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1 package plparser;
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2
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3 import java.io.FileNotFoundException;
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4 import java.io.FileReader;
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5 import java.io.IOException;
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6 import java.io.InputStreamReader;
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7 import java.nio.CharBuffer;
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8
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9 public abstract class PLCharScannerImpl<Node> extends PLScannerImpl<Node> {
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10
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11 public CharBuffer cb;
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12
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13
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14 public PLCharScannerImpl(PLScanner<Node> plScannerImpl, Dictionary<Node> dict,
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15 Token<Node> nullToken) {
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16 super(plScannerImpl, dict, nullToken);
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17 }
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18
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19 public PLCharScannerImpl() {
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20 super();
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21 }
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22
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23 public Token<Node> lookupDict(CharBuffer w, TokenID id) {
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24 Token<Node> t;
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25 String s = w.flip().toString();
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26 if ((t = dict.get(s))==null) {
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27 dict.put(s, t = new Token<Node>(s,id));
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28 }
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29 return nextToken = t;
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30 }
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31
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32 public char nextChar() {
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33 if (!cb.hasRemaining()) extendInput();
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34 char ch = cb.get();
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35 if (ch=='\n') lineno++;
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36 return ch;
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37 }
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38
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39 @Override
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40 public boolean hasRemaining() {
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41 return cb.hasRemaining()||extendInput();
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42 }
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43
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44 protected boolean extendInput() {
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45 if (file!=null && cb.position()!=0) {
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46 // move remaining data to the top, set position for next read
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47 cb.compact();
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48 try {
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49 if (prompt!=null) System.out.print(prompt);
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50 if (file.read(cb)>0) {
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51 cb.flip(); // prepare for get
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52 return true;
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53 } else {
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54 throw new IOException();
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55 }
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56 } catch (IOException e) {
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57 file = null ;
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58 cb.flip();
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59 }
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60 }
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61 return false;
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62 }
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63
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64 @Override
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65 public PLScanner<Node> set(String exp) {
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66 cb = CharBuffer.wrap(exp);
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67 filename = null; file = null;
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68 nextToken = nullToken;
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69 return this;
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70 }
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71
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72 @Override
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73 public PLScanner<Node> setFile(String file) throws FileNotFoundException {
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74 this.filename = file;
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75 nextToken = nullToken;
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76 set(new FileReader(file));
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77 return this;
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78 }
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79
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80 @Override
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81 public PLScanner<Node> set(InputStreamReader file) {
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82 this.file = file;
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83 cb = CharBuffer.allocate(BufferSize);
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84 try {
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85 if (prompt!=null) System.out.print(prompt);
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86 if (file.read(cb) <= 0) {
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87 throw new IOException();
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88 }
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89 } catch (IOException e) {
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90 file = null; cb = null;
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91 set("");
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92 return this;
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93 } finally {
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94 cb.flip();
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95 }
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96 lineno = 0;
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97 return this;
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98 }
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99
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100 } |
