Relaxed datetime/time parsing

Previously we strictly followed the RFC3339 format when parsing datetime
and time objects from strings. We now support a few common ISO8601
compatible relaxations:

- A `:` isn't required as part of the timezone component in both
  datetime and time strings (`2022-01-02T03:04:05.678+0102` and
  `2022-01-02T03:04:05.678+01:02` are treated the same).

- A ` ` may be used instead of `T`/`t` as a separator between date and
  time components when parsing datetime strings.

When encoding datetime/time objects we still strictly follow RFC3339.
This eases integrating msgspec with other systems that don't strictly
follow RFC3339.

msgspec/_core.c

@@ -10078,11 +10078,12 @@ ms_decode_time(const char *buf, Py_ssize_t size, TypeNode *type, PathNode *path)
  goto invalid;
  }
 
- /* Explicit offset requires exactly 5 bytes left */
- if (buf_end - buf != 5) goto invalid;
-
+ if (buf_end - buf < 3) goto invalid;
  if ((buf = ms_read_fixint(buf, 2, &offset_hour)) == NULL) goto invalid;
- if (*buf++ != ':') goto invalid;
+ /* RFC3339 requires a ':' separator, ISO8601 doesn't. We support
+ * either */
+ if (*buf == ':') buf++;
+ if (buf_end - buf != 2) goto invalid;
  if ((buf = ms_read_fixint(buf, 2, &offset_min)) == NULL) goto invalid;
  if (offset_hour > 23 || offset_min > 59) goto invalid;
  offset *= (offset_hour * 60 + offset_min);
@@ -10178,9 +10179,10 @@ ms_decode_datetime_from_str(
  if (*buf++ != '-') goto invalid;
  if ((buf = ms_read_fixint(buf, 2, &day)) == NULL) goto invalid;
 
- /* Date/time separator can be T or t */
+ /* RFC3339 date/time separator can be T or t. We also support ' ', which is
+ * ISO8601 compatible. */
  c = *buf++;
- if (!(c == 'T' || c == 't')) goto invalid;
+ if (!(c == 'T' || c == 't' || c == ' ')) goto invalid;
 
  /* Parse time */
  if ((buf = ms_read_fixint(buf, 2, &hour)) == NULL) goto invalid;
@@ -10251,11 +10253,12 @@ ms_decode_datetime_from_str(
  goto invalid;
  }
 
- /* Explicit offset requires exactly 5 bytes left */
- if (buf_end - buf != 5) goto invalid;
-
+ if (buf_end - buf < 3) goto invalid;
  if ((buf = ms_read_fixint(buf, 2, &offset_hour)) == NULL) goto invalid;
- if (*buf++ != ':') goto invalid;
+ /* RFC3339 requires a ':' separator, ISO8601 doesn't. We support
+ * either */
+ if (*buf == ':') buf++;
+ if (buf_end - buf != 2) goto invalid;
  if ((buf = ms_read_fixint(buf, 2, &offset_min)) == NULL) goto invalid;
  if (offset_hour > 23 || offset_min > 59) goto invalid;
  offset *= (offset_hour * 60 + offset_min);

tests/test_common.py

@@ -3211,6 +3211,20 @@ def test_decode_time_not_case_sensitive(self, proto, z):
  res = proto.decode(proto.encode(f"04:05:06.000007{z}"), type=datetime.time)
  assert res == sol
 
+ @pytest.mark.parametrize(
+ "lax, strict",
+ [
+ ("03:04:05+0102", "03:04:05+01:02"),
+ ("03:04:05-0102", "03:04:05-01:02"),
+ ],
+ )
+ def test_decode_time_rfc3339_relaxed(self, lax, strict, proto):
+ """msgspec supports a few relaxations of the RFC3339 format."""
+ sol = datetime.time.fromisoformat(strict)
+ msg = proto.encode(lax)
+ res = proto.decode(msg, type=datetime.time)
+ assert res == sol
+
  @pytest.mark.parametrize(
  "t, sol",
  [
@@ -3258,13 +3272,16 @@ def test_decode_time_nanos(self, proto, t, sol):
  "01:02:3.0000004Z",
  "01:02:03.0000004+5:06",
  "01:02:03.0000004+05:6",
+ "01:02:03.0000004+056",
+ "01:02:03.0000004+05600",
  # Trailing data
  "01:02:030",
  "01:02:03a",
  "01:02:03.a",
  "01:02:03.0a",
  "01:02:03.0000004a",
  "01:02:03.0000004+00:000",
+ "01:02:03.0000004+00000",
  "01:02:03.0000004Z0",
  # Truncated
  "01:02:3",
@@ -3280,6 +3297,8 @@ def test_decode_time_nanos(self, proto, t, sol):
  "01:02:03.00a+05:06",
  "01:02:03.004+0a:06",
  "01:02:03.004+05:0a",
+ "01:02:03.004+0a06",
+ "01:02:03.004+050a",
  # Hour out of range
  "24:02:03.004",
  # Minute out of range

tests/test_json.py

@@ -984,6 +984,21 @@ def test_decode_datetime_nanos(self, msg, sol):
  res = msgspec.json.decode(msg, type=datetime.datetime)
  assert res == sol
 
+ @pytest.mark.parametrize(
+ "lax, strict",
+ [
+ ("2022-01-02T03:04:05+0102", "2022-01-02T03:04:05+01:02"),
+ ("2022-01-02T03:04:05-0102", "2022-01-02T03:04:05-01:02"),
+ ("2022-01-02 03:04:05", "2022-01-02T03:04:05"),
+ ],
+ )
+ def test_decode_datetime_rfc3339_relaxed(self, lax, strict):
+ """msgspec supports a few relaxations of the RFC3339 format."""
+ sol = datetime.datetime.fromisoformat(strict)
+ msg = msgspec.json.encode(lax)
+ res = msgspec.json.decode(msg, type=datetime.datetime)
+ assert res == sol
+
  @pytest.mark.parametrize(
  "s",
  [
@@ -996,8 +1011,10 @@ def test_decode_datetime_nanos(self, msg, sol):
  b'"0001-02-03T04:05:6.000007Z"',
  b'"0001-02-03T04:05:06.000007+0:00"',
  b'"0001-02-03T04:05:06.000007+00:0"',
+ b'"0001-02-03T04:05:06.000007+000"',
  # Trailing data
  b'"0001-02-03T04:05:06.000007+00:000"',
+ b'"0001-02-03T04:05:06.000007+00000"',
  b'"0001-02-03T04:05:06.000007Z0"',
  b'"0001-02-03T04:05:06a"',
  b'"0001-02-03T04:05:06.000007a"',
@@ -1019,6 +1036,8 @@ def test_decode_datetime_nanos(self, msg, sol):
  b'"0001-02-03T04:05:06.000007a"',
  b'"0001-02-03T04:05:06.000007+0a:00"',
  b'"0001-02-03T04:05:06.000007+00:0a"',
+ b'"0001-02-03T04:05:06.000007+0a00"',
+ b'"0001-02-03T04:05:06.000007+000a"',
  # Year out of range
  b'"0000-02-03T04:05:06.000007Z"',
  # Month out of range