001package ball.annotation.processing; 002/*- 003 * ########################################################################## 004 * Utilities 005 * $Id: ServiceProviderForProcessor.java 6099 2020-06-03 17:01:31Z ball $ 006 * $HeadURL: svn+ssh://svn.hcf.dev/var/spool/scm/repository.svn/ball-util/trunk/src/main/java/ball/annotation/processing/ServiceProviderForProcessor.java $ 007 * %% 008 * Copyright (C) 2008 - 2020 Allen D. Ball 009 * %% 010 * Licensed under the Apache License, Version 2.0 (the "License"); 011 * you may not use this file except in compliance with the License. 012 * You may obtain a copy of the License at 013 * 014 * http://www.apache.org/licenses/LICENSE-2.0 015 * 016 * Unless required by applicable law or agreed to in writing, software 017 * distributed under the License is distributed on an "AS IS" BASIS, 018 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 019 * See the License for the specific language governing permissions and 020 * limitations under the License. 021 * ########################################################################## 022 */ 023import ball.annotation.ServiceProviderFor; 024import java.io.PrintWriter; 025import java.util.List; 026import java.util.Map; 027import java.util.Objects; 028import java.util.Set; 029import java.util.TreeMap; 030import java.util.TreeSet; 031import java.util.stream.Stream; 032import javax.annotation.processing.Processor; 033import javax.annotation.processing.RoundEnvironment; 034import javax.lang.model.element.AnnotationMirror; 035import javax.lang.model.element.AnnotationValue; 036import javax.lang.model.element.Element; 037import javax.lang.model.element.TypeElement; 038import javax.lang.model.type.TypeMirror; 039import javax.tools.FileObject; 040import javax.tools.JavaFileManager; 041import lombok.NoArgsConstructor; 042import lombok.ToString; 043 044import static java.lang.reflect.Modifier.isAbstract; 045import static java.util.stream.Collectors.toList; 046import static javax.tools.Diagnostic.Kind.ERROR; 047import static javax.tools.StandardLocation.CLASS_OUTPUT; 048import static org.apache.commons.lang3.StringUtils.EMPTY; 049 050/** 051 * {@link Processor} implementation to check {@link Class}es annotated with 052 * {@link ServiceProviderFor} to verify the annotated {@link Class}: 053 * <ol> 054 * <li value="1">Is concrete</li> 055 * <li value="2">Has a public no-argument constructor</li> 056 * <li value="3"> 057 * Implements the {@link Class}es specified by 058 * {@link ServiceProviderFor#value()} 059 * </li> 060 * </ol> 061 * 062 * Note: Google offers a similar 063 * {@link.uri https://github.com/google/auto/tree/master/service target=newtab AutoService} 064 * library. 065 * 066 * @author {@link.uri mailto:ball@hcf.dev Allen D. Ball} 067 * @version $Revision: 6099 $ 068 */ 069@ServiceProviderFor({ Processor.class }) 070@For({ ServiceProviderFor.class }) 071@NoArgsConstructor @ToString 072public class ServiceProviderForProcessor extends AnnotatedProcessor 073 implements ClassFileProcessor { 074 private static final String PATH = "META-INF/services/%s"; 075 076 @Override 077 protected void process(RoundEnvironment roundEnv, 078 TypeElement annotation, Element element) { 079 super.process(roundEnv, annotation, element); 080 081 AnnotationMirror mirror = getAnnotationMirror(element, annotation); 082 AnnotationValue value = getAnnotationValue(mirror, "value"); 083 084 if (! isEmptyArray(value)) { 085 String provider = 086 elements.getBinaryName((TypeElement) element).toString(); 087 List<TypeElement> services = 088 Stream.of(value) 089 .filter(Objects::nonNull) 090 .map(t -> (List<?>) t.getValue()) 091 .flatMap(List::stream) 092 .map(t -> (AnnotationValue) t) 093 .map(t -> (TypeMirror) t.getValue()) 094 .map(t -> (TypeElement) types.asElement(t)) 095 .collect(toList()); 096 097 for (TypeElement service : services) { 098 if (! types.isAssignable(element.asType(), service.asType())) { 099 print(ERROR, element, 100 "@%s: %s does not implement %s", 101 annotation.getSimpleName(), 102 element.getKind(), service.getQualifiedName()); 103 } 104 } 105 } else { 106 print(ERROR, element, mirror, value, "value() is empty"); 107 } 108 } 109 110 @Override 111 public void process(Set<Class<?>> set, 112 JavaFileManager fm) throws Throwable { 113 Map<String,Set<String>> map = new TreeMap<>(); 114 115 for (Class<?> provider : set) { 116 if (! isAbstract(provider.getModifiers())) { 117 ServiceProviderFor annotation = 118 provider.getAnnotation(ServiceProviderFor.class); 119 120 if (annotation != null) { 121 for (Class<?> service : annotation.value()) { 122 if (service.isAssignableFrom(provider)) { 123 map.computeIfAbsent(service.getName(), 124 k -> new TreeSet<>()) 125 .add(provider.getName()); 126 } 127 } 128 } 129 } 130 } 131 132 for (Map.Entry<String,Set<String>> entry : map.entrySet()) { 133 String service = entry.getKey(); 134 FileObject file = 135 fm.getFileForOutput(CLASS_OUTPUT, 136 EMPTY, String.format(PATH, service), null); 137 138 try (PrintWriter writer = new PrintWriter(file.openWriter())) { 139 writer.println("# " + service); 140 141 entry.getValue().stream().forEach(t -> writer.println(t)); 142 } 143 } 144 } 145}