treecontrol.java

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/*
 * Copyright 2001,2004 The Apache Software Foundation.
 * 
 * Licensed 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 netstore.framework.util.tree;

import java.io.Serializable;
import java.util.HashMap;

/**
 * <p>
 * The overall data structure representing a <em>tree control</em> that can be
 * rendered by the <code>TreeControlTag</code> custom tag. Each node of the
 * tree is represented by an instance of <code>TreeControlNode</code>.
 * </p>
 * 
 * @author Jazmin Jonson
 * @author Craig R. McClanahan
 * @version $Revision: 1.2 $ $Date: 2004/02/27 14:59:01 $
 */

public class TreeControl implements Serializable {

	// ----------------------------------------------------------- Constructors

	/**
	 * Construct a new instance with no predefined root node.
	 */
	public TreeControl() {

		super();
		setRoot(null);

	}

	/**
	 * Construct a new instance with the specified root node.
	 * 
	 * @param root
	 *            The new root node
	 */
	public TreeControl(TreeControlNode root) {

		super();
		setRoot(root);

	}

	// ----------------------------------------------------- Instance Variables

	/**
	 * The collection of nodes that represent this tree, keyed by name.
	 */
	protected HashMap registry = new HashMap();

	/**
	 * The most recently selected node.
	 */
	protected TreeControlNode selected = null;

	// ------------------------------------------------------------- Properties

	/**
	 * The root node of the entire tree.
	 */
	protected TreeControlNode root = null;

	public TreeControlNode getRoot() {
		return (this.root);
	}

	protected void setRoot(TreeControlNode root) {
		if (this.root != null)
			removeNode(this.root);
		if (root != null)
			addNode(root);
		root.setLast(true);
		this.root = root;
	}

	/**
	 * The current displayable "width" of this tree (that is, the maximum depth
	 * of the visible part of the tree).
	 */
	public int getWidth() {

		if (root == null)
			return (0);
		else
			return (getWidth(root));

	}

	// --------------------------------------------------------- Public Methods

	/**
	 * Find and return the <code>TreeControlNode</code> for the specified node
	 * name, if it exists; otherwise, return <code>null</code>.
	 * 
	 * @param name
	 *            Name of the <code>TreeControlNode</code> to be returned
	 */
	public TreeControlNode findNode(String name) {

		synchronized (registry) {
			return ((TreeControlNode) registry.get(name));
		}

	}

	/**
	 * Mark the specified node as the one-and-only currently selected one,
	 * deselecting any previous node that was so marked.
	 * 
	 * @param node
	 *            Name of the node to mark as selected, or <code>null</code>
	 *            if there should be no currently selected node
	 */
	public void selectNode(String name) {

		if (selected != null) {
			selected.setSelected(false);
			selected = null;
		}
		selected = findNode(name);
		if (selected != null)
			selected.setSelected(true);

	}

	// -------------------------------------------------------- Package Methods

	/**
	 * Register the specified node in our registry of the complete tree.
	 * 
	 * @param node
	 *            The <code>TreeControlNode</code> to be registered
	 * 
	 * @exception IllegalArgumentException
	 *                if the name of this node is not unique
	 */
	void addNode(TreeControlNode node) throws IllegalArgumentException {

		synchronized (registry) {
			String name = node.getName();
			if (registry.containsKey(name))
				throw new IllegalArgumentException("Name '" + name
						+ "' is not unique");
			node.setTree(this);
			registry.put(name, node);
		}

	}

	/**
	 * Calculate the width of the subtree below the specified node.
	 * 
	 * @param node
	 *            The node for which to calculate the width
	 */
	int getWidth(TreeControlNode node) {

		int width = node.getWidth();
		if (!node.isExpanded())
			return (width);
		TreeControlNode children[] = node.findChildren();
		for (int i = 0; i < children.length; i++) {
			int current = getWidth(children[i]);
			if (current > width)
				width = current;
		}
		return (width);

	}

	/**
	 * Deregister the specified node, as well as all child nodes of this node,
	 * from our registry of the complete tree. If this node is not present, no
	 * action is taken.
	 * 
	 * @param node
	 *            The <code>TreeControlNode</code> to be deregistered
	 */
	void removeNode(TreeControlNode node) {

		synchronized (registry) {
			TreeControlNode children[] = node.findChildren();
			for (int i = 0; i < children.length; i++)
				removeNode(children[i]);
			TreeControlNode parent = node.getParent();
			if (parent != null) {
				parent.removeChild(node);
			}
			node.setParent(null);
			node.setTree(null);
			if (node == this.root) {
				this.root = null;
			}
			registry.remove(node.getName());
		}

	}

}