com.google.gwt.dev.shell.rewrite.HasAnnotation.java Source code

Introduction

Here is the source code for com.google.gwt.dev.shell.rewrite.HasAnnotation.java

Source

/*
 * Copyright 2009 Google Inc.
 *
 * Licensed 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 com.google.gwt.dev.shell.rewrite;

import com.google.gwt.dev.javac.asmbridge.EmptyVisitor;

import org.objectweb.asm.AnnotationVisitor;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;

import java.lang.annotation.Annotation;

/**
 * A simple ClassAdapter that determines if a specific annotation is declared on
 * a type (ignoring any annotatons that may be present on supertypes or
 * superinterfaces).
 */
public class HasAnnotation extends ClassVisitor {
    /**
     * A utility method to determine if the class defined in
     * <code>classBytes</code> has a particular annotation.
     *
     * @param classBytes the class's bytecode
     * @param annotation the type of annotation to look for
     * @return <code>true</code> if the class defined in <code>classBytes</code>
     *         possesses the desired annotation
     */
    public static boolean hasAnnotation(byte[] classBytes, Class<? extends Annotation> annotation) {
        HasAnnotation v = new HasAnnotation(new EmptyVisitor(), annotation);
        new ClassReader(classBytes).accept(v,
                ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES);

        return v.isFound();
    }

    private boolean found;

    private final String targetDesc;

    public HasAnnotation(ClassVisitor v, Class<? extends Annotation> annotation) {
        super(Opcodes.ASM6, v);
        targetDesc = Type.getDescriptor(annotation);
    }

    public boolean isFound() {
        return found;
    }

    @Override
    public AnnotationVisitor visitAnnotation(String desc, boolean visible) {
        if (targetDesc.equals(desc)) {
            found = true;
        }
        return super.visitAnnotation(desc, visible);
    }
}