TreeNode.java

/* (c) 2016 Open Source Geospatial Foundation - all rights reserved
 * This code is licensed under the GPL 2.0 license, available at the root
 * application directory.
 */
package org.geoserver.web.treeview;

import java.io.Serializable;
import java.util.Collection;

import org.apache.wicket.model.IModel;

/** 
 * Model for a node in a Tree.
 * This interface must be implemented to make your own custom TreeView.
 * 
 * @author Niels Charlier
 *
 */
public interface TreeNode<T> extends Serializable {
    
    /**
     * Get collection of children (in order of display)
     * 
     * @return collection of children
     */
    public Collection<? extends TreeNode<T>> getChildren();
        
    /**
     * Get the parent.
     * 
     * @return the parent of the node (null if root).
     */
    public TreeNode<T> getParent();
    
    /**
     * Get node data object.
     * 
     * @return data object
     */
    public T getObject();
    
    /**
     * Provide a model for whether node is expanded or not. 
     * Must contain the same value for each instance representing the same node.
     * 
     * @return expanded model, null if the node is a leaf.
     */
    public IModel<Boolean> getExpanded();
    
    /**
     * Provide a unique ID for this node.
     * 
     * @return unique id
     */
    public String getUniqueId();
        
    /**
     * Determine if the node is a leaf.
     * 
     * @return true if the node is a leaf
     */
    default boolean isLeaf() {
        return getChildren().size() == 0;
    }
    
    /**
     *
     * Get label (textual representation) of node.
     * 
     * @return textual representation of node
     */
    default String getLabel() {
        return getObject().toString();
    }
    
    /**
     * 
     * Determine if this is the same node (all fields must be the same as well)
     * 
     * @param node
     * @return
     */
    default boolean isSameAs(TreeNode<T> node) {
        return(getUniqueId().equals(node.getUniqueId()));
    }

}