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/*******************************************************************************
 * Copyright (c) 2003, 2010 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.draw2d.graph;

import org.eclipse.draw2d.geometry.Insets;

/**
 * A Node which may contain other nodes. A Subgraph is a compound or container
 * node. It may have incoming and outgoing edges just like a node. Subgraphs are
 * used in {@link CompoundDirectedGraph}s. A proper layout of a compound graph
 * ensures that all of a subgraph's children are placed inside its rectangular
 * region. Nodes which do not belong to the subgraph must be placed outside that
 * region.
 * 
 * A Subgraph may contain another Subgraph.
 * 

 * A Subgraph has additional geometric properties which describe the containing
 * box. They are:
 * 

 * {@link #insets} - the size of the subgraph's border. A subgraph is
 * typically rendered as a thin rectangular box. Sometimes this box is labeled
 * or decorated. The insets can be used to reserve space for this purpose.
 * 
{@link #innerPadding} - the amount of empty space that must be preserved
 * just inside the subgraph's border. This is the minimum space between the
 * border, and the children node's contained inside the subgraph.
 * 
 * 
 * @author hudsonr
 * @since 2.1.2
 */
public class Subgraph extends Node {

	/**
	 * The children of this subgraph. Nodes may not belong to more than one
	 * subgraph.
	 */
	public NodeList members = new NodeList();

	Node head;
	Node tail;
	Node left;
	Node right;
	int nestingTreeMin;

	/**
	 * The space required for this subgraph's border. The default value is
	 * undefined.
	 */
	public Insets insets = new Insets(1);

	/**
	 * The minimum space between this subgraph's border and it's children.
	 */
	public Insets innerPadding = NO_INSETS;

	private static final Insets NO_INSETS = new Insets();

	/**
	 * Constructs a new subgraph with the given data object.
	 * 
	 * @see Node#Node(Object)
	 * @param data
	 *            an arbitrary data object
	 */
	public Subgraph(Object data) {
		this(data, null);
	}

	/**
	 * Constructs a new subgraph with the given data object and parent subgraph.
	 * 
	 * @see Node#Node(Object, Subgraph)
	 * @param data
	 *            an arbitrary data object
	 * @param parent
	 *            the parent
	 */
	public Subgraph(Object data, Subgraph parent) {
		super(data, parent);
	}

	/**
	 * Adds the given node to this subgraph.
	 * 
	 * @param n
	 *            the node to add
	 */
	public void addMember(Node n) {
		members.add(n);
	}

	/**
	 * Returns true if the given node is contained inside the
	 * branch represented by this subgraph.
	 * 
	 * @param n
	 *            the node in question
	 * @return true if nested
	 */
	boolean isNested(Node n) {
		return n.nestingIndex >= nestingTreeMin
				&& n.nestingIndex <= nestingIndex;
	}

}