annotate Implab/Formats/JSON/JSONScanner.cs @ 197:86187b01c4e0

fixed: the error handler should not handle handlers errors
author cin
date Thu, 01 Sep 2016 10:43:31 +0300
parents 4f82e0f161c3
children 7d07503621fe
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
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1 using System;
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2 using System.Globalization;
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3 using Implab.Automaton;
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4 using System.Text;
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5 using Implab.Components;
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6 using System.IO;
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7
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8 namespace Implab.Formats.JSON {
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9 /// <summary>
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10 /// Сканнер (лексер), разбивающий поток символов на токены JSON.
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11 /// </summary>
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12 public class JSONScanner : Disposable {
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13 readonly StringBuilder m_builder = new StringBuilder();
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14
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15 readonly ScannerContext<JSONGrammar.TokenType> m_jsonContext = JSONGrammar.Instance.JsonExpression;
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16 readonly ScannerContext<JSONGrammar.TokenType> m_stringContext = JSONGrammar.Instance.JsonStringExpression;
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18
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19 readonly TextScanner m_scanner;
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20
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21 /// <summary>
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22 /// Создает новый экземпляр сканнера
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23 /// </summary>
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24 public JSONScanner(string text) {
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25 Safe.ArgumentNotEmpty(text, "text");
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26
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27 m_scanner = new StringScanner(text);
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28 }
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29
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30 public JSONScanner(TextReader reader, int bufferMax, int chunkSize) {
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31 Safe.ArgumentNotNull(reader, "reader");
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32
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33 m_scanner = new ReaderScanner(reader, bufferMax, chunkSize);
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34 }
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35
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36 public JSONScanner(TextReader reader) : this(reader, 1024*1024, 1024){
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37 }
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38
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39 /// <summary>
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40 /// Читает следующий лексический элемент из входных данных.
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41 /// </summary>
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42 /// <param name="tokenValue">Возвращает значение прочитанного токена.</param>
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43 /// <param name="tokenType">Возвращает тип прочитанного токена.</param>
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44 /// <returns><c>true</c> - чтение произведено успешно. <c>false</c> - достигнут конец входных данных</returns>
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45 /// <remarks>В случе если токен не распознается, возникает исключение. Значения токенов обрабатываются, т.е.
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46 /// в строках обрабатываются экранированные символы, числа становтся типа double.</remarks>
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47 public bool ReadToken(out object tokenValue, out JsonTokenType tokenType) {
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48 JSONGrammar.TokenType[] tag;
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49 while (m_jsonContext.Execute(m_scanner, out tag)) {
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50 switch (tag[0]) {
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51 case JSONGrammar.TokenType.StringBound:
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52 tokenValue = ReadString();
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53 tokenType = JsonTokenType.String;
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54 break;
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55 case JSONGrammar.TokenType.Number:
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56 tokenValue = Double.Parse(m_scanner.GetTokenValue(), CultureInfo.InvariantCulture);
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57 tokenType = JsonTokenType.Number;
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58 break;
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59 case JSONGrammar.TokenType.Whitespace:
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60 continue;
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61 default:
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62 tokenType = (JsonTokenType)tag[0];
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63 tokenValue = m_scanner.GetTokenValue();
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64 break;
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65 }
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66 return true;
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67 }
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68 tokenValue = null;
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69 tokenType = JsonTokenType.None;
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70 return false;
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71 }
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72
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73 string ReadString() {
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74 int pos = 0;
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75 var buf = new char[6]; // the buffer for unescaping chars
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77 JSONGrammar.TokenType[] tag;
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78 m_builder.Clear();
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79
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80 while (m_stringContext.Execute(m_scanner, out tag)) {
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81 switch (tag[0]) {
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82 case JSONGrammar.TokenType.StringBound:
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83 return m_builder.ToString();
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84 case JSONGrammar.TokenType.UnescapedChar:
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85 m_scanner.CopyTokenTo(m_builder);
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86 break;
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87 case JSONGrammar.TokenType.EscapedUnicode: // \xXXXX - unicode escape sequence
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88 m_scanner.CopyTokenTo(buf, 0);
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89 m_builder.Append(StringTranslator.TranslateHexUnicode(buf, 2));
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90 pos++;
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91 break;
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92 case JSONGrammar.TokenType.EscapedChar: // \t - escape sequence
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93 m_scanner.CopyTokenTo(buf, 0);
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94 m_builder.Append(StringTranslator.TranslateEscapedChar(buf[1]));
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95 break;
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96 }
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98 }
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99
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100 throw new ParserException("Unexpected end of data");
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101 }
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102
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103 protected override void Dispose(bool disposing) {
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104 if (disposing)
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105 Safe.Dispose(m_scanner);
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106 base.Dispose(disposing);
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107 }
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108 }
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109 }