/*
* 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.builtin;
import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import org.apache.pig.EvalFunc;
import org.apache.pig.classification.InterfaceAudience;
import org.apache.pig.classification.InterfaceStability;
/**
* An EvalFunc can annotated with an <code>OutputSchema</code> to
* tell Pig what the expected output is. This can be used in place
* of {@link EvalFunc#outputSchema(Schema)}
* <p>
* The default implementation of {@link EvalFunc#outputSchema(Schema)}
* will look at this annotation and return an interpreted schema, if the annotation is present.
* <p>
* Implementing a custom {@link EvalFunc#outputSchema(Schema)} will
* override the annotation (unless you deal with it explicitly, or by calling <code>super.outputSchema(schema)</code>).
* <p>
* Here's an example of a complex schema declared in an annotation:
* <code>@OutputSchema("y:bag{t:tuple(len:int,word:chararray)}")</code>
*/
@InterfaceAudience.Public
@InterfaceStability.Unstable
@Documented
@Retention(value=RetentionPolicy.RUNTIME)
public @interface OutputSchema {
String value();
}