org.whole.examples.lang.imp.visitors.BytecodeGeneratorOperation.java Source code

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Here is the source code for org.whole.examples.lang.imp.visitors.BytecodeGeneratorOperation.java

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/**
 * Copyright 2004-2014 Riccardo Solmi. All rights reserved.
 * This file is part of the Whole Platform.
 *
 * The Whole Platform is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * The Whole Platform 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the Whole Platform. If not, see <http://www.gnu.org/licenses/>.
 */
package org.whole.examples.lang.imp.visitors;

import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.whole.lang.bindings.IBindingManager;
import org.whole.lang.model.IEntity;
import org.whole.lang.operations.AbstractOperation;

/**
 * @author Riccardo Solmi
 */
public class BytecodeGeneratorOperation extends AbstractOperation implements Opcodes {
    public static final String ID = "toASMBytecode";

    private ClassWriter classWriter;
    private ClassVisitor classVisitor;
    private MethodVisitor methodVisitor;

    public static byte[] compile(IEntity program, IBindingManager args) {
        BytecodeGeneratorOperation gen = new BytecodeGeneratorOperation(args);
        gen.stagedVisit(program);
        return gen.getResult();
    }

    protected BytecodeGeneratorOperation(IBindingManager args) {
        super(ID, args, false);
    }

    public byte[] getResult() {
        return classWriter.toByteArray();
    }

    public ClassVisitor getClassVisitor() {
        if (classVisitor == null) {
            classWriter = new ClassWriter(ClassWriter.COMPUTE_MAXS);

            //FIXME print nothing
            //         ClassVisitor cc = new CheckClassAdapter(classWriter);
            //         ClassVisitor tv = new TraceClassVisitor(cc, new PrintWriter(System.out));
            //         classVisitor = tv;
            classVisitor = classWriter;

            classVisitor.visit(V1_4, ACC_PUBLIC, "Example", null, "java/lang/Object", null);

            //default constructor
            MethodVisitor mv = classVisitor.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
            mv.visitCode();
            mv.visitVarInsn(ALOAD, 0);
            mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V");
            mv.visitInsn(RETURN);
            mv.visitMaxs(1, 1);
            mv.visitEnd();
        }
        return classVisitor;
    }

    public void setClassVisitor(ClassWriter cw) {
        this.classVisitor = cw;
    }

    public MethodVisitor getMethodVisitor() {
        return methodVisitor;
    }

    public void setMethodVisitor(MethodVisitor methodVisitor) {
        this.methodVisitor = methodVisitor;
    }

}