TextEditorAction


1   /*******************************************************************************
2    * Copyright (c) 2000, 2006 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.ui.texteditor;
12  
13  
14  import java.util.ResourceBundle  ;
15  
16  /**
17   * Skeleton of a standard text editor action. The action is
18   * initially associated with a text editor via the constructor,
19   * but can subsequently be changed using <code>setEditor</code>.
20   * Subclasses must implement the <code>run</code> method and if
21   * required override the <code>update</code> method.
22   * <p>
23   * Subclasses that may modify the editor content should use {@link #canModifyEditor()}
24   * in their <code>update</code> code to check whether updating the editor is most
25   * likely possible (even if it is read-only - this may change for editor contents
26   * that are under version control) and {@link #validateEditorInputState()} before
27   * actually modifying the editor contents.
28   * </p>
29   */
30  public abstract class TextEditorAction extends ResourceAction implements IUpdate {
31  
32      /** The action's editor */
33      private ITextEditor fTextEditor;
34  
35      /**
36       * Creates and initializes the action for the given text editor. The action
37       * configures its visual representation from the given resource bundle.
38       *
39       * @param bundle the resource bundle
40       * @param prefix a prefix to be prepended to the various resource keys
41       *   (described in <code>ResourceAction</code> constructor), or
42       *   <code>null</code> if none
43       * @param editor the text editor
44       * @see ResourceAction#ResourceAction(ResourceBundle, String)
45       */
46      protected TextEditorAction(ResourceBundle   bundle, String   prefix, ITextEditor editor) {
47          super(bundle, prefix);
48          setEditor(editor);
49          update();
50      }
51  
52      /**
53       * Creates and initializes the action for the given text editor. The action
54       * configures its visual representation from the given resource bundle.
55       *
56       * @param bundle the resource bundle
57       * @param prefix a prefix to be prepended to the various resource keys
58       *   (described in <code>ResourceAction</code> constructor), or
59       *   <code>null</code> if none
60       * @param editor the text editor
61       * @param style the style of this action
62       * @see ResourceAction#ResourceAction(ResourceBundle, String, int)
63       * @since 3.0
64       */
65      protected TextEditorAction(ResourceBundle   bundle, String   prefix, ITextEditor editor, int style) {
66          super(bundle, prefix, style);
67          setEditor(editor);
68          update();
69      }
70  
71      /**
72       * Returns the action's text editor.
73       *
74       * @return the action's text editor
75       */
76      protected ITextEditor getTextEditor() {
77          return fTextEditor;
78      }
79  
80      /**
81       * Retargets this action to the given editor.
82       *
83       * @param editor the new editor, or <code>null</code> if none
84       */
85      public void setEditor(ITextEditor editor) {
86          fTextEditor= editor;
87      }
88  
89      /**
90       * Always enables this action if it is connected to a text editor.
91       * If the associated editor is <code>null</code>, the action is disabled.
92       * Subclasses may override.
93       */
94      public void update() {
95          setEnabled(getTextEditor() != null);
96      }
97  
98      /**
99       * Checks the editor's modifiable state. Returns <code>true</code> if the editor can be modified,
100      * taking in account the possible editor extensions.
101      *
102      * <p>If the editor implements <code>ITextEditorExtension2</code>,
103      * this method returns {@link ITextEditorExtension2#isEditorInputModifiable()};<br> else if the editor
104      * implements <code>ITextEditorExtension</code>, it returns {@link ITextEditorExtension#isEditorInputReadOnly()};<br>
105      * else, {@link ITextEditor#isEditable()} is returned, or <code>false</code> if the editor is <code>null</code>.</p>
106      *
107      * <p>There is only a difference to {@link #validateEditorInputState()} if the editor implements
108      * <code>ITextEditorExtension2</code>.</p>
109      *
110      * @return <code>true</code> if a modifying action should be enabled, <code>false</code> otherwise
111      * @since 3.0
112      */
113     protected boolean canModifyEditor() {
114         ITextEditor editor= getTextEditor();
115         if (editor instanceof ITextEditorExtension2)
116             return ((ITextEditorExtension2) editor).isEditorInputModifiable();
117         else if (editor instanceof ITextEditorExtension)
118             return !((ITextEditorExtension) editor).isEditorInputReadOnly();
119         else if (editor != null)
120             return editor.isEditable();
121         else
122             return false;
123     }
124 
125     /**
126      * Checks and validates the editor's modifiable state. Returns <code>true</code> if an action
127      * can proceed modifying the editor's input, <code>false</code> if it should not.
128      *
129      * <p>If the editor implements <code>ITextEditorExtension2</code>,
130      * this method returns {@link ITextEditorExtension2#validateEditorInputState()};<br> else if the editor
131      * implements <code>ITextEditorExtension</code>, it returns {@link ITextEditorExtension#isEditorInputReadOnly()};<br>
132      * else, {@link ITextEditor#isEditable()} is returned, or <code>false</code> if the editor is <code>null</code>.</p>
133      *
134      * <p>There is only a difference to {@link #canModifyEditor()} if the editor implements
135      * <code>ITextEditorExtension2</code>.</p>
136      *
137      * @return <code>true</code> if a modifying action can proceed to modify the underlying document, <code>false</code> otherwise
138      * @since 3.0
139      */
140     protected boolean validateEditorInputState() {
141         ITextEditor editor= getTextEditor();
142         if (editor instanceof ITextEditorExtension2)
143             return ((ITextEditorExtension2) editor).validateEditorInputState();
144         else if (editor instanceof ITextEditorExtension)
145             return !((ITextEditorExtension) editor).isEditorInputReadOnly();
146         else if (editor != null)
147             return editor.isEditable();
148         else
149             return false;
150     }
151 }
152
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