org.eclipse.persistence.internal.jpa.parsing.NullIfNode Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of eclipselink Show documentation

EclipseLink build based upon Git transaction f2b9fc5

There is a newer version: 5.0.0-B03

/*
 * Copyright (c) 1998, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0,
 * or the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

// Contributors:
//     tware - initial implementation as part of JPA 2.0 RI
package org.eclipse.persistence.internal.jpa.parsing;

import org.eclipse.persistence.expressions.Expression;
import org.eclipse.persistence.queries.ObjectLevelReadQuery;
import org.eclipse.persistence.queries.ReportQuery;

/**
 * INTERNAL
 * Purpose: Represent an NULLIF in EJBQL
 * 
Responsibilities:

 *  Generate the correct expression for an NULLIF in EJBQL
 * 
 *    @author tware
 *    @since EclipseLink 1.2
 */
public class NullIfNode extends Node implements AliasableNode {

    public NullIfNode(){
        super();
    }

    /**
     * INTERNAL
     * Apply this node to the passed query
     */
    public void applyToQuery(ObjectLevelReadQuery theQuery, GenerationContext generationContext) {
        if (theQuery instanceof ReportQuery) {
            ReportQuery reportQuery = (ReportQuery)theQuery;
            Expression expression = generateExpression(generationContext);
            reportQuery.addItem("NullIf(" + getLeft().getAsString() + "," + getRight().getAsString() + ")", expression);
        }
    }

    /**
     * INTERNAL
     * Generate the a new EclipseLink NullIf expression for this node.
     */
    public Expression generateExpression(GenerationContext context) {
        Expression whereClause = getLeft().generateExpression(context).nullIf(getRight().generateExpression(context));
        return whereClause;
    }

    public void validate(ParseTreeContext context) {
        left.validate(context);
        right.validate(context);
        setType(left.getType());
    }

    public boolean isAliasableNode(){
        return true;
    }
}