LabelNode.java

/*
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 *    LabelNode.java
 *    Copyright (C) 2009-2010 Aristotle University of Thessaloniki, Thessaloniki, Greece
 */
package mulan.data;

import java.util.Set;

/**
 * Represents a label attribute as a node in the labels hierarchy.  
 * The identity of the node is represented by label name, which must be unique 
 * within labels hierarchy.
 * 
 * @author Jozef Vilcek
 */
public interface LabelNode {

    /**
     * Gets the name of the label this node represents.
     * The name corresponds to the ID of label attribute in the arff data set.
     * The name of the label must be unique within the data set, because the
     * identity of {@link LabelNode} is determined by the name.
     *
     * @return the name of the label this node represents
     */
    String getName();

    /**
     * Determines whether the {@link LabelNode} has a parent node in a hierarchy.
     *
     * @return <code>true</code> if the node has parent; <code>false</code> otherwise.
     */
    boolean hasParent();

    /**
     * Gets the parent {@link LabelNode} of this node if hierarchy exists.
     * If the node has not a parent {@link LabelNode}, <code>null</code> is returned.
     *
     * @return the parent {@link LabelNode} or <code>null</code> if the parent does not exists.
     */
    LabelNode getParent();

    /**
     * Determines whether the {@link LabelNode} has child nodes.
     *
     * @return <code>true</code> if the node has child nodes; <code>false</code> otherwise.
     */
    boolean hasChildren();

    /**
     * Gets the unmodifiable {@link Set} of child {@link LabelNode} of this node, if hierarchy exists.
     * If no child nodes exists for this {@link LabelNode}, empty {@link Set} is returned.
     *
     * @return the {@link Set} of child nodes
     */
    Set<LabelNode> getChildren();

    /**
     * Gets a {@link Set} of the names of descendant {@link LabelNode} of this node, if hierarchy exists.
     * If no descendant nodes exists for this {@link LabelNode}, empty {@link Set} is returned.
     *
     * @return the {@link Set} of child nodes
     */
    Set<String> getDescendantLabels();
}