| 460 | }
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| 461 | }
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[15410] | 462 |
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[13645] | 463 | #endif
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| 464 | }
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| 465 | }
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