fixes

automata/base/utils.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 """Miscellaneous utility functions and classes."""
+from __future__ import annotations
 
 import os
 import pathlib
@@ -17,7 +18,6 @@
     Literal,
     Set,
     Tuple,
-    TypeAlias,
     TypeVar,
     Union,
 )
@@ -31,10 +31,6 @@
     _visual_imports = False
 else:
     _visual_imports = True
-finally:
-    # create a type for type checker
-    # irrespective of whether the imports were successful
-    GraphT: TypeAlias = "pgv.AGraph"
 
 
 LayoutMethod = Literal["neato", "dot", "twopi", "circo", "fdp", "nop"]
@@ -86,7 +82,7 @@ def create_graph(
     reverse_orientation: bool = False,
     fig_size: Union[Tuple[float, float], Tuple[float], None] = None,
     state_separation: float = 0.5,
-) -> GraphT:
+) -> pgv.AGraph:
     """Creates and returns a graph object
     Args:
         - horizontal (bool, optional): Direction of node layout. Defaults
@@ -123,7 +119,7 @@ def create_graph(
 
 
 def save_graph(
-    graph: GraphT,
+    graph: pgv.AGraph,
     path: Union[str, os.PathLike],
 ) -> None:
     """Write `graph` to file given by `path`. PNG, SVG, etc.

automata/pda/npda.py

@@ -147,12 +147,12 @@ def _get_input_path(
 
         accepted = path[0] in self.final_states
 
-        for i in reversed(steps):
-            if len(i) == 1:
-                path.append(i.pop())
+        for step in reversed(steps):
+            if len(step) == 1:
+                path.append(step.pop())
                 continue
 
-            for curr_step in i:
+            for curr_step in step:
                 for next_step in self._get_next_configurations(curr_step):
                     if next_step == path[-1]:
                         path.append(curr_step)

automata/pda/pda.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 """Classes and methods for working with all pushdown automata."""
+from __future__ import annotations
 
 import abc
 import os
@@ -167,11 +168,11 @@ def show_diagram(
 
             if with_machine:
                 # initialize diagram with all states
-                graph = self._add_states_diagram(graph, arrow_size_str, font_size_str)
+                self._add_states_diagram(graph, arrow_size_str, font_size_str)
 
                 # add required transitions to show execution of the
                 # PDA for the given input string
-                graph = self._create_transitions_for_input_diagram(
+                self._create_transitions_for_input_diagram(
                     graph,
                     input_path,
                     is_edge_drawn,
@@ -182,13 +183,13 @@ def show_diagram(
                 )
 
                 # add all the necessary transitions between states
-                graph = self._add_transitions_diagram(
+                self._add_transitions_diagram(
                     graph, is_edge_drawn, arrow_size_str, font_size_str
                 )
 
             if with_stack:
                 # add the stack transitions
-                graph = self._create_stack_diagram(
+                self._create_stack_diagram(
                     input_path,
                     graph,
                     start_color,
@@ -198,10 +199,10 @@ def show_diagram(
                 )
         else:
             # initialize diagram with all states
-            graph = self._add_states_diagram(graph, arrow_size_str, font_size_str)
+            self._add_states_diagram(graph, arrow_size_str, font_size_str)
 
             # add all the necessary transitions between states
-            graph = self._add_transitions_diagram(
+            self._add_transitions_diagram(
                 graph, is_edge_drawn, arrow_size_str, font_size_str
             )
 
@@ -222,7 +223,7 @@ def _create_stack_diagram(
         end_color: coloraide.Color,
         font_size: str,
         arrow_size: str,
-    ) -> pgv.AGraph:
+    ) -> None:
         """
         Constructs stack for all the transitions in the `input_path` and
         adds the constructed stacks into `graph`. Returns the same `graph`
@@ -275,7 +276,7 @@ def _create_transitions_for_input_diagram(
         end_color: coloraide.Color,
         arrow_size: str,
         font_size: str,
-    ) -> pgv.AGraph:
+    ) -> None:
         """
         Add transitions to show execution of the PDA for the given input string
         """
@@ -302,15 +303,13 @@ def _create_transitions_for_input_diagram(
                 penwidth="2.5",
             )
 
-        return graph
-
     def _add_transitions_diagram(
         self,
         graph: pgv.AGraph,
         is_edge_drawn: EdgeDrawnDictT,
         arrow_size: str,
         font_size: str,
-    ) -> pgv.AGraph:
+    ) -> None:
         """
         Add transitions to between states
         """
@@ -334,14 +333,12 @@ def _add_transitions_diagram(
                 fontsize=font_size,
             )
 
-        return graph
-
     def _add_states_diagram(
         self,
         graph: pgv.AGraph,
         arrow_size: str,
         font_size: str,
-    ) -> pgv.AGraph:
+    ) -> None:
         """
         Add all the states of the PDA
         """
@@ -369,8 +366,6 @@ def _add_states_diagram(
         graph.add_nodes_from(nonfinal_states, shape="circle", fontsize=font_size)
         graph.add_nodes_from(final_states, shape="doublecircle", fontsize=font_size)
 
-        return graph
-
     def _validate_transition_invalid_input_symbols(
         self, start_state: PDAStateT, input_symbol: str
     ) -> None: