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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.util.VBStyleCollection;
import java.util.List;
import java.util.Set;
public class GenericDominatorEngine {
private IGraph graph;
private VBStyleCollection<IGraphNode, IGraphNode> colOrderedIDoms = new VBStyleCollection<IGraphNode, IGraphNode>();
private Set<? extends IGraphNode> setRoots;
public GenericDominatorEngine(IGraph graph) {
this.graph = graph;
}
public void initialize() {
calcIDoms();
}
private void orderNodes() {
setRoots = graph.getRoots();
for (IGraphNode node : graph.getReversePostOrderList()) {
colOrderedIDoms.addWithKey(null, node);
}
}
private static IGraphNode getCommonIDom(IGraphNode node1, IGraphNode node2, VBStyleCollection<IGraphNode, IGraphNode> orderedIDoms) {
IGraphNode nodeOld;
if (node1 == null) {
return node2;
}
else if (node2 == null) {
return node1;
}
int index1 = orderedIDoms.getIndexByKey(node1);
int index2 = orderedIDoms.getIndexByKey(node2);
while (index1 != index2) {
if (index1 > index2) {
nodeOld = node1;
node1 = orderedIDoms.getWithKey(node1);
if (nodeOld == node1) { // no idom - root or merging point
return null;
}
index1 = orderedIDoms.getIndexByKey(node1);
}
else {
nodeOld = node2;
node2 = orderedIDoms.getWithKey(node2);
if (nodeOld == node2) { // no idom - root or merging point
return null;
}
index2 = orderedIDoms.getIndexByKey(node2);
}
}
return node1;
}
private void calcIDoms() {
orderNodes();
List<IGraphNode> lstNodes = colOrderedIDoms.getLstKeys();
while (true) {
boolean changed = false;
for (IGraphNode node : lstNodes) {
IGraphNode idom = null;
if (!setRoots.contains(node)) {
for (IGraphNode pred : node.getPredecessors()) {
if (colOrderedIDoms.getWithKey(pred) != null) {
idom = getCommonIDom(idom, pred, colOrderedIDoms);
if (idom == null) {
break; // no idom found: merging point of two trees
}
}
}
}
if (idom == null) {
idom = node;
}
IGraphNode oldidom = colOrderedIDoms.putWithKey(idom, node);
if (!idom.equals(oldidom)) { // oldidom is null iff the node is touched for the first time
changed = true;
}
}
if (!changed) {
break;
}
}
}
public VBStyleCollection<IGraphNode, IGraphNode> getOrderedIDoms() {
return colOrderedIDoms;
}
public boolean isDominator(IGraphNode node, IGraphNode dom) {
while (!node.equals(dom)) {
IGraphNode idom = colOrderedIDoms.getWithKey(node);
if (idom == node) {
return false; // root node or merging point
}
else if (idom == null) {
throw new RuntimeException("Inconsistent idom sequence discovered!");
}
else {
node = idom;
}
}
return true;
}
}
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