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java_cup::production::production ( non_terminal  lhs_sym,
production_part  rhs_parts[],
int  rhs_l,
String  action_str 
) throws internal_error [inline]

Full constructor. This constructor accepts a LHS non terminal, an array of RHS parts (including terminals, non terminals, and actions), and a string for a final reduce action. It does several manipulations in the process of creating a production object. After some validity checking it translates labels that appear in actions into code for accessing objects on the runtime parse stack. It them merges adjacent actions if they appear and moves any trailing action into the final reduce actions string. Next it removes any embedded actions by factoring them out with new action productions. Finally it assigns a unique index to the production.

Factoring out of actions is accomplished by creating new "hidden" non terminals. For example if the production was originally:

    A ::= B {action} C D
  
then it is factored into two productions:
    A ::= B X C D
    X ::= {action}
  
(where X is a unique new non terminal). This has the effect of placing all actions at the end where they can be handled as part of a reduce by the parser.

Definition at line 56 of file production.java.

References _action, _all, _index, _lhs, _rhs, _rhs_length, _rhs_prec, java_cup::action_part::code_string(), declare_labels(), merge_adjacent_actions(), next_index, precedence_num(), remove_embedded_actions(), and strip_trailing_action().

    {
      int         i;
      action_part tail_action;
      String declare_str;
      int rightlen = rhs_l;

      /* remember the length */
      if (rhs_l >= 0)
      _rhs_length = rhs_l;
      else if (rhs_parts != null)
      _rhs_length = rhs_parts.length;
      else
      _rhs_length = 0;
      
      /* make sure we have a valid left-hand-side */
      if (lhs_sym == null) 
      throw new internal_error(
        "Attempt to construct a production with a null LHS");

      /* I'm not translating labels anymore, I'm adding code to declare
       labels as valid variables.  This way, the users code string is
       untouched 
       6/96 frankf */

      /* check if the last part of the right hand side is an action.  If
         it is, it won't be on the stack, so we don't want to count it 
       in the rightlen.  Then when we search down the stack for a
         Symbol, we don't try to search past action */

      if (rhs_l > 0) {
      if (rhs_parts[rhs_l - 1].is_action()) {
        rightlen = rhs_l - 1;
      } else {
        rightlen = rhs_l;
      }
      }

      /* get the generated declaration code for the necessary labels. */
      declare_str = declare_labels(
                rhs_parts, rightlen, action_str);

      if (action_str == null) 
      action_str = declare_str;
      else 
      action_str = declare_str + action_str;            

      /* count use of lhs */
      lhs_sym.note_use();

      /* create the part for left-hand-side */
      _lhs = new symbol_part(lhs_sym);

      /* merge adjacent actions (if any) */
      _rhs_length = merge_adjacent_actions(rhs_parts, _rhs_length);

      /* strip off any trailing action */
      tail_action = strip_trailing_action(rhs_parts, _rhs_length);
      if (tail_action != null) _rhs_length--;

      /* Why does this run through the right hand side happen
       over and over?  here a quick combination of two 
       prior runs plus one I wanted of my own
       frankf 6/25/96 */
      /* allocate and copy over the right-hand-side */
      /* count use of each rhs symbol */
      _rhs = new production_part[_rhs_length];
      for (i=0; i<_rhs_length; i++) {
      _rhs[i] = rhs_parts[i];
      if (!_rhs[i].is_action()) {
        ((symbol_part)_rhs[i]).the_symbol().note_use();
        if (((symbol_part)_rhs[i]).the_symbol() instanceof terminal) {
          _rhs_prec = 
            ((terminal)((symbol_part)_rhs[i]).the_symbol()).precedence_num();
          _rhs_assoc = 
            ((terminal)((symbol_part)_rhs[i]).the_symbol()).precedence_side();
        }
      }
      }

      /*now action string is really declaration string, so put it in front!
      6/14/96 frankf */
      if (action_str == null) action_str = "";
      if (tail_action != null && tail_action.code_string() != null)
      action_str = action_str + "\t\t" +  tail_action.code_string();

      /* stash the action */
      _action = new action_part(action_str);

      /* rewrite production to remove any embedded actions */
      remove_embedded_actions();

      /* assign an index */
      _index = next_index++;

      /* put us in the global collection of productions */
      _all.put(new Integer(_index),this);

      /* put us in the production list of the lhs non terminal */
      lhs_sym.add_production(this);
    }


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