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/*
 * Generic graph library
 * Copyright (C) 2000,2003,2004,2007 University of Maryland
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.graph;

/**
 * GraphVertex implementation for use with AbstractGraph.
 *
 * @see GraphVertex
 * @see AbstractGraph
 * @see AbstractEdge
 * @author David Hovemeyer
 */
public class AbstractVertex, ActualVertexType extends AbstractVertex>
        implements GraphVertex {

    private int label;

    EdgeType firstIncomingEdge, lastIncomingEdge;

    EdgeType firstOutgoingEdge, lastOutgoingEdge;

    @Override
    public int getLabel() {
        return label;
    }

    @Override
    public void setLabel(int label) {
        this.label = label;
    }

    @Override
    public int hashCode() {
        return label;
    }

    @Override
    public boolean equals(Object o) {
        if (o == null || o.getClass() != this.getClass()) {
            return false;
        }
        AbstractVertex other = (AbstractVertex) o;
        return other.getLabel() == this.getLabel();
    }

    @Override
    public int compareTo(ActualVertexType other) {
        if (this.getLabel() < other.getLabel()) {
            return -1;
        } else if (this.getLabel() > other.getLabel()) {
            return 1;
        } else {
            return 0;
        }
    }

    void addOutgoingEdge(EdgeType edge) {
        if (firstOutgoingEdge == null) {
            firstOutgoingEdge = lastOutgoingEdge = edge;
        } else {
            lastOutgoingEdge.setNextOutgoingEdge(edge);
            lastOutgoingEdge = edge;
        }
    }

    EdgeType getFirstOutgoingEdge() {
        return firstOutgoingEdge;
    }

    void addIncomingEdge(EdgeType edge) {
        if (firstIncomingEdge == null) {
            firstIncomingEdge = lastIncomingEdge = edge;
        } else {
            lastIncomingEdge.setNextIncomingEdge(edge);
            lastIncomingEdge = edge;
        }
    }

    EdgeType getFirstIncomingEdge() {
        return firstIncomingEdge;
    }

    void removeIncomingEdge(EdgeType edge) {
        EdgeType prev = null, cur = firstIncomingEdge;
        while (cur != null) {
            EdgeType next = cur.getNextIncomingEdge();
            if (cur.equals(edge)) {
                if (prev != null) {
                    prev.setNextIncomingEdge(next);
                } else {
                    firstIncomingEdge = next;
                }
                return;
            }
            prev = cur;
            cur = next;
        }
        throw new IllegalArgumentException("removing nonexistent edge!");
    }

    void removeOutgoingEdge(EdgeType edge) {
        EdgeType prev = null, cur = firstOutgoingEdge;
        while (cur != null) {
            EdgeType next = cur.getNextOutgoingEdge();
            if (cur.equals(edge)) {
                if (prev != null) {
                    prev.setNextOutgoingEdge(next);
                } else {
                    firstOutgoingEdge = next;
                }
                return;
            }
            prev = cur;
            cur = cur.getNextOutgoingEdge();
        }
        throw new IllegalArgumentException("removing nonexistent edge!");
    }

}