| /* |
| * 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.hadoop.hive.ql.exec; |
| |
| /** |
| * <strong>Please see the deprecation notice</strong> |
| * <br> |
| * Base class for all User-defined Aggregation Function (UDAF) classes. |
| * <br> |
| * Requirements for a UDAF class: |
| * <ol> |
| * <li>Implement the {@code init()} method, which resets the status of the aggregation function.</li> |
| * <li>Implement a single method called {@code aggregate} that returns {@code boolean}. |
| * The method should always return {@code true} on valid inputs, or the framework will throw an Exception. |
| * Following are some examples: |
| * <ul> |
| * <li>{@code public boolean aggregate(double a);}</li> |
| * <li>{@code public boolean aggregate(int b);}</li> |
| * <li>{@code public boolean aggregate(double c, double d);}</li> |
| * </ul> |
| * </li> |
| * <li>Implement a single method called {@code evaluate} that returns the FINAL aggregation result. |
| * {@code evaluate} should never return {@code null} or an Exception will be thrown. |
| * Following are some examples: |
| * <ul> |
| * <li>{@code public int evaluate();}</li> |
| * <li>{@code public long evaluate();}</li> |
| * <li>{@code public double evaluate();}</li> |
| * <li>{@code public Double evaluate();}</li> |
| * <li>{@code public String evaluate();}</li> |
| * </ul> |
| * </li> |
| * </ol> |
| * |
| * Optional for a UDAF class (by implementing these two methods, the user declares |
| * that the UDAF supports partial aggregations): |
| * <ol> |
| * <li>Implement a single method called {@code evaluatePartial} that returns the PARTIAL aggregation result. |
| * {@code evaluatePartial} should never return {@code null} or an Exception will be thrown.</li> |
| * <li>Implement a single method called {@code aggregatePartial} that takes a PARTIAL |
| * aggregation result and returns a boolean. The method should always return |
| * {@code true} on valid inputs, or the framework will throw an Exception.</li> |
| * </ol> |
| * <br> |
| * Following are some examples: |
| * <ul> |
| * <li>public int evaluatePartial();</li> |
| * <li>public boolean aggregatePartial(int partial);</li> |
| * <li>public String evaluatePartial();</li> |
| * <li>public boolean aggregatePartial(String partial);</li> |
| * </ul> |
| * |
| * @deprecated Either implement org.apache.hadoop.hive.ql.udf.generic.GenericUDAFResolver2 or extend |
| * org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver instead. |
| */ |
| @Deprecated |
| public class UDAF { |
| |
| /** |
| * The resolver used for method resolution. |
| */ |
| UDAFEvaluatorResolver rslv; |
| |
| /** |
| * The default constructor. |
| */ |
| public UDAF() { |
| rslv = new DefaultUDAFEvaluatorResolver(this.getClass()); |
| } |
| |
| /** |
| * The constructor with a particular type of resolver. |
| */ |
| public UDAF(UDAFEvaluatorResolver rslv) { |
| this.rslv = rslv; |
| } |
| |
| /** |
| * Sets the resolver. |
| * |
| * @param rslv |
| * The method resolver to use for method resolution. |
| */ |
| public void setResolver(UDAFEvaluatorResolver rslv) { |
| this.rslv = rslv; |
| } |
| |
| /** |
| * Gets the resolver. |
| */ |
| public UDAFEvaluatorResolver getResolver() { |
| return rslv; |
| } |
| } |