asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/NullIfTypeComputer.java

/*
 * 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.asterix.om.typecomputer.impl;

import org.apache.asterix.om.typecomputer.base.AbstractResultTypeComputer;
import org.apache.asterix.om.types.ATypeTag;
import org.apache.asterix.om.types.AUnionType;
import org.apache.asterix.om.types.IAType;
import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;

public class NullIfTypeComputer extends AbstractResultTypeComputer {

    public static final NullIfTypeComputer INSTANCE = new NullIfTypeComputer();

    @Override
    public IAType getResultType(ILogicalExpression expr, IAType... strippedInputTypes) throws AlgebricksException {
        IAType inputType = strippedInputTypes[0];
        return inputType.getTypeTag() == ATypeTag.ANY ? inputType : AUnionType.createNullableType(inputType);
    }
}