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jode/jode/jode/decompiler/LocalInfo.java

214 lines
6.5 KiB

/*
* LocalInfo (c) 1998 Jochen Hoenicke
*
* You may distribute under the terms of the GNU General Public License.
*
* IN NO EVENT SHALL JOCHEN HOENICKE BE LIABLE TO ANY PARTY FOR DIRECT,
* INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF
* THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF JOCHEN HOENICKE
* HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* JOCHEN HOENICKE SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS"
* BASIS, AND JOCHEN HOENICKE HAS NO OBLIGATION TO PROVIDE MAINTENANCE,
* SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* $Id$
*/
package jode;
import java.util.Enumeration;
import java.util.Vector;
/**
* The LocalInfo represents a local variable of a method.
* The problem is that two different local variables may use the same
* slot. The current strategie is to make the range of a local variable
* as small as possible.<p>
*
* There may be more than one LocalInfo for a single local variable,
* because the algorithm begins with totally disjunct variables and
* then unifies locals. One of the local is then a shadow object which
* calls the member functions of the other local.<p>
*/
public class LocalInfo {
private static int serialnr = 0;
private int slot;
private boolean isUnique;
private String name;
private Type type;
private LocalInfo shadow;
private Vector operators = new Vector();
/* The current implementation may use very much stack. This
* should be changed someday.
*/
/**
* Create a new local info. The name will be a string
* @param slot The slot of this variable.
*/
public LocalInfo(int slot) {
name = null;
type = Type.tUnknown;
this.slot = slot;
}
public void setOperator(LocalVarOperator operator) {
getLocalInfo().operators.addElement(operator);
}
/**
* Combines the LocalInfo with another. This will make this
* a shadow object to the other local info. That is all member
* functions will use the new local info instead of data in this
* object. <p>
* If this is called with ourself nothing will happen.
* @param li the local info that we want to shadow.
*/
public void combineWith(LocalInfo li) {
li = li.getLocalInfo();
if (shadow != null) {
getLocalInfo().combineWith(li);
} else {
if (this != li) {
shadow = li;
// System.err.println("combining "+name+"("+type+") and "
// +li.name+"("+li.type+")");
li.setType(type);
boolean needTypeUpdate = !li.type.equals(type);
java.util.Enumeration enum = operators.elements();
while (enum.hasMoreElements()) {
LocalVarOperator lvo =
(LocalVarOperator) enum.nextElement();
if (needTypeUpdate) {
if (Decompiler.isTypeDebugging)
System.err.println("updating " + lvo + " in "
+ ((Expression)lvo).parent);
lvo.updateType();
}
shadow.operators.addElement(lvo);
}
/* Clear unused fields, to allow garbage collection.
*/
type = null;
name = null;
operators = null;
}
}
}
/**
* Get the real LocalInfo. This may be different from the
* current object if this is a shadow local info.
*/
public LocalInfo getLocalInfo() {
if (shadow != null) {
while (shadow.shadow != null) {
shadow = shadow.shadow;
}
return shadow;
}
return this;
}
/**
* Get the name of this local.
*/
public String getName() {
if (shadow != null) {
while (shadow.shadow != null) {
shadow = shadow.shadow;
}
return shadow.getName();
}
if (name == null) {
if (jode.Decompiler.prettyLocals && type != null) {
name = type.getDefaultName();
} else {
name = "local_"+slot+"__"+serialnr+++"_";
isUnique = true;
}
}
return name;
}
/**
* Get the slot of this local.
*/
public int getSlot() {
/* The slot does not change when shadowing */
return slot;
}
/**
* Set the name of this local.
*/
public void setName(String name) {
LocalInfo li = getLocalInfo();
li.name = name;
}
/**
* Set the name of this local.
*/
public void makeNameUnique() {
LocalInfo li = getLocalInfo();
String name = li.getName();
if (!li.isUnique) {
li.name = name + "__"+serialnr+++"_";
li.isUnique = true;
}
}
/**
* Get the type of this local.
*/
public Type getType() {
return getLocalInfo().type;
}
/**
* Sets a new information about the type of this local.
* The type of the local is may be made more specific by this call.
* @param The new type information to be set.
* @return The new type of the local.
*/
public Type setType(Type newType) {
LocalInfo li = getLocalInfo();
newType = li.type.intersection(newType);
if (Decompiler.isTypeDebugging)
System.err.println(getName()+" setType, new: "+newType
+ " old: "+li.type);
if (!li.type.equals(newType)) {
li.type = newType;
java.util.Enumeration enum = li.operators.elements();
while (enum.hasMoreElements()) {
LocalVarOperator lvo = (LocalVarOperator) enum.nextElement();
if (Decompiler.isTypeDebugging)
System.err.println("updating "+lvo+" in "
+ ((Expression)lvo).parent);
lvo.updateType();
}
}
return li.type;
}
public boolean isShadow() {
return (shadow != null);
}
public boolean equals(Object obj) {
return (obj instanceof LocalInfo
&& ((LocalInfo)obj).getLocalInfo() == getLocalInfo());
}
public String toString() {
return getName().toString();
}
}