add package info support

src/main/java/io/quarkus/gizmo/PackageCreator.java

@@ -0,0 +1,101 @@
+package io.quarkus.gizmo;
+
+import org.objectweb.asm.AnnotationVisitor;
+import org.objectweb.asm.ClassWriter;
+import org.objectweb.asm.Opcodes;
+
+import java.lang.annotation.RetentionPolicy;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+
+public class PackageCreator implements AutoCloseable, AnnotatedElement {
+
+    public static PackageCreator.Builder builder() {
+        return new PackageCreator.Builder();
+    }
+
+    private final List<AnnotationCreatorImpl> annotations = new ArrayList<>();
+    private final BytecodeCreatorImpl enclosing;
+    private final ClassOutput classOutput;
+    private final String packageName;
+
+    PackageCreator(BytecodeCreatorImpl enclosing, ClassOutput classOutput, String packageName) {
+        this.enclosing = enclosing;
+        this.classOutput = classOutput;
+        this.packageName = packageName.replace('.', '/') + "/package-info";
+    }
+
+    @Override
+    public AnnotationCreator addAnnotation(String annotationType, RetentionPolicy retentionPolicy) {
+        AnnotationCreatorImpl ac = new AnnotationCreatorImpl(annotationType, retentionPolicy);
+        annotations.add(ac);
+        return ac;
+    }
+
+    /**
+     * Write the class bytes to the given class output.
+     *
+     * @param classOutput the class output (must not be {@code null})
+     */
+    public void writeTo(ClassOutput classOutput) {
+        Objects.requireNonNull(classOutput);
+        ClassWriter file = new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);
+        final GizmoClassVisitor cv = new GizmoClassVisitor(Gizmo.ASM_API_VERSION, file, classOutput.getSourceWriter(packageName));
+        cv.visit(Opcodes.V1_5, Opcodes.ACC_ABSTRACT + Opcodes.ACC_INTERFACE, packageName, null,
+                "java/lang/Object", null);
+
+        for(AnnotationCreatorImpl annotation : annotations) {
+            AnnotationVisitor av = cv.visitAnnotation(DescriptorUtils.extToInt(annotation.getAnnotationType()), annotation.getRetentionPolicy() == RetentionPolicy.RUNTIME);
+            for(Map.Entry<String, Object> e : annotation.getValues().entrySet()) {
+                AnnotationUtils.visitAnnotationValue(av, e.getKey(), e.getValue());
+            }
+            av.visitEnd();
+        }
+
+        cv.visitEnd();
+
+        classOutput.write(packageName, file.toByteArray());
+    }
+
+    @Override
+    public void close() throws Exception {
+        final ClassOutput classOutput = this.classOutput;
+        if (classOutput != null) {
+            writeTo(classOutput);
+        }
+    }
+    public static class Builder {
+
+        private ClassOutput classOutput;
+
+        private BytecodeCreatorImpl enclosing;
+
+        private String packageName;
+
+        Builder() {
+        }
+
+        PackageCreator.Builder enclosing(BytecodeCreatorImpl enclosing) {
+            this.enclosing = enclosing;
+            return this;
+        }
+
+        public PackageCreator.Builder classOutput(ClassOutput classOutput) {
+            this.classOutput = classOutput;
+            return this;
+        }
+
+        public PackageCreator.Builder packageName(String packageName) {
+            this.packageName = packageName;
+            return this;
+        }
+
+        public PackageCreator build() {
+            Objects.requireNonNull(packageName);
+            return new PackageCreator(enclosing, classOutput, packageName);
+        }
+
+    }
+}

src/test/java/io/quarkus/gizmo/MyAnnotation.java

@@ -5,7 +5,7 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
-@Target({ ElementType.TYPE, ElementType.METHOD, ElementType.FIELD})
+@Target({ ElementType.TYPE, ElementType.METHOD, ElementType.FIELD, ElementType.PACKAGE})
 @Retention(RetentionPolicy.RUNTIME)
 public @interface MyAnnotation {
 

src/test/java/io/quarkus/gizmo/PackageCreatorTest.java

@@ -0,0 +1,26 @@
+package io.quarkus.gizmo;
+
+import org.jboss.jandex.AnnotationInstance;
+import org.jboss.jandex.AnnotationValue;
+import org.jboss.jandex.DotName;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class PackageCreatorTest {
+    @Test
+    public void testPackageAnnotationWithString() throws Exception {
+        TestClassLoader cl = new TestClassLoader(getClass().getClassLoader());
+        try (PackageCreator creator = PackageCreator.builder().classOutput(cl).packageName("com.myTest").build()) {
+            creator.addAnnotation(AnnotationInstance.create(DotName.createSimple(MyAnnotation.class.getName()), null, new AnnotationValue[] {
+                AnnotationValue.createEnumValue("enumVal", DotName.createSimple("io.quarkus.gizmo.MyEnum"), "NO")
+            } ));
+        }
+        //supported only with java 9
+        /*
+        MyAnnotation annotation = cl.getDefinedPackage("com.MyTest")
+                .getAnnotation(MyAnnotation.class);
+        Assert.assertEquals(MyEnum.NO, annotation.enumVal());
+
+         */
+    }
+}