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// org.debian.cpbs.Bag
// A class representing an unordered collection of Objects
// Written by Charles Briscoe-Smith; refer to the file LEGAL for details.
package org.debian.cpbs;
import java.util.Enumeration;
import java.util.NoSuchElementException;
class BagEnumeration implements Enumeration {
private int nextElement=0;
private Object[] elements;
private int elementsLeft;
BagEnumeration(Object[] elems, int count)
{
elements=elems;
elementsLeft=count;
}
public boolean hasMoreElements()
{
return elementsLeft>0;
}
public Object nextElement() throws NoSuchElementException
{
if (!hasMoreElements())
throw new NoSuchElementException();
while (elements[nextElement]==null)
nextElement++;
elementsLeft--;
return elements[nextElement++];
}
}
public class Bag {
private Object[] elements;
private int size;
private int maxfill;
private float fillfactor;
public Bag(int cap, float factor)
{
elements=new Object[cap];
fillfactor=factor;
size=0;
maxfill=(int) (cap*fillfactor);
}
public Bag(int cap)
{
this(cap, 0.75f);
}
public Bag()
{
this(16);
}
public synchronized String toString()
{
StringBuffer output=new StringBuffer();
output.append('[');
int flag=0;
for (int i=0; i<elements.length; i++) {
if (elements[i]!=null) {
if (flag==0) {
flag=1;
} else {
output.append(", ");
}
output.append(elements[i]);
}
}
output.append(']');
return output.toString();
}
public synchronized int size()
{
return size;
}
public synchronized boolean isEmpty()
{
return size==0;
}
private synchronized int getIndex(Object o)
{
int hash=o.hashCode()%elements.length;
if (hash<0) hash+=elements.length;
for (int i=hash; i<elements.length; i++) {
if (o.equals(elements[i])) return i;
if (elements[i]==null) return -1;
}
for (int i=0; i<hash; i++) {
if (o.equals(elements[i])) return i;
if (elements[i]==null) return -1;
}
return -1;
}
public synchronized Object get(Object o)
{
int i=getIndex(o);
return i==-1 ? (Object) null : elements[i];
}
private void hashIn(Object o)
{
int hash=o.hashCode()%elements.length;
if (hash<0) hash+=elements.length;
for (int i=hash; i<elements.length; i++) {
if (elements[i]==null) {
elements[i]=o;
return;
}
}
for (int i=0; i<hash; i++) {
if (elements[i]==null) {
elements[i]=o;
return;
}
}
throw new InternalError("Can't hash element into Bag");
}
public synchronized void put(Object o)
{
if (size+1>maxfill) rehash();
size++;
hashIn(o);
}
public synchronized void putContents(Enumeration e)
{
while (e.hasMoreElements()) {
put(e.nextElement());
}
}
public synchronized void remove(Object obj)
{
int start=getIndex(obj);
if (start==-1) return;
elements[start]=null;
for (int i=start+1; i<elements.length; i++) {
Object o=elements[i];
elements[i]=null;
if (o==null) return;
hashIn(o);
}
for (int i=0; i<start; i++) {
Object o=elements[i];
elements[i]=null;
if (o==null) return;
hashIn(o);
}
}
public Enumeration elements()
{
return new BagEnumeration(elements, size);
}
public boolean contains(Object o)
{
return getIndex(o)!=-1;
}
protected synchronized void rehash()
{
Object[] oldelements=elements;
elements=new Object[oldelements.length*2];
for (int i=0; i<oldelements.length; i++) {
hashIn(oldelements[i]);
}
maxfill=(int) (elements.length*fillfactor);
}
public synchronized void clear()
{
size=0;
for (int i=0; i<elements.length; i++) {
elements[i]=null;
}
}
}
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