/* Soot - a J*va Optimization Framework
* Copyright (C) 1997-1999 Raja Vallee-Rai
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/*
* Modified by the Sable Research Group and others 1997-1999.
* See the 'credits' file distributed with Soot for the complete list of
* contributors. (Soot is distributed at http://www.sable.mcgill.ca/soot)
*/
package soot.toolkits.scalar;
import java.util.*;
/**
* Reference implementation for a FlowSet. Items are stored in an Array.
*/
public class ArraySparseSet extends AbstractFlowSet
{
protected static final int DEFAULT_SIZE = 8;
protected int numElements;
protected int maxElements;
protected Object[] elements;
public ArraySparseSet()
{
maxElements = DEFAULT_SIZE;
elements = new Object[DEFAULT_SIZE];
numElements = 0;
}
private ArraySparseSet(ArraySparseSet other)
{
numElements = other.numElements;
maxElements = other.maxElements;
elements = other.elements.clone();
}
/** Returns true if flowSet is the same type of flow set as this. */
private boolean sameType(Object flowSet)
{
return (flowSet instanceof ArraySparseSet);
}
public ArraySparseSet clone()
{
return new ArraySparseSet(this);
}
public Object emptySet()
{
return new ArraySparseSet();
}
public void clear()
{
numElements = 0;
}
public int size()
{
return numElements;
}
public boolean isEmpty()
{
return numElements == 0;
}
/** Returns a unbacked list of elements in this set. */
public List toList()
{
Object[] copiedElements = new Object[numElements];
System.arraycopy(elements, 0, copiedElements, 0, numElements);
return Arrays.asList(copiedElements);
}
/* Expand array only when necessary, pointed out by Florian Loitsch
* March 08, 2002
*/
public void add(Object e)
{
/* Expand only if necessary! and removes one if too:) */
// Add element
if(!contains(e)) {
// Expand array if necessary
if(numElements == maxElements)
doubleCapacity();
elements[numElements++] = e;
}
}
private void doubleCapacity()
{
int newSize = maxElements * 2;
Object[] newElements = new Object[newSize];
System.arraycopy(elements, 0, newElements, 0, numElements);
elements = newElements;
maxElements = newSize;
}
public void remove(Object obj)
{
int i = 0;
while (i < this.numElements) {
if (elements[i].equals(obj))
{
numElements--;
//copy last element to deleted position
elements[i] = elements[numElements];
//delete reference in last cell so that
//we only retain a single reference to the
//"old last" element, for memory safety
elements[numElements] = null;
return;
} else
i++;
}
}
public void union(FlowSet otherFlow, FlowSet destFlow)
{
if (sameType(otherFlow) &&
sameType(destFlow)) {
ArraySparseSet other = (ArraySparseSet) otherFlow;
ArraySparseSet dest = (ArraySparseSet) destFlow;
// For the special case that dest == other
if(dest == other)
{
for(int i = 0; i < this.numElements; i++)
dest.add(this.elements[i]);
}
// Else, force that dest starts with contents of this
else {
if(this != dest)
copy(dest);
for(int i = 0; i < other.numElements; i++)
dest.add(other.elements[i]);
}
} else
super.union(otherFlow, destFlow);
}
public void intersection(FlowSet otherFlow, FlowSet destFlow)
{
if (sameType(otherFlow) &&
sameType(destFlow)) {
ArraySparseSet other = (ArraySparseSet) otherFlow;
ArraySparseSet dest = (ArraySparseSet) destFlow;
ArraySparseSet workingSet;
if(dest == other || dest == this)
workingSet = new ArraySparseSet();
else {
workingSet = dest;
workingSet.clear();
}
for(int i = 0; i < this.numElements; i++)
{
if(other.contains(this.elements[i]))
workingSet.add(this.elements[i]);
}
if(workingSet != dest)
workingSet.copy(dest);
} else
super.intersection(otherFlow, destFlow);
}
public void difference(FlowSet otherFlow, FlowSet destFlow)
{
if (sameType(otherFlow) &&
sameType(destFlow)) {
ArraySparseSet other = (ArraySparseSet) otherFlow;
ArraySparseSet dest = (ArraySparseSet) destFlow;
ArraySparseSet workingSet;
if(dest == other || dest == this)
workingSet = new ArraySparseSet();
else {
workingSet = dest;
workingSet.clear();
}
for(int i = 0; i < this.numElements; i++)
{
if(!other.contains(this.elements[i]))
workingSet.add(this.elements[i]);
}
if(workingSet != dest)
workingSet.copy(dest);
} else
super.difference(otherFlow, destFlow);
}
/**
* @deprecated This method uses linear-time lookup.
* For better performance, consider using a {@link HashSet} instead, if you require this operation.
*/
public boolean contains(Object obj)
{
for(int i = 0; i < numElements; i++)
if(elements[i].equals(obj))
return true;
return false;
}
public boolean equals(Object otherFlow)
{
if (sameType(otherFlow)) {
ArraySparseSet other = (ArraySparseSet) otherFlow;
if(other.numElements != this.numElements)
return false;
int size = this.numElements;
// Make sure that thisFlow is contained in otherFlow
for(int i = 0; i < size; i++)
if(!other.contains(this.elements[i]))
return false;
/* both arrays have the same size, no element appears twice in one
* array, all elements of ThisFlow are in otherFlow -> they are
* equal! we don't need to test again!
// Make sure that otherFlow is contained in ThisFlow
for(int i = 0; i < size; i++)
if(!this.contains(other.elements[i]))
return false;
*/
return true;
} else
return super.equals(otherFlow);
}
public void copy(FlowSet destFlow)
{
if (sameType(destFlow)) {
ArraySparseSet dest = (ArraySparseSet) destFlow;
while(dest.maxElements < this.maxElements)
dest.doubleCapacity();
dest.numElements = this.numElements;
System.arraycopy(this.elements, 0,
dest.elements, 0, this.numElements);
} else
super.copy(destFlow);
}
}