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package java_cup;
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/** This class represents one row (corresponding to one machine state) of the
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* parse action table.
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*/
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public class parse_action_row {
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/*-----------------------------------------------------------*/
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/*--- Constructor(s) ----------------------------------------*/
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/*-----------------------------------------------------------*/
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/** Simple constructor. Note: this should not be used until the number of
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* terminals in the grammar has been established.
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*/
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public parse_action_row()
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{
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/* make sure the size is set */
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if (_size <= 0 ) _size = terminal.number();
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/* allocate the array */
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under_term = new parse_action[size()];
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/* set each element to an error action */
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for (int i=0; i<_size; i++)
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under_term[i] = new parse_action();
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}
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/*-----------------------------------------------------------*/
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/*--- (Access to) Static (Class) Variables ------------------*/
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/*-----------------------------------------------------------*/
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/** Number of columns (terminals) in every row. */
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protected static int _size = 0;
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/** Number of columns (terminals) in every row. */
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public static int size() {return _size;}
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/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
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/** Table of reduction counts (reused by compute_default()). */
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protected static int reduction_count[] = null;
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/*-----------------------------------------------------------*/
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/*--- (Access to) Instance Variables ------------------------*/
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/*-----------------------------------------------------------*/
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/** Actual action entries for the row. */
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public parse_action under_term[];
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/*. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*/
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/** Default (reduce) action for this row. -1 will represent default
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* of error.
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*/
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public int default_reduce;
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/*-----------------------------------------------------------*/
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/*--- General Methods ---------------------------------------*/
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/*-----------------------------------------------------------*/
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/** Compute the default (reduce) action for this row and store it in
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* default_reduce. In the case of non-zero default we will have the
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* effect of replacing all errors by that reduction. This may cause
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* us to do erroneous reduces, but will never cause us to shift past
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* the point of the error and never cause an incorrect parse. -1 will
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* be used to encode the fact that no reduction can be used as a
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* default (in which case error will be used).
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*/
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public void compute_default()
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{
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int i, prod, max_prod, max_red;
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/* if we haven't allocated the count table, do so now */
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if (reduction_count == null)
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reduction_count = new int[production.number()];
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/* clear the reduction count table and maximums */
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for (i = 0; i < production.number(); i++)
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reduction_count[i] = 0;
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max_prod = -1;
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max_red = 0;
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/* walk down the row and look at the reduces */
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for (i = 0; i < size(); i++)
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if (under_term[i].kind() == parse_action.REDUCE)
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{
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/* count the reduce in the proper production slot and keep the
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max up to date */
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prod = ((reduce_action)under_term[i]).reduce_with().index();
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reduction_count[prod]++;
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if (reduction_count[prod] > max_red)
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{
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max_red = reduction_count[prod];
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max_prod = prod;
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}
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}
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/* record the max as the default (or -1 for not found) */
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default_reduce = max_prod;
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}
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/*-----------------------------------------------------------*/
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};
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