asmlib.GenericFieldVisitorAdapter.java Source code

Introduction

Here is the source code for asmlib.GenericFieldVisitorAdapter.java

Source

/*
 * asmlib: a toolkit based on ASM for working with java bytecode
 * Copyright (C) 2015 Ivo Anjo <ivo.anjo@ist.utl.pt>
 *
 * This file is part of asmlib.
 *
 * asmlib is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * asmlib is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with asmlib.  If not, see <http://www.gnu.org/licenses/>.
 */

package asmlib;

import java.lang.reflect.*;
import java.util.ArrayList;
import java.util.Arrays;

import org.objectweb.asm.*;

/**
  * Generic ClassVisitor adapter for FieldVisitors.
  *
  * The idea of this class is to avoid having to write a boilerplate ClassVisitor when all we want is
  * for the FieldVisitor to be included in the chain of Visitors.
  **/
public class GenericFieldVisitorAdapter extends ClassVisitor {

    private final Class<? extends FieldVisitor> _fieldVisitorClass;
    private final Object[] _extraInfo;

    public GenericFieldVisitorAdapter(ClassVisitor cv, Class<? extends FieldVisitor> fieldVisitorClass,
            Object... extraInfo) {
        super(Opcodes.ASM4, cv);
        _fieldVisitorClass = fieldVisitorClass;
        _extraInfo = extraInfo;
    }

    @Override
    public FieldVisitor visitField(int access, String name, String desc, String signature, Object value) {
        // Signature for the constructor
        ArrayList<Class<?>> ctorArgTypes = new ArrayList<Class<?>>();
        ctorArgTypes.addAll(Arrays.<Class<?>>asList(int.class, String.class, String.class, String.class,
                Object.class, ClassVisitor.class));
        // Add types from the extra arguments
        for (Object o : _extraInfo)
            ctorArgTypes.add(o.getClass());

        // Create list of arguments
        ArrayList<Object> ctorArgs = new ArrayList<Object>();
        ctorArgs.addAll(Arrays.asList(access, name, desc, signature, value, cv));
        ctorArgs.addAll(Arrays.asList(_extraInfo));

        Exception inner = null;
        try {
            // Instantiate the MethodVisitor using reflection
            Constructor<? extends FieldVisitor> ctor = _fieldVisitorClass
                    .getConstructor(ctorArgTypes.toArray(new Class[0]));
            return ctor.newInstance(ctorArgs.toArray());
        } catch (NoSuchMethodException e) {
            inner = e;
        } catch (InstantiationException e) {
            inner = e;
        } catch (IllegalAccessException e) {
            inner = e;
        } catch (InvocationTargetException e) {
            Throwable cause = e.getCause();
            if (cause instanceof RuntimeException)
                throw (RuntimeException) cause;
            if (cause instanceof Error)
                throw (Error) cause;
            throw new Error(cause);
        }
        throw new Error("Error while using reflection to create a new instance", inner);
    }

}