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/*
* Copyright 2000-2014 JetBrains s.r.o.
*
* 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.jetbrains.java.decompiler.modules.decompiler.decompose;
import org.jetbrains.java.decompiler.modules.decompiler.StatEdge;
import org.jetbrains.java.decompiler.modules.decompiler.stats.Statement;
import org.jetbrains.java.decompiler.util.VBStyleCollection;
import java.util.List;
public class DominatorEngine {
private Statement statement;
private VBStyleCollection<Integer, Integer> colOrderedIDoms = new VBStyleCollection<Integer, Integer>();
public DominatorEngine(Statement statement) {
this.statement = statement;
}
public void initialize() {
calcIDoms();
}
private void orderStatements() {
for (Statement stat : statement.getReversePostOrderList()) {
colOrderedIDoms.addWithKey(null, stat.id);
}
}
private static Integer getCommonIDom(Integer key1, Integer key2, VBStyleCollection<Integer, Integer> orderedIDoms) {
if (key1 == null) {
return key2;
}
else if (key2 == null) {
return key1;
}
int index1 = orderedIDoms.getIndexByKey(key1);
int index2 = orderedIDoms.getIndexByKey(key2);
while (index1 != index2) {
if (index1 > index2) {
key1 = orderedIDoms.getWithKey(key1);
index1 = orderedIDoms.getIndexByKey(key1);
}
else {
key2 = orderedIDoms.getWithKey(key2);
index2 = orderedIDoms.getIndexByKey(key2);
}
}
return key1;
}
private void calcIDoms() {
orderStatements();
colOrderedIDoms.putWithKey(statement.getFirst().id, statement.getFirst().id);
// exclude first statement
List<Integer> lstIds = colOrderedIDoms.getLstKeys().subList(1, colOrderedIDoms.getLstKeys().size());
while (true) {
boolean changed = false;
for (Integer id : lstIds) {
Statement stat = statement.getStats().getWithKey(id);
Integer idom = null;
for (StatEdge edge : stat.getAllPredecessorEdges()) {
if (colOrderedIDoms.getWithKey(edge.getSource().id) != null) {
idom = getCommonIDom(idom, edge.getSource().id, colOrderedIDoms);
}
}
Integer oldidom = colOrderedIDoms.putWithKey(idom, id);
if (!idom.equals(oldidom)) {
changed = true;
}
}
if (!changed) {
break;
}
}
}
public VBStyleCollection<Integer, Integer> getOrderedIDoms() {
return colOrderedIDoms;
}
public boolean isDominator(Integer node, Integer dom) {
while (!node.equals(dom)) {
Integer idom = colOrderedIDoms.getWithKey(node);
if (idom.equals(node)) {
return false; // root node
}
else {
node = idom;
}
}
return true;
}
}
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