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1 using Implab;
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2 using Implab.Parsing;
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3 using System;
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4 using System.Collections.Generic;
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5 using System.Diagnostics;
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6 using System.Linq;
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7 using System.Text;
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8 using System.Threading.Tasks;
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9
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10 namespace Implab.JSON {
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11 /// <summary>
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12 /// internal
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13 /// </summary>
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14 public struct JSONParserContext {
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15 public string memberName;
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16 public JSONElementContext elementContext;
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17 }
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18
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19 /// <summary>
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20 /// Pull парсер JSON данных.
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21 /// </summary>
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22 public class JSONParser : DFAutomaton<JSONParserContext> {
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23
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24 enum MemberContext {
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25 MemberName,
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26 MemberValue
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27 }
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28
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29 static readonly EnumAlphabet<JsonTokenType> _alphabet = EnumAlphabet<JsonTokenType>.FullAlphabet;
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30 static readonly DFAStateDescriptior[] _jsonDFA;
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31 static readonly DFAStateDescriptior[] _objectDFA;
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32 static readonly DFAStateDescriptior[] _arrayDFA;
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33
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34 static JSONParser() {
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35 var jsonExpression = Token.New(JsonTokenType.BeginObject, JsonTokenType.BeginArray).Tag(0);
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36
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37 var valueExpression = Token.New(JsonTokenType.BeginArray, JsonTokenType.BeginObject, JsonTokenType.Literal, JsonTokenType.Number, JsonTokenType.String);
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38 var memberExpression = Token.New(JsonTokenType.String).Cat(Token.New(JsonTokenType.NameSeparator)).Cat(valueExpression);
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39 var objectExpression = memberExpression
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40 .Cat(
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41 Token.New(JsonTokenType.ValueSeparator)
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42 .Cat(memberExpression)
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43 .EClosure()
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44 )
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45 .Optional()
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46 .Cat(Token.New(JsonTokenType.EndObject))
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47 .Tag(0);
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48 var arrayExpression = valueExpression
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49 .Cat(
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50 Token.New(JsonTokenType.ValueSeparator)
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51 .Cat(valueExpression)
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52 .EClosure()
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53 )
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54 .Optional()
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55 .Cat(Token.New(JsonTokenType.EndArray))
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56 .Tag(0);
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57
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58 _jsonDFA = BuildDFA(jsonExpression).States;
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59 _objectDFA = BuildDFA(objectExpression).States;
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60 _arrayDFA = BuildDFA(arrayExpression).States;
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61 }
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62
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63 static EDFADefinition<JsonTokenType> BuildDFA(Token expr) {
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64 var builder = new DFABuilder();
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65 var dfa = new EDFADefinition<JsonTokenType>(_alphabet);
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66 expr.Accept(builder);
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67
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68 builder.BuildDFA(dfa);
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69 return dfa;
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70 }
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71
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72 JSONScanner m_scanner;
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73 MemberContext m_memberContext;
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74
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75 JSONElementType m_elementType;
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76 object m_elementValue;
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77
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78 public JSONParser(string text)
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79 : base(_jsonDFA, INITIAL_STATE, new JSONParserContext { elementContext = JSONElementContext.None, memberName = String.Empty } ) {
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80 Safe.ArgumentNotEmpty(text, "text");
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81 m_scanner = new JSONScanner();
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82 m_scanner.Feed(text.ToCharArray());
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83 }
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84
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85 public JSONElementType ElementType {
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86 get { return m_elementType; }
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87 }
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88
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89 public string ElementName {
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90 get { return m_context.info.memberName; }
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91 }
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92
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93 public object ElementValue {
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94 get { return m_elementValue; }
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95 }
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96
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97 public bool Read() {
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98 if (m_context.current == UNREACHEBLE_STATE)
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99 throw new InvalidOperationException("The parser is in invalid state");
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100 object tokenValue;
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101 JsonTokenType tokenType;
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102 m_context.info.memberName = String.Empty;
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103 while (m_scanner.ReadToken(out tokenValue, out tokenType)) {
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104 Move((int)tokenType);
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105 if (m_context.current == UNREACHEBLE_STATE)
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106 UnexpectedToken(tokenValue, tokenType);
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107 switch (tokenType) {
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108 case JsonTokenType.BeginObject:
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109 Switch(
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110 _objectDFA,
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111 INITIAL_STATE,
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112 new JSONParserContext {
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113 memberName = m_context.info.memberName,
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114 elementContext = JSONElementContext.Object
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115 }
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116 );
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117 m_elementValue = null;
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118 m_memberContext = MemberContext.MemberName;
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119 m_elementType = JSONElementType.BeginObject;
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120 return true;
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121 case JsonTokenType.EndObject:
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122 Restore();
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123 m_elementValue = null;
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124 m_elementType = JSONElementType.EndObject;
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125 return true;
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126 case JsonTokenType.BeginArray:
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127 Switch(
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128 _arrayDFA,
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129 INITIAL_STATE,
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130 new JSONParserContext {
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131 memberName = m_context.info.memberName,
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132 elementContext = JSONElementContext.Array
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133 }
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134 );
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135 m_elementValue = null;
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136 m_memberContext = MemberContext.MemberValue;
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137 m_elementType = JSONElementType.BeginArray;
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138 return true;
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139 case JsonTokenType.EndArray:
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140 Restore();
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141 m_elementValue = null;
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142 m_elementType = JSONElementType.EndArray;
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143 return true;
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144 case JsonTokenType.String:
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145 if (m_memberContext == MemberContext.MemberName) {
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146 m_context.info.memberName = (string)tokenValue;
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147 break;
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148 } else {
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149 m_elementType = JSONElementType.Value;
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150 m_elementValue = tokenValue;
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151 return true;
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152 }
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153 case JsonTokenType.Number:
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154 m_elementType = JSONElementType.Value;
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155 m_elementValue = tokenValue;
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156 return true;
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157 case JsonTokenType.Literal:
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158 m_elementType = JSONElementType.Value;
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159 m_elementValue = ParseLiteral((string)tokenValue);
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160 return true;
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161 case JsonTokenType.NameSeparator:
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162 m_memberContext = MemberContext.MemberValue;
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163 break;
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164 case JsonTokenType.ValueSeparator:
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165 m_memberContext = m_context.info.elementContext == JSONElementContext.Object ? MemberContext.MemberName : MemberContext.MemberValue;
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166 break;
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167 default:
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168 UnexpectedToken(tokenValue, tokenType);
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169 break;
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170 }
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171 }
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172 if (m_context.info.elementContext != JSONElementContext.None)
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173 throw new ParserException("Unexpedted end of data");
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174 return false;
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175 }
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176
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177 object ParseLiteral(string literal) {
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178 switch (literal) {
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179 case "null":
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180 return null;
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181 case "false" :
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182 return false;
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183 case "true":
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184 return true;
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185 default:
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186 UnexpectedToken(literal, JsonTokenType.Literal);
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187 return null; // avoid compliler error
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188 }
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189 }
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190
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191 void UnexpectedToken(object value, JsonTokenType tokenType) {
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192 throw new ParserException(String.Format("Unexpected token {0}: '{1}'", tokenType, value));
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193 }
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194
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195 }
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196
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197 }
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