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55
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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.IO;
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7 using System.Linq;
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8 using System.Text;
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9 using System.Threading.Tasks;
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10
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11 namespace Implab.JSON {
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12 /// <summary>
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13 /// internal
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14 /// </summary>
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15 public struct JSONParserContext {
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16 public string memberName;
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17 public JSONElementContext elementContext;
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18 }
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19
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20 /// <summary>
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21 /// Pull парсер JSON данных.
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22 /// </summary>
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23 public class JSONParser : DFAutomaton<JSONParserContext>, IDisposable {
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24
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25 enum MemberContext {
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26 MemberName,
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27 MemberValue
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28 }
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29
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30 static readonly EnumAlphabet<JsonTokenType> _alphabet = EnumAlphabet<JsonTokenType>.FullAlphabet;
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31 static readonly DFAStateDescriptior[] _jsonDFA;
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32 static readonly DFAStateDescriptior[] _objectDFA;
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33 static readonly DFAStateDescriptior[] _arrayDFA;
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34
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35 static JSONParser() {
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36 var jsonExpression = Token.New(JsonTokenType.BeginObject, JsonTokenType.BeginArray).Tag(0);
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37
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38 var valueExpression = Token.New(JsonTokenType.BeginArray, JsonTokenType.BeginObject, JsonTokenType.Literal, JsonTokenType.Number, JsonTokenType.String);
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39 var memberExpression = Token.New(JsonTokenType.String).Cat(Token.New(JsonTokenType.NameSeparator)).Cat(valueExpression);
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40 var objectExpression = memberExpression
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41 .Cat(
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42 Token.New(JsonTokenType.ValueSeparator)
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43 .Cat(memberExpression)
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44 .EClosure()
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45 )
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46 .Optional()
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47 .Cat(Token.New(JsonTokenType.EndObject))
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48 .Tag(0);
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49 var arrayExpression = valueExpression
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50 .Cat(
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51 Token.New(JsonTokenType.ValueSeparator)
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52 .Cat(valueExpression)
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53 .EClosure()
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54 )
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55 .Optional()
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56 .Cat(Token.New(JsonTokenType.EndArray))
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57 .Tag(0);
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58
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59 _jsonDFA = BuildDFA(jsonExpression).States;
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60 _objectDFA = BuildDFA(objectExpression).States;
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61 _arrayDFA = BuildDFA(arrayExpression).States;
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62 }
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63
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64 static EDFADefinition<JsonTokenType> BuildDFA(Token expr) {
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65 var builder = new DFABuilder();
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66 var dfa = new EDFADefinition<JsonTokenType>(_alphabet);
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67 expr.Accept(builder);
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68
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69 builder.BuildDFA(dfa);
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70 return dfa;
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71 }
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72
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73 JSONScanner m_scanner;
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74 MemberContext m_memberContext;
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75
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76 JSONElementType m_elementType;
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77 object m_elementValue;
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78
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79 /// <summary>
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80 /// Создает новый парсер на основе строки, содержащей JSON
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81 /// </summary>
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82 /// <param name="text"></param>
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83 public JSONParser(string text)
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84 : base(_jsonDFA, INITIAL_STATE, new JSONParserContext { elementContext = JSONElementContext.None, memberName = String.Empty }) {
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85 Safe.ArgumentNotEmpty(text, "text");
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86 m_scanner = new JSONScanner();
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87 m_scanner.Feed(text.ToCharArray());
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88 }
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89
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90 /// <summary>
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91 /// Создает новый экземпляр парсера, на основе текстового потока.
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92 /// </summary>
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93 /// <param name="reader">Текстовый поток.</param>
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94 /// <param name="dispose">Признак того, что парсер должен конролировать время жизни входного потока.</param>
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95 public JSONParser(TextReader reader, bool dispose)
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96 : base(_jsonDFA, INITIAL_STATE, new JSONParserContext { elementContext = JSONElementContext.None, memberName = String.Empty }) {
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97 Safe.ArgumentNotNull(reader, "reader");
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98 m_scanner = new JSONScanner();
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99 m_scanner.Feed(reader, dispose);
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100 }
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101
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102 /// <summary>
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103 /// Тип текущего элемента на котором стоит парсер.
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104 /// </summary>
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105 public JSONElementType ElementType {
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106 get { return m_elementType; }
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107 }
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108
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109 /// <summary>
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110 /// Имя элемента - имя свойства родительского контейнера. Для элементов массивов и корневого всегда
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111 /// пустая строка.
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112 /// </summary>
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113 public string ElementName {
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114 get { return m_context.info.memberName; }
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115 }
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116
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117 /// <summary>
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118 /// Значение элемента. Только для элементов типа <see cref="JSONElementType.Value"/>, для остальных <c>null</c>
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119 /// </summary>
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120 public object ElementValue {
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121 get { return m_elementValue; }
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122 }
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123
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124 /// <summary>
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125 /// Читает слеюудущий объект из потока
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126 /// </summary>
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127 /// <returns><c>true</c> - операция чтения прошла успешно, <c>false</c> - конец данных</returns>
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128 public bool Read() {
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129 if (m_context.current == UNREACHEBLE_STATE)
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130 throw new InvalidOperationException("The parser is in invalid state");
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131 object tokenValue;
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132 JsonTokenType tokenType;
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133 m_context.info.memberName = String.Empty;
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134 while (m_scanner.ReadToken(out tokenValue, out tokenType)) {
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135 Move((int)tokenType);
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136 if (m_context.current == UNREACHEBLE_STATE)
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137 UnexpectedToken(tokenValue, tokenType);
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138 switch (tokenType) {
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139 case JsonTokenType.BeginObject:
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140 Switch(
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141 _objectDFA,
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142 INITIAL_STATE,
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143 new JSONParserContext {
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144 memberName = m_context.info.memberName,
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145 elementContext = JSONElementContext.Object
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146 }
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147 );
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148 m_elementValue = null;
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149 m_memberContext = MemberContext.MemberName;
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150 m_elementType = JSONElementType.BeginObject;
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151 return true;
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152 case JsonTokenType.EndObject:
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153 Restore();
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154 m_elementValue = null;
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155 m_elementType = JSONElementType.EndObject;
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156 return true;
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157 case JsonTokenType.BeginArray:
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158 Switch(
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159 _arrayDFA,
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160 INITIAL_STATE,
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161 new JSONParserContext {
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162 memberName = m_context.info.memberName,
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163 elementContext = JSONElementContext.Array
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164 }
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165 );
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166 m_elementValue = null;
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167 m_memberContext = MemberContext.MemberValue;
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168 m_elementType = JSONElementType.BeginArray;
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169 return true;
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170 case JsonTokenType.EndArray:
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171 Restore();
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172 m_elementValue = null;
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173 m_elementType = JSONElementType.EndArray;
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174 return true;
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175 case JsonTokenType.String:
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176 if (m_memberContext == MemberContext.MemberName) {
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177 m_context.info.memberName = (string)tokenValue;
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178 break;
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179 } else {
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180 m_elementType = JSONElementType.Value;
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181 m_elementValue = tokenValue;
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182 return true;
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183 }
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184 case JsonTokenType.Number:
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185 m_elementType = JSONElementType.Value;
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186 m_elementValue = tokenValue;
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187 return true;
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188 case JsonTokenType.Literal:
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189 m_elementType = JSONElementType.Value;
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190 m_elementValue = ParseLiteral((string)tokenValue);
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191 return true;
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192 case JsonTokenType.NameSeparator:
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193 m_memberContext = MemberContext.MemberValue;
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194 break;
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195 case JsonTokenType.ValueSeparator:
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196 m_memberContext = m_context.info.elementContext == JSONElementContext.Object ? MemberContext.MemberName : MemberContext.MemberValue;
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197 break;
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198 default:
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199 UnexpectedToken(tokenValue, tokenType);
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200 break;
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201 }
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202 }
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203 if (m_context.info.elementContext != JSONElementContext.None)
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204 throw new ParserException("Unexpedted end of data");
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205 return false;
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206 }
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207
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208 object ParseLiteral(string literal) {
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209 switch (literal) {
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210 case "null":
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211 return null;
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212 case "false":
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213 return false;
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214 case "true":
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215 return true;
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216 default:
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217 UnexpectedToken(literal, JsonTokenType.Literal);
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218 return null; // avoid compliler error
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219 }
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220 }
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221
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222 void UnexpectedToken(object value, JsonTokenType tokenType) {
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223 throw new ParserException(String.Format("Unexpected token {0}: '{1}'", tokenType, value));
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224 }
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225
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226
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227 /// <summary>
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228 /// Признак конца потока
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229 /// </summary>
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230 public bool EOF {
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231 get {
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232 return m_scanner.EOF;
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233 }
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234 }
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235
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236 protected virtual void Dispose(bool disposing) {
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237 if (disposing) {
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238 m_scanner.Dispose();
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239 }
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240 }
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241
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242 /// <summary>
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243 /// Освобождает парсер и связанный с ним сканнер.
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244 /// </summary>
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245 public void Dispose() {
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246 Dispose(true);
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247 GC.SuppressFinalize(this);
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248 }
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249
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250 ~JSONParser() {
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251 Dispose(false);
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252 }
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55
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253 }
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254
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255 }
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