package nl.bluering;
import java.util.*;

public class Vertical
{
 Stack s=new Stack();
 String name;
 
 Vertical(String name)
 {this.name=name;
 }
 Variable newlocal()
 {
  return newlocal(new Variable(name));
 }
 Variable newlocal(Variable v)
 {s.push(v);
  return v;
 }
 Variable goodbye()
 {
  if(canget())
   return (Variable)s.pop();
  return null;
 }
 
 Variable set(Variable e)
 {s.pop();
  s.push(e); 
  return e;
 }
 Variable get()
 {
  if(canget())
   return (Variable)s.peek();
  return null;
 }
 boolean canget()
 {return s.size()>0;
 }
 String getname()
 {return name;
 }
 public String toString()
 {
  return name;
 }
 
 
}