Match month and weekday names case-insensitively in from_format

Fixes #668

Agent: claude

Author: tlq5l

src/pendulum/formatting/formatter.py

@@ -68,6 +68,11 @@ class Formatter:
 
     _FROM_FORMAT_RE: re.Pattern[str] = re.compile(r"(?<!\\\[)" + _TOKENS + r"(?!\\\])")
 
+    # Names are matched regardless of case, as in "14nov22" or "MONDAY".
+    _CASE_INSENSITIVE_TOKENS: ClassVar[frozenset[str]] = frozenset(
+        {"MMMM", "MMM", "dddd", "ddd", "dd"}
+    )
+
     _LOCALIZABLE_TOKENS: ClassVar[
         dict[str, str | Callable[[Locale], Sequence[str]] | None]
     ] = {
@@ -694,5 +699,7 @@ def _replace_tokens(self, token: str, locale: Locale) -> str:
             candidates = (cast("str", candidates),)
 
         pattern = f"(?P<{token}>{'|'.join(candidates)})"
+        if token in self._CASE_INSENSITIVE_TOKENS:
+            pattern = f"(?i:{pattern})"
 
         return pattern

src/pendulum/locales/locale.py

@@ -90,10 +90,11 @@ def ordinalize(self, number: int) -> str:
 
     def match_translation(self, key: str, value: Any) -> dict[str, str] | None:
         translations = self.translation(key)
-        if value not in translations.values():
+        by_value = {v.lower(): k for k, v in translations.items()}
+        if value.lower() not in by_value:
             return None
 
-        return cast(Dict[str, str], {v: k for k, v in translations.items()}[value])
+        return cast(Dict[str, str], by_value[value.lower()])
 
     def __repr__(self) -> str:
         return f"{self.__class__.__name__}('{self._locale}')"

tests/datetime/test_from_format.py

@@ -104,6 +104,11 @@ def test_from_format_with_invalid_padded_day():
         ("1", "E", "2018-01-29T00:00:00+00:00", "2018-02-02"),
         ("March", "MMMM", "2018-03-01T00:00:00+00:00", "2018-02-02"),
         ("Mar", "MMM", "2018-03-01T00:00:00+00:00", "2018-02-02"),
+        ("mar", "MMM", "2018-03-01T00:00:00+00:00", "2018-02-02"),
+        ("MARCH", "MMMM", "2018-03-01T00:00:00+00:00", "2018-02-02"),
+        ("14nov22", "DDMMMYY", "2022-11-14T00:00:00+00:00", None),
+        ("monday", "dddd", "2018-01-29T00:00:00+00:00", "2018-02-02"),
+        ("MON", "ddd", "2018-01-29T00:00:00+00:00", "2018-02-02"),
         (
             "Thursday 25th December 1975 02:15:16 PM",
             "dddd Do MMMM YYYY hh:mm:ss A",
@@ -164,6 +169,8 @@ def test_from_format(text, fmt, expected, now):
         ("lu", "dd", "2018-01-29T00:00:00+00:00"),
         ("mars", "MMMM", "2018-03-01T00:00:00+00:00"),
         ("mars", "MMM", "2018-03-01T00:00:00+00:00"),
+        ("Mars", "MMMM", "2018-03-01T00:00:00+00:00"),
+        ("LUNDI", "dddd", "2018-01-29T00:00:00+00:00"),
     ],
 )
 def test_from_format_with_locale(text, fmt, expected):