add fst annotations

Author: bygu4

pyformlang/finite_automaton/finite_automaton.py

@@ -436,14 +436,14 @@ def to_fst(self) -> FST:
         """
         fst = FST()
         for start_state in self._start_states:
-            fst.add_start_state(start_state.value)
+            fst.add_start_state(start_state)
         for final_state in self._final_states:
-            fst.add_final_state(final_state.value)
+            fst.add_final_state(final_state)
         for s_from, symb_by, s_to in self._transition_function:
-            fst.add_transition(s_from.value,
-                               symb_by.value,
-                               s_to.value,
-                               [symb_by.value])
+            fst.add_transition(s_from,
+                               symb_by,
+                               s_to,
+                               [symb_by])
         return fst
 
     def is_acyclic(self) -> bool:

pyformlang/fst/__init__.py

@@ -12,7 +12,10 @@
 
 """
 
-from .fst import FST
+from .fst import FST, State, Symbol, Epsilon
 
 
-__all__ = ["FST"]
+__all__ = ["FST",
+           "State",
+           "Symbol",
+           "Epsilon"]