taverna-selection-api/src/main/java/org/apache/taverna/workbench/selection/DataflowSelectionModel.java

/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/

package org.apache.taverna.workbench.selection;

import java.util.Set;

import org.apache.taverna.lang.observer.Observable;
import org.apache.taverna.lang.observer.Observer;
import org.apache.taverna.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();
}