org.eclipse.ui.workbench.texteditor/src/org/eclipse/ui/internal/texteditor/quickdiff/RevertBlockAction.java

/*******************************************************************************
 * 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 Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.internal.texteditor.quickdiff;


import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.source.ILineDiffInfo;
import org.eclipse.jface.text.source.ILineDiffer;
import org.eclipse.jface.text.source.IVerticalRulerInfo;

import org.eclipse.ui.texteditor.ITextEditor;

/**
 * Action that will revert a contiguous block of added, deleted and changes lines in the currently 
 * displayed document to the state in the reference document.
 * 
 * @since 3.0
 */
public class RevertBlockAction extends QuickDiffRestoreAction {
	/** Resource key prefix. */
	private static final String PREFIX= "RevertBlockAction."; //$NON-NLS-1$

	/** The line to be restored. Set in <code>update()</code>. */
	private int fLine;

	/**
	 * Creates a new instance.
	 * 
	 * @param editor the editor this action belongs to
	 */	
	public RevertBlockAction(ITextEditor editor) {
		super(QuickDiffMessages.getResourceBundle(), PREFIX, editor);
	}

	/*
	 * @see org.eclipse.ui.texteditor.IUpdate#update()
	 */
	public void update() {
		super.update();
		
		if (!isEnabled())
			return;
		
		setEnabled(false);
		IVerticalRulerInfo ruler= getRuler();
		if (ruler == null)
			return;
		fLine= ruler.getLineOfLastMouseButtonActivity();
		ILineDiffer differ= getDiffer();
		if (differ == null)
			return;
		ILineDiffInfo info= differ.getLineInfo(fLine);
		if (info != null && info.getChangeType() != ILineDiffInfo.UNCHANGED) {
			boolean hasBlock= false;
			if (fLine > 0) {
				info= differ.getLineInfo(fLine - 1);
				hasBlock= info != null && info.hasChanges();
			}
			if (!hasBlock) {
				info= differ.getLineInfo(fLine + 1);
				hasBlock= info != null && info.hasChanges();
			}
			if (hasBlock)
				setEnabled(true);
		}
	}

	/*
	 * @see org.eclipse.ui.internal.editors.quickdiff.QuickDiffRestoreAction#runCompoundChange()
	 */
	public void runCompoundChange() {
		if (!isEnabled())
			return;
		ILineDiffer differ= getDiffer();
		if (differ != null) {
			try {
				differ.revertBlock(fLine);
			} catch (BadLocationException e) {
				setStatus(e.getMessage());
			}
		}
	}
}