GraphNode.java

import org.apache.commons.collections15.Factory;

import java.awt.Color;

/**
 *  A node representation for the graph simulation.
 *
 *  @author Katherine (Raven) Russell
 */
class GraphNode extends GraphComp {
    /**
     *  The number of nodes created so far (for gerating unique ids
     *  from the factory method).
     */
    public static int nodeCount = 0;

    /**
     *  The boolean flag to indicate whether a node is active or not.
     *  Used to support certain graph algorithms.
     */
    private boolean active;

    /**
     *  The integer cost associated with each node.
     *  Used to support certain graph algorithms.
     */
    private int cost;

    /**
     *  The byte used as 8 boolean bits used to support graph coloring algorithms.
     *  Assume no more than 8 possible color and they are defined in ThreeTenColor.COLORS.
     *  nbrColorFlag[i] == 1: this node has a nbr taking color ThreeTenColor.COLORS[i]
     *  nbrColorFlag[i] == 0: this node has no nbr taking color ThreeTenColor.COLORS[i]
     */
    private byte nbrColors;

    /**
     *  Constructs a node with a given id.
     *
     *  @param id the unique id of the node
     */
    public GraphNode(int id) {
        this.id = id; this.color = Color.WHITE;
        this.active = false;
        this.cost = 0;
        this.nbrColors = 0;
    }

    /**
     *  Set this node to be active.
     */
    public void setActive(){ active = true; }

    /**
     *  Set this node to be inactive.
     */
    public void unsetActive(){ active = false; }

    /**
     *  Report the active status of this node.
     *  @return whether this node is active or not
     */
    public boolean isActive() {return active; }

    /**
     *  Set the cost of this node to be the incoming value.
     *
     *  @param cost the cost to set for this node
     */
    public void setCost(int cost) { this.cost = cost; }

    /**
     *  Report the cost of this node.
     *  @return the cost of this node
     */
    public int getCost() { return this.cost; }

    /**
     *  Clear the information about the colors of neighbor nodes.
     *  Set all 8 bits to be 0.
     */
    public void clearNbrColors(){
        nbrColors = 0;
    }

    /**
     *  One neighbor of this node has been assigned color ThreeTenColor.COLORS[index].
     *  Update the record of nbrColors of this node based on this color assignment.
     *
     *  @param index the color index assigned to one neighbor
     *  @return return false if invalid index; return true otherwise
     */
    public boolean setNbrColor(int index){
        if (index<0 || index>=ThreeTenColor.COLORS.length)
            return false;

        nbrColors = (byte) (nbrColors | (1<<index));
        return true;
    }

    /**
     *  Report whether this node has any neighbor with the color
     *  defined as ThreeTenColor.COLORS[index].
     *
     *  @param index the color index
     *  @return return true if there is a neighbor of this node taken the color; false otherwise
     */
    public boolean nbrHasColor(int index){
        if (index<0 || index>=ThreeTenColor.COLORS.length)
            throw new IllegalArgumentException("Invalid color index.");

        return (((nbrColors>>index) & 1) != 0);
    }


    /**
     *  {@inheritDoc}
     */
    @Override
    public int compareTo(GraphComp n) {
        if (!(n instanceof GraphNode)){
            return super.compareTo(n);
        }
        GraphNode node = (GraphNode) n;
        if (this.cost!=node.cost)
            return node.cost - this.cost;
        else
            return this.id-n.id; //use id to break the tie
    }


    /**
     *  {@inheritDoc}
     */
    @Override
    public String toString() {
        return "" + id + (active ? ":"+cost : "");
    }

    /**
     *  Generates a new node with a (probably) unique id.
     *
     *  @return a new node
     */
    public static Factory<GraphNode> getFactory() {
        return new Factory<GraphNode> () {
            public GraphNode create() {
                return new GraphNode(nodeCount++);
            }
        };
    }
}