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/*******************************************************************************
* Copyright (c) 2000, 2004 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.text.edits;
import org.eclipse.jface.text.Assert;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DocumentEvent;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IDocumentListener;
/* package */ class UndoCollector implements IDocumentListener {
protected UndoEdit undo;
private int fOffset;
private int fLength;
/**
* @since 3.1
*/
private String fLastCurrentText;
public UndoCollector(TextEdit root) {
fOffset= root.getOffset();
fLength= root.getLength();
}
public void connect(IDocument document) {
document.addDocumentListener(this);
undo= new UndoEdit();
}
public void disconnect(IDocument document) {
if (undo != null) {
document.removeDocumentListener(this);
undo.defineRegion(fOffset, fLength);
}
}
public void documentChanged(DocumentEvent event) {
fLength+= getDelta(event);
}
private static int getDelta(DocumentEvent event) {
String text= event.getText();
return text == null ? -event.getLength() : (text.length() - event.getLength());
}
public void documentAboutToBeChanged(DocumentEvent event) {
int offset= event.getOffset();
int currentLength= event.getLength();
String currentText= null;
try {
currentText= event.getDocument().get(offset, currentLength);
} catch (BadLocationException cannotHappen) {
Assert.isTrue(false, "Can't happen"); //$NON-NLS-1$
}
/*
* see https://bugs.eclipse.org/bugs/show_bug.cgi?id=93634
* If the same string is replaced on many documents (e.g. rename
* package), the size of the undo can be reduced by using the same
* String instance in all edits, instead of using the unique String
* returned from IDocument.get(int, int).
*/
if (fLastCurrentText != null && fLastCurrentText.equals(currentText))
currentText= fLastCurrentText;
else
fLastCurrentText= currentText;
String newText = event.getText();
undo.add(new ReplaceEdit(offset, newText != null ? newText.length() : 0, currentText));
}
}
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