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173
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1 using System;
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2 using Implab.Automaton.RegularExpressions;
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3 using Implab.Automaton;
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4
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5 namespace Implab.Formats {
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6 public struct BufferScanner<TTag> {
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7 char[] m_buffer;
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8 int m_offset;
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9 int m_position;
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10 int m_hi;
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11
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12 readonly int m_chunk;
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13 readonly int m_limit;
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14
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15 readonly DFAStateDescriptor<TTag>[] m_dfa;
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16 int m_state;
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17
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18 public BufferScanner(DFAStateDescriptor<TTag>[] dfa, int initialState, int chunk, int limit) {
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19 m_dfa = dfa;
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20 m_state = initialState;
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21 m_chunk = chunk;
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22 m_limit = limit;
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23 m_buffer = null;
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24 m_offset = 0;
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25 m_position = 0;
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26 m_hi = 0;
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27 }
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28
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29 public char[] Buffer {
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30 get {
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31 return m_buffer;
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32 }
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33 }
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34
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35 public int HiMark {
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36 get {
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37 return m_hi;
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38 }
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39 }
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40
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41 public int Position {
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42 get {
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43 return m_position;
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44 }
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45 }
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46
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47 public int Length {
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48 get {
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49 return m_hi - m_position;
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50 }
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51 }
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52
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53 public int TokenOffset {
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54 get {
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55 return m_offset;
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56 }
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57 }
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58
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59 public int TokenLength {
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60 get {
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61 return m_position - m_offset;
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62 }
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63 }
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64
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65 public void Init(char[] buffer, int position, int length) {
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66 m_buffer = buffer;
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67 m_position = position;
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68 m_offset = position;
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69 m_hi = position + length;
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70 }
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71
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72 public int Extend() {
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73 // free space
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74 var free = m_buffer.Length - m_hi;
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75
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76 // if the buffer have enough free space
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77 if (free > 0)
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78 return free;
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79
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80 // effective size of the buffer
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81 var size = m_buffer.Length - m_offset;
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82
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83 // calculate the new size
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84 int grow = Math.Min(m_limit - size, m_chunk);
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85 if (grow <= 0)
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86 throw new ParserException(String.Format("Input buffer {0} bytes limit exceeded", m_limit));
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87
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88 var temp = new char[size + grow];
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89 Array.Copy(m_buffer, m_offset, temp, 0, m_hi - m_offset);
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90 m_position -= m_offset;
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91 m_hi -= m_offset;
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92 m_offset = 0;
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93 m_buffer = temp;
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94
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95 return free + grow;
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96 }
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97
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98 public void RaiseMark(int size) {
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99 m_hi += size;
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100 }
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101
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102 /// <summary>
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103 /// Scan this instance.
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104 /// </summary>
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105 /// <returns><c>true</c> - additional data required</returns>
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106 public bool Scan() {
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107 while (m_position < m_hi) {
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108 var ch = m_buffer[m_position];
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109 var next = m_dfa[m_state].transitions[(int)ch];
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110 if (next == DFAConst.UNREACHABLE_STATE) {
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111 if (m_dfa[m_state].final)
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112 return false;
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113
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114 throw new ParserException(
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115 String.Format(
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116 "Unexpected token '{0}'",
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117 new string(m_buffer, m_offset, m_position - m_offset)
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118 )
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119 );
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120 }
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121 m_state = next;
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122 m_position++;
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123 }
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124
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125 return true;
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126 }
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127
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128 public void Eof() {
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129 if (!m_dfa[m_state].final)
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130 throw new ParserException(
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131 String.Format(
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132 "Unexpected token '{0}'",
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133 new string(m_buffer, m_offset, m_position - m_offset)
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134 )
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135 );
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136 }
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137
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138 public TTag[] GetTokenTags() {
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139 return m_dfa[m_state].tags;
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140 }
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141 }
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142 }
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143
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