Bug340635Proc.java

/*******************************************************************************
 * Copyright (c) 2015 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     Kevin Pollet - SERLI - (kevin.pollet@serli.com) - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.compiler.apt.tests.processors.AnnotationProcessorTests;

import java.util.Set;

import javax.annotation.processing.AbstractProcessor;
import javax.annotation.processing.Messager;
import javax.annotation.processing.RoundEnvironment;
import javax.annotation.processing.SupportedAnnotationTypes;
import javax.annotation.processing.SupportedSourceVersion;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.Element;
import javax.lang.model.element.TypeElement;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.type.TypeMirror;
import javax.lang.model.util.SimpleTypeVisitor6;
import javax.lang.model.util.Types;
import javax.tools.Diagnostic.Kind;

@SupportedSourceVersion(SourceVersion.RELEASE_6)
@SupportedAnnotationTypes("annotation.GetType")
public class Bug340635Proc extends AbstractProcessor {

	private static final boolean ALLOW_OTHER_PROCESSORS_TO_PROCESS = false;

	@Override
	public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
		final Types types = processingEnv.getTypeUtils();
		final Messager messager = processingEnv.getMessager();

		for (TypeElement annotation : annotations) {
			final Set<? extends Element> elements = roundEnv.getElementsAnnotatedWith(annotation);

			// process the annotations
			for (Element element : elements) {
				// search and display informations about the first generic type
				// found in the
				// class or interface hierarchy.
				if (element.getKind().isInterface() || element.getKind().isClass()) {
					DeclaredType genericType = element.asType().accept(new GenericTypeVisitor(types), null);
					DeclaredType erasedType = (DeclaredType) types.erasure(genericType);

					StringBuffer message = new StringBuffer();
					message.append("Erased type: " + erasedType);
					message.append(" - type arguments: ");
					for (TypeMirror typeArgument : erasedType.getTypeArguments()) {
						message.append(typeArgument + ",");
					}
					messager.printMessage(Kind.WARNING, message.toString(), element);
				}
			}

		}

		return ALLOW_OTHER_PROCESSORS_TO_PROCESS;
	}

	private class GenericTypeVisitor extends SimpleTypeVisitor6<DeclaredType, Void> {
		private final Types types;

		public GenericTypeVisitor(Types types) {
			this.types = types;
		}

		@Override
		public DeclaredType visitDeclared(DeclaredType t, Void p) {
			if (t.getTypeArguments().size() > 0) {
				return t;
			}
			for (TypeMirror superType : types.directSupertypes(t)) {
				DeclaredType tmp = superType.accept(this, p);
				if (tmp != null) {
					return tmp;
				}
			}
			return null;
		}
	}

}