Let generic type of TypeComponent extend AnnotatedElement

configlib-core/src/main/java/de/exlll/configlib/CommentNodeExtractor.java

@@ -7,6 +7,7 @@ import java.lang.reflect.AnnotatedElement;
 import java.util.*;
 
 import static de.exlll.configlib.Validator.requireConfigurationOrRecord;
+import static de.exlll.configlib.Validator.requireNonNull;
 
 final class CommentNodeExtractor {
     private final FieldFilter fieldFilter;
@@ -14,8 +15,8 @@ final class CommentNodeExtractor {
     private final boolean outputNull;
 
     CommentNodeExtractor(ConfigurationProperties properties) {
-        this.fieldFilter = Validator.requireNonNull(properties.getFieldFilter(), "field filter");
-        this.nameFormatter = Validator.requireNonNull(properties.getNameFormatter(), "name formatter");
+        this.fieldFilter = requireNonNull(properties.getFieldFilter(), "field filter");
+        this.nameFormatter = requireNonNull(properties.getNameFormatter(), "name formatter");
         this.outputNull = properties.outputNulls();
     }
 
@@ -48,33 +49,22 @@ final class CommentNodeExtractor {
                 if ((componentValue == null) && !outputNull)
                     continue;
 
-                // pattern switch not yet supported in Java 17
-                final AnnotatedElement element = (component instanceof ConfigurationField cf)
-                        ? cf.component()
-                        : (component instanceof ConfigurationRecordComponent crc)
-                        ? crc.component()
-                        : null;
-
-                // The element cannot be null because we require a configuration or record
-                // at the beginning of this method.
-                assert element != null;
-
                 final var componentName = component.componentName();
                 final var commentNode = createNodeIfCommentPresent(
-                        element,
+                        component.component(),
                         componentName,
                         elementNameStack
                 );
                 commentNode.ifPresent(result::add);
 
-                if ((componentValue == null) ||
-                    (!Reflect.isConfiguration(component.componentType()) &&
-                     !component.componentType().isRecord()))
-                    continue;
-
-                stateStack.addLast(new State(state.iterator, state.componentHolder));
-                elementNameStack.addLast(nameFormatter.format(componentName));
-                state = stateFromObject(componentValue);
+                final var componentType = component.componentType();
+                if ((componentValue != null) &&
+                    (Reflect.isConfiguration(componentType) ||
+                     componentType.isRecord())) {
+                    stateStack.addLast(state);
+                    elementNameStack.addLast(nameFormatter.format(componentName));
+                    state = stateFromObject(componentValue);
+                }
             }
         }
 

configlib-core/src/main/java/de/exlll/configlib/TypeComponent.java

@@ -1,5 +1,7 @@
 package de.exlll.configlib;
 
+import java.lang.annotation.Annotation;
+import java.lang.reflect.AnnotatedElement;
 import java.lang.reflect.Field;
 import java.lang.reflect.RecordComponent;
 
@@ -11,7 +13,7 @@ import static de.exlll.configlib.Validator.requireNonNull;
  *
  * @param <T> the type of the component
  */
-sealed interface TypeComponent<T> {
+sealed interface TypeComponent<T extends AnnotatedElement> {
     /**
      * Returns the component itself.
      *
@@ -50,6 +52,19 @@ sealed interface TypeComponent<T> {
      */
     Class<?> declaringType();
 
+    /**
+     * Returns the annotation of the given type or null if the component is not annotated
+     * with such an annotation.
+     *
+     * @param annotationType the type of annotation
+     * @param <A>            the type of annotation
+     * @return the annotation or null
+     * @throws NullPointerException if {@code annotationType} is null
+     */
+    default <A extends Annotation> A annotation(Class<A> annotationType) {
+        return component().getAnnotation(annotationType);
+    }
+
     record ConfigurationField(Field component) implements TypeComponent<Field> {
         public ConfigurationField(Field component) {
             this.component = requireNonNull(component, "component");
@@ -103,4 +118,3 @@ sealed interface TypeComponent<T> {
         }
     }
 }
-

configlib-core/src/test/java/de/exlll/configlib/TypeComponentTest.java

@@ -8,8 +8,7 @@ import java.lang.reflect.Field;
 import java.lang.reflect.RecordComponent;
 
 import static org.hamcrest.MatcherAssert.assertThat;
-import static org.hamcrest.Matchers.equalTo;
-import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.*;
 
 class TypeComponentTest {
 
@@ -18,6 +17,7 @@ class TypeComponentTest {
         private static final ConfigurationField COMPONENT = new ConfigurationField(FIELD);
 
         static final class C {
+            @Comment("")
             int field = 20;
         }
 
@@ -40,6 +40,11 @@ class TypeComponentTest {
         void declaringType() {
             assertThat(COMPONENT.declaringType(), equalTo(C.class));
         }
+
+        @Test
+        void annotation() {
+            assertThat(COMPONENT.annotation(Comment.class), notNullValue());
+        }
     }
 
     static final class ConfigurationRecordComponentTest {
@@ -47,7 +52,7 @@ class TypeComponentTest {
         private static final ConfigurationRecordComponent COMPONENT =
                 new ConfigurationRecordComponent(RECORD_COMPONENT);
 
-        record R(float comp) {}
+        record R(@Comment("") float comp) {}
 
         @Test
         void componentName() {
@@ -68,5 +73,10 @@ class TypeComponentTest {
         void declaringType() {
             assertThat(COMPONENT.declaringType(), equalTo(R.class));
         }
+
+        @Test
+        void annotation() {
+            assertThat(COMPONENT.annotation(Comment.class), notNullValue());
+        }
     }
-}
+}