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/*******************************************************************************
* Copyright (c) 2001, 2007 Oracle Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Oracle Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.jst.jsf.common.sets;
import java.util.Iterator;
import java.util.Set;
/**
* Generic (unoptimized) utilities for doing set operations.
*
* <p><b>Provisional API - subject to change</b></p>
*
* @author cbateman
*
*/
public class AxiomaticSetUtil
{
/**
* Creates the union of firstSet and secondSet in newSet.
* @param newSet
* @param firstSet
* @param secondSet
*/
public static void union(AxiomaticSet newSet, AxiomaticSet firstSet, AxiomaticSet secondSet)
{
newSet.addAll(firstSet);
newSet.addAll(secondSet);
}
/**
* Creates an intersection of firstSet and secondSet in newSet
* @param newSet
* @param firstSet
* @param secondSet
*/
public static void intersect(AxiomaticSet newSet, AxiomaticSet firstSet, AxiomaticSet secondSet)
{
// minor optimization: always iterate through the smaller of the
// two sets. This way we iterate through the smallest number
// of elements
Iterator it = null;
Set testSet = null;
// if other set smaller, get its iterator
if (secondSet.size() < firstSet.size())
{
it = secondSet.iterator();
// test set is other set
testSet = firstSet;
}
// first set is smaller or same
else
{
it = firstSet.iterator();
testSet = secondSet;
}
while (it.hasNext())
{
Object member = it.next();
if (testSet.contains(member))
{
newSet.add(member);
}
}
}
/**
* @param firstSet
* @param secondSet
* @return true firstSet and secondSet have no common elements (their intersection is empty)
*/
public static boolean isDisjoint(AxiomaticSet firstSet, AxiomaticSet secondSet)
{
return firstSet.intersect(secondSet).isEmpty();
}
/**
* @param firstOperand
* @param secondOperand
* @return the set formed by removing the intersection of firstOperand and secondOperand
* from firstOperand, leaving only those elements in firstOperand that are not in secondOperand
*/
public static AxiomaticSet subtract(
AxiomaticSet firstOperand, AxiomaticSet secondOperand)
{
ConcreteAxiomaticSet relativeComplement = new ConcreteAxiomaticSet();
// iterate through firstOperand and add each element to the result
// set that is not in secondOperand
for (final Iterator it = firstOperand.iterator(); it.hasNext();)
{
Object member = it.next();
if (!secondOperand.contains(member))
{
relativeComplement.add(member);
}
}
return relativeComplement;
}
}
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