src/org/apache/pig/scripting/groovy/AlgebraicInitial.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.pig.scripting.groovy;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * This annotation is to be used on a Groovy method which
 * is part of an Algebraic UDF to indicate that it will
 * act as the exec method of the 'Initial' class of the UDF.
 *
 * The value of the annotation is the name of the Algebraic UDF
 * it belongs to.
 *
 * The annotated method MUST accept a single groovy.lang.Tuple parameter,
 * and MUST return a groovy.lang.Tuple or Object[].
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface AlgebraicInitial {
  String value();
}