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/*
* This file is part of the Javassist toolkit.
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* either http://www.mozilla.org/MPL/.
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* The Original Code is Javassist.
*
* The Initial Developer of the Original Code is Shigeru Chiba. Portions
* created by Shigeru Chiba are Copyright (C) 1999-2003 Shigeru Chiba.
* All Rights Reserved.
*
* Contributor(s):
*
* The development of this software is supported in part by the PRESTO
* program (Sakigake Kenkyu 21) of Japan Science and Technology Corporation.
*/
package javassist.convert;
import javassist.bytecode.*;
import javassist.CtClass;
import javassist.CannotCompileException;
final public class TransformNew extends Transformer {
private int nested;
private String classname, trapClass, trapMethod;
public TransformNew(Transformer next,
String classname, String trapClass, String trapMethod) {
super(next);
this.classname = classname;
this.trapClass = trapClass;
this.trapMethod = trapMethod;
}
public void initialize(ConstPool cp, CodeAttribute attr) {
nested = 0;
}
/**
* Replace a sequence of
* NEW classname
* DUP
* ...
* INVOKESPECIAL
* with
* NOP
* NOP
* ...
* INVOKESTATIC trapMethod in trapClass
*/
public int transform(CtClass clazz, int pos, CodeIterator iterator,
ConstPool cp) throws CannotCompileException
{
int index;
int c = iterator.byteAt(pos);
if (c == NEW) {
index = iterator.u16bitAt(pos + 1);
if (cp.getClassInfo(index).equals(classname)) {
if (iterator.byteAt(pos + 3) != DUP)
throw new CannotCompileException(
"NEW followed by no DUP was found");
iterator.writeByte(NOP, pos);
iterator.writeByte(NOP, pos + 1);
iterator.writeByte(NOP, pos + 2);
iterator.writeByte(NOP, pos + 3);
++nested;
}
}
else if (c == INVOKESPECIAL) {
index = iterator.u16bitAt(pos + 1);
int typedesc = cp.isConstructor(classname, index);
if (typedesc != 0 && nested > 0) {
int methodref = computeMethodref(typedesc, cp);
iterator.writeByte(INVOKESTATIC, pos);
iterator.write16bit(methodref, pos + 1);
--nested;
}
}
return pos;
}
private int computeMethodref(int typedesc, ConstPool cp) {
int classIndex = cp.addClassInfo(trapClass);
int mnameIndex = cp.addUtf8Info(trapMethod);
typedesc = cp.addUtf8Info(
Descriptor.changeReturnType(classname,
cp.getUtf8Info(typedesc)));
return cp.addMethodrefInfo(classIndex,
cp.addNameAndTypeInfo(mnameIndex, typedesc));
}
}
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