parse_action.java

package java_cup ;


/**
 * This class serves as the base class for entries in a parse action table. Full
 * entries will either be SHIFT(state_num), REDUCE(production), NONASSOC, or
 * ERROR. Objects of this base class will default to ERROR, while the other
 * three types will be represented by subclasses.
 * 
 * @see java_cup.reduce_action
 * @see java_cup.shift_action
 * @version last updated: 7/2/96
 * @author Frank Flannery
 */
public class parse_action
{
  /*-----------------------------------------------------------*/
  /*--- Constructor(s) ----------------------------------------*/
  /*-----------------------------------------------------------*/
  /** Simple constructor. */
  public parse_action ( )
  {
    /* nothing to do in the base class */
  }


  /*-----------------------------------------------------------*/
  /*--- (Access to) Static (Class) Variables ------------------*/
  /*-----------------------------------------------------------*/
  /** Constant for action type -- error action. */
  public static final int ERROR = 0 ;


  /* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
  /** Constant for action type -- shift action. */
  public static final int SHIFT = 1 ;


  /* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
  /** Constants for action type -- reduce action. */
  public static final int REDUCE = 2 ;


  /* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
  /** Constants for action type -- reduce action. */
  public static final int NONASSOC = 3 ;


  /*-----------------------------------------------------------*/
  /*--- General Methods ---------------------------------------*/
  /*-----------------------------------------------------------*/
  /** Quick access to the type -- base class defaults to error. */
  public int kind ( )
  {
    return ERROR ;
  }


  /* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
  /** Equality test. */
  public boolean equals ( parse_action other )
  {
    /* we match all error actions */
    return other != null && other.kind ( ) == ERROR ;
  }


  /* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
  /** Generic equality test. */
  public boolean equals ( Object other )
  {
    if ( other instanceof parse_action )
      return equals ( ( parse_action ) other ) ;
    else return false ;
  }


  /* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
  /** Compute a hash code. */
  public int hashCode ( )
  {
    /* all objects of this class hash together */
    return 0xCafe123 ;
  }


  /* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
  /** Convert to string. */
  public String toString ( )
  {
    return "ERROR" ;
  }
  /*-----------------------------------------------------------*/
}