/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.    
 */
package org.apache.openjpa.jdbc.kernel.exps;

import org.apache.openjpa.jdbc.sql.SQLBuffer;
import org.apache.openjpa.jdbc.sql.Select;

/**
 * A literal null value in a filter.
 *
 * @author Abe White
 */
public class Null
    extends Const {

    public Class getType() {
        return Object.class;
    }

    public void setImplicitType(Class type) {
    }

    public Object getValue(Object[] params) {
        return null;
    }

    public void calculateValue(Select sel, ExpContext ctx, ExpState state, 
        Val other, ExpState otherState) {
    }

    public void appendTo(Select sel, ExpContext ctx, ExpState state, 
        SQLBuffer sql, int index) {
        sql.appendValue(null);
    }
}