package com.onaro.util.jfc.grouping;

/**
 * A grouping criterion that is associated with a single table column. The value
 * that identifies the group is the value of the node at that column.
 */
public class ColumnCriterion implements Criterion {

    /**
     * The column number of the encapsulated table with which this criterion is
     * associated.
     */
    private int columnNumber;

    /**
     * Sets the column number of the encapsulated table with which this criterion is
     * associated.
     * @param columnNumber the column number
     */
    public ColumnCriterion(int columnNumber) {
        this.columnNumber = columnNumber;
    }

    /**
     * Gets the value of the node at the column this criterion is associated with.
     * @param node the node to get its criterion value
     * @return the value at the {@link ColumnCriterion#columnNumber}
     */
    public Object getValue(Node node) {
        return node.getValueAt(columnNumber);
    }

    /**
     * Gets the number of the column used by this criterion. Used for unit
     * tests only.
     * @return an array of the column numbers the criterion is using
     */
    public int[] getColumnNumbers() {
        return new int[] {columnNumber};
    }
}