public class SymTable
  {
  private int currentLevel = -1;
  private Entry last;
  
  public void openScope() { currentLevel++; }
  
  // Dumps all entries at the current level.
  public void closeScope()
    {
    Entry e = last;
    while (e != null && e.level == currentLevel) e = e.prev;
    last = e;
    currentLevel--;
    }
  
  // Adds a new Entry to our list.
  public void enter(String spelling, Node node, int type)
    {
    Entry e = new Entry(spelling, node, type, currentLevel);
    e.prev = last;
    last = e;
    }

  public void enter(String spelling, Node node, int type, int returntype)
    {
    Entry e = new Entry(spelling, node, type, currentLevel, returntype);
    e.prev = last;
    last = e;
    }

  
  // Looks for and returns an Entry whose name is same as spelling.
  public Entry lookup(String spelling)
    {
    for (Entry e = last; e != null; e = e.prev)
      if (spelling.compareTo(e.spelling) == 0)
        return e;
    return null;
    }
  
  public String toString()
    {
    String result = "";
    for (Entry e = last; e != null; e = e.prev) result += e;
    return result;
    }
  }