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path: root/src/main/javassist/CtNewWrappedMethod.java
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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;

import javassist.bytecode.*;
import javassist.compiler.JvstCodeGen;
import java.util.Hashtable;
import javassist.CtMethod.ConstParameter;

class CtNewWrappedMethod {

    private static final String addedWrappedMethod = "_added_m$";

    public static CtMethod wrapped(CtClass returnType, String mname,
				   CtClass[] parameterTypes,
				   CtClass[] exceptionTypes,
				   CtMethod body, ConstParameter constParam,
				   CtClass declaring)
	throws CannotCompileException
    {
	CtMethod mt = new CtMethod(returnType, mname, parameterTypes,
				   declaring);
	mt.setModifiers(body.getModifiers());
	try {
	    mt.setExceptionTypes(exceptionTypes);
	}
	catch (NotFoundException e) {
	    throw new CannotCompileException(e);
	}

	Bytecode code = makeBody(declaring, declaring.getClassFile2(), body,
				 parameterTypes, returnType, constParam);
	mt.getMethodInfo2().setCodeAttribute(code.toCodeAttribute());
	return mt;
    }

    static Bytecode makeBody(CtClass clazz, ClassFile classfile,
			     CtMethod wrappedBody,
			     CtClass[] parameters,
			     CtClass returnType,
			     ConstParameter cparam)
	throws CannotCompileException
    {
	boolean isStatic = Modifier.isStatic(wrappedBody.getModifiers());
	Bytecode code = new Bytecode(classfile.getConstPool(), 0, 0);
	int stacksize = makeBody0(clazz, classfile, wrappedBody, isStatic,
				  parameters, returnType, cparam, code);
	code.setMaxStack(stacksize);
	code.setMaxLocals(isStatic, parameters, 0);
	return code;
    }

    protected static int makeBody0(CtClass clazz, ClassFile classfile,
				   CtMethod wrappedBody,
				   boolean isStatic, CtClass[] parameters,
				   CtClass returnType, ConstParameter cparam,
				   Bytecode code)
	throws CannotCompileException
    {
	if (!(clazz instanceof CtClassType))
	    throw new CannotCompileException("bad declaring class"
					     + clazz.getName());

	if (!isStatic)
	    code.addAload(0);

	int stacksize = compileParameterList(code, parameters,
					     (isStatic ? 0 : 1));
	int stacksize2;
	String desc;
	if (cparam == null) {
	    stacksize2 = 0;
	    desc = ConstParameter.defaultDescriptor();
	}
	else {
	    stacksize2 = cparam.compile(code);
	    desc = cparam.descriptor();
	}

	checkSignature(wrappedBody, desc);

	String bodyname;
	try {
	    bodyname = addBodyMethod((CtClassType)clazz, classfile,
				     wrappedBody);
	    /* if an exception is thrown below, the method added above
	     * should be removed. (future work :<)
	     */
	}
	catch (BadBytecode e) {
	    throw new CannotCompileException(e);
	}

	if (isStatic)
	    code.addInvokestatic(Bytecode.THIS, bodyname, desc);
	else
	    code.addInvokespecial(Bytecode.THIS, bodyname, desc);

	compileReturn(code, returnType);	// consumes 2 stack entries

	if (stacksize < stacksize2 + 2)
	    stacksize = stacksize2 + 2;

	return stacksize;
    }

    private static void checkSignature(CtMethod wrappedBody,
				       String descriptor)
	throws CannotCompileException
    {
	if (!descriptor.equals(wrappedBody.getMethodInfo2().getDescriptor()))
	    throw new CannotCompileException(
			"wrapped method with a bad signature: "
			+ wrappedBody.getDeclaringClass().getName()
			+ '.' + wrappedBody.getName());
    }

    private static String addBodyMethod(CtClassType clazz,
					ClassFile classfile,
					CtMethod src)
	throws BadBytecode
    {
	Hashtable bodies = clazz.getHiddenMethods();
	String bodyname = (String)bodies.get(src);
	if (bodyname == null) {
	    do {
		bodyname = addedWrappedMethod + clazz.getUniqueNumber();
	    } while (classfile.getMethod(bodyname) != null);

	    ClassMap map = new ClassMap();
	    map.put(src.getDeclaringClass().getName(), clazz.getName());
	    MethodInfo body = new MethodInfo(classfile.getConstPool(),
					     bodyname, src.getMethodInfo2(),
					     map);
	    int acc = body.getAccessFlags();
	    body.setAccessFlags(AccessFlag.setPrivate(acc));
	    classfile.addMethod(body);
	    bodies.put(src, bodyname);
	}

	return bodyname;
    }

    /* compileParameterList() returns the stack size used
     * by the produced code.
     *
     * @param regno	the index of the local variable in which
     *			the first argument is received.
     *			(0: static method, 1: regular method.)
     */
    static int compileParameterList(Bytecode code,
				    CtClass[] params, int regno) {
	return JvstCodeGen.compileParameterList(code, params, regno);
    }

    /*
     * The produced codes cosume 1 or 2 stack entries.
     */
    private static void compileReturn(Bytecode code, CtClass type) {
	if (type.isPrimitive()) {
	    CtPrimitiveType pt = (CtPrimitiveType)type;
	    if (pt != CtClass.voidType) {
		String wrapper = pt.getWrapperName();
		code.addCheckcast(wrapper);
		code.addInvokevirtual(wrapper, pt.getGetMethodName(),
				      pt.getGetMethodDescriptor());
	    }

	    code.addOpcode(pt.getReturnOp());
	}
	else {
	    code.addCheckcast(type);
	    code.addOpcode(Bytecode.ARETURN);
	}
    }
}