com.phoenixst.plexus.util.DefaultIncidentEdgeGetter.java Source code

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Here is the source code for com.phoenixst.plexus.util.DefaultIncidentEdgeGetter.java

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/*
 *  $Id: DefaultIncidentEdgeGetter.java,v 1.13 2006/06/07 20:25:53 rconner Exp $
 *
 *  Copyright (C) 1994-2006 by Phoenix Software Technologists,
 *  Inc. and others.  All rights reserved.
 *
 *  THIS PROGRAM AND DOCUMENTATION IS PROVIDED UNDER THE TERMS OF THE
 *  COMMON PUBLIC LICENSE ("AGREEMENT") WHICH ACCOMPANIES IT.  ANY
 *  USE, REPRODUCTION OR DISTRIBUTION OF THE PROGRAM CONSTITUTES
 *  RECIPIENT'S ACCEPTANCE OF THE AGREEMENT.
 *
 *  The license text can also be found at
 *    http://opensource.org/licenses/cpl.php
 */

package com.phoenixst.plexus.util;

import java.io.*;

import org.apache.commons.collections.*;

import com.phoenixst.plexus.Graph;

/**
 *  A <code>Transformer</code> which when given a node, returns a
 *  single <code>Edge</code> incident to that node, specified by a
 *  <code>Graph</code> and a <code>Predicate</code>.
 *
 *  @version    $Revision: 1.13 $
 *  @author     Ray A. Conner
 *
 *  @since      1.0
 */
public class DefaultIncidentEdgeGetter implements Transformer, Serializable {

    private static final long serialVersionUID = 1L;

    ////////////////////////////////////////
    // Instance Fields
    ////////////////////////////////////////

    /**
     *  @serial
     */
    private final Graph graph;

    /**
     *  @serial
     */
    private final Predicate traverserPredicate;

    ////////////////////////////////////////
    // Constructors
    ////////////////////////////////////////

    /**
     *  Creates a new <code>DefaultIncidentEdgeGetter</code>.
     */
    public DefaultIncidentEdgeGetter(Graph graph, Predicate traverserPredicate) {
        super();
        this.graph = graph;
        this.traverserPredicate = traverserPredicate;
        if (graph == null) {
            throw new IllegalArgumentException("Graph is null.");
        }
        if (traverserPredicate == null) {
            throw new IllegalArgumentException("Traverser predicate is null.");
        }
    }

    ////////////////////////////////////////
    // Serialization
    ////////////////////////////////////////

    private void readObject(ObjectInputStream in) throws ClassNotFoundException, IOException {
        in.defaultReadObject();
        if (graph == null) {
            throw new InvalidObjectException("Graph is null.");
        }
        if (traverserPredicate == null) {
            throw new InvalidObjectException("Traverser predicate is null.");
        }
    }

    ////////////////////////////////////////
    // Transformer
    ////////////////////////////////////////

    public Object transform(Object node) {
        return graph.getIncidentEdge(node, traverserPredicate);
    }

    ////////////////////////////////////////
    // Get Methods
    ////////////////////////////////////////

    /**
     *  Gets the <code>Graph</code> for this
     *  <code>DefaultIncidentEdgeGetter</code>.
     */
    public Graph getGraph() {
        return graph;
    }

    /**
     *  Gets the <code>Predicate</code> for this
     *  <code>DefaultIncidentEdgeGetter</code>.
     */
    public Predicate getTraverserPredicate() {
        return traverserPredicate;
    }

}