package com.planet_ink.coffee_mud.core.collections;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Vector;
/*
Copyright 2010-2019 Bo Zimmerman
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
public class FilteredEnumeration<K> implements Enumeration<K>
{
private final Enumeration<K> enumer;
private Filterer<K> filterer;
private K nextElement = null;
private boolean initialized = false;
public FilteredEnumeration(final Enumeration<K> eset, final Filterer<K> fil)
{
enumer=eset;
filterer=fil;
}
public void setFilterer(final Filterer<K> fil)
{
filterer=fil;
}
private void stageNextElement()
{
nextElement = null;
while((nextElement==null) && (enumer.hasMoreElements()))
{
nextElement = enumer.nextElement();
if(filterer.passesFilter(nextElement))
return;
nextElement = null;
}
}
private void initialize()
{
if(!initialized)
{
stageNextElement();
initialized=true;
}
}
@Override
public boolean hasMoreElements()
{
if(!initialized)
initialize();
return nextElement!=null;
}
@Override
public K nextElement()
{
if(!hasMoreElements())
throw new NoSuchElementException();
final K element = nextElement;
stageNextElement();
return element;
}
}
