/*
* Copyright 2002-2005 the original author or authors.
*
* 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 net.sf.sojo.util;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
/**
* This is a helper class, to find cycles in Collections or Maps. <br>
* This implementation don't find all possibillities of cycles!
*
* @author linke
*
*/
public class CycleDetector {
public static final int DEFAULT_MAX_COUNTER = 100;
private int counter = 0;
private int maxCounter = DEFAULT_MAX_COUNTER;
public CycleDetector() {
counter = 0;
}
public int getCounter() { return counter; }
public int getMaxCounter() { return maxCounter; }
public void setMaxCounter(int pvMaxCounter) { maxCounter = pvMaxCounter; }
public boolean cycleDetection (Object pvSearchObject) {
counter = 0;
return cycleDetection(pvSearchObject, pvSearchObject);
}
private boolean cycleDetectionCollection (Object pvRootObject, Collection pvCollection) {
Iterator it = pvCollection.iterator();
return cycleDetectionIntern(pvRootObject, it);
}
private boolean cycleDetectionMap (Object pvRootObject, Map pvMap) {
boolean lvReturn = cycleDetectionIntern(pvRootObject, pvMap.values().iterator());
if (lvReturn == false && counter < maxCounter) {
lvReturn = cycleDetectionIntern(pvRootObject, pvMap.keySet().iterator());
}
return lvReturn;
}
private boolean cycleDetection (Object pvRootObject, Object pvSearchObject) {
boolean lvResult = false;
if (pvSearchObject instanceof Collection) {
lvResult = cycleDetectionCollection(pvRootObject, (Collection) pvSearchObject);
}
else if (pvSearchObject instanceof Map) {
lvResult = cycleDetectionMap(pvRootObject, (Map) pvSearchObject);
}
return lvResult;
}
private boolean cycleDetectionIntern (Object pvRootObject, Iterator pvIterator) {
counter++;
boolean b = false;
if (counter < maxCounter) {
while (pvIterator.hasNext()) {
Object o = pvIterator.next();
if (pvRootObject == o) {
b = true;
break;
}
if (b == false) {
b = cycleDetection(pvRootObject, o);
}
}
}
return b;
}
}
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