parse_reduce_table.java

package java_cup ;


/**
 * This class represents the complete "reduce-goto" table of the parser. It has
 * one row for each state in the parse machines, and a column for each terminal
 * symbol. Each entry contains a state number to shift to as the last step of a
 * reduce.
 * 
 * @see java_cup.parse_reduce_row
 * @version last updated: 11/25/95
 * @author Scott Hudson
 */
public class parse_reduce_table
{
  /*-----------------------------------------------------------*/
  /*--- Constructor(s) ----------------------------------------*/
  /*-----------------------------------------------------------*/
  /**
   * Simple constructor. Note: all terminals, non-terminals, and productions
   * must already have been entered, and the viable prefix recognizer should
   * have been constructed before this is called.
   */
  public parse_reduce_table ( )
  {
    /* determine how many states we are working with */
    _num_states = lalr_state.number ( ) ;
    /* allocate the array and fill it in with empty rows */
    under_state = new parse_reduce_row [ _num_states ] ;
    for ( int i = 0 ; i < _num_states ; i ++ )
      under_state [ i ] = new parse_reduce_row ( ) ;
  }


  /*-----------------------------------------------------------*/
  /*--- (Access to) Instance Variables ------------------------*/
  /*-----------------------------------------------------------*/
  /** How many rows/states in the machine/table. */
  protected int _num_states ;


  /** How many rows/states in the machine/table. */
  public int num_states ( )
  {
    return _num_states ;
  }


  /* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . */
  /** Actual array of rows, one per state */
  public parse_reduce_row [ ] under_state ;


  /*-----------------------------------------------------------*/
  /*--- General Methods ---------------------------------------*/
  /*-----------------------------------------------------------*/
  /** Convert to a string. */
  public String toString ( )
  {
    String result ;
    lalr_state goto_st ;
    int cnt ;
    result = "-------- REDUCE_TABLE --------\n" ;
    for ( int row = 0 ; row < num_states ( ) ; row ++ )
    {
      result += "From state #" + row + "\n" ;
      cnt = 0 ;
      for ( int col = 0 ; col < parse_reduce_row.size ( ) ; col ++ )
      {
        /* pull out the table entry */
        goto_st = under_state [ row ].under_non_term [ col ] ;
        /* if it has action in it, print it */
        if ( goto_st != null )
        {
          result += " [non term " + col + "->" ;
          result += "state " + goto_st.index ( ) + "]" ;
          /* end the line after the 3rd one */
          cnt ++ ;
          if ( cnt == 3 )
          {
            result += "\n" ;
            cnt = 0 ;
          }
        }
      }
      /* finish the line if we haven't just done that */
      if ( cnt != 0 ) result += "\n" ;
    }
    result += "-----------------------------" ;
    return result ;
  }
  /*-----------------------------------------------------------*/
}