[MNG-8249] Provide an annotation processor for DI (#1704)

Author: gnodet

api/maven-api-di/pom.xml

@@ -30,4 +30,7 @@
   <name>Maven 4 API :: Dependency Injection</name>
   <description>Maven 4 API - Dependency Injection</description>
 
+  <properties>
+    <maven.compiler.proc>none</maven.compiler.proc>
+  </properties>
 </project>

api/maven-api-di/src/main/java/org/apache/maven/di/tool/DiIndexProcessor.java

@@ -0,0 +1,95 @@
+/*
+ * 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.maven.di.tool;
+
+import javax.annotation.processing.AbstractProcessor;
+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.tools.Diagnostic;
+import javax.tools.FileObject;
+import javax.tools.StandardLocation;
+
+import java.io.IOException;
+import java.io.Writer;
+import java.util.Set;
+
+import org.apache.maven.api.di.Named;
+
+// Auto-register the annotation processor
+@SupportedAnnotationTypes("org.apache.maven.api.di.Named")
+@SupportedSourceVersion(SourceVersion.RELEASE_17)
+public class DiIndexProcessor extends AbstractProcessor {
+
+    @Override
+    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
+        // Collect the fully qualified names of classes annotated with @Named
+        StringBuilder builder = new StringBuilder();
+
+        processingEnv
+                .getMessager()
+                .printMessage(
+                        Diagnostic.Kind.NOTE,
+                        "Processing " + roundEnv.getRootElements().size() + " classes");
+
+        for (Element element : roundEnv.getElementsAnnotatedWith(Named.class)) {
+            if (element instanceof TypeElement typeElement) {
+                // Get the fully qualified class name
+                String className = typeElement.getQualifiedName().toString();
+
+                // Handle inner classes by checking if the enclosing element is a class or interface
+                Element enclosingElement = typeElement.getEnclosingElement();
+                if (enclosingElement instanceof TypeElement) {
+                    // It's an inner class, replace the last dot with a '$'
+                    String enclosingClassName =
+                            ((TypeElement) enclosingElement).getQualifiedName().toString();
+                    className = enclosingClassName + "$" + typeElement.getSimpleName();
+                }
+
+                builder.append(className).append("\n");
+            }
+        }
+
+        if (!builder.isEmpty()) { // Check if the StringBuilder is non-empty
+            try {
+                writeFile(builder.toString());
+            } catch (IOException e) {
+                processingEnv
+                        .getMessager()
+                        .printMessage(Diagnostic.Kind.ERROR, "Error writing file: " + e.getMessage());
+            }
+        }
+
+        return true; // Indicate that annotations are claimed by this processor
+    }
+
+    private void writeFile(String content) throws IOException {
+        // Create the file META-INF/maven/org.apache.maven.api.di.Inject
+        FileObject fileObject = processingEnv
+                .getFiler()
+                .createResource(StandardLocation.CLASS_OUTPUT, "", "META-INF/maven/org.apache.maven.api.di.Inject");
+
+        try (Writer writer = fileObject.openWriter()) {
+            writer.write(content);
+        }
+    }
+}

api/maven-api-di/src/main/resources/META-INF/services/javax.annotation.processing.Processor

@@ -0,0 +1 @@
+org.apache.maven.di.tool.DiIndexProcessor

api/maven-api-spi/pom.xml

@@ -43,6 +43,10 @@
       <groupId>org.apache.maven</groupId>
       <artifactId>maven-api-core</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.apache.maven</groupId>
+      <artifactId>maven-api-di</artifactId>
+    </dependency>
   </dependencies>
 
 </project>

api/maven-api-spi/src/main/java/org/apache/maven/api/spi/LanguageProvider.java

@@ -21,10 +21,12 @@
 import org.apache.maven.api.Language;
 import org.apache.maven.api.annotations.Consumer;
 import org.apache.maven.api.annotations.Experimental;
+import org.apache.maven.api.di.Named;
 
 /**
  * @since 4.0.0
  */
 @Experimental
 @Consumer
+@Named
 public interface LanguageProvider extends ExtensibleEnumProvider<Language> {}

api/maven-api-spi/src/main/java/org/apache/maven/api/spi/LifecycleProvider.java

@@ -21,7 +21,9 @@
 import org.apache.maven.api.Lifecycle;
 import org.apache.maven.api.annotations.Consumer;
 import org.apache.maven.api.annotations.Experimental;
+import org.apache.maven.api.di.Named;
 
 @Experimental
 @Consumer
+@Named
 public interface LifecycleProvider extends ExtensibleEnumProvider<Lifecycle> {}

api/maven-api-spi/src/main/java/org/apache/maven/api/spi/ModelParser.java

@@ -26,6 +26,7 @@
 import org.apache.maven.api.annotations.Experimental;
 import org.apache.maven.api.annotations.Nonnull;
 import org.apache.maven.api.annotations.Nullable;
+import org.apache.maven.api.di.Named;
 import org.apache.maven.api.model.Model;
 import org.apache.maven.api.services.Source;
 
@@ -37,6 +38,7 @@
  */
 @Experimental
 @Consumer
+@Named
 public interface ModelParser extends SpiService {
 
     /**

api/maven-api-spi/src/main/java/org/apache/maven/api/spi/PackagingProvider.java

@@ -21,7 +21,9 @@
 import org.apache.maven.api.Packaging;
 import org.apache.maven.api.annotations.Consumer;
 import org.apache.maven.api.annotations.Experimental;
+import org.apache.maven.api.di.Named;
 
 @Experimental
 @Consumer
+@Named
 public interface PackagingProvider extends ExtensibleEnumProvider<Packaging> {}

api/maven-api-spi/src/main/java/org/apache/maven/api/spi/PathScopeProvider.java

@@ -21,10 +21,12 @@
 import org.apache.maven.api.PathScope;
 import org.apache.maven.api.annotations.Consumer;
 import org.apache.maven.api.annotations.Experimental;
+import org.apache.maven.api.di.Named;
 
 /**
  * @since 4.0.0
  */
 @Experimental
 @Consumer
+@Named
 public interface PathScopeProvider extends ExtensibleEnumProvider<PathScope> {}

api/maven-api-spi/src/main/java/org/apache/maven/api/spi/ProjectScopeProvider.java

@@ -21,10 +21,12 @@
 import org.apache.maven.api.ProjectScope;
 import org.apache.maven.api.annotations.Consumer;
 import org.apache.maven.api.annotations.Experimental;
+import org.apache.maven.api.di.Named;
 
 /**
  * @since 4.0.0
  */
 @Experimental
 @Consumer
+@Named
 public interface ProjectScopeProvider extends ExtensibleEnumProvider<ProjectScope> {}

api/maven-api-spi/src/main/java/org/apache/maven/api/spi/PropertyContributor.java

@@ -22,6 +22,7 @@
 
 import org.apache.maven.api.annotations.Consumer;
 import org.apache.maven.api.annotations.Experimental;
+import org.apache.maven.api.di.Named;
 
 /**
  * Component able to contribute to Maven session user properties. This SPI component is invoked
@@ -31,6 +32,7 @@
  */
 @Experimental
 @Consumer
+@Named
 public interface PropertyContributor extends SpiService {
     /**
      * Invoked just before session is created with a mutable map that carries collected user properties so far.

api/maven-api-spi/src/main/java/org/apache/maven/api/spi/TypeProvider.java

@@ -21,10 +21,12 @@
 import org.apache.maven.api.Type;
 import org.apache.maven.api.annotations.Consumer;
 import org.apache.maven.api.annotations.Experimental;
+import org.apache.maven.api.di.Named;
 
 /**
  * @since 4.0.0
  */
 @Experimental
 @Consumer
+@Named
 public interface TypeProvider extends ExtensibleEnumProvider<Type> {}