OperationsManager.java

/*******************************************************************************
 * Copyright (c) 2010 Oak Ridge National Laboratory.
 * 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
 ******************************************************************************/
package org.eclipse.nebula.visualization.internal.xygraph.undo;

import java.util.ArrayList;
import java.util.List;

/**
 * The operation manager will help to manage the undoable and redoable
 * operations.
 * 
 * @author Xihui Chen
 *
 */
public class OperationsManager {

	private SizeLimitedStack<IUndoableCommand> undoStack;

	private SizeLimitedStack<IUndoableCommand> redoStack;

	private List<IOperationsManagerListener> listeners;

	/**
	 * Constructor.
	 */
	public OperationsManager() {
		undoStack = new SizeLimitedStack<IUndoableCommand>(30);

		redoStack = new SizeLimitedStack<IUndoableCommand>(30);
		listeners = new ArrayList<IOperationsManagerListener>();
	}

	/**
	 * Execute a command and push it to undo stack.
	 * 
	 * @param command
	 *            the command to be executed.
	 */
	public void addCommand(IUndoableCommand command) {
		undoStack.push(command);
		redoStack.clear();
		fireOperationsHistoryChanged();
	}

	/**
	 * Undo the command. Restore the state of the target to the previous state
	 * before this command has been executed.
	 * 
	 * @param command
	 */
	public void undoCommand(IUndoableCommand command) {
		IUndoableCommand temp;
		do {
			temp = undoStack.pop();
			temp.undo();
			redoStack.push(temp);
		} while (temp != command);
		fireOperationsHistoryChanged();
	}

	/**
	 * Re-do the command. Restore the state of the target to the state after
	 * this command has been executed.
	 * 
	 * @param command
	 */
	public void redoCommand(IUndoableCommand command) {
		IUndoableCommand temp;
		do {
			temp = redoStack.pop();
			temp.redo();
			undoStack.push(temp);
		} while (temp != command);
		fireOperationsHistoryChanged();
	}

	/**
	 * undo the last command. Do nothing if there is no last command.
	 */
	public void undo() {
		if (undoStack.size() > 0)
			undoCommand(undoStack.peek());
	}

	/**
	 * redo the last undone command. Do nothing if there is no last undone
	 * command.
	 */
	public void redo() {
		if (redoStack.size() > 0)
			redoCommand(redoStack.peek());
	}

	/**
	 * @return the undo commands array. The first element is the oldest commands
	 *         and the last element is the latest commands.
	 */
	public Object[] getUndoCommands() {
		return undoStack.toArray();
	}

	/**
	 * @return the redo commands array. The first element is the oldest commands
	 *         and the last element is the latest commands.
	 */
	public Object[] getRedoCommands() {
		return redoStack.toArray();
	}

	public void addListener(IOperationsManagerListener listener) {
		listeners.add(listener);
	}

	public boolean removeListener(IOperationsManagerListener listener) {
		return listeners.remove(listener);
	}

	private void fireOperationsHistoryChanged() {
		for (IOperationsManagerListener listener : listeners)
			listener.operationsHistoryChanged(this);
	}

	public int getUndoCommandsSize() {
		return undoStack.size();
	}

	public int getRedoCommandsSize() {
		return redoStack.size();
	}

}