/*
 * 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.hyracks.algebricks.core.algebra.expressions;

/**
 * This interface is in charge of resolving conflicting types and returning
 * a resolved type that conform to all input types in the case there are conflicting
 * types during type inference. For example, a UNION ALL operator can union a sequence
 * of integers with a sequence of records, where the two input sequences have
 * conflicting types.
 */
@FunctionalInterface
public interface IConflictingTypeResolver {

    /**
     * Resolves conflicting input types and return a type that conforms to every input type.
     *
     * @param inputTypes,
     *            conflicting types that need to be resolved.
     * @return a (potentially relaxed) type that conform to all input types.
     */
    public Object resolve(Object... inputTypes);

}
