/**
* Returns true if the constraint is associated with the given FromElement.
*
* @param constraint the constraint in question
* @param fromElement the FromElement to check
* @return true if associated
*/
public static boolean isRelatedTo(Constraint constraint, FromElement fromElement) {
if (isAssociatedWith(constraint, fromElement)) {
return true;
}
// also want to find out if this is referred to in a Contains or Subquery
// constraint that is associated with another fromElement.
if (constraint instanceof ContainsConstraint) {
if (fromElement == ((ContainsConstraint) constraint).getQueryClass()) {
return true;
}
} else if (constraint instanceof SubqueryConstraint) {
if (fromElement == ((SubqueryConstraint) constraint).getQuery()) {
return true;
}
} else if (constraint instanceof SimpleConstraint) {
SimpleConstraint sc = (SimpleConstraint) constraint;
Set<QueryField> qFields = getQueryFields(sc.getArg1());
qFields.addAll(getQueryFields(sc.getArg2()));
for (QueryField qf : qFields) {
if (fromElement == qf.getFromElement()) {
return true;
}
}
}
return false;
}
/**
* Returns true if the given constraint is related to no FromElement. This should only return true
* if c is a SimpleConstraint that only references constants.
*
* @param c the constraint to examine
* @return true if constraint is not associated with a FromElement
*/
public static boolean isRelatedToNothing(Constraint c) {
if (c instanceof SimpleConstraint) {
SimpleConstraint sc = (SimpleConstraint) c;
Set<QueryField> fields = getQueryFields(sc.getArg1());
fields.addAll(getQueryFields(sc.getArg2()));
if (fields.size() == 0) {
return true;
}
}
return false;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append('[').append('\n');
for (BaseConstraint bc : getBaseConstraints()) {
sb.append('{').append(bc.getSubVar()).append("} \u2286 ");
sb.append(bc.getSuperVar()).append('\n');
}
for (SimpleConstraint bc : getSimpleConstraints()) {
sb.append(bc.getSubVar()).append(" \u2286 ");
sb.append(bc.getSuperVar()).append('\n');
}
for (ComplexConstraint bc : getComplexConstraints()) {
sb.append(bc.getSubVar()).append(" \u2286 ");
sb.append(bc.getSuperVar()).append('\n');
}
int size =
getBaseConstraints().size()
+ getSimpleConstraints().size()
+ getComplexConstraints().size();
sb.append("] size-> ").append(size);
// points-to sets
sb.append('\n');
sb.append('[').append('\n');
Map<String, String[]> ptSet = getPointsToSets();
for (String key : ptSet.keySet()) {
sb.append(key).append(" -> {");
String[] vals = ptSet.get(key);
for (String val : vals) {
sb.append(val).append(',');
}
if (vals.length > 0) {
sb.setLength(sb.length() - 1);
}
sb.append('}').append('\n');
}
sb.append(']').append('\n');
return sb.toString();
}
/**
* Constructs the online graph for the analysis. Additionally an offline graph for HCD is
* constructed to speed up the computation of the dynamic transitive closure with it.
*
* @param bConstr List of all {@link BaseConstraint}s that should be considered.<br>
* A {@link BaseConstraint} leads to an entry in a nodes points-to set.
* @param sConstr List of all {@link SimpleConstraint}s that should be considered.<br>
* A {@link SimpleConstraint} represents an edge in the graph.
* @param cConstr List of all {@link ComplexConstraint}s that should be considered.<br>
* {@link ComplexConstraint}s are stored in nodes, so they can be accessed faster when
* computing the dynamic transitive closure.
* @param g The resulting graph. Should be empty.
*/
private static void buildGraph(
Set<BaseConstraint> bConstr,
Set<SimpleConstraint> sConstr,
Set<ComplexConstraint> cConstr,
DirectedGraph g) {
// HCD offline - build offline graph
List<List<String>> sccs = buildOfflineGraphAndFindSCCs(sConstr, cConstr);
// build online graph
for (BaseConstraint bc : bConstr) {
DirectedGraph.Node n = g.getNode(bc.getSuperVar());
n.addPointerTarget(bc.getSubVar());
}
for (SimpleConstraint sc : sConstr) {
DirectedGraph.Node src = g.getNode(sc.getSubVar());
DirectedGraph.Node dest = g.getNode(sc.getSuperVar());
g.addEdge(src, dest);
}
for (ComplexConstraint cc : cConstr) {
DirectedGraph.Node n;
if (cc.isSubDerefed()) {
n = g.getNode(cc.getSubVar());
n.complexConstrMeSub.add(cc.getSuperVar());
} else {
n = g.getNode(cc.getSuperVar());
n.complexConstrMeSuper.add(cc.getSubVar());
}
}
// for HCD
mergeOrMarkSCCs(g, sccs); // ... in online graph
}
/**
* Builds an offline graph for HCD and finds all SCCs in it.<br>
* For the offline version {@link BaseConstraint}s are not relevant and {@link SimpleConstraint}s
* and {@link ComplexConstraint}s represents an edge in graph.
*
* @param sConstr List of all {@link SimpleConstraint}s that should be considered.
* @param cConstr List of all {@link ComplexConstraint}s that should be considered.
* @return a list of all SCCs. One SCC is represented as a list of all variables it contains.
*/
private static List<List<String>> buildOfflineGraphAndFindSCCs(
Collection<SimpleConstraint> sConstr, Collection<ComplexConstraint> cConstr) {
HashSet<DirectedGraph.Node> workset = new HashSet<>();
DirectedGraph g = new DirectedGraph();
HashMap<DirectedGraph.Node, String> nodeStrMap = new HashMap<>();
for (SimpleConstraint sc : sConstr) {
String srcStr = sc.getSubVar();
String destStr = sc.getSuperVar();
DirectedGraph.Node src = g.getNode(srcStr);
DirectedGraph.Node dest = g.getNode(destStr);
g.addEdge(src, dest);
workset.add(src);
workset.add(dest);
nodeStrMap.put(src, srcStr);
nodeStrMap.put(dest, destStr);
}
for (ComplexConstraint cc : cConstr) {
String srcStr, destStr;
if (cc.isSubDerefed()) {
srcStr = '*' + cc.getSubVar();
destStr = cc.getSuperVar();
} else {
srcStr = cc.getSubVar();
destStr = '*' + cc.getSuperVar();
}
DirectedGraph.Node src = g.getNode(srcStr);
DirectedGraph.Node dest = g.getNode(destStr);
g.addEdge(src, dest);
workset.add(src);
workset.add(dest);
nodeStrMap.put(src, srcStr);
nodeStrMap.put(dest, destStr);
}
// find strongly-connected components (using tarjans linear algorithm)
int maxdfs = 1;
LinkedList<DirectedGraph.Node> stack = new LinkedList<>();
List<List<String>> sccs = new LinkedList<>();
while (!workset.isEmpty()) {
DirectedGraph.Node n = workset.iterator().next();
maxdfs = tarjan(maxdfs, n, workset, stack, nodeStrMap, sccs);
}
return sccs;
}
