package java_cup;

/** This class represents one row (corresponding to one machine state) of the 
 *  parse action table.
 */
public class parse_action_row {

    /*-----------------------------------------------------------*/
    /*--- Constructor(s) ----------------------------------------*/
    /*-----------------------------------------------------------*/

    /** Simple constructor.  Note: this should not be used until the number of
     *  terminals in the grammar has been established.
     */
    public parse_action_row() {
        /* make sure the size is set */
        if (_size <= 0) _size = terminal.number();

        /* allocate the array */
        under_term = new parse_action[size()];

        /* set each element to an error action */
        for (int i = 0; i < _size; i++)
            under_term[i] = new parse_action();
    }

    /*-----------------------------------------------------------*/
    /*--- (Access to) Static (Class) Variables ------------------*/
    /*-----------------------------------------------------------*/

    /** Number of columns (terminals) in every row. */
    protected static int _size = 0;

    /** Number of columns (terminals) in every row. */
    public static int size() {
        return _size;
    }

    //Hm Added clear  to clear all static fields
    public static void clear() {
        _size = 0;
        reduction_count = null;
    }

    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

    /** Table of reduction counts (reused by compute_default()). */
    protected static int reduction_count[] = null;

    /*-----------------------------------------------------------*/
    /*--- (Access to) Instance Variables ------------------------*/
    /*-----------------------------------------------------------*/

    /** Actual action entries for the row. */
    public parse_action under_term[];

    /*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/

    /** Default (reduce) action for this row.  -1 will represent default 
     *  of error. 
     */
    public int default_reduce;

    /*-----------------------------------------------------------*/
    /*--- General Methods ---------------------------------------*/
    /*-----------------------------------------------------------*/

    /** Compute the default (reduce) action for this row and store it in 
     *  default_reduce.  In the case of non-zero default we will have the 
     *  effect of replacing all errors by that reduction.  This may cause 
     *  us to do erroneous reduces, but will never cause us to shift past 
     *  the point of the error and never cause an incorrect parse.  -1 will 
     *  be used to encode the fact that no reduction can be used as a 
     *  default (in which case error will be used).
     */
    public void compute_default() {
        int i, prod, max_prod, max_red;

        /* if we haven't allocated the count table, do so now */
        if (reduction_count == null)
            reduction_count = new int[production.number()];

        /* clear the reduction count table and maximums */
        for (i = 0; i < production.number(); i++)
            reduction_count[i] = 0;
        max_prod = -1;
        max_red = 0;

        /* walk down the row and look at the reduces */
        for (i = 0; i < size(); i++)
            if (under_term[i].kind() == parse_action.REDUCE) {
                /* count the reduce in the proper production slot and keep the 
                   max up to date */
                prod = ((reduce_action) under_term[i]).reduce_with().index();
                reduction_count[prod]++;
                if (reduction_count[prod] > max_red) {
                    max_red = reduction_count[prod];
                    max_prod = prod;
                }
            }

        /* record the max as the default (or -1 for not found) */
        default_reduce = max_prod;
    }

    /*-----------------------------------------------------------*/

}
