package com.onaro.util.jfc.grouping;


/**
 * A criterion is used to identify the group a node belongs to.
 */
public interface Criterion {

    /**
     * Gets the value that identifies the group a node belongs to.
     * @param node the node
     * @return a value that identifies the group
     */
    public Object getValue(Node node);

    /**
     * Gets the numbers of the columns used by this criterion.
     * @return an array of the column numbers the criterion is using
     */
    public int[] getColumnNumbers();

}