- package com.sun.org.apache.bcel.internal.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
- * <http://www.apache.org/>.
- */
- import com.sun.org.apache.bcel.internal.Constants;
- import com.sun.org.apache.bcel.internal.Repository;
- import com.sun.org.apache.bcel.internal.classfile.JavaClass;
-
- /**
- * Super class for objects and arrays.
- *
- * @version $Id: ReferenceType.java,v 1.1.1.1 2001/10/29 20:00:26 jvanzyl Exp $
- * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
- */
- 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, "<null 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<Constants.INTERFACES_IMPLEMENTED_BY_ARRAYS.length; ii++){
- if (T.equals(new ObjectType(Constants.INTERFACES_IMPLEMENTED_BY_ARRAYS[ii]))) return true;
- }
- }
- }
- return false; // default.
- }
-
- /**
- * This commutative operation returns the first common superclass (narrowest ReferenceType
- * referencing a class, not an interface).
- * If one of the types is a superclass of the other, the former is returned.
- * If "this" is Type.NULL, then t is returned.
- * If t is Type.NULL, then "this" is returned.
- * If "this" equals t ['this.equals(t)'] "this" is returned.
- * If "this" or t is an ArrayType, then Type.OBJECT is returned.
- * If "this" or t is a ReferenceType referencing an interface, then Type.OBJECT is returned.
- * If not all of the two classes' superclasses cannot be found, "null" is returned.
- * See the JVM specification edition 2, "&247;4.9.2 The Bytecode Verifier".
- */
- public ReferenceType firstCommonSuperclass(ReferenceType t){
- if (this.equals(Type.NULL)) return t;
-
- if (t.equals(Type.NULL)) return this;
-
- if (this.equals(t)) return this;
-
- // TODO: This sounds a little arbitrary. On the other hand, there is
- // no object referenced by Type.NULL so we can also say all the objects
- // referenced by Type.NULL were derived from java.lang.Object.
- // However, the Java Language's "instanceof" operator proves us wrong:
- // "null" is not referring to an instance of java.lang.Object :)
-
- if ((this instanceof ArrayType) || (t instanceof ArrayType))
- return Type.OBJECT;
- // TODO: Is there a proof of OBJECT being the direct ancestor of every ArrayType?
-
- if ( ((this instanceof ObjectType) && ((ObjectType) this).referencesInterface()) ||
- (( t instanceof ObjectType) && ((ObjectType) t).referencesInterface()) )
- return Type.OBJECT;
- // TODO: The above line is correct comparing to the vmspec2. But one could
- // make class file verification a bit stronger here by using the notion of
- // superinterfaces or even castability or assignment compatibility.
-
-
- // this and t are ObjectTypes, see above.
- ObjectType thiz = (ObjectType) this;
- ObjectType other = (ObjectType) t;
- JavaClass[] thiz_sups = Repository.getSuperClasses( thiz.getClassName());
- JavaClass[] other_sups = Repository.getSuperClasses(other.getClassName());
-
- if ((thiz_sups == null) || (other_sups==null)){
- return null;
- }
-
- // Waaahh...
- JavaClass[] this_sups = new JavaClass[thiz_sups.length+1];
- JavaClass[] t_sups = new JavaClass[other_sups.length+1];
- System.arraycopy( thiz_sups, 0, this_sups, 1, thiz_sups.length);
- System.arraycopy(other_sups, 0, t_sups , 1, other_sups.length);
- this_sups[0] = Repository.lookupClass(thiz.getClassName());
- t_sups[0] = Repository.lookupClass(other.getClassName());
-
- for (int i=0; i<t_sups.length; i++){
- for (int j=0; j<this_sups.length; j++){
- if (this_sups[j].equals(t_sups[i])) return new ObjectType(this_sups[j].getClassName());
- }
- }
-
- // Huh? Did you ask for Type.OBJECT's superclass??
- return null;
- }
- }