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1 using System.Linq;
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2 using Implab.Automaton.RegularExpressions;
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3 using System;
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4 using Implab.Automaton;
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5 using Implab.Components;
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6
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7 namespace Implab.Formats.JSON {
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8 class JSONGrammar : Grammar<char> {
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9 public enum TokenType {
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10 None,
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11 BeginObject,
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12 EndObject,
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13 BeginArray,
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14 EndArray,
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15 String,
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16 Number,
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17 Literal,
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18 NameSeparator,
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19 ValueSeparator,
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20
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21 StringBound,
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22 EscapedChar,
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23 UnescapedChar,
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24 EscapedUnicode
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25 }
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26
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27 static LazyAndWeak<JSONGrammar> _instance = new LazyAndWeak<JSONGrammar>(() => new JSONGrammar());
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28
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29 public static JSONGrammar Instance {
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30 get { return _instance.Value; }
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31 }
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32
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33 readonly ScannerContext<TokenType> m_jsonExpression;
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34 readonly ScannerContext<TokenType> m_stringExpression;
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35 readonly CharAlphabet m_defaultAlphabet = new CharAlphabet();
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36
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37 public JSONGrammar() {
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38 DefineAlphabet(Enumerable.Range(0, 0x20).Select(x => (char)x));
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39 var hexDigit = SymbolRangeToken('a','f').Or(SymbolRangeToken('A','F')).Or(SymbolRangeToken('0','9'));
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40 var digit9 = SymbolRangeToken('1', '9');
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41 var zero = SymbolToken('0');
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42 var digit = zero.Or(digit9);
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43 var dot = SymbolToken('.');
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44 var minus = SymbolToken('-');
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45 var sign = SymbolSetToken('-', '+');
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46 var expSign = SymbolSetToken('e', 'E');
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47 var letters = SymbolRangeToken('a', 'z');
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48 var integer = zero.Or(digit9.Cat(digit.EClosure()));
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49 var frac = dot.Cat(digit.Closure());
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50 var exp = expSign.Cat(sign.Optional()).Cat(digit.Closure());
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51 var quote = SymbolToken('"');
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52 var backSlash = SymbolToken('\\');
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53 var specialEscapeChars = SymbolSetToken('\\', '"', '/', 'b', 'f', 't', 'n', 'r');
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54 var unicodeEspace = SymbolToken('u').Cat(hexDigit.Repeat(4));
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55 var whitespace = SymbolSetToken('\n', '\r', '\t', ' ').EClosure();
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56 var beginObject = whitespace.Cat(SymbolToken('{')).Cat(whitespace);
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57 var endObject = whitespace.Cat(SymbolToken('}')).Cat(whitespace);
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58 var beginArray = whitespace.Cat(SymbolToken('[')).Cat(whitespace);
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59 var endArray = whitespace.Cat(SymbolToken(']')).Cat(whitespace);
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60 var nameSep = whitespace.Cat(SymbolToken(':')).Cat(whitespace);
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61 var valueSep = whitespace.Cat(SymbolToken(',')).Cat(whitespace);
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62
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63 var number = minus.Optional().Cat(integer).Cat(frac.Optional()).Cat(exp.Optional());
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64 var literal = letters.Closure();
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65 var unescaped = SymbolTokenExcept(Enumerable.Range(0, 0x20).Union(new int[] { '\\', '"' }).Select(x => (char)x));
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66
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67 var jsonExpression =
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68 number.Tag(TokenType.Number)
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69 .Or(literal.Tag(TokenType.Literal))
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70 .Or(quote.Tag(TokenType.StringBound))
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71 .Or(beginObject.Tag(TokenType.BeginObject))
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72 .Or(endObject.Tag(TokenType.EndObject))
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73 .Or(beginArray.Tag(TokenType.BeginArray))
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74 .Or(endArray.Tag(TokenType.EndArray))
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75 .Or(nameSep.Tag(TokenType.NameSeparator))
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76 .Or(valueSep.Tag(TokenType.ValueSeparator));
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77
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78
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79 var jsonStringExpression =
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80 quote.Tag(TokenType.StringBound)
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81 .Or(backSlash.Cat(specialEscapeChars).Tag(TokenType.EscapedChar))
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82 .Or(backSlash.Cat(unicodeEspace).Tag(TokenType.EscapedUnicode))
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83 .Or(unescaped.Closure().Tag(TokenType.UnescapedChar));
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84
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85
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86 m_jsonExpression = BuildScannerContext<TokenType>(jsonExpression);
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87 m_stringExpression = BuildScannerContext<TokenType>(jsonStringExpression);
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88
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89
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90 }
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91
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92 protected override IAlphabetBuilder<char> AlphabetBuilder {
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93 get {
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94 return m_defaultAlphabet;
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95 }
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96 }
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97
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98 public ScannerContext<TokenType> JsonExpression {
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99 get {
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100 return m_jsonExpression;
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101 }
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102 }
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103
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104 public ScannerContext<TokenType> JsonStringExpression {
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105 get {
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106 return m_stringExpression;
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107 }
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108 }
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109
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110 Token SymbolRangeToken(char start, char stop) {
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111 return SymbolToken(Enumerable.Range(start,stop - start).Cast<char>());
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112 }
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113
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114 protected override IndexedAlphabetBase<char> CreateAlphabet() {
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115 return new CharAlphabet();
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116 }
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117
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118 }
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119 }
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