public Relation ResolveRelation(Relation r, Stack <Constraint> visited, Relation parent)
{
/// NOTES: It may become neccessary to resolve in stages, first resolve variables, then
/// resolve relations. This would make it easier to catch variables which are just
/// aliases for each other. I am not sure at this point, whether such a condition
/// could arise. I may alternatively choose to simply rename all generics, but that
/// would have a significant computational cost.
r.SetParent(parent);
r.GetNonGenericsForChildren().AddRange(r.GetAllVarNames());
Vector vLeft = new Vector();
Vector vRight = new Vector();
VarNameList allVars = new VarNameList();
VarNameList topVars = new VarNameList();
foreach (Constraint c in r.GetLeft())
{
vLeft.Add(ResolveRelationConstraint(c, visited, r, topVars, allVars));
}
foreach (Constraint c in r.GetRight())
{
vRight.Add(ResolveRelationConstraint(c, visited, r, topVars, allVars));
}
Relation ret = new Relation(vLeft, vRight);
// Make sure we set the parent for the newly created relation as well
ret.SetParent(parent);
Log("Resolved relation " + r.ToString());
Log("to " + ret.ToString());
Log("non-generics = " + r.GetNonGenericsForChildren());
return(ret);
}
public Constraint ResolveRelationConstraint(Constraint c, Stack <Constraint> visited,
Relation parent, VarNameList topVars, VarNameList allVars)
{
VarNameList nonGenerics = parent.GetNonGenericsForChildren();
if (c is Var)
{
Var v = c as Var;
Constraint u = Resolve(v, visited, parent);
if (u is Relation)
{
Relation r = u as Relation;
// Make sure we don't add variables to the non-generics
// list which occured in a duplicate.
if (!topVars.Contains(v))
{
VarNameList subVars = r.GetAllVarNames();
foreach (string s in subVars)
{
if (allVars.Contains(s))
{
nonGenerics.Add(s);
}
}
allVars.AddRange(subVars);
}
else
{
Log("duplicate of variable " + v.ToString() + ", with unifier " + r.ToString());
QueueForRenamingOfGenerics(r);
}
}
else if (u is Var)
{
nonGenerics.Add(u as Var);
}
topVars.Add(v);
return(u);
}
else
{
Constraint u = Resolve(c, visited, parent);
// non-vars should not resolve to vars
Trace.Assert(!(u is Var));
if (u is Relation)
{
Relation r = u as Relation;
VarNameList subVars = r.GetAllVarNames();
foreach (string s in subVars)
{
if (allVars.Contains(s))
{
nonGenerics.Add(s);
}
}
allVars.AddRange(subVars);
}
return(u);
}
}
