Tweaked AST to correct for pyserde issues

Changed AST representation to avoid using collections that contain
Optional values per yukinarit/pyserde#329.

Author: minkedup

yass/ast.py

@@ -2,7 +2,7 @@
 An AST.
 """
 
-from typing import TypeAlias, NewType
+from typing import TypeAlias, NewType, Literal
 import enum
 import datetime
 import dataclasses
@@ -15,6 +15,7 @@ class StopPart(enum.Enum):
     A part of a Stop (e.g. Gleason Circle *Arrival*).
     """
 
+    NONE = "none"
     ARRIVAL = "arrival"
     DEPARTURE = "departure"
 
@@ -23,8 +24,8 @@ class StopPart(enum.Enum):
 StopIdx = NewType("StopIdx", int)
 
 
-TimeTableColumn: TypeAlias = tuple[StopIdx, StopPart | None]
-TimeTableCell: TypeAlias = datetime.time | None
+TimeTableColumn: TypeAlias = tuple[StopIdx, StopPart]
+TimeTableCell: TypeAlias = datetime.time | Literal["none"]
 
 
 @serde.serde

yass/parse.py

@@ -135,7 +135,7 @@ def _route(s_route: ScrapedRoute) -> Route:
 LAST_WORD_RE = re.compile("(.*) (.*)$")
 
 
-def _stop(s_time_table_col: ScrapedTimeTableColumn) -> tuple[Stop, StopPart | None]:
+def _stop(s_time_table_col: ScrapedTimeTableColumn) -> tuple[Stop, StopPart]:
     last_match = LAST_WORD_RE.match(s_time_table_col)
     last = last_match[2] if last_match is not None else None
 
@@ -147,7 +147,7 @@ def _stop(s_time_table_col: ScrapedTimeTableColumn) -> tuple[Stop, StopPart | No
         assert last_match is not None
         stop = last_match[1].strip()
     except ValueError:
-        stop_part = None
+        stop_part = StopPart("none")
         stop = s_time_table_col
 
     return (stop, stop_part)
@@ -178,7 +178,7 @@ def _time_table_n_stop(
 
     def _time_table_cell(s_time_table_cell: ScrapedTimeTableCell) -> TimeTableCell:
         if s_time_table_cell is None:
-            return None
+            return "none"
 
         date_time = datetime.datetime.strptime(s_time_table_cell, RAW_CELL_TIME_FORMAT)
         return date_time.time()