/*
* Since it is not allowed to reference `this' before the
* super type constructor has been called, we can not
* write `super(v,One(this))'
* Instead, we set the second argument first to `null', and
* set it to its proper value afterwards.
*/
public OnceTopDown(IVisitor v)
: base(v,null)
{
then = new One(this);
}
/*
* Since it is not allowed to reference `this' before the
* super type constructor has been called, we can not
* write `super(One(this),v)'
* Instead, we set the first argument first to `null', and
* set it to its proper value afterwards.
*/
public OnceBottomUp(IVisitor v)
: base(null,v)
{
first = new One(this);
}