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git-svn-id: http://anonsvn.jboss.org/repos/javassist/trunk@6 30ef5769-5b8d-40dd-aea6-55b5d6557bb3

8 files changed, 691 insertions, 0 deletions

diff --git a/src/main/javassist/convert/TransformAfter.java b/src/main/javassist/convert/TransformAfter.java
new file mode 100644
index 00000000..e9704348
--- /dev/null
+++ b/src/main/javassist/convert/TransformAfter.java
@@ -0,0 +1,56 @@
+/*
+ * 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.CtClass;
+import javassist.CtMethod;
+import javassist.NotFoundException;
+import javassist.bytecode.*;
+import javassist.CannotCompileException;
+
+public class TransformAfter extends TransformBefore {
+    public TransformAfter(Transformer next,
+			   CtMethod origMethod, CtMethod afterMethod)
+	throws NotFoundException
+    {
+	super(next, origMethod, afterMethod);
+    }
+
+    protected int match2(int pos, CodeIterator iterator) throws BadBytecode {
+	iterator.move(pos);
+	iterator.insert(saveCode);
+	iterator.insert(loadCode);
+	int p = iterator.insertGap(3);
+	iterator.insert(loadCode);
+	pos = iterator.next();
+	iterator.writeByte(iterator.byteAt(pos), p);
+	iterator.write16bit(iterator.u16bitAt(pos + 1), p + 1);
+	iterator.writeByte(INVOKESTATIC, pos);
+	iterator.write16bit(newIndex, pos + 1);
+	iterator.move(p);
+	return iterator.next();
+    }
+}
diff --git a/src/main/javassist/convert/TransformBefore.java b/src/main/javassist/convert/TransformBefore.java
new file mode 100644
index 00000000..79deb10f
--- /dev/null
+++ b/src/main/javassist/convert/TransformBefore.java
@@ -0,0 +1,114 @@
+/*
+ * 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.CtClass;
+import javassist.CtMethod;
+import javassist.NotFoundException;
+import javassist.bytecode.*;
+import javassist.CannotCompileException;
+
+public class TransformBefore extends TransformCall {
+    protected CtClass[] parameterTypes;
+    protected int locals;
+    protected int maxLocals;
+    protected byte[] saveCode, loadCode;
+
+    public TransformBefore(Transformer next,
+			   CtMethod origMethod, CtMethod beforeMethod)
+	throws NotFoundException
+    {
+	super(next, origMethod, beforeMethod);
+	parameterTypes = origMethod.getParameterTypes();
+	locals = 0;
+	maxLocals = 0;
+	saveCode = loadCode = null;
+    }
+
+    public void initialize(ConstPool cp, CodeAttribute attr) {
+	super.initialize(cp, attr);
+	locals = 0;
+	maxLocals = attr.getMaxLocals();
+	saveCode = loadCode = null;
+    }
+
+    protected int match(int c, int pos, CodeIterator iterator,
+			int typedesc, ConstPool cp) throws BadBytecode
+    {
+	if (newIndex == 0) {
+	    String desc = Descriptor.ofParameters(parameterTypes) + 'V';
+	    desc = Descriptor.insertParameter(classname, desc);
+	    int nt = cp.addNameAndTypeInfo(newMethodname, desc);
+	    int ci = cp.addClassInfo(newClassname);
+	    newIndex = cp.addMethodrefInfo(ci, nt);
+	    constPool = cp;
+	}
+
+	if (saveCode == null)
+	    makeCode(parameterTypes, cp);
+
+	return match2(pos, iterator);
+    }
+
+    protected int match2(int pos, CodeIterator iterator) throws BadBytecode {
+	iterator.move(pos);
+	iterator.insert(saveCode);
+	iterator.insert(loadCode);
+	int p = iterator.insertGap(3);
+	iterator.writeByte(INVOKESTATIC, p);
+	iterator.write16bit(newIndex, p + 1);
+	iterator.insert(loadCode);
+	return iterator.next();
+    }
+
+    public int extraLocals() { return locals; }
+
+    protected void makeCode(CtClass[] paramTypes, ConstPool cp) {
+	Bytecode save = new Bytecode(cp, 0, 0);
+	Bytecode load = new Bytecode(cp, 0, 0);
+
+	int var = maxLocals;
+	int len = (paramTypes == null) ? 0 : paramTypes.length;
+	load.addAload(var);
+	makeCode2(save, load, 0, len, paramTypes, var + 1);
+	save.addAstore(var);
+
+	saveCode = save.get();
+	loadCode = load.get();
+    }
+
+    private void makeCode2(Bytecode save, Bytecode load,
+			   int i, int n, CtClass[] paramTypes, int var)
+    {
+	if (i < n) {
+	    int size = load.addLoad(var, paramTypes[i]);
+	    makeCode2(save, load, i + 1, n, paramTypes, var + size);
+	    save.addStore(var, paramTypes[i]);
+	}
+	else
+	    locals = var - maxLocals;
+    }
+}
diff --git a/src/main/javassist/convert/TransformCall.java b/src/main/javassist/convert/TransformCall.java
new file mode 100644
index 00000000..985a8bbb
--- /dev/null
+++ b/src/main/javassist/convert/TransformCall.java
@@ -0,0 +1,96 @@
+/*
+ * 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.CtClass;
+import javassist.CtMethod;
+import javassist.bytecode.*;
+import javassist.CannotCompileException;
+
+public class TransformCall extends Transformer {
+    protected String classname, methodname, methodDescriptor;
+    protected String newClassname, newMethodname;
+
+    /* cache */
+    protected int newIndex;
+    protected ConstPool constPool;
+
+    public TransformCall(Transformer next, CtMethod origMethod,
+			 CtMethod substMethod)
+    {
+	super(next);
+	this.classname = origMethod.getDeclaringClass().getName();
+	this.methodname = origMethod.getName();
+	this.methodDescriptor = origMethod.getMethodInfo2().getDescriptor();
+	this.newClassname = substMethod.getDeclaringClass().getName();
+	this.newMethodname = substMethod.getName();
+	this.constPool = null;
+    }
+
+    public void initialize(ConstPool cp, CodeAttribute attr) {
+	if (constPool != cp)
+	    newIndex = 0;
+    }
+
+    /**
+     * Modify INVOKEINTERFACE, INVOKESPECIAL, INVOKESTATIC and INVOKEVIRTUAL
+     * so that a different method is invoked.
+     */
+    public int transform(CtClass clazz, int pos, CodeIterator iterator,
+			 ConstPool cp) throws BadBytecode
+    {
+	int c = iterator.byteAt(pos);
+	if (c == INVOKEINTERFACE || c == INVOKESPECIAL
+			|| c == INVOKESTATIC || c == INVOKEVIRTUAL) {
+	    int index = iterator.u16bitAt(pos + 1);
+	    int typedesc = cp.isMember(classname, methodname, index);
+	    if (typedesc != 0)
+		if (cp.getUtf8Info(typedesc).equals(methodDescriptor))
+		    pos = match(c, pos, iterator, typedesc, cp);
+	}
+
+	return pos;
+    }
+
+    protected int match(int c, int pos, CodeIterator iterator,
+			int typedesc, ConstPool cp) throws BadBytecode
+    {
+	if (newIndex == 0) {
+	    int nt = cp.addNameAndTypeInfo(cp.addUtf8Info(newMethodname),
+					   typedesc);
+	    int ci = cp.addClassInfo(newClassname);
+	    if (c == INVOKEINTERFACE)
+		newIndex = cp.addInterfaceMethodrefInfo(ci, nt);
+	    else
+		newIndex = cp.addMethodrefInfo(ci, nt);
+
+	    constPool = cp;
+	}
+
+	iterator.write16bit(newIndex, pos + 1);
+	return pos;
+    }
+}
diff --git a/src/main/javassist/convert/TransformFieldAccess.java b/src/main/javassist/convert/TransformFieldAccess.java
new file mode 100644
index 00000000..bce010da
--- /dev/null
+++ b/src/main/javassist/convert/TransformFieldAccess.java
@@ -0,0 +1,92 @@
+/*
+ * 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.CtField;
+import javassist.Modifier;
+import javassist.CannotCompileException;
+
+final public class TransformFieldAccess extends Transformer {
+    private String newClassname, newFieldname;
+    private String fieldname;
+    private CtClass fieldClass;
+    private boolean isPrivate;
+
+    /* cache */
+    private int newIndex;
+    private ConstPool constPool;
+
+    public TransformFieldAccess(Transformer next, CtField field,
+				String newClassname, String newFieldname)
+    {
+	super(next);
+	this.fieldClass = field.getDeclaringClass();
+	this.fieldname = field.getName();
+	this.isPrivate = Modifier.isPrivate(field.getModifiers());
+	this.newClassname = newClassname;
+	this.newFieldname = newFieldname;
+	this.constPool = null;
+    }
+
+    public void initialize(ConstPool cp, CodeAttribute attr) {
+	if (constPool != cp)
+	    newIndex = 0;
+    }
+
+    /**
+     * Modify GETFIELD, GETSTATIC, PUTFIELD, and PUTSTATIC so that
+     * a different field is accessed.  The new field must be declared
+     * in a superclass of the class in which the original field is
+     * declared.
+     */
+    public int transform(CtClass clazz, int pos,
+			 CodeIterator iterator, ConstPool cp)
+    {
+	int c = iterator.byteAt(pos);
+	if (c == GETFIELD || c == GETSTATIC
+				|| c == PUTFIELD || c == PUTSTATIC) {
+	    int index = iterator.u16bitAt(pos + 1);
+	    String typedesc
+		= TransformReadField.isField(clazz.getClassPool(), cp,
+				fieldClass, fieldname, isPrivate, index);
+	    if (typedesc != null) {
+		if (newIndex == 0) {
+		    int nt = cp.addNameAndTypeInfo(newFieldname,
+						   typedesc);
+		    newIndex = cp.addFieldrefInfo(
+					cp.addClassInfo(newClassname), nt);
+		    constPool = cp;
+		}
+
+		iterator.write16bit(newIndex, pos + 1);
+	    }
+	}
+
+	return pos;
+    }
+}
diff --git a/src/main/javassist/convert/TransformNew.java b/src/main/javassist/convert/TransformNew.java
new file mode 100644
index 00000000..a69918d8
--- /dev/null
+++ b/src/main/javassist/convert/TransformNew.java
@@ -0,0 +1,102 @@
+/*
+ * 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));
+    }
+}
diff --git a/src/main/javassist/convert/TransformReadField.java b/src/main/javassist/convert/TransformReadField.java
new file mode 100644
index 00000000..fda192c1
--- /dev/null
+++ b/src/main/javassist/convert/TransformReadField.java
@@ -0,0 +1,94 @@
+/*
+ * 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.ClassPool;
+import javassist.CtClass;
+import javassist.CtField;
+import javassist.CannotCompileException;
+import javassist.NotFoundException;
+import javassist.Modifier;
+
+public class TransformReadField extends Transformer {
+    protected String fieldname;
+    protected CtClass fieldClass;
+    protected boolean isPrivate;
+    protected String methodClassname, methodName;
+
+    public TransformReadField(Transformer next, CtField field,
+			      String methodClassname, String methodName)
+    {
+	super(next);
+	this.fieldClass = field.getDeclaringClass();
+	this.fieldname = field.getName();
+	this.methodClassname = methodClassname;
+	this.methodName = methodName;
+	this.isPrivate = Modifier.isPrivate(field.getModifiers());
+    }
+
+    static String isField(ClassPool pool, ConstPool cp, CtClass fclass,
+			  String fname, boolean is_private, int index) {
+	if (!cp.getFieldrefName(index).equals(fname))
+	    return null;
+
+	try {
+	    CtClass c = pool.get(cp.getFieldrefClassName(index));
+	    if (is_private ? c == fclass : c.subclassOf(fclass))
+		return cp.getFieldrefType(index);
+	}
+	catch (NotFoundException e) {}
+	return null;
+    }
+
+    public int transform(CtClass tclazz, int pos, CodeIterator iterator,
+			 ConstPool cp) throws BadBytecode
+    {
+	int c = iterator.byteAt(pos);
+	if (c == GETFIELD || c == GETSTATIC) {
+	    int index = iterator.u16bitAt(pos + 1);
+	    String typedesc = isField(tclazz.getClassPool(), cp,
+				fieldClass, fieldname, isPrivate, index);
+	    if (typedesc != null) {
+		if (c == GETSTATIC) {
+		    iterator.move(pos);
+		    iterator.insertGap(1); // insertGap() may insert 4 bytes.
+		    iterator.writeByte(ACONST_NULL, pos);
+		    pos = iterator.next();
+		}
+
+		String type = "(Ljava/lang/Object;)" + typedesc;
+		int mi = cp.addClassInfo(methodClassname);
+		int methodref = cp.addMethodrefInfo(mi, methodName, type);
+		iterator.writeByte(INVOKESTATIC, pos);
+		iterator.write16bit(methodref, pos + 1);
+		return pos;
+	    }
+	}
+
+	return pos;
+    }
+}
diff --git a/src/main/javassist/convert/TransformWriteField.java b/src/main/javassist/convert/TransformWriteField.java
new file mode 100644
index 00000000..8c37c7fd
--- /dev/null
+++ b/src/main/javassist/convert/TransformWriteField.java
@@ -0,0 +1,82 @@
+/*
+ * 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.CtClass;
+import javassist.CtField;
+import javassist.bytecode.*;
+import javassist.CannotCompileException;
+
+final public class TransformWriteField extends TransformReadField {
+    public TransformWriteField(Transformer next, CtField field,
+			       String methodClassname, String methodName)
+    {
+	super(next, field, methodClassname, methodName);
+    }
+
+    public int transform(CtClass tclazz, int pos, CodeIterator iterator,
+			 ConstPool cp) throws BadBytecode
+    {
+	int c = iterator.byteAt(pos);
+	if (c == PUTFIELD || c == PUTSTATIC) {
+	    int index = iterator.u16bitAt(pos + 1);
+	    String typedesc = isField(tclazz.getClassPool(), cp,
+				fieldClass, fieldname, isPrivate, index);
+	    if (typedesc != null) {
+		if (c == PUTSTATIC) {
+		    CodeAttribute ca = iterator.get();
+		    iterator.move(pos);
+		    char c0 = typedesc.charAt(0);
+		    if (c0 == 'J' || c0 == 'D') {	// long or double
+			// insertGap() may insert 4 bytes.
+			iterator.insertGap(3);
+			iterator.writeByte(ACONST_NULL, pos);
+			iterator.writeByte(DUP_X2, pos + 1);
+			iterator.writeByte(POP, pos + 2);
+			ca.setMaxStack(ca.getMaxStack() + 2);
+		    }
+		    else {
+			// insertGap() may insert 4 bytes.
+			iterator.insertGap(2);
+			iterator.writeByte(ACONST_NULL, pos);
+			iterator.writeByte(SWAP, pos + 1);
+			ca.setMaxStack(ca.getMaxStack() + 1);
+		    }
+
+		    pos = iterator.next();
+		}
+
+		int mi = cp.addClassInfo(methodClassname);
+		String type = "(Ljava/lang/Object;" + typedesc + ")V";
+		int methodref = cp.addMethodrefInfo(mi, methodName, type);
+		iterator.writeByte(INVOKESTATIC, pos);
+		iterator.write16bit(methodref, pos + 1);
+	    }
+	}
+
+	return pos;
+    }
+}
diff --git a/src/main/javassist/convert/Transformer.java b/src/main/javassist/convert/Transformer.java
new file mode 100644
index 00000000..f1a4b566
--- /dev/null
+++ b/src/main/javassist/convert/Transformer.java
@@ -0,0 +1,55 @@
+/*
+ * 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;
+
+/**
+ * Transformer and its subclasses are used for executing
+ * code transformation specified by CodeConverter.
+ *
+ * @see javassist.CodeConverter
+ */
+public abstract class Transformer implements Opcode {
+    private Transformer next;
+
+    public Transformer(Transformer t) {
+	next = t;
+    }
+
+    public Transformer getNext() { return next; }
+
+    public void initialize(ConstPool cp, CodeAttribute attr) {}
+
+    public void clean() {}
+
+    public abstract int transform(CtClass clazz, int pos, CodeIterator it,
+		ConstPool cp) throws CannotCompileException, BadBytecode;
+
+    public int extraLocals() { return 0; }
+}