#20 - Add AnnotationUsage#toAnnotation

src/main/java/org/hibernate/models/internal/AnnotationProxy.java

@@ -0,0 +1,50 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright: Red Hat Inc. and Hibernate Authors
+ */
+
+package org.hibernate.models.internal;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.util.Map;
+
+import org.hibernate.models.spi.AnnotationDescriptor;
+import org.hibernate.models.spi.AttributeDescriptor;
+
+/**
+ * @author Steve Ebersole
+ */
+public class AnnotationProxy<A extends Annotation> implements InvocationHandler {
+	private final AnnotationDescriptor<A> annotationDescriptor;
+	private final Map<String,?> valueMap;
+
+	public AnnotationProxy(AnnotationDescriptor<A> annotationDescriptor, Map<String, ?> valueMap) {
+		this.annotationDescriptor = annotationDescriptor;
+		this.valueMap = valueMap;
+	}
+
+	@Override
+	public Object invoke(Object proxy, Method method, Object[] args) {
+		final AttributeDescriptor<Object> attributeDescriptor = annotationDescriptor.getAttribute( method.getName() );
+		return attributeDescriptor.getTypeDescriptor().unwrap( valueMap.get( method.getName() ) );
+	}
+
+
+	public static <A extends Annotation> A makeProxy(
+			AnnotationDescriptor<A> descriptor,
+			Map<String,?> valueMap) {
+		final AnnotationProxy<A> handler = new AnnotationProxy<>( descriptor, valueMap );
+		//noinspection unchecked
+		return (A) Proxy.newProxyInstance(
+				AnnotationProxy.class.getClassLoader(),
+				new Class<?>[] { descriptor.getAnnotationType() },
+				handler
+		);
+	}
+
+}

src/main/java/org/hibernate/models/internal/ArrayTypeDescriptor.java

@@ -120,4 +120,13 @@ public ValueWrapper<List<V>,Object[]> resolveJkWrapper(SourceModelBuildingContex
 		}
 		return jdkValueWrapper;
 	}
+
+	@Override
+	public Object unwrap(List<V> value) {
+		final Object[] result = new Object[value.size()];
+		for ( int i = 0; i < value.size(); i++ ) {
+			result[i] = elementTypeDescriptor.unwrap( value.get(i) );
+		}
+		return result;
+	}
 }

src/main/java/org/hibernate/models/internal/BooleanTypeDescriptor.java

@@ -54,4 +54,9 @@ public ValueExtractor<Annotation, Boolean> createJdkExtractor(SourceModelBuildin
 		//noinspection unchecked
 		return PassThruExtractor.PASS_THRU_EXTRACTOR;
 	}
+
+	@Override
+	public Object unwrap(Boolean value) {
+		return value;
+	}
 }

src/main/java/org/hibernate/models/internal/ByteTypeDescriptor.java

@@ -54,4 +54,9 @@ public ValueExtractor<Annotation, Byte> createJdkExtractor(SourceModelBuildingCo
 		//noinspection unchecked
 		return PassThruExtractor.PASS_THRU_EXTRACTOR;
 	}
+
+	@Override
+	public Object unwrap(Byte value) {
+		return value;
+	}
 }

src/main/java/org/hibernate/models/internal/CharacterTypeDescriptor.java

@@ -54,4 +54,9 @@ public ValueExtractor<Annotation, Character> createJdkExtractor(SourceModelBuild
 		//noinspection unchecked
 		return PassThruExtractor.PASS_THRU_EXTRACTOR;
 	}
+
+	@Override
+	public Object unwrap(Character value) {
+		return value;
+	}
 }

src/main/java/org/hibernate/models/internal/ClassTypeDescriptor.java

@@ -50,4 +50,9 @@ public ValueExtractor<AnnotationInstance, ClassDetails> createJandexExtractor(So
 	public ValueExtractor<Annotation, ClassDetails> createJdkExtractor(SourceModelBuildingContext buildingContext) {
 		return org.hibernate.models.internal.jdk.ClassValueExtractor.JDK_CLASS_EXTRACTOR;
 	}
+
+	@Override
+	public Object unwrap(ClassDetails value) {
+		return value.toJavaClass();
+	}
 }

src/main/java/org/hibernate/models/internal/DoubleTypeDescriptor.java

@@ -54,4 +54,9 @@ public ValueExtractor<Annotation, Double> createJdkExtractor(SourceModelBuilding
 		//noinspection unchecked
 		return PassThruExtractor.PASS_THRU_EXTRACTOR;
 	}
+
+	@Override
+	public Object unwrap(Double value) {
+		return value;
+	}
 }

src/main/java/org/hibernate/models/internal/EnumTypeDescriptor.java

@@ -63,4 +63,9 @@ public ValueExtractor<Annotation, E> createJdkExtractor(SourceModelBuildingConte
 		//noinspection unchecked
 		return PassThruExtractor.PASS_THRU_EXTRACTOR;
 	}
+
+	@Override
+	public Object unwrap(E value) {
+		return value;
+	}
 }

src/main/java/org/hibernate/models/internal/FloatTypeDescriptor.java

@@ -54,4 +54,9 @@ public ValueExtractor<Annotation, Float> createJdkExtractor(SourceModelBuildingC
 		//noinspection unchecked
 		return PassThruExtractor.PASS_THRU_EXTRACTOR;
 	}
+
+	@Override
+	public Object unwrap(Float value) {
+		return value;
+	}
 }

src/main/java/org/hibernate/models/internal/IntegerTypeDescriptor.java

@@ -54,4 +54,9 @@ public ValueExtractor<Annotation, Integer> createJdkExtractor(SourceModelBuildin
 		//noinspection unchecked
 		return PassThruExtractor.PASS_THRU_EXTRACTOR;
 	}
+
+	@Override
+	public Object unwrap(Integer value) {
+		return value;
+	}
 }

src/main/java/org/hibernate/models/internal/LongTypeDescriptor.java

@@ -54,4 +54,9 @@ public ValueExtractor<Annotation, Long> createJdkExtractor(SourceModelBuildingCo
 		//noinspection unchecked
 		return PassThruExtractor.PASS_THRU_EXTRACTOR;
 	}
+
+	@Override
+	public Object unwrap(Long value) {
+		return value;
+	}
 }

src/main/java/org/hibernate/models/internal/NestedTypeDescriptor.java

@@ -97,6 +97,11 @@ public ValueExtractor<Annotation, AnnotationUsage<A>> createJdkExtractor(SourceM
 		return resolveJdkExtractor( buildingContext );
 	}
 
+	@Override
+	public Object unwrap(AnnotationUsage<A> value) {
+		return value.toAnnotation();
+	}
+
 	public ValueExtractor<Annotation, AnnotationUsage<A>> resolveJdkExtractor(SourceModelBuildingContext buildingContext) {
 		if ( jdkExtractor == null ) {
 			jdkExtractor = new org.hibernate.models.internal.jdk.NestedValueExtractor<>( resolveJdkWrapper( buildingContext ) );

src/main/java/org/hibernate/models/internal/ShortTypeDescriptor.java

@@ -54,4 +54,9 @@ public ValueExtractor<Annotation, Short> createJdkExtractor(SourceModelBuildingC
 		//noinspection unchecked
 		return PassThruExtractor.PASS_THRU_EXTRACTOR;
 	}
+
+	@Override
+	public Object unwrap(Short value) {
+		return value;
+	}
 }

src/main/java/org/hibernate/models/internal/StringTypeDescriptor.java

@@ -54,4 +54,9 @@ public ValueExtractor<Annotation, String> createJdkExtractor(SourceModelBuilding
 		//noinspection unchecked
 		return PassThruExtractor.PASS_THRU_EXTRACTOR;
 	}
+
+	@Override
+	public Object unwrap(String value) {
+		return value;
+	}
 }

src/main/java/org/hibernate/models/internal/dynamic/DynamicAnnotationUsage.java

@@ -12,6 +12,7 @@
 import java.util.Map;
 
 import org.hibernate.models.UnknownAnnotationAttributeException;
+import org.hibernate.models.internal.AnnotationProxy;
 import org.hibernate.models.spi.MutableAnnotationUsage;
 import org.hibernate.models.spi.AnnotationDescriptor;
 import org.hibernate.models.spi.AnnotationTarget;
@@ -44,6 +45,11 @@ public AnnotationTarget getAnnotationTarget() {
 		return target;
 	}
 
+	@Override
+	public A toAnnotation() {
+		return AnnotationProxy.makeProxy( annotationDescriptor, values );
+	}
+
 	@Override
 	public <V> V findAttributeValue(String name) {
 		if ( values != null ) {

src/main/java/org/hibernate/models/internal/jandex/JandexAnnotationUsage.java

@@ -9,6 +9,7 @@
 import java.lang.annotation.Annotation;
 import java.util.Map;
 
+import org.hibernate.models.internal.AnnotationProxy;
 import org.hibernate.models.spi.MutableAnnotationUsage;
 import org.hibernate.models.spi.AnnotationDescriptor;
 import org.hibernate.models.spi.AnnotationTarget;
@@ -56,6 +57,11 @@ public AnnotationTarget getAnnotationTarget() {
 		return annotationTarget;
 	}
 
+	@Override
+	public A toAnnotation() {
+		return AnnotationProxy.makeProxy( annotationDescriptor, attributeValueMap );
+	}
+
 	@Override
 	public <W> W findAttributeValue(String name) {
 		//noinspection unchecked

src/main/java/org/hibernate/models/internal/jdk/JdkAnnotationUsage.java

@@ -18,6 +18,7 @@
  * @author Steve Ebersole
  */
 public class JdkAnnotationUsage<A extends Annotation> implements MutableAnnotationUsage<A> {
+	private final A annotation;
 	private final AnnotationDescriptor<A> annotationDescriptor;
 	private final AnnotationTarget location;
 
@@ -28,6 +29,7 @@ public JdkAnnotationUsage(
 			AnnotationDescriptor<A> annotationDescriptor,
 			AnnotationTarget location,
 			SourceModelBuildingContext buildingContext) {
+		this.annotation = annotation;
 		this.annotationDescriptor = annotationDescriptor;
 		this.location = location;
 
@@ -44,6 +46,11 @@ public AnnotationTarget getAnnotationTarget() {
 		return location;
 	}
 
+	@Override
+	public A toAnnotation() {
+		return annotation;
+	}
+
 	@Override
 	public <W> W findAttributeValue(String name) {
 		//noinspection unchecked

src/main/java/org/hibernate/models/spi/AnnotationUsage.java

@@ -53,6 +53,11 @@ default Class<A> getAnnotationType() {
 	 */
 	AnnotationTarget getAnnotationTarget();
 
+	/**
+	 * Create the Annotation representation of this usage
+	 */
+	A toAnnotation();
+
 	/**
 	 * The value of the named annotation attribute
 	 */

src/main/java/org/hibernate/models/spi/ValueTypeDescriptor.java

@@ -40,4 +40,6 @@ public interface ValueTypeDescriptor<V> {
 	ValueWrapper<V,?> createJdkWrapper(SourceModelBuildingContext buildingContext);
 
 	ValueExtractor<Annotation,V> createJdkExtractor(SourceModelBuildingContext buildingContext);
+
+	Object unwrap(V value);
 }

src/test/java/org/hibernate/models/annotations/AnnotationUsageTests.java

@@ -224,4 +224,42 @@ void badAttributeNamesChecks(Index index) {
 		catch (UnknownAnnotationAttributeException expected) {
 		}
 	}
+
+	@Test
+	void testToAnnotationJandex() {
+		toAnnotationChecks( buildJandexIndex( SimpleEntity.class ) );
+	}
+
+	@Test
+	void testToAnnotationWithoutJandex() {
+		toAnnotationChecks( null );
+	}
+
+	private void toAnnotationChecks(Index index) {
+		final SourceModelBuildingContextImpl buildingContext = createBuildingContext( index, SimpleEntity.class );
+		final ClassDetailsRegistry classDetailsRegistry = buildingContext.getClassDetailsRegistry();
+
+		final ClassDetails classDetails = classDetailsRegistry.getClassDetails( SimpleEntity.class.getName() );
+
+		{
+			final AnnotationUsage<CustomAnnotation> annotationUsage = classDetails.getAnnotationUsage( CustomAnnotation.class );
+			final CustomAnnotation annotation = annotationUsage.toAnnotation();
+			assertThat( annotation ).isNotNull();
+		}
+
+		{
+			final AnnotationUsage<Entity> annotationUsage = classDetails.getAnnotationUsage( Entity.class );
+			final Entity annotation = annotationUsage.toAnnotation();
+			assertThat( annotation.name() ).isEqualTo( "SimpleColumnEntity" );
+		}
+
+		{
+			final AnnotationUsage<Column> annotationUsage = classDetails.findFieldByName( "name" ).getAnnotationUsage( Column.class );
+			final Column annotation = annotationUsage.toAnnotation();
+			assertThat( annotation.name() ).isEqualTo( "description" );
+			assertThat( annotation.table() ).isEqualTo( "" );
+			assertThat( annotation.nullable() ).isFalse();
+			assertThat( annotation.unique() ).isTrue();
+		}
+	}
 }