/*
* reserved comment block
* DO NOT REMOVE OR ALTER!
*/
/* ====================================================================
* 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.
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* 2. Redistributions in binary form must reproduce the above copyright
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* distribution.
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* 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
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* written permission, please contact apache@apache.org.
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* 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
*/
/**
* Super class for object and array types.
*
* @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
*/
super(t, s);
}
/** Class is non-abstract but not instantiable from the outside
*/
ReferenceType() {
}
/**
* 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.
*/
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.
*/
if (!(t instanceof ReferenceType))
return false;
ReferenceType T = (ReferenceType) t;
return true; // This is not explicitely stated, but clear. Isn't it?
/* If this is a class type then
*/
/* If T is a class type, then this must be the same class as T,
or this must be a subclass of T;
*/
if (this.equals(T))
return true;
((ObjectType) T).getClassName()))
return true;
}
/* If T is an interface type, this must implement interface T.
*/
((ObjectType) T).getClassName()))
return true;
}
}
/* If this is an interface type, then:
*/
/* If T is a class type, then T must be Object (2.4.7).
*/
}
/* If T is an interface type, then T must be the same interface
* as this or a superinterface of this (2.13.2).
*/
if (this.equals(T)) return true;
((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 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).
*/
return true;
/* TC and SC are reference types (2.4.6), and type SC is
* assignable to TC by these runtime rules.
*/
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'"
}
}
}
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;
* unless their dimensions match. Then an ArrayType of the same
* number of dimensions is returned, with its basic type being the
* first common super class of the basic types of "this" and t.
* 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, "4.9.2 The Bytecode Verifier".
*/
if (this.equals(t)) return this;
/*
* TODO: Above 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 :)
*/
/* This code is from a bug report by Konstantin Shagin <konst@cs.technion.ac.il> */
if (
return new ArrayType(
((ObjectType) arrType1.getBasicType()).getFirstCommonSuperclass((ObjectType) arrType2.getBasicType()),
);
}
}
// TODO: Is there a proof of OBJECT being the direct ancestor of every ArrayType?
// 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.
return null;
}
// Waaahh...
}
}
// Huh? Did you ask for Type.OBJECT's superclass??
return null;
}
/**
* 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, "4.9.2 The Bytecode Verifier".
*
* @deprecated use getFirstCommonSuperclass(ReferenceType t) which has
* slightly changed semantics.
*/
if (this.equals(t)) return this;
/*
* TODO: Above 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 :)
*/
// TODO: Is there a proof of OBJECT being the direct ancestor of every ArrayType?
// 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.
return null;
}
// Waaahh...
}
}
// Huh? Did you ask for Type.OBJECT's superclass??
return null;
}
}