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'databene commons' is an open source Java library by Volker Bergmann.
It provides extensions to the Java core library by utility classes, abstract concepts
and concrete implementations.
/*
* Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
* All rights reserved.
*
* 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.
*/
package org.databene.commons.visitor;
import org.databene.commons.ComparableComparator;
import org.databene.commons.Element;
import org.databene.commons.Visitor;
import java.util.Comparator;
/**
* Utility that navigates Elements with the Visitor Pattern and
* uses a Comparator for determining a minimum or maximum value in the graph.
* Created: 04.02.2007 08:50:13
* @param the type of the elements to examine
* @author Volker Bergmann
*/
public class ExtremeElementFinder {
public static > E findMax(Element root) {
return findMax(root, new ComparableComparator());
}
public static E findMax(Element root, Comparator comparator) {
return findExtreme(root, comparator, 1);
}
public static > E findMin(Element root) {
return findMin(root, new ComparableComparator());
}
public static E findMin(Element root, Comparator comparator) {
return findExtreme(root, comparator, -1);
}
private static E findExtreme(Element root, Comparator comparator, int extreme) {
ExtremeVisitor visitor = new ExtremeVisitor(comparator, extreme);
root.accept(visitor);
return visitor.extremeElement;
}
static final class ExtremeVisitor implements Visitor {
private Comparator comparator;
private int extreme;
E extremeElement;
public ExtremeVisitor(Comparator comparator, int extreme) {
this.comparator = comparator;
this.extreme = extreme;
this.extremeElement = null;
}
@Override
public void visit(C element) {
if (extremeElement == null || comparator.compare(element, extremeElement) == extreme)
extremeElement = element;
}
}
}