CompareNavigator


1   /*******************************************************************************
2    * Copyright (c) 2000, 2007 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    *
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  package org.eclipse.compare;
12  
13  import org.eclipse.compare.internal.Utilities;
14  import org.eclipse.core.runtime.IAdaptable;
15  
16  /**
17   * Supports cross-pane navigation through the differences of a compare container.
18   * <p>
19   * Clients may subclass this class.
20   * </p>
21   * @see INavigatable
22   * @since 3.3
23   */
24  public abstract class CompareNavigator implements ICompareNavigator {
25      
26      /* (non-Javadoc)
27       * @see org.eclipse.compare.ICompareNavigator#selectChange(boolean)
28       */
29      public boolean selectChange(boolean next) {
30          // find most down stream CompareViewerPane
31          INavigatable[] navigators= getNavigatables();
32          Object   downStreamInput = null;                      
33          for (int i = navigators.length - 1; i >=0; i--) {
34              INavigatable navigatable = navigators[i];
35              if (navigatable.getInput() == downStreamInput) {
36                  // Skip to up stream pane if it has the same input
37                  continue;
38              }
39              if (navigatable.selectChange(next ? INavigatable.NEXT_CHANGE : INavigatable.PREVIOUS_CHANGE)) {
40                  // at end of this navigator
41                  downStreamInput = navigatable.getInput();
42                  continue;
43              }
44              // not at end
45              if (i + 1 < navigators.length && navigators[i+1] != null && navigators[i+1].getInput() != downStreamInput) {
46                  // The navigation has invoked a change in a downstream pane.
47                  // Set the selected change depending on the direction we are navigating
48                  navigators[i+1].selectChange(next ? INavigatable.FIRST_CHANGE : INavigatable.LAST_CHANGE);
49              }
50              return false;
51          }
52          
53          return true;
54      }
55      
56      protected abstract INavigatable[] getNavigatables();
57      
58      /**
59       * Return the {@link INavigatable} for the given object.
60       * If the object implements {@link INavigatable}, then
61       * the object is returned. Otherwise, if the object
62       * implements {@link IAdaptable}, the object is
63       * adapted to {@link INavigatable}.
64       * @param object the object
65       * @return the {@link INavigatable} for the given object or <code>null</code>
66       */
67      protected final INavigatable getNavigator(Object   object) {
68          if (object == null)
69              return null;
70          Object   data= Utilities.getAdapter(object, INavigatable.class);
71          if (data instanceof INavigatable)
72              return (INavigatable) data;
73          return null;
74      }
75  
76      /**
77       * Return whether a call to {@link ICompareNavigator#selectChange(boolean)} with the same parameter
78       * would succeed.
79       * @param next if <code>true</code> the next change is selected, otherwise the previous change
80       * @return whether a call to {@link ICompareNavigator#selectChange(boolean)} with the same parameter
81       * would succeed.
82       * @since 3.3
83       */
84      public boolean hasChange(boolean next) {
85          INavigatable[] navigators= getNavigatables();
86          Object   downStreamInput = null;                      
87          for (int i = navigators.length - 1; i >=0; i--) {
88              INavigatable navigatable = navigators[i];
89              if (navigatable.getInput() == downStreamInput) {
90                  // Skip to up stream pane if it has the same input
91                  continue;
92              }
93              if (navigatable.hasChange(next ? INavigatable.NEXT_CHANGE : INavigatable.PREVIOUS_CHANGE)) {
94                  return true;
95              }
96              // at end of this navigator
97              downStreamInput = navigatable.getInput();
98          }
99          return false;
100     }   
101 }
102
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