JoinLinesAction


1   /*******************************************************************************
2    * Copyright (c) 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    *     Benjamin Muskalla - initial API and implementation - https://bugs.eclipse.org/bugs/show_bug.cgi?id=41573 
10   *******************************************************************************/
11  package org.eclipse.ui.texteditor;
12  
13  import java.util.ResourceBundle  ;
14  
15  import org.eclipse.core.runtime.Assert;
16  
17  import org.eclipse.jface.viewers.ISelection;
18  import org.eclipse.jface.viewers.ISelectionProvider;
19  
20  import org.eclipse.jface.text.BadLocationException;
21  import org.eclipse.jface.text.IDocument;
22  import org.eclipse.jface.text.ITextSelection;
23  
24  
25  /**
26   * Action for joining two or more lines together by deleting the
27   * line delimiters and trimming the whitespace between them.
28   * 
29   * @since 3.3
30   */
31  public class JoinLinesAction extends TextEditorAction {
32  
33      private String   fJoint= null;
34      
35      
36      /**
37       * Creates a line joining action.
38       * 
39       * @param bundle the resource bundle for UI strings
40       * @param prefix the prefix for the property keys into <code>bundle</code>
41       * @param editor the editor
42       * @param joint the string to put between the lines
43       */
44      public JoinLinesAction(ResourceBundle   bundle, String   prefix, ITextEditor editor, String   joint) {
45          super(bundle, prefix, editor);
46          Assert.isLegal(joint != null);
47          fJoint= joint;
48          update();
49      }
50  
51      /*
52       * @see org.eclipse.jface.action.Action#run()
53       */
54      public void run() {
55          
56          ITextEditor editor= getTextEditor();
57          if (editor == null)
58              return;
59  
60          if (!validateEditorInputState())
61              return;
62  
63          IDocument document= getDocument(editor);
64          if (document == null)
65              return;
66  
67          ITextSelection selection= getSelection(editor);
68          if (selection == null)
69              return;
70  
71          int startLine= selection.getStartLine();
72          int endLine= selection.getEndLine();
73          try {
74              int caretOffset= joinLines(document, startLine, endLine);
75              if (caretOffset > -1)
76                  editor.selectAndReveal(caretOffset, 0);
77          } catch (BadLocationException e) {
78              // should not happen
79          }
80          
81      }
82  
83      /**
84       * Returns the editor's document.
85       * 
86       * @param editor the editor
87       * @return the editor's document
88       */
89      private static IDocument getDocument(ITextEditor editor) {
90  
91          IDocumentProvider documentProvider= editor.getDocumentProvider();
92          if (documentProvider == null)
93              return null;
94  
95          IDocument document= documentProvider.getDocument(editor.getEditorInput());
96          if (document == null)
97              return null;
98  
99          return document;
100     }
101 
102     /**
103      * Returns the editor's selection.
104      * 
105      * @param editor the editor
106      * @return the editor's selection
107      */
108     private static ITextSelection getSelection(ITextEditor editor) {
109 
110         ISelectionProvider selectionProvider= editor.getSelectionProvider();
111         if (selectionProvider == null)
112             return null;
113 
114         ISelection selection= selectionProvider.getSelection();
115         if (!(selection instanceof ITextSelection))
116             return null;
117 
118         return (ITextSelection) selection;
119     }
120     
121     /*
122      * @see org.eclipse.ui.texteditor.TextEditorAction#update()
123      */
124     public void update() {
125         super.update();
126         if (!isEnabled())
127             return;
128 
129         if (!canModifyEditor()) {
130             setEnabled(false);
131             return;
132         }
133 
134         ITextEditor editor= getTextEditor();
135         setEnabled(editor.isEditable());
136     }
137     
138     /**
139      * Joins several text lines to one line.
140      * 
141      * @param document the document
142      * @param startLine the start line
143      * @param endLine the end line
144      * @return the new caret offset
145      * @throws BadLocationException
146      */
147     private int joinLines(IDocument document, int startLine, int endLine) throws BadLocationException {
148         if (startLine == document.getNumberOfLines() - 1) {
149             // do nothing because we are in the last line
150             return -1;
151         }
152 
153         if (startLine == endLine)
154             endLine++; // append join with the next line
155 
156         StringBuffer   buffer= new StringBuffer  ();
157         for (int line= startLine; line <= endLine; line++) {
158             buffer.append(trim(document, line, line == startLine));
159             if (line != endLine)
160                 buffer.append(fJoint);
161         }
162 
163         int startLineOffset= document.getLineOffset(startLine);
164         int endLineOffset= document.getLineOffset(endLine)  + document.getLineLength(endLine) - getLineDelimiterLength(document, endLine);
165         String   replaceString= buffer.toString();
166         document.replace(startLineOffset, endLineOffset - startLineOffset, replaceString);
167         return startLineOffset + replaceString.length();
168     }
169 
170     private String   trim(IDocument document, int line, boolean ignoreLeadingWhitespace) throws BadLocationException {
171         int lineOffset= document.getLineOffset(line);
172         int lineLength= document.getLineLength(line);
173         lineLength= lineLength - getLineDelimiterLength(document, line);
174         if (!ignoreLeadingWhitespace)
175             return document.get(lineOffset, lineLength).trim();
176         
177         while (lineLength > 0 && Character.isWhitespace(document.getChar(lineOffset + lineLength - 1)))
178             lineLength--;
179         
180         return document.get(lineOffset, lineLength);
181     }
182     
183     private int getLineDelimiterLength(IDocument document, int line) throws BadLocationException {
184         String   lineDelimiter= document.getLineDelimiter(line);
185         return lineDelimiter != null ? lineDelimiter.length() : 0;
186         
187     }
188 
189 }
190
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