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

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

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/**********************************************************************
 * This file is part of "Object Teams Dynamic Runtime Environment"
 * 
 * Copyright 2009, 2015 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.objectweb.asm.ClassVisitor;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;

import static org.eclipse.objectteams.otredyn.bytecode.asm.AsmBoundClass.ASM_API;

/**
 * This class adds an method only with a return statement
 * to the bytecode of a class with the ASM Core API  
 * @author Oliver Frank
 */
class AddEmptyMethodAdapter extends ClassVisitor {

    private int access;
    private String name;
    private String desc;
    private String signature;
    private String[] exceptions;
    private int maxLocals;
    private String superToCall;

    public AddEmptyMethodAdapter(ClassVisitor cv, String name, int access, String desc, String[] exceptions,
            String signature, int maxLocals, String superToCall) {
        super(ASM_API, cv);
        this.access = access;
        this.desc = desc;
        this.exceptions = exceptions;
        this.name = name;
        this.signature = signature;
        this.maxLocals = maxLocals;
        this.superToCall = superToCall;
    }

    @Override
    public void visitEnd() {
        MethodVisitor mv = cv.visitMethod(access, name, desc, signature, exceptions);
        if ((this.access & Opcodes.ACC_ABSTRACT) != 0) {
            mv.visitEnd();
            return;
        }
        mv.visitCode();
        boolean needConstValue = true;
        if (superToCall != null) {
            needConstValue = false;
            boolean isStatic = (this.access & Opcodes.ACC_STATIC) != 0;
            int firstArgIndex = isStatic ? 0 : 1;
            if (!isStatic)
                mv.visitVarInsn(Opcodes.ALOAD, 0); // "this"
            Type[] args = Type.getArgumentTypes(desc);
            for (int i = 0, slot = firstArgIndex; i < args.length; slot += args[i++].getSize())
                mv.visitVarInsn(args[i].getOpcode(Opcodes.ILOAD), slot);
            mv.visitMethodInsn(Opcodes.INVOKESPECIAL, superToCall, name, desc, false);
        }
        Type returnType = Type.getReturnType(this.desc);
        switch (returnType.getSort()) {
        case Type.VOID:
            mv.visitInsn(Opcodes.RETURN);
            break;
        case Type.INT:
        case Type.BOOLEAN:
        case Type.CHAR:
        case Type.BYTE:
        case Type.SHORT:
            if (needConstValue)
                mv.visitInsn(Opcodes.ICONST_1);
            mv.visitInsn(Opcodes.IRETURN);
            break;
        case Type.FLOAT:
            if (needConstValue)
                mv.visitInsn(Opcodes.FCONST_1);
            mv.visitInsn(Opcodes.FRETURN);
            break;
        case Type.LONG:
            if (needConstValue)
                mv.visitInsn(Opcodes.LCONST_1);
            mv.visitInsn(Opcodes.LRETURN);
            break;
        case Type.DOUBLE:
        case Type.OBJECT:
        case Type.ARRAY:
            if (needConstValue)
                mv.visitInsn(Opcodes.ACONST_NULL);
            mv.visitInsn(Opcodes.ARETURN);
            break;
        }
        mv.visitMaxs(1, maxLocals);
        mv.visitEnd();
    }

    @Override
    public MethodVisitor visitMethod(int arg0, String arg1, String arg2, String arg3, String[] arg4) {
        return null; // also consider other visitors
    }
}