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;
	}

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

}
