lib: Add slots to CFG data structures

lib/grammars_cfg.py

@@ -111,6 +111,8 @@ def zip_fill(seqa: Iterable[TA], seqb: Iterable[TB], sentinel: bool = False) \
 
 
 class ChangeTracker:
+    __slots__ = ["_changed"]
+
     def __init__(self):
         self._changed = True
 
@@ -135,6 +137,8 @@ class CFG:
     Word = Tuple[Terminal, ...]
     Rules = Dict[Nonterminal, Set[Production]]
 
+    __slots__ = ["nonterminals", "terminals", "rules", "init"]
+
     def __init__(self, nonterminals: Set[Nonterminal],
                  terminals: Set[Terminal],
                  rules: CFG.Rules,
@@ -651,6 +655,8 @@ class WordGenerator:
     CountMap = Dict[Nonterminal, int]
     ProdCountMap = Dict[CFG.Production, int]
 
+    __slots__ = ["cfg", "_seen", "_stack", "_cur_lenght", "_next_length", "last", "counts", "prod_counts"]
+
     def __init__(self, cfg: CFG):
         self.cfg = cfg.proper()
         self._seen: Set[CFG.Symbols] = set()
@@ -832,6 +838,9 @@ class WordGenerator:
 
 
 class CachedCYK:
+
+    __slots__ = ["cfg", "cache"]
+
     def __init__(self, cfg: CFG):
         self.cfg = cfg.cnf()
         self.cache: Dict[CFG.Word, Set[Nonterminal]] = dict()