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1 /*******************************************************************************
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2 * Copyright (c) 2000, 2008 IBM Corporation and others.
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3 * All rights reserved. This program and the accompanying materials
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4 * are made available under the terms of the Eclipse Public License v1.0
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5 * which accompanies this distribution, and is available at
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6 * http://www.eclipse.org/legal/epl-v10.html
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7 *
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8 * Contributors:
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9 * IBM Corporation - initial API and implementation
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10 * Port to the D programming language:
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11 * Frank Benoit <benoit@tionex.de>
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12 *******************************************************************************/
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13
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14 module dwtx.jface.text.rules.BufferedRuleBasedScanner;
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15
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16 import dwt.dwthelper.utils;
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17
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18
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19 import dwtx.core.runtime.Assert;
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20 import dwtx.jface.text.BadLocationException;
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21 import dwtx.jface.text.IDocument;
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22
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23 /**
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24 * A buffered rule based scanner. The buffer always contains a section
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25 * of a fixed size of the document to be scanned. Completely adheres to
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26 * the contract of <code>RuleBasedScanner</code>.
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27 */
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28 public class BufferedRuleBasedScanner : RuleBasedScanner {
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29
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30 /** The default buffer size. Value = 500 */
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31 private final static int DEFAULT_BUFFER_SIZE= 500;
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32 /** The actual size of the buffer. Initially set to <code>DEFAULT_BUFFER_SIZE</code> */
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33 private int fBufferSize= DEFAULT_BUFFER_SIZE;
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34 /** The buffer */
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35 private char[] fBuffer= new char[DEFAULT_BUFFER_SIZE];
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36 /** The offset of the document at which the buffer starts */
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37 private int fStart;
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38 /** The offset of the document at which the buffer ends */
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39 private int fEnd;
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40 /** The cached length of the document */
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41 private int fDocumentLength;
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42
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43
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44 /**
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45 * Creates a new buffered rule based scanner which does
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46 * not have any rule and a default buffer size of 500 characters.
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47 */
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48 protected BufferedRuleBasedScanner() {
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49 super();
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50 }
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51
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52 /**
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53 * Creates a new buffered rule based scanner which does
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54 * not have any rule. The buffer size is set to the given
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55 * number of characters.
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56 *
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57 * @param size the buffer size
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58 */
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59 public BufferedRuleBasedScanner(int size) {
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60 super();
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61 setBufferSize(size);
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62 }
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63
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64 /**
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65 * Sets the buffer to the given number of characters.
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66 *
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67 * @param size the buffer size
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68 */
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69 protected void setBufferSize(int size) {
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70 Assert.isTrue(size > 0);
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71 fBufferSize= size;
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72 fBuffer= new char[size];
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73 }
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74
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75 /**
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76 * Shifts the buffer so that the buffer starts at the
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77 * given document offset.
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78 *
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79 * @param offset the document offset at which the buffer starts
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80 */
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81 private void shiftBuffer(int offset) {
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82
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83 fStart= offset;
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84 fEnd= fStart + fBufferSize;
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85 if (fEnd > fDocumentLength)
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86 fEnd= fDocumentLength;
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87
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88 try {
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89
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90 String content= fDocument.get(fStart, fEnd - fStart);
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91 content.getChars(0, fEnd - fStart, fBuffer, 0);
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92
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93 } catch (BadLocationException x) {
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94 }
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95 }
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96
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97 /*
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98 * @see RuleBasedScanner#setRange(IDocument, int, int)
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99 */
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100 public void setRange(IDocument document, int offset, int length) {
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101
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102 super.setRange(document, offset, length);
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103
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104 fDocumentLength= document.getLength();
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105 shiftBuffer(offset);
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106 }
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107
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108 /*
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109 * @see RuleBasedScanner#read()
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110 */
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111 public int read() {
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112 fColumn= UNDEFINED;
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113 if (fOffset >= fRangeEnd) {
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114 ++ fOffset;
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115 return EOF;
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116 }
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117
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118 if (fOffset is fEnd)
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119 shiftBuffer(fEnd);
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120 else if (fOffset < fStart || fEnd < fOffset)
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121 shiftBuffer(fOffset);
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122
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123 return fBuffer[fOffset++ - fStart];
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124 }
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125
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126 /*
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127 * @see RuleBasedScanner#unread()
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128 */
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129 public void unread() {
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130
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131 if (fOffset is fStart)
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132 shiftBuffer(Math.max(0, fStart - (fBufferSize / 2)));
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133
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134 --fOffset;
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135 fColumn= UNDEFINED;
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136 }
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137 }
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138
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139
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