/*******************************************************************************
* Copyright (c) 2006 IBM Corporation.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package com.ibm.wala.dataflow.IFDS;
import java.util.Collection;
import java.util.Iterator;
import com.ibm.wala.util.MonitorUtil.IProgressMonitor;
import com.ibm.wala.util.collections.HashSetFactory;
import com.ibm.wala.util.collections.Pair;
import com.ibm.wala.util.debug.Assertions;
import com.ibm.wala.util.intset.IntIterator;
import com.ibm.wala.util.intset.IntSet;
/**
* Utilities for dealing with tabulation with partially balanced parentheses.
*
* @param <T> type of node in the supergraph
* @param <P> type of a procedure (like a box in an RSM)
* @param <F> type of factoids propagated when solving this problem
*/
public class PartiallyBalancedTabulationSolver<T, P, F> extends TabulationSolver<T, P, F> {
public static <T, P, F> PartiallyBalancedTabulationSolver<T, P, F> createPartiallyBalancedTabulationSolver(
PartiallyBalancedTabulationProblem<T, P, F> p, IProgressMonitor monitor) {
return new PartiallyBalancedTabulationSolver<T, P, F>(p, monitor);
}
private final Collection<Pair<T,Integer>> unbalancedSeeds = HashSetFactory.make();
protected PartiallyBalancedTabulationSolver(PartiallyBalancedTabulationProblem<T, P, F> p, IProgressMonitor monitor) {
super(p, monitor);
}
@Override
protected boolean propagate(T s_p, int i, T n, int j) {
boolean result = super.propagate(s_p, i, n, j);
if (result && wasUsedAsUnbalancedSeed(s_p, i) && supergraph.isExit(n)) {
// j was reached from an entry seed. if there are any facts which are reachable from j, even without
// balanced parentheses, we can use these as new seeds.
for (Iterator<? extends T> it2 = supergraph.getSuccNodes(n); it2.hasNext();) {
T retSite = it2.next();
PartiallyBalancedTabulationProblem<T, P, F> problem = (PartiallyBalancedTabulationProblem<T, P, F>) getProblem();
IFlowFunction f = problem.getFunctionMap().getUnbalancedReturnFlowFunction(n, retSite);
// for each fact that can be reached by the return flow ...
if (f instanceof IUnaryFlowFunction) {
IUnaryFlowFunction uf = (IUnaryFlowFunction) f;
IntSet facts = uf.getTargets(j);
if (facts != null) {
for (IntIterator it4 = facts.intIterator(); it4.hasNext();) {
int d3 = it4.next();
// d3 would be reached if we ignored parentheses. use it as a new seed.
T fakeEntry = problem.getFakeEntry(retSite);
PathEdge<T> seed = PathEdge.createPathEdge(fakeEntry, d3, retSite, d3);
addSeed(seed);
}
}
} else {
Assertions.UNREACHABLE("Partially balanced logic not supported for binary return flow functions");
}
}
}
return result;
}
@Override
public void addSeed(PathEdge<T> seed) {
if (getSeeds().contains(seed)) {
return;
}
unbalancedSeeds.add(Pair.make(seed.entry, seed.d1));
super.addSeed(seed);
}
/**
* Was the fact number i named at node s_p introduced as an "unbalanced" seed during partial tabulation?
* If so, any facts "reached" from here can be further propagated with unbalanced parens.
*/
private boolean wasUsedAsUnbalancedSeed(T s_p, int i) {
return unbalancedSeeds.contains(Pair.make(s_p, i));
}
}