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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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174
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4 using System.Diagnostics;
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173
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5
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6 namespace Implab.Formats {
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7 public struct BufferScanner<TTag> {
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8 readonly DFAStateDescriptor<TTag>[] m_dfa;
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9 int m_state;
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174
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10 int m_pos;
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11
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12 public BufferScanner(DFAStateDescriptor<TTag>[] dfa, int initialState) {
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13 m_dfa = dfa;
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14 m_state = initialState;
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15 }
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16
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17 public int Position {
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174
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18 get { return m_pos; }
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19 }
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20
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21 /// <summary>
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22 /// Scan this instance.
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23 /// </summary>
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24 /// <returns><c>true</c> - additional data required</returns>
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174
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25 public bool Scan(int[] buffer, int position, int length) {
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26 var hi = position + length;
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27 m_pos = position;
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28
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29 while (position < hi) {
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30 var next = m_dfa[m_state].transitions[buffer[position]];
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173
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31 if (next == DFAConst.UNREACHABLE_STATE) {
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32 if (m_dfa[m_state].final)
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33 return false;
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34
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35 throw new ParserException(
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36 String.Format(
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174
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37 "Unexpected symbol"
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38 )
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39 );
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40 }
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174
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41 m_pos++;
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42 m_state = next;
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43 }
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44
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45 return true;
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46 }
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47
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48 public void Eof() {
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49 if (!m_dfa[m_state].final)
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50 throw new ParserException(
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51 String.Format(
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52 "Unexpected EOF"
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53 )
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54 );
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55 }
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56
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57 public TTag[] GetTokenTags() {
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58 return m_dfa[m_state].tags;
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59 }
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60 }
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61 }
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62
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