/* Soot - a J*va Optimization Framework
* Copyright (C) 2003 Navindra Umanee <navindra@cs.mcgill.ca>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
package soot.toolkits.graph;
import java.util.*;
/**
* Constructs a dominator tree structure from the given
* DominatorsFinder. The nodes in DominatorTree are of type
* DominatorNode.
*
* <p>
*
* Note: DominatorTree does not currently implement DirectedGraph
* since it provides 4 methods of navigating the nodes where the
* meaning of getPredsOf and getSuccsOf diverge from the usual meaning
* in a DirectedGraph implementation.
*
* <p>
*
* If you need a DirectedGraph implementation, see DominatorTreeAdapter.
*
* @author Navindra Umanee
**/
public class DominatorTree
{
protected DominatorsFinder dominators;
protected DirectedGraph graph;
protected DominatorNode head;
protected ArrayList tails;
/**
* "gode" is a node in the original graph, "dode" is a node in the
* dominator tree.
**/
protected HashMap godeToDode;
public DominatorTree(DominatorsFinder dominators)
{
// if(Options.v().verbose())
// G.v().out.println("[" + graph.getBody().getMethod().getName() +
// "] Constructing DominatorTree...");
this.dominators = dominators;
this.graph = dominators.getGraph();
head = null;
tails = new ArrayList();
godeToDode = new HashMap();
buildTree();
}
/**
* Returns the original graph to which the Dominator tree
* pertains.
**/
public DirectedGraph getGraph()
{
return dominators.getGraph();
}
/**
* Returns the root of the dominator tree.
**/
public DominatorNode getHead()
{
return head;
}
/**
* Returns a list of the tails of the dominator tree.
**/
public List getTails()
{
return (List) tails.clone();
}
/**
* Returns the parent of node in the tree, null if the node is at
* the root.
**/
public DominatorNode getParentOf(DominatorNode node)
{
return node.getParent();
}
/**
* Returns the children of node in the tree.
**/
public List getChildrenOf(DominatorNode node)
{
return (List)((ArrayList)node.getChildren()).clone();
}
/**
* Finds all the predecessors of node in the original
* DirectedGraph and returns a list of the corresponding
* DominatorNodes.
**/
public List<DominatorNode> getPredsOf(DominatorNode node)
{
List preds = graph.getPredsOf(node.getGode());
List<DominatorNode> predNodes = new ArrayList<DominatorNode>();
for(Iterator predsIt = preds.iterator(); predsIt.hasNext();){
Object pred = predsIt.next();
predNodes.add(getDode(pred));
}
return predNodes;
}
/**
* Finds all the successors of node in the original DirectedGraph
* and returns a list of the corresponding DominatorNodes.
**/
public List<DominatorNode> getSuccsOf(DominatorNode node)
{
List succs = graph.getSuccsOf(node.getGode());
List<DominatorNode> succNodes = new ArrayList<DominatorNode>();
for(Iterator succsIt = succs.iterator(); succsIt.hasNext();){
Object succ = succsIt.next();
succNodes.add(getDode(succ));
}
return succNodes;
}
/**
* Returns true if idom immediately dominates node.
**/
public boolean isImmediateDominatorOf(DominatorNode idom, DominatorNode node)
{
// node.getParent() could be null
return (node.getParent() == idom);
}
/**
* Returns true if dom dominates node.
**/
public boolean isDominatorOf(DominatorNode dom, DominatorNode node)
{
return dominators.isDominatedBy(node.getGode(), dom.getGode());
}
/**
* Returns the DominatorNode for a given node in the original
* DirectedGraph.
**/
public DominatorNode getDode(Object gode)
{
DominatorNode dode = (DominatorNode) godeToDode.get(gode);
if(dode == null)
throw new RuntimeException("Assertion failed: Dominator tree does not have a corresponding dode for gode (" + gode + ")");
return dode;
}
/**
* Returns an iterator over the nodes in the tree. No ordering is
* implied.
**/
public Iterator iterator()
{
return godeToDode.values().iterator();
}
/**
* Returns the number of nodes in the tree.
**/
public int size()
{
return godeToDode.size();
}
/**
* Add all the necessary links between nodes to form a meaningful
* tree structure.
**/
protected void buildTree()
{
// hook up children with parents and vice-versa
{
for(Iterator godesIt = graph.iterator(); godesIt.hasNext();){
Object gode = godesIt.next();
DominatorNode dode = fetchDode(gode);
DominatorNode parent = fetchParent(gode);
if(parent == null){
if(head != null)
throw new RuntimeException("Assertion failed.");
head = dode;
}
else{
parent.addChild(dode);
dode.setParent(parent);
}
}
}
// identify the tail nodes
{
for(Iterator dodesIt = this.iterator(); dodesIt.hasNext();){
DominatorNode dode = (DominatorNode) dodesIt.next();
if(dode.isTail())
tails.add(dode);
}
}
}
/**
* Convenience method, ensures we don't create more than one
* DominatorNode for a given block.
**/
protected DominatorNode fetchDode(Object gode)
{
DominatorNode dode;
if(godeToDode.containsKey(gode)){
dode = (DominatorNode) godeToDode.get(gode);
}
else{
dode = new DominatorNode(gode);
godeToDode.put(gode, dode);
}
return dode;
}
protected DominatorNode fetchParent(Object gode)
{
Object immediateDominator = dominators.getImmediateDominator(gode);
if(immediateDominator == null)
return null;
return fetchDode(immediateDominator);
}
}