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package oracle.toplink.essentials.internal.parsing;


// Java imports
import java.util.*;

// TopLink Imports
import oracle.toplink.essentials.queryframework.ReadAllQuery;
import oracle.toplink.essentials.queryframework.ObjectLevelReadQuery;

/**
 * INTERNAL
 * <p><b>Purpose</b>: Represent an ORDER BY
 * <p><b>Responsibilities</b>:<ul>
 * <li> Generate the correct expression for an ORDER BY
 * </ul>
 *    @author Jon Driscoll
 *    @since TopLink 5.0
 */
public class OrderByNode extends MajorNode {

    List orderByItems = null;

    /**
     * Return a new OrderByNode.
     */
    public OrderByNode() {
        super();
    }

    /**
     * INTERNAL
     * Add an Order By Item to this node
     */
    private void addOrderByItem(Object theNode) {
        getOrderByItems().add(theNode);
    }

    /**
     * INTERNAL
     * Add the ordering expressions to the passed query
     */
    public void addOrderingToQuery(ObjectLevelReadQuery theQuery, GenerationContext context) {
        if (theQuery.isReadAllQuery()) {
            Iterator iter = getOrderByItems().iterator();
            while (iter.hasNext()) {
                Node nextNode = (Node)iter.next();
                ((ReadAllQuery)theQuery).addOrdering(nextNode.generateExpression(context));
            }
        }
    }

    /**
     * INTERNAL
     * Validate node.
     */
    public void validate(ParseTreeContext context, SelectNode selectNode) {
        for (Iterator i = orderByItems.iterator(); i.hasNext(); ) {
            Node item = (Node)i.next();
            item.validate(context);
        }
    }
    
    /**
     * INTERNAL
     * Return the order by statements
     */
    public List getOrderByItems() {
        if (orderByItems == null) {
            setOrderByItems(new Vector());
        }
        return orderByItems;
    }

    /**
     * INTERNAL
     * Set the order by statements
     */
    public void setOrderByItems(List newItems) {
        orderByItems = newItems;
    }
}