public HashSet<GeneratorNode> spawn(FOExists op)
{
HashSet<GeneratorNode> outSet = new HashSet<GeneratorNode>();
Atom x = op.getQuantifiedVariable();
string qualifier = op.getQualifier();
if (m_encounteredQualifiers.Contains(qualifier))
{
// We add something along a path where a ForAll has already
// been evaluated: soundness is no longer guaranteed for this node
m_sound = false;
}
if (op.isAnOPlus())
{
// This is an OPlus; return a node with op transferred to the OPlus set
GeneratorNode wn = new GeneratorNode(this);
if (!wn.addToOPluses(op.toOPlus()))
{
// We can't add this OPlus to the current set. Contradiction! Return the empty set
return new HashSet<GeneratorNode>();
}
return wn.spawn();
}
if (op.isPathAssertion())
{
GeneratorNode wn = new GeneratorNode();
OPlus opl = new OPlus();
opl.setQualifier(op.getQualifier());
opl.setOperand(Operator.m_trueAtom);
if (!wn.addToOPluses(opl))
{
// We can't add this OPlus to the current set. Contradiction! Return the empty set
return new HashSet<GeneratorNode>();
}
return wn.spawn();
}
// Iterate over domain
//HashSet<Constant> oplus_domain = getOPlusDomain(qualifier);
HashSet<Constant> domain = op.getDomain();
SubsetIterator<Constant> it = new SubsetIterator<Constant>(domain); //,oplus_domain
while (it.hasNext())
{
GeneratorNode wn = new GeneratorNode(this);
HashSet<Constant> subset = it.next();
foreach (Atom v in subset)
{
Operator o2 = op .getOperand();
Operator o3 = o2.evaluate(x, v);
if (!op.isPathAssertion())
{
wn.addToGamma(o3);
}
OPlus opl = new OPlus(qualifier, v);
if (!wn.addToOPluses(opl))
{
// We can't add this OPlus to the current set. Contradiction! Skip that branch
continue;
}
}
HashSet<GeneratorNode> spawnedSet = wn.spawn();
if (spawnedSet != null)
{
foreach (GeneratorNode gn in spawnedSet)
{
outSet.Add(gn);
}
}
}
return outSet;
}
