fix: LR(1) items lookahead set calculation

Author: igordejanovic

CHANGELOG.md

@@ -21,6 +21,7 @@ backward incompatible changes will start to apply when the projects goes 1.0
 ### Fixed
 - Fix `to_str` failure when calculating the number of solutions in the context
   of optional match ([#147]). Thanks @LVrecar for the report and fix.
+- Fix lookahead calculation in closure
 
 ### Changed
 - Drop support for Python 3.6/3.7

parglare/closure.py

@@ -30,7 +30,7 @@ def closure(state, itemset_type, first_sets=None):
         for prod in [p for p in state.grammar.productions
                      if p.symbol == symbol]:
             new_item = LRItem(prod, 0,
-                              follow if itemset_type is LR_1 else None)
+                              set(follow) if itemset_type is LR_1 else None)
             if new_item not in state.items:
                 # If the item doesn't exists yet add it and reprocess it.
                 state.items.append(new_item)

parglare/tables/__init__.py

@@ -238,10 +238,10 @@ def create_table(grammar, itemset_type=LR_1, start_production=1,
             update = False
 
             for state in states:
-
-                # First refresh current state's follows
+                # First refresh state's follows
                 closure(state, LR_1, first_sets)
 
+            for state in states:
                 # Propagate follows to next states. GOTOs/ACTIONs keep
                 # information about states created from this state
                 inc_items = [i.get_pos_inc() for i in state.items]