content: package java_cup;
  
  /** This abstract class serves as the base class for grammar symbols (i.e.,
   * both terminals and non-terminals).  Each symbol has a name string, and
   * a string giving the type of object that the symbol will be represented by
   * on the runtime parse stack.  In addition, each symbol maintains a use count
   * in order to detect symbols that are declared but never used, and an index
   * number that indicates where it appears in parse tables (index numbers are
   * unique within terminals or non terminals, but not across both).
   *
   * @see     java_cup.terminal
   * @see     java_cup.non_terminal
   * @version last updated: 7/3/96
   * @author  Frank Flannery
   */
  public abstract class symbol {
     /*-----------------------------------------------------------*/
     /*--- Constructor(s) ----------------------------------------*/
     /*-----------------------------------------------------------*/
  
     /** Full constructor.
      * @param nm the name of the symbol.
      * @param tp a string with the type name.
      */
     public symbol(String nm, String tp)
       {
         /* sanity check */
         if (nm == null) nm = "";
  
         /* apply default if no type given */
         if (tp == null) tp = "Object";
  
         _name = nm;
         _stack_type = tp;
       }
  
    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
  
     /** Constructor with default type. 
      * @param nm the name of the symbol.
      */
     public symbol(String nm)
       {
         this(nm, null);
       }
  
     /*-----------------------------------------------------------*/
     /*--- (Access to) Instance Variables ------------------------*/
     /*-----------------------------------------------------------*/
  
     /** String for the human readable name of the symbol. */
     protected String _name; 
   
     /** String for the human readable name of the symbol. */
     public String name() {return _name;}
  
    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
  
     /** String for the type of object used for the symbol on the parse stack. */
     protected String _stack_type;
  
     /** String for the type of object used for the symbol on the parse stack. */
     public String stack_type() {return _stack_type;}
  
    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
  
     /** Count of how many times the symbol appears in productions. */
     protected int _use_count = 0;
  
     /** Count of how many times the symbol appears in productions. */
     public int use_count() {return _use_count;}
  
     /** Increment the use count. */ 
     public void note_use() {_use_count++;}
   
    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
   
    /** Index of this symbol (terminal or non terminal) in the parse tables.
     *  Note: indexes are unique among terminals and unique among non terminals,
     *  however, a terminal may have the same index as a non-terminal, etc. 
     */
     protected int _index;
   
    /** Index of this symbol (terminal or non terminal) in the parse tables.
     *  Note: indexes are unique among terminals and unique among non terminals,
     *  however, a terminal may have the same index as a non-terminal, etc. 
     */
     public int index() {return _index;}
  
    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
  
    /** Indicate if this is a non-terminal.  Here in the base class we
     *  don't know, so this is abstract.  
     */
    public abstract boolean is_non_term();
  
    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
  
    /** Convert to a string. */
    public String toString()
      {
        return name();
      }
  
    /*-----------------------------------------------------------*/
  
  }
  