public Expression CreateSequence(Expression exp1, Expression exp2)
{
if (exp1 == Expression.Empty)
{
return(exp2);
}
if (exp2 == Expression.Empty)
{
return(exp1);
}
if (exp1 == Expression.NotAllowed || exp2 == Expression.NotAllowed)
{
return(Expression.NotAllowed);
}
if (exp2 is GroupExp)
{
// operators are left-associative.
GroupExp right = (GroupExp)exp2;
return(CreateSequence(CreateSequence(exp1, right.exp1), right.exp2));
}
return(Unify(new GroupExp(exp1, exp2)));
}
public void OnGroup(GroupExp exp)
{
OnBinExp(exp, ",");
}
