package java_cup;

import java.util.Enumeration;

/** This class represents the complete "action" table of the parser. 
 *  It has one row for each state in the parse machine, and a column for
 *  each terminal symbol.  Each entry in the table represents a shift,
 *  reduce, or an error.  
 *
 * @see     java_cup.parse_action
 * @see     java_cup.parse_action_row
 * @version last updated: 11/25/95
 * @author  Scott Hudson
 */
public class parse_action_table {

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

	/** Simple constructor.  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_action_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_action_row[_num_states];
		for (int i = 0; i < _num_states; i++)
			under_state[i] = new parse_action_row();
	}

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

	/** How many rows/states are in the machine/table. */
	protected int _num_states;

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

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

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

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

	/** Check the table to ensure that all productions have been reduced. 
	 *  Issue a warning message (to System.err) for each production that
	 *  is never reduced.
	 */
	public void check_reductions()
			throws internal_error
	{
		parse_action act;
		production prod;

		/* tabulate reductions -- look at every table entry */
		for (int row = 0; row < num_states(); row++)
		{
			for (int col = 0; col < parse_action_row.size(); col++)
			{
				/* look at the action entry to see if its a reduce */
				act = under_state[row].under_term[col];
				if (act != null && act.kind() == parse_action.REDUCE)
				{
					/* tell production that we used it */
					((reduce_action) act).reduce_with().note_reduction_use();
				}
			}
		}

		/* now go across every production and make sure we hit it */
		for (Enumeration p = production.all(); p.hasMoreElements();)
		{
			prod = (production) p.nextElement();

			/* if we didn't hit it give a warning */
			if (prod.num_reductions() == 0)
			{
				/* count it *
				emit.not_reduced++;

				/* give a warning if they haven't been turned off */
				if (!emit.nowarn)
				{

					ErrorManager.getManager().emit_warning("*** Production \"" +
							prod.to_simple_string() + "\" never reduced");
				}
			}
		}
	}

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

	/** Convert to a string. */
	public String toString()
	{
		String result;
		int cnt;

		result = "-------- ACTION_TABLE --------\n";
		for (int row = 0; row < num_states(); row++)
		{
			result += "From state #" + row + "\n";
			cnt = 0;
			for (int col = 0; col < parse_action_row.size(); col++)
			{
				/* if the action is not an error print it */
				if (under_state[row].under_term[col].kind() != parse_action.ERROR)
				{
					result += " [term " + col + ":" + under_state[row].under_term[col] + "]";

					/* end the line after the 2nd one */
					cnt++;
					if (cnt == 2)
					{
						result += "\n";
						cnt = 0;
					}
				}
			}
			/* finish the line if we haven't just done that */
			if (cnt != 0)
				result += "\n";
		}
		result += "------------------------------";

		return result;
	}

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

}
