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/*
 * The contents of this file are subject to the terms 
 * of the Common Development and Distribution License 
 * (the "License").  You may not use this file except 
 * in compliance with the License.
 * 
 * You can obtain a copy of the license at 
 * glassfish/bootstrap/legal/CDDLv1.0.txt or 
 * https://glassfish.dev.java.net/public/CDDLv1.0.html. 
 * See the License for the specific language governing 
 * permissions and limitations under the License.
 * 
 * When distributing Covered Code, include this CDDL 
 * HEADER in each file and include the License file at 
 * glassfish/bootstrap/legal/CDDLv1.0.txt.  If applicable, 
 * add the following below this CDDL HEADER, with the 
 * fields enclosed by brackets "[]" replaced with your 
 * own identifying information: Portions Copyright [yyyy] 
 * [name of copyright owner]
 */
// Copyright (c) 1998, 2005, Oracle. All rights reserved.  
package oracle.toplink.essentials.internal.parsing;

import oracle.toplink.essentials.expressions.*;

/**
 * INTERNAL
 * Purpose: Represent a '-' in EJBQL
 * 
Responsibilities:

 *  Generate the correct expression for a '-'
 * 
 *    @author Jon Driscoll and Joel Lucuik
 *    @since July 2003
 */
public class MinusNode extends BinaryOperatorNode {
    public MinusNode() {
        super();
    }

    /**
     * INTERNAL
     * Validate node and calculates its type.
     */
    public void validate(ParseTreeContext context) {
        super.validate(context);
        if ((left != null) && (right != null)) {
            TypeHelper typeHelper = context.getTypeHelper();
            setType(typeHelper.extendedBinaryNumericPromotion(
                        left.getType(), right.getType()));
        }
    }

    /**
     * INTERNAL
     * Generate the expression. The steps are:
     * 1. Generate the expression for the left node
     * 2. Add the .subtract to the where clause returned from step 1
     * 3. Generate the expression for the right side and use it as the parameter for the .subtract()
     * 4. Return the completed where clause to the caller
     */
    public Expression generateExpression(GenerationContext context) {
        Expression whereClause = getLeft().generateExpression(context);
        whereClause = ExpressionMath.subtract(whereClause, getRight().generateExpression(context));
        return whereClause;
    }

    public boolean isMinusNode() {
        return true;
    }
}