package graph;

/**
 * A basic graph element which can be annotated.  The annotation
 * is currently an array of Object slots.
 *
 * @see AttributeManager
 * @see Node
 * @see Graph
 * @see Edge
 * @author Michael Shilman (michaels@eecs.berkeley.edu)
 * @version $Id$
 */
public abstract class Element {
    public static final int MAX_ATTR = 3;
    
    /**
     * The storage for the attributes.
     */
    public Object attrs[] = null;
	
    /**
     * Get the <i>i'th</i> attribute.  Allocate the
     * attribute array if necessary.
     *
     * @param i		The array index.
     */
    public Object getAttr(int i) {
    	if(attrs == null) {
    		attrs = new Object[MAX_ATTR];
    	}
    	return attrs[i];
    }
    
    /**
     * Set the <i>i'th</i> attribute.  Allocate the
     * attribute array if necessary.
     *
     * @param i		The array index.
     * @param attr	The attribute value.
     */
    public void setAttr(int i, Object attr) {
    	if(attrs == null) {
    		attrs = new Object[MAX_ATTR];
    	}
    	attrs[i] = attr;
    }
}