ASCReader: Improve datetime parsing and support double-defined AM/PM cases (#2009)

* ASCReader: Improve datetime parsing and support double-defined AM/PM cases

* Fixed code formatting and add a news fragment for PR 2009

* Updated formatting of logformats_test.py

* Updated test for cross-platform compatibility and (hopefully) fixed formatting for good now

* Corrected micro- to milliseconds

Author: Gedlex

can/io/asc.py

@@ -116,41 +116,50 @@ def _extract_header(self) -> None:
 
     @staticmethod
     def _datetime_to_timestamp(datetime_string: str) -> float:
-        # ugly locale independent solution
         month_map = {
-            "Jan": 1,
-            "Feb": 2,
-            "Mar": 3,
-            "Apr": 4,
-            "May": 5,
-            "Jun": 6,
-            "Jul": 7,
-            "Aug": 8,
-            "Sep": 9,
-            "Oct": 10,
-            "Nov": 11,
-            "Dec": 12,
-            "Mär": 3,
-            "Mai": 5,
-            "Okt": 10,
-            "Dez": 12,
+            "jan": 1,
+            "feb": 2,
+            "mar": 3,
+            "apr": 4,
+            "may": 5,
+            "jun": 6,
+            "jul": 7,
+            "aug": 8,
+            "sep": 9,
+            "oct": 10,
+            "nov": 11,
+            "dec": 12,
+            "mär": 3,
+            "mai": 5,
+            "okt": 10,
+            "dez": 12,
         }
-        for name, number in month_map.items():
-            datetime_string = datetime_string.replace(name, str(number).zfill(2))
 
         datetime_formats = (
             "%m %d %I:%M:%S.%f %p %Y",
             "%m %d %I:%M:%S %p %Y",
             "%m %d %H:%M:%S.%f %Y",
             "%m %d %H:%M:%S %Y",
+            "%m %d %H:%M:%S.%f %p %Y",
+            "%m %d %H:%M:%S %p %Y",
         )
+
+        datetime_string_parts = datetime_string.split(" ", 1)
+        month = datetime_string_parts[0].strip().lower()
+
+        try:
+            datetime_string_parts[0] = f"{month_map[month]:02d}"
+        except KeyError:
+            raise ValueError(f"Unsupported month abbreviation: {month}") from None
+        datetime_string = " ".join(datetime_string_parts)
+
         for format_str in datetime_formats:
             try:
                 return datetime.strptime(datetime_string, format_str).timestamp()
             except ValueError:
                 continue
 
-        raise ValueError(f"Incompatible datetime string {datetime_string}")
+        raise ValueError(f"Unsupported datetime format: '{datetime_string}'")
 
     def _extract_can_id(self, str_can_id: str, msg_kwargs: dict[str, Any]) -> None:
         if str_can_id[-1:].lower() == "x":

doc/changelog.d/2009.changed.md

@@ -0,0 +1 @@
+Improved datetime parsing and added support for “double-defined” datetime strings (such as, e.g., `"30 15:06:13.191 pm 2017"`) for ASCReader class.

test/logformats_test.py

@@ -680,6 +680,40 @@ def test_write(self):
 
         self.assertEqual(expected_file.read_text(), actual_file.read_text())
 
+    @parameterized.expand(
+        [
+            (
+                "May 27 04:09:35.000 pm 2014",
+                datetime(2014, 5, 27, 16, 9, 35, 0).timestamp(),
+            ),
+            (
+                "Mai 27 04:09:35.000 pm 2014",
+                datetime(2014, 5, 27, 16, 9, 35, 0).timestamp(),
+            ),
+            (
+                "Apr 28 10:44:52.480 2022",
+                datetime(2022, 4, 28, 10, 44, 52, 480000).timestamp(),
+            ),
+            (
+                "Sep 30 15:06:13.191 2017",
+                datetime(2017, 9, 30, 15, 6, 13, 191000).timestamp(),
+            ),
+            (
+                "Sep 30 15:06:13.191 pm 2017",
+                datetime(2017, 9, 30, 15, 6, 13, 191000).timestamp(),
+            ),
+            (
+                "Sep 30 15:06:13.191 am 2017",
+                datetime(2017, 9, 30, 15, 6, 13, 191000).timestamp(),
+            ),
+        ]
+    )
+    def test_datetime_to_timestamp(
+        self, datetime_string: str, expected_timestamp: float
+    ):
+        timestamp = can.ASCReader._datetime_to_timestamp(datetime_string)
+        self.assertAlmostEqual(timestamp, expected_timestamp)
+
 
 class TestBlfFileFormat(ReaderWriterTest):
     """Tests can.BLFWriter and can.BLFReader.