package org.apache.bcel.generic;
/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2001 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Apache" and "Apache Software Foundation" and
* "Apache BCEL" must not be used to endorse or promote products
* derived from this software without prior written permission. For
* written permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache",
* "Apache BCEL", nor may "Apache" appear in their name, without
* prior written permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* .
*/
import org.apache.bcel.Constants;
import org.apache.bcel.Repository;
import org.apache.bcel.classfile.JavaClass;
/**
* Super class for objects and arrays.
*
* @version $Id$
* @author M. Dahm
*/
public class ReferenceType extends Type {
protected ReferenceType(byte t, String s) {
super(t, s);
}
/** Class is non-abstract but not instantiable from the outside
*/
ReferenceType() {
super(Constants.T_OBJECT, "");
}
/**
* Return true iff this type is castable to another type t as defined in
* the JVM specification. The case where this is Type.NULL is not
* defined (see the CHECKCAST definition in the JVM specification).
* However, because e.g. CHECKCAST doesn't throw a
* ClassCastException when casting a null reference to any Object,
* true is returned in this case.
*/
public boolean isCastableTo(Type t){
if(this.equals(Type.NULL))
return true; // If this is ever changed in isAssignmentCompatible()
return isAssignmentCompatibleWith(t); /* Yes, it's true: It's the same definition.
* See vmspec2 AASTORE / CHECKCAST definitions.
*/
}
/**
* Return true iff this is assignment compatible with another type t
* as defined in the JVM specification; see the AASTORE definition
* there.
*/
public boolean isAssignmentCompatibleWith(Type t) {
if(!(t instanceof ReferenceType))
return false;
ReferenceType T = (ReferenceType)t;
if(this.equals(Type.NULL))
return true; // This is not explicitely stated, but clear. Isn't it?
/* If this is a class type then
*/
if((this instanceof ObjectType) && (((ObjectType) this).referencesClass())) {
/* If T is a class type, then this must be the same class as T,
or this must be a subclass of T;
*/
if((T instanceof ObjectType) && (((ObjectType) T).referencesClass())) {
if(this.equals(T))
return true;
if(Repository.instanceOf( ((ObjectType) this).getClassName(),
((ObjectType) T).getClassName()))
return true;
}
/* If T is an interface type, this must implement interface T.
*/
if ((T instanceof ObjectType) && (((ObjectType) T).referencesInterface())) {
if (Repository.implementationOf( ((ObjectType) this).getClassName(),
((ObjectType) T).getClassName() ))
return true;
}
}
/* If this is an interface type, then:
*/
if ((this instanceof ObjectType) && (((ObjectType) this).referencesInterface())){
/* If T is a class type, then T must be Object (§2.4.7).
*/
if ((T instanceof ObjectType) && (((ObjectType) T).referencesClass())){
if (T.equals(Type.OBJECT)) return true;
}
/* If T is an interface type, then T must be the same interface
as this or a superinterface of this (§2.13.2).
*/
if ((T instanceof ObjectType) && (((ObjectType) T).referencesInterface())){
if (this.equals(T)) return true;
if (Repository.implementationOf( ((ObjectType) this).getClassName(),
((ObjectType) T).getClassName() )) return true;
}
}
/* If this is an array type, namely, the type SC[], that is, an
array of components of type SC, then:
*/
if(this instanceof ArrayType){
/* If T is a class type, then T must be Object (§2.4.7).
*/
if ((T instanceof ObjectType) && (((ObjectType) T).referencesClass())){
if (T.equals(Type.OBJECT)) return true;
}
/* If T is an array type TC[], that is, an array of components
of type TC, then one of the following must be true:
*/
if (T instanceof ArrayType) {
/* TC and SC are the same primitive type (§2.4.1).
*/
Type sc = ((ArrayType) this).getElementType();
Type tc = ((ArrayType) this).getElementType();
if (sc instanceof BasicType && tc instanceof BasicType && sc.equals(tc))
return true;
/* TC and SC are reference types (§2.4.6), and type SC is
assignable to TC by these runtime rules.*/
if (tc instanceof ReferenceType && sc instanceof ReferenceType &&
((ReferenceType) sc).isAssignmentCompatibleWith((ReferenceType) tc)) return true;
}
/* If T is an interface type, T must be one of the interfaces implemented by arrays (§2.15). */
// TODO: Check if this is still valid or find a way to dynamically find out which
// interfaces arrays implement. However, as of the JVM specification edition 2, there
// are at least two different pages where assignment compatibility is defined and
// on one of them "interfaces implemented by arrays" is exchanged with "'Cloneable' or
// 'java.io.Serializable'"
if ((T instanceof ObjectType) && (((ObjectType) T).referencesInterface())){
for (int ii=0; ii