taverna-workbench-selection-api/src/main/java/net/sf/taverna/t2/workbench/selection/DataflowSelectionModel.java

/*******************************************************************************
 * Copyright (C) 2007 The University of Manchester
 *
 *  Modifications to the initial code base are copyright of their
 *  respective authors, or their employers as appropriate.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public License
 *  as published by the Free Software Foundation; either version 2.1 of
 *  the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 ******************************************************************************/
package net.sf.taverna.t2.workbench.selection;

import java.util.Set;

import net.sf.taverna.t2.lang.observer.Observable;
import net.sf.taverna.t2.lang.observer.Observer;
import net.sf.taverna.t2.workbench.selection.events.DataflowSelectionMessage;

/**
 * The current state of the selection of dataflow objects.
 * 
 * @author David Withers
 */
public interface DataflowSelectionModel extends
		Observable<DataflowSelectionMessage> {
	/**
	 * Adds an element to the current selection.
	 * 
	 * If the element is not in the selection the {@link Observer}s are
	 * notified. If <code>element</code> is null, this method has no effect.
	 * 
	 * @param element
	 *            the element to add
	 */
	void addSelection(Object element);

	/**
	 * Removes an element from the current selection.
	 * 
	 * If the element is in the selection the {@link Observer}s are notified. If
	 * <code>element</code> is null, this method has no effect.
	 * 
	 * @param element
	 *            the element to remove
	 */
	void removeSelection(Object element);

	/**
	 * Sets the current selection.
	 * 
	 * If this changes the selection the {@link Observer}s are notified. If
	 * <code>elements</code> is null, this has the same effect as invoking
	 * <code>clearSelection</code>.
	 * 
	 * @param elements
	 *            the current selection
	 */
	void setSelection(Set<Object> elements);

	/**
	 * Returns the current selection.
	 * 
	 * Returns an empty set if nothing is currently selected.
	 * 
	 * @return the current selection
	 */
	Set<Object> getSelection();

	/**
	 * Clears the current selection.
	 * 
	 * If this changes the selection the {@link Observer}s are notified.
	 */
	void clearSelection();
}