org.glassfish.apf.AnnotationHandler Maven / Gradle / Ivy
/*
* Copyright (c) 2022 Contributors to the Eclipse Foundation
* Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package org.glassfish.apf;
import java.lang.annotation.Annotation;
import org.jvnet.hk2.annotations.Contract;
/**
* This interface defines the contract for annotation handlers
* and the annotation processing engine. Each annotation handler
* is registered for a particular annotation type and will be
* called by the engine when such annotation type is encountered.
* The AnnotationHandler is a stateless object, no state should
* be stored, instead users should use the ProcessingContext.
* Annotation can be defined or processed in random orders on a
* particular type, however, a particular annotation may need
* other annotation to be processed before itself in order to be
* processed successfully. An annotation type can indicate through
* the getAnnotations() method which annotation types should
* be processed before itself.
*
* Each implementation of this interface must specify the annotation that it can handle using
* {@link AnnotationHandlerFor} annotation.
*
* @author Jerome Dochez
*/
@Contract
public interface AnnotationHandler {
String ANNOTATION_HANDLER_METADATA = "AnnotationHandlerFor";
/**
* @return the annotation type this annotation handler is handling
*/
Class getAnnotationType();
/**
* Process a particular annotation which type is the same as the
* one returned by @see getAnnotationType(). All information
* pertinent to the annotation and its context is encapsulated
* in the passed AnnotationInfo instance.
*
* @param element the annotation information
* @return {@link HandlerProcessingResult}
* @throws AnnotationProcessorException
*/
HandlerProcessingResult processAnnotation(AnnotationInfo element) throws AnnotationProcessorException;
/**
* @return an array of annotation types this annotation handler would
* require to be processed (if present) before it processes it's own
* annotation type.
*/
Class[] getTypeDependencies();
}