001package ball.annotation.processing;
002/*-
003 * ##########################################################################
004 * Utilities
005 * %%
006 * Copyright (C) 2008 - 2022 Allen D. Ball
007 * %%
008 * Licensed under the Apache License, Version 2.0 (the "License");
009 * you may not use this file except in compliance with the License.
010 * You may obtain a copy of the License at
011 *
012 *      http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing, software
015 * distributed under the License is distributed on an "AS IS" BASIS,
016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017 * See the License for the specific language governing permissions and
018 * limitations under the License.
019 * ##########################################################################
020 */
021import ball.annotation.ServiceProviderFor;
022import java.lang.annotation.Documented;
023import java.lang.annotation.Retention;
024import java.lang.annotation.Target;
025import javax.annotation.processing.Processor;
026import javax.annotation.processing.RoundEnvironment;
027import javax.lang.model.element.AnnotationMirror;
028import javax.lang.model.element.AnnotationValue;
029import javax.lang.model.element.Element;
030import javax.lang.model.element.TypeElement;
031import lombok.NoArgsConstructor;
032import lombok.ToString;
033
034import static java.lang.annotation.ElementType.TYPE;
035import static java.lang.annotation.RetentionPolicy.RUNTIME;
036import static javax.tools.Diagnostic.Kind.ERROR;
037
038/**
039 * {@link java.lang.annotation.Annotation} to specify required
040 * super-{@link Class} criteria a {@link Class} must implement.
041 *
042 * @author {@link.uri mailto:ball@hcf.dev Allen D. Ball}
043 */
044@Documented
045@Retention(RUNTIME)
046@Target({ TYPE })
047@TargetMustExtend(AnnotatedNoAnnotationProcessor.class)
048public @interface MustImplement {
049    Class<?>[] value() default { };
050
051    /**
052     * {@link Processor} implementation.
053     */
054    @ServiceProviderFor({ Processor.class })
055    @For({ MustImplement.class })
056    @NoArgsConstructor @ToString
057    public static class ProcessorImpl extends AnnotatedProcessor {
058        @Override
059        public void process(RoundEnvironment roundEnv, TypeElement annotation, Element element) {
060            super.process(roundEnv, annotation, element);
061
062            AnnotationMirror mirror = getAnnotationMirror(element, annotation);
063            AnnotationValue value = getAnnotationValue(mirror, "value");
064
065            if (isEmptyArray(value)) {
066                print(ERROR, element, mirror, value, "value() is empty");
067            }
068        }
069    }
070}