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, 14 insertions, 43 deletions

diff --git a/lib/sqlalchemy/cyextension/processors.pyx b/lib/sqlalchemy/cyextension/processors.pyx
index 9f23e73b1..b0ad865c5 100644
--- a/lib/sqlalchemy/cyextension/processors.pyx
+++ b/lib/sqlalchemy/cyextension/processors.pyx
@@ -1,7 +1,9 @@
 import datetime
+from datetime import datetime as datetime_cls
+from datetime import time as time_cls
+from datetime import date as date_cls
 import re
 
-from cpython.datetime cimport date_new, datetime_new, import_datetime, time_new
 from cpython.object cimport PyObject_Str
 from cpython.unicode cimport PyUnicode_AsASCIIString, PyUnicode_Check, PyUnicode_Decode
 from libc.stdio cimport sscanf
@@ -27,53 +29,22 @@ cdef inline bytes to_bytes(object value, str type_name):
             "- value is not a string."
         ) from e
 
-import_datetime()  # required to call datetime_new/date_new/time_new
-
 def str_to_datetime(value):
-    if value is None:
-        return None
-    cdef int numparsed
-    cdef unsigned int year, month, day, hour, minute, second, microsecond = 0
-    cdef bytes value_b = to_bytes(value, 'datetime')
-    cdef const char * string = value_b
-
-    numparsed = sscanf(string, "%4u-%2u-%2u %2u:%2u:%2u.%6u",
-        &year, &month, &day, &hour, &minute, &second, &microsecond)
-    if numparsed < 6:
-        raise ValueError(
-                "Couldn't parse datetime string: '%s'" % (value)
-            )
-    return datetime_new(year, month, day, hour, minute, second, microsecond, None)
+    if value is not None:
+        value = datetime_cls.fromisoformat(value)
+    return value
 
-def str_to_date(value):
-    if value is None:
-        return None
-    cdef int numparsed
-    cdef unsigned int year, month, day
-    cdef bytes value_b = to_bytes(value, 'date')
-    cdef const char * string = value_b
+def str_to_time(value):
+    if value is not None:
+        value = time_cls.fromisoformat(value)
+    return value
 
-    numparsed = sscanf(string, "%4u-%2u-%2u", &year, &month, &day)
-    if numparsed != 3:
-        raise ValueError(
-                "Couldn't parse date string: '%s'" % (value)
-            )
-    return date_new(year, month, day)
 
-def str_to_time(value):
-    if value is None:
-        return None
-    cdef int numparsed
-    cdef unsigned int hour, minute, second, microsecond = 0
-    cdef bytes value_b = to_bytes(value, 'time')
-    cdef const char * string = value_b
+def str_to_date(value):
+    if value is not None:
+        value = date_cls.fromisoformat(value)
+    return value
 
-    numparsed = sscanf(string, "%2u:%2u:%2u.%6u", &hour, &minute, &second, &microsecond)
-    if numparsed < 3:
-        raise ValueError(
-                "Couldn't parse time string: '%s'" % (value)
-            )
-    return time_new(hour, minute, second, microsecond, None)
 
 
 cdef class DecimalResultProcessor: