AggregateFunction.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.metamodel.query;

import org.apache.metamodel.schema.ColumnType;
import org.apache.metamodel.util.AggregateBuilder;

/**
 * Interface that contains the aggregation specific methods
 * related to the AggregateBuilder.
 *
 */
public interface AggregateFunction extends FunctionType {

    /**
     * Creates a specific aggregate builder.
     *
     * @return an AggregateBuilder instance
     */
    public AggregateBuilder<?> createAggregateBuilder();

    /**
     * Shorthand for creating an aggregate builder, adding all
     * the values and then calculating the value.
     *
     * @param values
     * @return the aggregated value
     */
    public Object evaluate(Object... values);

    /**
     * Returns the function ColumnType.
     *
     * @param type
     * @return the ColumnType
     */
    public ColumnType getExpectedColumnType(ColumnType type);
}