You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
86 lines
2.6 KiB
86 lines
2.6 KiB
/* NullType Copyright (C) 1999 Jochen Hoenicke.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2, or (at your option)
|
|
* any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; see the file COPYING. If not, write to
|
|
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
|
|
*
|
|
* $Id$
|
|
*/
|
|
|
|
package jode.type;
|
|
import jode.AssertError;
|
|
import java.util.Stack;
|
|
///#def COLLECTIONEXTRA java.lang
|
|
import java.lang.UnsupportedOperationException;
|
|
///#enddef
|
|
|
|
/**
|
|
* This class represents the NullType. The null type is special as it
|
|
* may only occur as top type in a range type. It represents the type
|
|
* of the null constant, which may be casted to any object. <br>
|
|
*
|
|
* Question: Should we replace tUObject = tRange(tObject, tNull) by tNull?
|
|
* Question2: if not, should null have type tNull?
|
|
*
|
|
* @author Jochen Hoenicke
|
|
*/
|
|
public class NullType extends ReferenceType {
|
|
public NullType() {
|
|
super(TC_NULL);
|
|
}
|
|
|
|
public Type getSubType() {
|
|
return this;
|
|
}
|
|
|
|
public Type createRangeType(ReferenceType bottomType) {
|
|
return tRange(bottomType, this);
|
|
}
|
|
|
|
/**
|
|
* Returns the generalized type of this and type. We have two
|
|
* classes and multiple interfaces. The result should be the
|
|
* object that is the the super class of both objects and all
|
|
* interfaces, that one class or interface of each type
|
|
* implements.
|
|
*/
|
|
public Type getGeneralizedType(Type type) {
|
|
if (type.typecode == TC_RANGE)
|
|
type = ((RangeType) type).getTop();
|
|
if (type instanceof ReferenceType)
|
|
return type;
|
|
return tError;
|
|
}
|
|
|
|
/**
|
|
* Returns the specialized type of this and type.
|
|
* We have two classes and multiple interfaces. The result
|
|
* should be the object that extends both objects
|
|
* and the union of all interfaces.
|
|
*/
|
|
public Type getSpecializedType(Type type) {
|
|
if (type.typecode == TC_RANGE)
|
|
type = ((RangeType) type).getBottom();
|
|
if (type != tNull)
|
|
return tError;
|
|
return tNull;
|
|
}
|
|
|
|
public String toString() {
|
|
return "tNull";
|
|
}
|
|
|
|
public Type findCommonClassTypes(Stack otherTypes) {
|
|
throw new UnsupportedOperationException();
|
|
}
|
|
}
|
|
|