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1 /*******************************************************************************
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2 * Copyright (c) 2006, 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 * Matthew Hall - bug 208858
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11 *******************************************************************************/
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12
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13 module org.eclipse.core.databinding.observable.list.ListDiff;
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81
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14 import org.eclipse.core.databinding.observable.list.ListDiffEntry;
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15 import org.eclipse.core.databinding.observable.list.ListDiffVisitor;
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78
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16
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17 import java.lang.all;
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18
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19 import org.eclipse.core.internal.databinding.Util;
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20
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21 /**
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22 * Object describing a diff between two lists.
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23 *
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24 * @since 1.0
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25 */
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26 public abstract class ListDiff {
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27
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28 /**
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29 * Returns a ListDiffEntry array representing the differences in the list,
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30 * in the order they are to be processed.
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31 *
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32 * @return a ListDiffEntry array representing the differences in the list,
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33 * in the order they are to be processed.
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34 */
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35 public abstract ListDiffEntry[] getDifferences();
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36
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37 /**
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38 * Traverses the {@link #getDifferences()} array, calling the appropriate
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39 * method in <code>visitor</code> for each difference.
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40 * <ol>
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41 * <li>{@link ListDiffVisitor#handleReplace(int, Object, Object)} is called
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42 * whenever a remove entry is immediately followed by an add entry which
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43 * shares the same list index.
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44 * <li>{@link ListDiffVisitor#handleMove(int, int, Object)} is called
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45 * whenever a remove entry is immediately followed by an add entry with an
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46 * equivalent element.
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47 * <li>{@link ListDiffVisitor#handleRemove(int, Object)} is called whenever
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48 * a remove entry does not match conditions 1 or 2.
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49 * <li>{@link ListDiffVisitor#handleAdd(int, Object)} is called whenever an
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50 * add entry does not match conditions in 1 or 2.
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51 * </ol>
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52 *
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53 * @param visitor
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54 * the visitor to receive callbacks.
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55 * @see ListDiffVisitor
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56 * @since 1.1
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57 */
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58 public void accept(ListDiffVisitor visitor) {
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59 ListDiffEntry[] differences = getDifferences();
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60 for (int i = 0; i < differences.length; i++) {
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61 ListDiffEntry entry = differences[i];
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62 int position = entry.getPosition();
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63 Object element = entry.getElement();
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64 bool addition = entry.isAddition();
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65
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66 if (!addition && i + 1 < differences.length) {
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67 ListDiffEntry entry2 = differences[i + 1];
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68 if (entry2.isAddition()) {
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69 int position2 = entry2.getPosition();
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70 Object element2 = entry2.getElement();
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71 if (position is position2) {
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72 visitor.handleReplace(position, element, element2);
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73 i++;
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74 continue;
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75 }
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76 if (Util.equals(element, element2)) {
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77 visitor.handleMove(position, position2, element);
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78 i++;
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79 continue;
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80 }
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81 }
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82 }
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83 if (addition)
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84 visitor.handleAdd(position, element);
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85 else
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86 visitor.handleRemove(position, element);
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87 }
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88 }
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89
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90 /**
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91 * @see java.lang.Object#toString()
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92 */
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93 public String toString() {
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94 ListDiffEntry[] differences = getDifferences();
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95 StringBuffer buffer = new StringBuffer();
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96 buffer.append(getClass().getName());
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97
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98 if (differences is null || differences.length is 0) {
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99 buffer
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100 .append("{}"); //$NON-NLS-1$
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101 } else {
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102 buffer
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103 .append("{"); //$NON-NLS-1$
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104
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105 for (int i = 0; i < differences.length; i++) {
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106 if (i > 0)
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107 buffer.append(", "); //$NON-NLS-1$
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108
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109 buffer
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110 .append("difference[") //$NON-NLS-1$
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111 .append(i)
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112 .append("] [") //$NON-NLS-1$
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113 .append(differences[i] !is null ? differences[i].toString() : "null") //$NON-NLS-1$
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114 .append("]"); //$NON-NLS-1$
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115 }
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116 buffer.append("}"); //$NON-NLS-1$
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117 }
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118
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119 return buffer.toString();
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120 }
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121 }
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