NodeKey.java

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2022, by David Gilbert and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
 * Other names may be trademarks of their respective owners.]
 *
 * ------------
 * NodeKey.java
 * ------------
 * (C) Copyright 2021-2022, by David Gilbert and Contributors.
 *
 * Original Author:  David Gilbert;
 * Contributor(s):   -;
 *
 */

package org.jfree.data.flow;

import java.io.Serializable;
import java.util.Objects;
import org.jfree.chart.internal.Args;
import org.jfree.chart.api.PublicCloneable;

/**
 * A key that identifies a node in a {@link FlowDataset}.  Instances of this
 * class are immutable.
 * 
 * @param <K> the type for the keys used to identify sources and destinations 
 *     ({@code String} is a good default choice).
 * 
 * @since 1.5.3
 */
public class NodeKey <K extends Comparable<K>> implements PublicCloneable, Serializable {

    /** 
     * The key for a node property that, if defined (at the dataset level), 
     * contains a {@code Boolean} value for the selection status of the node.
     */
    public static final String SELECTED_PROPERTY_KEY = "selected";
    
    /** The stage. */
    private final int stage;
    
    /* The source node. */
    private final K node;
    
    /**
     * Creates a new key referencing a node in a {@link FlowDataset}.
     * 
     * @param stage  the stage.
     * @param node  the node key.
     */
    public NodeKey(int stage, K node) {
        Args.nullNotPermitted(node, "node");
        this.stage = stage;
        this.node = node;
    }

    /**
     * Returns the stage number.
     * 
     * @return The stage number. 
     */
    public int getStage() {
        return this.stage;
    }

    /**
     * Returns the identifier for the node.
     * 
     * @return The identifier for the node (never {@code null}).
     */
    public K getNode() {
        return this.node;
    }
    
    /**
     * Returns a string representation of this instance, primarily for 
     * debugging purposes.
     * 
     * @return A string. 
     */
    @Override
    public String toString() {
        return "[NodeKey: " + stage + ", " + node + "]";
    }

    /**
     * Tests this instance for equality with an arbitrary object.
     * 
     * @param obj  the object ({@code null} permitted).
     * 
     * @return A boolean. 
     */
    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final NodeKey<?> other = (NodeKey<?>) obj;
        if (this.stage != other.stage) {
            return false;
        }
        if (!Objects.equals(this.node, other.node)) {
            return false;
        }
        return true;
    }
    
    /**
     * Returns a hashcode for this instance.
     * 
     * @return A hashcode.
     */
    @Override
    public int hashCode() {
        int hash = 3;
        hash = 53 * hash + this.stage;
        hash = 53 * hash + Objects.hashCode(this.node);
        return hash;
    }

    @Override
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }

}