public override Expr VisitOldExpr(OldExpr node) {
Set freeVars = new Set();
node.Expr.ComputeFreeVariables(freeVars);
foreach (var v in freeVars) {
// Note, "v" is either a Variable or a TypeVariable
if (v is Variable) {
FreeOldVars.Add((Variable)v);
}
}
return node; // don't visit subexpressions, since ComputeFreeVariables has already gone through those
}
public static GSet <T> /*!*/ Filter(GSet <T> /*!*/ a, Func <T, bool> filter)
{
Contract.Requires(filter != null);
Contract.Requires(a != null);
Contract.Ensures(Contract.Result <GSet <T> >() != null);
GSet <T> inter = new GSet <T>();
foreach (T elem in a)
{
Contract.Assert(elem != null);
if (filter(elem))
{
inter.Add(elem);
}
}
return(inter);
}