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

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

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/*
 *  $Id: AdjacentNodeCollection.java,v 1.7 2005/10/03 15:20:46 rconner Exp $
 *
 *  Copyright (C) 1994-2005 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.util.*;

import org.apache.commons.collections.Predicate;

import com.phoenixst.collections.TruePredicate;
import com.phoenixst.plexus.*;

/**
 *  A <code>Collection</code> for nodes to help implement the {@link
 *  Graph#adjacentNodes Graph.adjacentNodes( Predicate )} method.
 *
 *  @version    $Revision: 1.7 $
 *  @author     Ray A. Conner
 *
 *  @since      1.0
 */
public class AdjacentNodeCollection extends AbstractCollection {

    private final Graph graph;

    private final Object baseNode;

    private final Predicate traverserPredicate;

    /**
     *  Creates a new <code>AdjacentNodeCollection</code>.  If a
     *  <code>null</code> <code>Predicate</code> is passed to this
     *  constructor, {@link TruePredicate} is used internally.
     */
    public AdjacentNodeCollection(Graph graph, Object baseNode, Predicate traverserPredicate) {
        super();
        this.graph = graph;
        this.baseNode = baseNode;
        this.traverserPredicate = (traverserPredicate != null) ? traverserPredicate : TruePredicate.INSTANCE;

        if (!graph.containsNode(baseNode)) {
            throw new IllegalArgumentException("Graph does not contain base node: " + baseNode);
        }
    }

    /**
     *  This implementation delegates to {@link
     *  Graph#degree(Object,Predicate) Graph.degree( node, predicate
     *  )}.
     */
    public int size() {
        return graph.degree(baseNode, traverserPredicate);
    }

    /**
     *  This implementation uses {@link
     *  Graph#traverser(Object,Predicate) Graph.traverser( node,
     *  predicate )} and removes the <code>Graph.Edge</code> to the
     *  node, if found.
     */
    public boolean remove(Object object) {
        for (Traverser t = graph.traverser(baseNode, traverserPredicate); t.hasNext();) {
            if (GraphUtils.equals(object, t.next())) {
                t.removeEdge();
                return true;
            }
        }
        return false;
    }

    /**
     *  This implementation uses {@link
     *  Graph#traverser(Object,Predicate) Graph.traverser( node,
     *  predicate )} and returns <code>true</code>, if found.
     */
    public boolean contains(Object object) {
        for (Iterator i = graph.traverser(baseNode, traverserPredicate); i.hasNext();) {
            if (GraphUtils.equals(object, i.next())) {
                return true;
            }
        }
        return false;
    }

    /**
     *  This implementation returns a wrapper around {@link
     *  Graph#traverser(Object,Predicate) Graph.traverser( node,
     *  predicate )}.
     */
    public Iterator iterator() {
        return new TraverserAdjacentNodeIteratorAdapter(graph.traverser(baseNode, traverserPredicate));
    }

    /**
     *  Throws an <code>UnsupportedOperationException</code>.
     */
    public boolean addAll(Collection collection) {
        throw new UnsupportedOperationException();
    }

}