feat(objectionary#534): use DirectivesAnnotationDefault to read annot…

…ations default values

src/it/annotations/src/main/java/org/eolang/jeo/annotations/AnnotationsApplication.java

@@ -18,7 +18,7 @@
     doubles = {1.0, 2.0, 3.0},
     floats = {1.0f, 2.0f, 3.0f},
     classes = {AnnotationsApplication.class},
-    nested = @NestedAnnotation,
+    nested = @NestedAnnotation(name = "single-nested"),
     nestedArray = {
         @NestedAnnotation(name = "nested1"),
         @NestedAnnotation(name = "nested2")

src/it/annotations/src/main/java/org/eolang/jeo/annotations/NestedAnnotation.java

@@ -6,7 +6,7 @@
 import java.lang.annotation.Target;
 
 @Retention(RetentionPolicy.RUNTIME)
-@Target(ElementType.TYPE)
+@Target({ElementType.TYPE, ElementType.METHOD})
 public @interface NestedAnnotation {
-    String name() default "nested";
+    String name() default "nested-default";
 }

src/main/java/org/eolang/jeo/representation/directives/DirectivesAnnotationDefault.java

@@ -0,0 +1,43 @@
+package org.eolang.jeo.representation.directives;
+
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.concurrent.atomic.AtomicReference;
+import org.xembly.Directive;
+import org.xembly.Directives;
+
+public final class DirectivesAnnotationDefault implements Iterable<Directive>, Composite {
+
+    private final AtomicReference<Iterable<Directive>> value;
+
+    public DirectivesAnnotationDefault() {
+        this(new AtomicReference<>());
+    }
+
+    public DirectivesAnnotationDefault(final AtomicReference<Iterable<Directive>> value) {
+        this.value = value;
+    }
+
+    @Override
+    public Iterator<Directive> iterator() {
+        if (this.value.get() != null) {
+            final Directives directives = new Directives()
+                .add("o")
+                .attr("name", "annotation-default-value");
+            directives.append(this.value.get());
+            return directives.up().iterator();
+        } else {
+            return Collections.emptyIterator();
+        }
+    }
+
+    @Override
+    public void append(final Iterable<Directive> directives) {
+        this.value.set(directives);
+    }
+
+    @Override
+    public Iterable<Directive> build() {
+        return this;
+    }
+}

src/main/java/org/eolang/jeo/representation/directives/DirectivesMethodVisitor.java

@@ -23,6 +23,7 @@
  */
 package org.eolang.jeo.representation.directives;
 
+import com.jcabi.log.Logger;
 import java.util.Arrays;
 import java.util.Iterator;
 import java.util.stream.Stream;
@@ -215,6 +216,15 @@ public AnnotationVisitor visitAnnotation(final String descriptor, final boolean
         );
     }
 
+    @Override
+    public AnnotationVisitor visitAnnotationDefault() {
+        final AnnotationVisitor visitor = super.visitAnnotationDefault();
+        Logger.debug(this, String.format("Visit annotation default by %s visitor", visitor));
+        return new DirectivesAnnotationVisitor(
+            this.api, visitor, new DirectivesAnnotationDefault()
+        );
+    }
+
     @Override
     public void visitTryCatchBlock(
         final Label start,