/*
  Macro tables are organized into a tree. Look up of a macro name
  starts with a specified macro table, working its way back up the
  path to the root table.
*/

MacroTable {
(@
  // map macro name to its definition
  private Hashtable def_;
  private MacroTable parent_;
@)
  init (@
    def_ = new Hashtable();
    parent_ = null;
  @)
(@
  MacroTable(MacroTable parent) {
    this();
    parent_ = parent;
  }
  MacroTable parent() {
    return parent_;
  }
  void define(String name, String value){
    def_.put(name,value);
  }
  String getValue(String name){
    String result = (String)def_.get(name);
    if(result == null && parent_ != null)
      result = parent_.getValue(name);
    return result;
  }
  Enumeration keys(){
    return new MacroTableKeyEnumeration(this);
  }
  Enumeration currentKeys(){
    return def_.keys();
  }
  void display(){
    Enumeration itr = keys();
    System.out.println("MacroTable - start");
    while(itr.hasMoreElements()){
      String name = (String)(itr.nextElement());
      String value = getValue(name);
      System.out.println("name="+name+", value="+value);
    }
    System.out.println("MacroTable - end");
  }
@)
}
MacroTableKeyEnumeration{
(@
   private MacroTable table_ = null;
   private Enumeration itr_ = null;

   MacroTableKeyEnumeration(MacroTable table){
     itr_ = table.currentKeys();
     table_ = table.parent();
   }

   public boolean hasMoreElements(){
     if(itr_ == null)
       return false;
     boolean result = itr_.hasMoreElements();
     while( result == false && itr_ != null){
       if(table_ == null){
         itr_ = null;
         result = false;
       }
       else{
         itr_ = table_.currentKeys();
         table_ = table_.parent();
         result = itr_.hasMoreElements();
       }
     }
     return result;
   }
   public Object nextElement(){
     return itr_.nextElement();
   }
@)
}