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1 using System;
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2 using Implab.Components;
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175
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3 using System.Diagnostics;
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4 using Implab.Automaton;
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176
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5 using System.Text;
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6
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7 namespace Implab.Formats {
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8 public abstract class TextScanner : Disposable {
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9 readonly int m_bufferMax;
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10 readonly int m_chunkSize;
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11
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12 char[] m_buffer;
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13 int m_bufferOffset;
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14 int m_bufferSize;
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15 int m_tokenOffset;
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16 int m_tokenLength;
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17
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18 /// <summary>
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19 /// Initializes a new instance of the <see cref="Implab.Formats.TextScanner"/> class.
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20 /// </summary>
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21 /// <param name="bufferMax">Buffer max.</param>
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22 /// <param name="chunkSize">Chunk size.</param>
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23 protected TextScanner(int bufferMax, int chunkSize) {
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24 Debug.Assert(m_chunkSize <= m_bufferMax);
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25
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26 m_bufferMax = bufferMax;
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27 m_chunkSize = chunkSize;
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28 }
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29
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30 /// <summary>
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31 /// Initializes a new instance of the <see cref="Implab.Formats.TextScanner"/> class.
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32 /// </summary>
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33 /// <param name="buffer">Buffer.</param>
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34 protected TextScanner(char[] buffer) {
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35 if (buffer != null) {
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36 m_buffer = buffer;
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37 m_bufferSize = buffer.Length;
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38 }
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39 }
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40
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41 /// <summary>
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42 /// (hungry) Reads the next token.
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43 /// </summary>
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44 /// <returns><c>true</c>, if token internal was read, <c>false</c> if there is no more tokens in the stream.</returns>
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45 /// <param name="dfa">The transition map for the automaton</param>
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46 /// <param name="final">Final states of the automaton.</param>
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47 /// <param name="tags">Tags.</param>
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48 /// <param name="state">The initial state for the automaton.</param>
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49 /// <param name="alphabet"></param>
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50 /// <param name = "tag"></param>
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51 internal bool ReadToken<TTag>(int[,] dfa, bool[] final, TTag[][] tags, int state, int[] alphabet, out TTag[] tag) {
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52 m_tokenLength = 0;
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53 tag = null;
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54
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55 var maxSymbol = alphabet.Length - 1;
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56
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57 do {
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58 // after the next chunk is read the offset in the buffer may change
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59 int pos = m_bufferOffset + m_tokenLength;
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60
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61 while (pos < m_bufferSize) {
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62 var ch = m_buffer[pos];
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63
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64 state = dfa[state, ch > maxSymbol ? AutomatonConst.UNCLASSIFIED_INPUT : alphabet[ch]];
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65 if (state == AutomatonConst.UNREACHABLE_STATE)
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66 break;
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67
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68 pos++;
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69 }
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70
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71 m_tokenLength = pos - m_bufferOffset;
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72 } while (state != AutomatonConst.UNREACHABLE_STATE && Feed());
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73
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74 m_tokenOffset = m_bufferOffset;
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75 m_bufferOffset += m_tokenLength;
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76
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77 if (final[state]) {
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78 tag = tags[state];
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79 return true;
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80 }
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81
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82 if (m_bufferOffset == m_bufferSize) {
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83 if (m_tokenLength == 0) //EOF
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84 return false;
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85
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86 throw new ParserException();
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87 }
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88
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89 throw new ParserException(String.Format("Unexpected symbol '{0}'", m_buffer[m_bufferOffset]));
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90
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91 }
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92
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93 protected void Feed(char[] buffer, int offset, int length) {
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94 m_buffer = buffer;
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95 m_bufferOffset = offset;
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96 m_bufferSize = offset + length;
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97 }
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98
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99 protected bool Feed() {
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100 if (m_chunkSize <= 0)
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101 return false;
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102
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103 if (m_buffer != null) {
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104 var free = m_buffer.Length - m_bufferSize;
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105
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106 if (free < m_chunkSize) {
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107 free += m_chunkSize;
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108 var used = m_bufferSize - m_bufferOffset;
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109 var size = used + free;
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110
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111 if (size > m_bufferMax)
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112 throw new ParserException(String.Format("The buffer limit ({0} Kb) is reached", m_bufferMax / 1024));
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113
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114 var temp = new char[size];
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115
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116 var read = Read(temp, used, m_chunkSize);
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117 if (read == 0)
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118 return false;
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119
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120 Array.Copy(m_buffer, m_bufferOffset, temp, 0, used);
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121
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122 m_bufferOffset = 0;
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123 m_bufferSize = used + read;
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124 m_buffer = temp;
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125 } else {
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126 var read = Read(m_buffer, m_bufferSize, m_chunkSize);
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127 if (read == 0)
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128 return false;
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129 m_bufferSize += m_chunkSize;
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130 }
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131 return true;
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132 } else {
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133 Debug.Assert(m_bufferOffset == 0);
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134 m_buffer = new char[m_chunkSize];
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135 m_bufferSize = Read(m_buffer, 0, m_chunkSize);
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136 return (m_bufferSize != 0);
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137 }
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138 }
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139
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140 protected abstract int Read(char[] buffer, int offset, int size);
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141
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142 public string GetTokenValue() {
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143 return new String(m_buffer, m_tokenOffset, m_tokenLength);
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144 }
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145
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146 public void CopyTokenTo(char[] buffer, int offset) {
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147 m_buffer.CopyTo(buffer, offset);
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148 }
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149
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150 public void CopyTokenTo(StringBuilder sb) {
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151 sb.Append(m_buffer, m_tokenOffset, m_tokenLength);
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152 }
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153
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154 }
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155 }
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156
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