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comparison Implab/JSON/JSONParser.cs @ 55:c0bf853aa04f

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Added initial JSON support +JSONParser +JSONWriter
author cin
date Sun, 15 Jun 2014 19:39:11 +0400
parents
children 7759c80cad95
comparison
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51:2c332a9c64c0 55:c0bf853aa04f
1 using Implab;
2 using Implab.Parsing;
3 using System;
4 using System.Collections.Generic;
5 using System.Diagnostics;
6 using System.Linq;
7 using System.Text;
8 using System.Threading.Tasks;
9
10 namespace Implab.JSON {
11 /// <summary>
12 /// internal
13 /// </summary>
14 public struct JSONParserContext {
15 public string memberName;
16 public JSONElementContext elementContext;
17 }
18
19 /// <summary>
20 /// Pull парсер JSON данных.
21 /// </summary>
22 public class JSONParser : DFAutomaton<JSONParserContext> {
23
24 enum MemberContext {
25 MemberName,
26 MemberValue
27 }
28
29 static readonly EnumAlphabet<JsonTokenType> _alphabet = EnumAlphabet<JsonTokenType>.FullAlphabet;
30 static readonly DFAStateDescriptior[] _jsonDFA;
31 static readonly DFAStateDescriptior[] _objectDFA;
32 static readonly DFAStateDescriptior[] _arrayDFA;
33
34 static JSONParser() {
35 var jsonExpression = Token.New(JsonTokenType.BeginObject, JsonTokenType.BeginArray).Tag(0);
36
37 var valueExpression = Token.New(JsonTokenType.BeginArray, JsonTokenType.BeginObject, JsonTokenType.Literal, JsonTokenType.Number, JsonTokenType.String);
38 var memberExpression = Token.New(JsonTokenType.String).Cat(Token.New(JsonTokenType.NameSeparator)).Cat(valueExpression);
39 var objectExpression = memberExpression
40 .Cat(
41 Token.New(JsonTokenType.ValueSeparator)
42 .Cat(memberExpression)
43 .EClosure()
44 )
45 .Optional()
46 .Cat(Token.New(JsonTokenType.EndObject))
47 .Tag(0);
48 var arrayExpression = valueExpression
49 .Cat(
50 Token.New(JsonTokenType.ValueSeparator)
51 .Cat(valueExpression)
52 .EClosure()
53 )
54 .Optional()
55 .Cat(Token.New(JsonTokenType.EndArray))
56 .Tag(0);
57
58 _jsonDFA = BuildDFA(jsonExpression).States;
59 _objectDFA = BuildDFA(objectExpression).States;
60 _arrayDFA = BuildDFA(arrayExpression).States;
61 }
62
63 static EDFADefinition<JsonTokenType> BuildDFA(Token expr) {
64 var builder = new DFABuilder();
65 var dfa = new EDFADefinition<JsonTokenType>(_alphabet);
66 expr.Accept(builder);
67
68 builder.BuildDFA(dfa);
69 return dfa;
70 }
71
72 JSONScanner m_scanner;
73 MemberContext m_memberContext;
74
75 JSONElementType m_elementType;
76 object m_elementValue;
77
78 public JSONParser(string text)
79 : base(_jsonDFA, INITIAL_STATE, new JSONParserContext { elementContext = JSONElementContext.None, memberName = String.Empty } ) {
80 Safe.ArgumentNotEmpty(text, "text");
81 m_scanner = new JSONScanner();
82 m_scanner.Feed(text.ToCharArray());
83 }
84
85 public JSONElementType ElementType {
86 get { return m_elementType; }
87 }
88
89 public string ElementName {
90 get { return m_context.info.memberName; }
91 }
92
93 public object ElementValue {
94 get { return m_elementValue; }
95 }
96
97 public bool Read() {
98 if (m_context.current == UNREACHEBLE_STATE)
99 throw new InvalidOperationException("The parser is in invalid state");
100 object tokenValue;
101 JsonTokenType tokenType;
102 m_context.info.memberName = String.Empty;
103 while (m_scanner.ReadToken(out tokenValue, out tokenType)) {
104 Move((int)tokenType);
105 if (m_context.current == UNREACHEBLE_STATE)
106 UnexpectedToken(tokenValue, tokenType);
107 switch (tokenType) {
108 case JsonTokenType.BeginObject:
109 Switch(
110 _objectDFA,
111 INITIAL_STATE,
112 new JSONParserContext {
113 memberName = m_context.info.memberName,
114 elementContext = JSONElementContext.Object
115 }
116 );
117 m_elementValue = null;
118 m_memberContext = MemberContext.MemberName;
119 m_elementType = JSONElementType.BeginObject;
120 return true;
121 case JsonTokenType.EndObject:
122 Restore();
123 m_elementValue = null;
124 m_elementType = JSONElementType.EndObject;
125 return true;
126 case JsonTokenType.BeginArray:
127 Switch(
128 _arrayDFA,
129 INITIAL_STATE,
130 new JSONParserContext {
131 memberName = m_context.info.memberName,
132 elementContext = JSONElementContext.Array
133 }
134 );
135 m_elementValue = null;
136 m_memberContext = MemberContext.MemberValue;
137 m_elementType = JSONElementType.BeginArray;
138 return true;
139 case JsonTokenType.EndArray:
140 Restore();
141 m_elementValue = null;
142 m_elementType = JSONElementType.EndArray;
143 return true;
144 case JsonTokenType.String:
145 if (m_memberContext == MemberContext.MemberName) {
146 m_context.info.memberName = (string)tokenValue;
147 break;
148 } else {
149 m_elementType = JSONElementType.Value;
150 m_elementValue = tokenValue;
151 return true;
152 }
153 case JsonTokenType.Number:
154 m_elementType = JSONElementType.Value;
155 m_elementValue = tokenValue;
156 return true;
157 case JsonTokenType.Literal:
158 m_elementType = JSONElementType.Value;
159 m_elementValue = ParseLiteral((string)tokenValue);
160 return true;
161 case JsonTokenType.NameSeparator:
162 m_memberContext = MemberContext.MemberValue;
163 break;
164 case JsonTokenType.ValueSeparator:
165 m_memberContext = m_context.info.elementContext == JSONElementContext.Object ? MemberContext.MemberName : MemberContext.MemberValue;
166 break;
167 default:
168 UnexpectedToken(tokenValue, tokenType);
169 break;
170 }
171 }
172 if (m_context.info.elementContext != JSONElementContext.None)
173 throw new ParserException("Unexpedted end of data");
174 return false;
175 }
176
177 object ParseLiteral(string literal) {
178 switch (literal) {
179 case "null":
180 return null;
181 case "false" :
182 return false;
183 case "true":
184 return true;
185 default:
186 UnexpectedToken(literal, JsonTokenType.Literal);
187 return null; // avoid compliler error
188 }
189 }
190
191 void UnexpectedToken(object value, JsonTokenType tokenType) {
192 throw new ParserException(String.Format("Unexpected token {0}: '{1}'", tokenType, value));
193 }
194
195 }
196
197 }