org.eclipse.objectteams.otredyn.bytecode.asm.CreateSwitchAdapter.java Source code

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Here is the source code for org.eclipse.objectteams.otredyn.bytecode.asm.CreateSwitchAdapter.java

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/**********************************************************************
 * This file is part of "Object Teams Dynamic Runtime Environment"
 * 
 * Copyright 2009, 2014 Oliver Frank and others.
 * 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Please visit http://www.eclipse.org/objectteams for updates and contact.
 * 
 * Contributors:
 *      Oliver Frank - Initial API and implementation
 *      Stephan Herrmann - Initial API and implementation
 **********************************************************************/
package org.eclipse.objectteams.otredyn.bytecode.asm;

import org.eclipse.objectteams.otredyn.bytecode.Method;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.tree.InsnNode;
import org.objectweb.asm.tree.IntInsnNode;
import org.objectweb.asm.tree.LabelNode;
import org.objectweb.asm.tree.LookupSwitchInsnNode;
import org.objectweb.asm.tree.MethodNode;

/**
 * This class creates an empty switch statement in a method.
 * @author Oliver Frank
 */
public class CreateSwitchAdapter extends AbstractTransformableClassNode {
    private Method method;

    private int firstArgIndex;

    public CreateSwitchAdapter(Method method) {
        this.method = method;
        if (method.isStatic()) {
            firstArgIndex = 0;
        } else {
            firstArgIndex = 1;
        }
    }

    public CreateSwitchAdapter(Method method, boolean isRoleMethod) {
        this.method = method;
        if (method.isStatic()) {
            if (isRoleMethod)
                firstArgIndex = 2;
            else
                firstArgIndex = 0;
        } else {
            firstArgIndex = 1;
        }
    }

    @Override
    public boolean transform() {
        MethodNode methodNode = getMethod(method);
        if (methodNode == null)
            return false; // doesn't exist, don't transform
        methodNode.instructions.clear();

        addPreSwitchInstructions(methodNode);

        LabelNode def = new LabelNode();
        LookupSwitchInsnNode switchNode = new LookupSwitchInsnNode(def, new int[0], new LabelNode[0]);

        methodNode.instructions.add(switchNode);
        methodNode.instructions.add(def);
        addInstructionForDefaultLabel(methodNode);

        addPostSwitchInstructions(methodNode);
        methodNode.maxStack = getMaxStack();
        return true;
    }

    /**
     * Adds instructions after the switch statement
     * @param method
     */
    protected void addPostSwitchInstructions(MethodNode method) {
    }

    /**
     * Adds instructions before the switch statement.
     * @param method
     */
    protected void addPreSwitchInstructions(MethodNode method) {
        method.instructions.add(new IntInsnNode(Opcodes.ILOAD, firstArgIndex));
    }

    /**
     * Adds instructions for the default label.
     * @param method
     */
    protected void addInstructionForDefaultLabel(MethodNode method) {
        method.instructions.add(new InsnNode(Opcodes.ACONST_NULL));
        method.instructions.add(new InsnNode(Opcodes.ARETURN));
    }

    protected int getMaxStack() {
        return 1;
    }

    protected int getFirstArgIndex() {
        return firstArgIndex;
    }

    protected Method getMethod() {
        return method;
    }

}