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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.tuscany.sca.implementation.guardian.common;
import java.util.Collections;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import org.apache.axiom.om.OMAttribute;
import org.apache.axiom.om.OMElement;
public class ResolutionTreeUtils {
//E: Euler tour of the tree obtained by listing the nodes visited in a depth first search of the tree starting from the root. Contains 2n-1 elements
private List<String> eulerTour;
//L: Array of level numbers such that L[i] contains the tree-depth of the node E[i]. Contains 2n-1 elements
private List<Integer> levels;
//R: Map of size n such that R<K> contains the index of the first ocurrence of node 'K' in E
private Map<String, Integer> rMap;
private OMElement root;
private int treeSize;
public ResolutionTreeUtils() {
init(null);
}
public ResolutionTreeUtils(OMElement root) {
init(root);
}
public void setRoot(OMElement root) {
init(root);
}
public List<String> getEulerTourDepthFirstSearch() {
if (root == null) {
throw new NullPointerException("The root musn't be null");
}
if (eulerTour == null) {
eulerTour = new LinkedList<String>();
levels = new LinkedList<Integer>();
eulerTourDFSRecursive(root, 0);
}
return eulerTour;
}
public String getLowestCommonAncestor(String node1, String node2) {
String lca = null;
Integer indexNode1, indexNode2;
Map<String, Integer> r = getRMap();
indexNode1 = r.get(node1);
indexNode2 = r.get(node2);
//Check nodes existence
if (indexNode1 == null && indexNode2 == null) {
throw new InvalidNodeException("Could not find the specified nodes: " + node1 + " and " + node2);
} else if (indexNode1 == null) {
throw new InvalidNodeException("Could not find the specified nodes: " + node1);
} else if (indexNode2 == null) {
throw new InvalidNodeException("Could not find the specified nodes: " + node2);
}
int indexLCA;
if (indexNode1 < indexNode2) {
indexLCA = getRangeMinimumQuery(levels, indexNode1, indexNode2);
} else {
indexLCA = getRangeMinimumQuery(levels, indexNode2, indexNode1);
}
lca = eulerTour.get(indexLCA);
return lca;
}
//Get the index of the smallest element between beginIndex and endIndex (both inclusive) in the list
private int getRangeMinimumQuery(List list, int beginIndex, int endIndex) {
List sublist = list.subList(beginIndex, endIndex + 1);
Object elem = Collections.min(sublist);
return sublist.indexOf(elem) + beginIndex;
}
private void init(OMElement root) {
this.root = root;
eulerTour = null;
levels = null;
rMap = null;
treeSize = 0;
}
private void eulerTourDFSRecursive(OMElement node, int level) {
String classAttribute = ((OMAttribute) node.getAllAttributes().next()).getAttributeValue();
eulerTour.add(classAttribute);
levels.add(level);
treeSize++;
Iterator children = node.getChildElements();
OMElement child;
while (children.hasNext()) {
child = (OMElement) children.next();
eulerTourDFSRecursive(child, level + 1);
eulerTour.add(classAttribute);
levels.add(level);
}
}
private Map<String, Integer> getRMap() {
if (rMap == null) {
rMap = new Hashtable<String, Integer>();
List<String> tour = getEulerTourDepthFirstSearch();
for (int i = 0; i < tour.size(); i++) {
String key = tour.get(i);
if (!rMap.containsKey(key)) {
rMap.put(key, i);
}
if (rMap.size() == treeSize) {
break;
}
}
}
return rMap;
}
}
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