use .fromisoformat() for sqlite datetime, date, time parsing

SQLite datetime, date, and time datatypes now use Python standard lib
``fromisoformat()`` methods in order to parse incoming datetime, date, and
time string values. This improves performance vs. the previous regular
expression-based approach, and also automatically accommodates for datetime
and time formats that contain either a six-digit "microseconds" format or a
three-digit "milliseconds" format.

Fixes: #7029
Change-Id: I67aab4fe5ee3055e5996050cf4564981413cc221

1 files changed, 26 insertions, 9 deletions

diff --git a/lib/sqlalchemy/engine/_py_processors.py b/lib/sqlalchemy/engine/_py_processors.py
index 27cb9e939..63f03466a 100644
--- a/lib/sqlalchemy/engine/_py_processors.py
+++ b/lib/sqlalchemy/engine/_py_processors.py
@@ -16,8 +16,10 @@ They all share one common characteristic: None is passed through unchanged.
 from __future__ import annotations
 
 import datetime
+from datetime import date as date_cls
+from datetime import datetime as datetime_cls
+from datetime import time as time_cls
 from decimal import Decimal
-import re
 import typing
 from typing import Any
 from typing import Callable
@@ -26,6 +28,7 @@ from typing import Type
 from typing import TypeVar
 from typing import Union
 
+
 _DT = TypeVar(
     "_DT", bound=Union[datetime.datetime, datetime.time, datetime.date]
 )
@@ -50,6 +53,7 @@ def str_to_datetime_processor_factory(
                     "Couldn't parse %s string '%r' "
                     "- value is not a string." % (type_.__name__, value)
                 ) from err
+
             if m is None:
                 raise ValueError(
                     "Couldn't parse %s string: "
@@ -108,12 +112,25 @@ def int_to_boolean(value: Optional[int]) -> Optional[bool]:
         return bool(value)
 
 
-DATETIME_RE = re.compile(r"(\d+)-(\d+)-(\d+) (\d+):(\d+):(\d+)(?:\.(\d+))?")
-TIME_RE = re.compile(r"(\d+):(\d+):(\d+)(?:\.(\d+))?")
-DATE_RE = re.compile(r"(\d+)-(\d+)-(\d+)")
+def str_to_datetime(value: Optional[str]) -> Optional[datetime.datetime]:
+    if value is not None:
+        dt_value = datetime_cls.fromisoformat(value)
+    else:
+        dt_value = None
+    return dt_value
 
-str_to_datetime = str_to_datetime_processor_factory(
-    DATETIME_RE, datetime.datetime
-)
-str_to_time = str_to_datetime_processor_factory(TIME_RE, datetime.time)
-str_to_date = str_to_datetime_processor_factory(DATE_RE, datetime.date)
+
+def str_to_time(value: Optional[str]) -> Optional[datetime.time]:
+    if value is not None:
+        dt_value = time_cls.fromisoformat(value)
+    else:
+        dt_value = None
+    return dt_value
+
+
+def str_to_date(value: Optional[str]) -> Optional[datetime.date]:
+    if value is not None:
+        dt_value = date_cls.fromisoformat(value)
+    else:
+        dt_value = None
+    return dt_value