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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 System.Text;
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6 using System.Threading.Tasks;
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7
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8 namespace Implab.Parsing {
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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 /// <typeparam name="TGrammar"></typeparam>
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13 public abstract class Grammar<TGrammar> where TGrammar: Grammar<TGrammar>, new() {
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14 static TGrammar _instance;
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15
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16 public static TGrammar Instance{
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17 get {
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18 if (_instance == null)
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19 _instance = new TGrammar();
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20 return _instance;
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21 }
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22 }
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23
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158
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24 readonly CharAlphabet m_alphabet = new CharAlphabet();
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25
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26 public CharAlphabet Alphabet {
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27 get { return m_alphabet; }
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28 }
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29
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30 public SymbolToken UnclassifiedToken() {
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158
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31 return new SymbolToken(CharAlphabet.UNCLASSIFIED);
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32 }
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33
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34 public void DefineAlphabet(IEnumerable<char> alphabet) {
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35 Safe.ArgumentNotNull(alphabet, "alphabet");
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36
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37 foreach (var ch in alphabet)
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38 m_alphabet.DefineSymbol(ch);
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39 }
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40 public Token SymbolRangeToken(char start, char end) {
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41 return SymbolToken(Enumerable.Range(start, end - start + 1).Select(x => (char)x));
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42 }
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43
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44 public Token SymbolToken(char symbol) {
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45 return Token.New(TranslateOrAdd(symbol));
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46 }
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47
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48 public Token SymbolToken(IEnumerable<char> symbols) {
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49 Safe.ArgumentNotNull(symbols, "symbols");
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50
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51 return Token.New(TranslateOrAdd(symbols).ToArray());
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52 }
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53
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54 public Token SymbolSetToken(params char[] set) {
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55 return SymbolToken(set);
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56 }
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57
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58 int TranslateOrAdd(char ch) {
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59 var t = m_alphabet.Translate(ch);
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158
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60 if (t == CharAlphabet.UNCLASSIFIED)
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61 t = m_alphabet.DefineSymbol(ch);
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62 return t;
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63 }
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64
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65 IEnumerable<int> TranslateOrAdd(IEnumerable<char> symbols) {
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66 return symbols.Distinct().Select(TranslateOrAdd);
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67 }
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68
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69 int TranslateOrDie(char ch) {
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70 var t = m_alphabet.Translate(ch);
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158
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71 if (t == CharAlphabet.UNCLASSIFIED)
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72 throw new ApplicationException(String.Format("Symbol '{0}' is UNCLASSIFIED", ch));
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73 return t;
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74 }
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75
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76 IEnumerable<int> TranslateOrDie(IEnumerable<char> symbols) {
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77 return symbols.Distinct().Select(TranslateOrDie);
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78 }
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79
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80 public Token SymbolTokenExcept(IEnumerable<char> symbols) {
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81 Safe.ArgumentNotNull(symbols, "symbols");
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82
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83 return Token.New( Enumerable.Range(0, m_alphabet.Count).Except(TranslateOrDie(symbols)).ToArray());
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84 }
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85
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86 protected CDFADefinition BuildDFA(Token lang) {
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87 Safe.ArgumentNotNull(lang, "lang");
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88
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89 var dfa = new CDFADefinition(m_alphabet);
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90
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91 var builder = new DFABuilder();
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92
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93 lang.Accept( builder );
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94
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95 builder.BuildDFA(dfa);
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96 if (dfa.InitialStateIsFinal)
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97 throw new ApplicationException("The specified language contains empty token");
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98
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99 return dfa.Optimize();
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100 }
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101
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102
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103
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104 //protected abstract TGrammar CreateInstance();
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105 }
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106
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107
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108 }
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