content: package java_cup;
  
  /** This class represents one part (either a symbol or an action) of a 
   *  production.  In this base class it contains only an optional label 
   *  string that the user can use to refer to the part within actions.<p>
   *
   *  This is an abstract class.
   *
   * @see     java_cup.production
   * @version last updated: 11/25/95
   * @author  Scott Hudson
   */
  public abstract class production_part {
  
    /*-----------------------------------------------------------*/
    /*--- Constructor(s) ----------------------------------------*/
    /*-----------------------------------------------------------*/
         
    /** Simple constructor. */
    public production_part(String lab)
      {
        _label = lab;
      }
  
    /*-----------------------------------------------------------*/
    /*--- (Access to) Instance Variables ------------------------*/
    /*-----------------------------------------------------------*/
         
    /** Optional label for referring to the part within an action (null for 
     *  no label). 
     */
    protected String _label;
  
    /** Optional label for referring to the part within an action (null for 
     *  no label). 
     */
    public String label() {return _label;}
  
    /*-----------------------------------------------------------*/
    /*--- General Methods ---------------------------------------*/
    /*-----------------------------------------------------------*/
         
    /** Indicate if this is an action (rather than a symbol).  Here in the 
     * base class, we don't this know yet, so its an abstract method.
     */
    public abstract boolean is_action();
  
    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
  
    /** Equality comparison. */
    public boolean equals(production_part other)
      {
        if (other == null) return false;
  
        /* compare the labels */
        if (label() != null)
  	return label().equals(other.label());
        else
  	return other.label() == null;
      }
  
    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
  
    /** Generic equality comparison. */
    public boolean equals(Object other)
      {
        if (!(other instanceof production_part))
          return false;
        else
  	return equals((production_part)other);
      }
  
    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
  
    /** Produce a hash code. */
    public int hashCode()
      {
        return label()==null ? 0 : label().hashCode();
      }
  
    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
  
    /** Convert to a string. */
    public String toString()
      {
        if (label() != null)
  	return label() + ":";
        else
  	return " ";
      }
  
    /*-----------------------------------------------------------*/
  
  }
  