production_part.java

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 " " ;
  }
  /*-----------------------------------------------------------*/
}