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177
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1 using Implab;
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2 using System;
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3 using System.Collections.Generic;
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4 using System.Linq;
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5 using Implab.Automaton;
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6 using Implab.Automaton.RegularExpressions;
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7
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8 namespace Implab.Formats {
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9 /// <summary>
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10 /// Базовый абстрактный класс. Грамматика, позволяет формулировать выражения над алфавитом типа <c>char</c>.
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11 /// </summary>
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12 public abstract class Grammar<TSymbol, TTag> {
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13
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14 protected abstract IAlphabetBuilder<TSymbol> AlphabetBuilder {
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15 get;
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16 }
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17
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18 protected SymbolToken<TTag> UnclassifiedToken() {
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19 return new SymbolToken<TTag>(DFAConst.UNCLASSIFIED_INPUT);
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20 }
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21
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22 protected void DefineAlphabet(IEnumerable<TSymbol> alphabet) {
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23 Safe.ArgumentNotNull(alphabet, "alphabet");
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24
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25 foreach (var ch in alphabet)
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26 AlphabetBuilder.DefineSymbol(ch);
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27 }
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28
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29 protected Token<TTag> SymbolToken(TSymbol symbol) {
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30 return Token<TTag>.New(TranslateOrAdd(symbol));
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31 }
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32
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33 protected Token<TTag> SymbolToken(IEnumerable<TSymbol> symbols) {
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34 Safe.ArgumentNotNull(symbols, "symbols");
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35
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36 return Token<TTag>.New(TranslateOrAdd(symbols).ToArray());
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37 }
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38
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39 protected Token<TTag> SymbolSetToken(params TSymbol[] set) {
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40 return SymbolToken(set);
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41 }
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42
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43 int TranslateOrAdd(TSymbol ch) {
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44 var t = AlphabetBuilder.Translate(ch);
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45 if (t == DFAConst.UNCLASSIFIED_INPUT)
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46 t = AlphabetBuilder.DefineSymbol(ch);
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47 return t;
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48 }
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49
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50 IEnumerable<int> TranslateOrAdd(IEnumerable<TSymbol> symbols) {
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51 return symbols.Distinct().Select(TranslateOrAdd);
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52 }
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53
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54 int TranslateOrDie(TSymbol ch) {
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55 var t = AlphabetBuilder.Translate(ch);
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56 if (t == DFAConst.UNCLASSIFIED_INPUT)
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57 throw new ApplicationException(String.Format("Symbol '{0}' is UNCLASSIFIED", ch));
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58 return t;
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59 }
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60
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61 IEnumerable<int> TranslateOrDie(IEnumerable<TSymbol> symbols) {
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62 return symbols.Distinct().Select(TranslateOrDie);
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63 }
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64
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65 protected Token<TTag> SymbolTokenExcept(IEnumerable<TSymbol> symbols) {
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66 Safe.ArgumentNotNull(symbols, "symbols");
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67
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68 return Token<TTag>.New( Enumerable.Range(0, AlphabetBuilder.Count).Except(TranslateOrDie(symbols)).ToArray() );
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69 }
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70
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71 protected abstract IndexedAlphabetBase<TSymbol> CreateAlphabet();
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72
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73 protected ScannerContext<TTag> BuildScannerContext(Token<TTag> regexp) {
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74
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75 var dfa = new RegularDFA<TSymbol, TTag>(AlphabetBuilder);
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76
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77 var visitor = new RegularExpressionVisitor<TTag>();
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78 regexp.Accept( visitor );
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79
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80 visitor.BuildDFA(dfa);
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81
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82 if (dfa.IsFinalState(dfa.InitialState))
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83 throw new ApplicationException("The specified language contains empty token");
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84
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85 var ab = CreateAlphabet();
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86 var optimal = dfa.Optimize(ab);
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87
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88 return new ScannerContext<TTag>(
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89 optimal.CreateTransitionTable(),
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90 optimal.CreateFinalStateTable(),
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91 optimal.CreateTagTable(),
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92 optimal.InitialState,
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93 ab.GetTranslationMap()
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94 );
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95 }
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96
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97 }
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98
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99
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100 }
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