Tree.java

/*******************************************************************************
 * Copyright (c) 2012, 2013 Original authors 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:
 *     Original authors and others - initial API and implementation
 ******************************************************************************/
package org.eclipse.nebula.widgets.nattable.columnCategories;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import org.eclipse.nebula.widgets.nattable.util.ObjectUtils;

/**
 * Represents a Tree of Objects. The Tree is represented as a single rootElement
 * which points to a List<Node> of children.
 *
 * Adapted from public domain code at http://sujitpal.blogspot.com/.
 */
public class Tree implements Serializable {

    private static final long serialVersionUID = 6182L;
    private Node rootElement;

    /**
     * Default ctor.
     */
    public Tree() {
        super();
    }

    /**
     * Return the root Node of the tree.
     *
     * @return the root element.
     */
    public Node getRootElement() {
        return this.rootElement;
    }

    /**
     * Set the root Element for the tree.
     *
     * @param rootElement
     *            the root element to set.
     */
    public void setRootElement(Node rootElement) {
        this.rootElement = rootElement;
    }

    /**
     * Returns the Tree as a List of Node objects. The elements of the List are
     * generated from a pre-order traversal of the tree.
     *
     * @return a List<Node>.
     */
    public List<Node> toList() {
        List<Node> list = new ArrayList<Node>();
        walk(this.rootElement, list);
        return list;
    }

    /**
     * Returns a String representation of the Tree. The elements are generated
     * from a pre-order traversal of the Tree.
     *
     * @return the String representation of the Tree.
     */
    @Override
    public String toString() {
        return toList().toString();
    }

    /**
     * Walks the Tree in pre-order style. This is a recursive method, and is
     * called from the toList() method with the root element as the first
     * argument. It appends to the second argument, which is passed by reference
     * as it recurses down the tree.
     *
     * @param element
     *            the starting element.
     * @param list
     *            the output of the walk.
     */
    private void walk(Node element, List<Node> list) {
        list.add(element);
        for (Node data : element.getChildren()) {
            walk(data, list);
        }
    }

    /**
     * Find the Node in the tree containing the supplied data. Stops searching
     * at the first match.
     *
     * @param nodeData
     *            the node data
     * @return matching Node if found, NULL otherwise
     */
    public Node find(String nodeData) {
        return find(getRootElement(), nodeData);
    }

    /**
     * Find a Node in a tree, containing the given data
     *
     * @param element
     *            Node to start searching at
     * @param nodeData
     *            to search for
     * @return matching Node if found, NULL otherwise
     */
    public Node find(Node element, String nodeData) {
        if (nodeData.equals(element.getData())) {
            return element;
        }
        for (Node data : element.getChildren()) {
            Node result = find(data, nodeData);
            if (result != null) {
                return result;
            }
        }
        return null;
    }

    public void clear() {
        this.rootElement = null;
    }

    /**
     * Removes the node with the supplied node data. Deletes the first matching
     * node.
     *
     * @param nodeData
     *            the node data
     * @return TRUE if a node was found and removed
     */
    public boolean remove(String nodeData) {
        Node nodeToRemove = find(nodeData);
        if (ObjectUtils.isNotNull(nodeToRemove)) {
            nodeToRemove.getParent().getChildren().remove(nodeToRemove);
            nodeToRemove.setParent(null);
            return true;
        }
        return false;
    }
}