Added support for time zones. Thanks Luke Plant for the review. Fixed #2626.

For more information on this project, see this thread:
cf0423bbb8



git-svn-id: http://code.djangoproject.com/svn/django/trunk@17106 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/utils/dateparse.py

@@ -0,0 +1,93 @@
+"""Functions to parse datetime objects."""
+
+# We're using regular expressions rather than time.strptime because:
+# - they provide both validation and parsing,
+# - they're more flexible for datetimes,
+# - the date/datetime/time constructors produce friendlier error messages.
+
+
+import datetime
+import re
+
+from django.utils.timezone import utc
+from django.utils.tzinfo import FixedOffset
+
+
+date_re = re.compile(
+        r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})$'
+)
+
+
+datetime_re = re.compile(
+        r'(?P<year>\d{4})-(?P<month>\d{1,2})-(?P<day>\d{1,2})'
+        r'[T ](?P<hour>\d{1,2}):(?P<minute>\d{1,2})'
+        r'(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?'
+        r'(?P<tzinfo>Z|[+-]\d{1,2}:\d{1,2})?$'
+)
+
+
+time_re = re.compile(
+        r'(?P<hour>\d{1,2}):(?P<minute>\d{1,2})'
+        r'(?::(?P<second>\d{1,2})(?:\.(?P<microsecond>\d{1,6})\d{0,6})?)?'
+)
+
+
+def parse_date(value):
+    """Parse a string and return a datetime.date.
+
+    Raise ValueError if the input is well formatted but not a valid date.
+    Return None if the input isn't well formatted.
+    """
+    match = date_re.match(value)
+    if match:
+        kw = dict((k, int(v)) for k, v in match.groupdict().iteritems())
+        return datetime.date(**kw)
+
+
+def parse_time(value):
+    """Parse a string and return a datetime.time.
+
+    This function doesn't support time zone offsets.
+
+    Sub-microsecond precision is accepted, but ignored.
+
+    Raise ValueError if the input is well formatted but not a valid time.
+    Return None if the input isn't well formatted, in particular if it
+    contains an offset.
+    """
+    match = time_re.match(value)
+    if match:
+        kw = match.groupdict()
+        if kw['microsecond']:
+            kw['microsecond'] = kw['microsecond'].ljust(6, '0')
+        kw = dict((k, int(v)) for k, v in kw.iteritems() if v is not None)
+        return datetime.time(**kw)
+
+
+def parse_datetime(value):
+    """Parse a string and return a datetime.datetime.
+
+    This function supports time zone offsets. When the input contains one,
+    the output uses an instance of FixedOffset as tzinfo.
+
+    Sub-microsecond precision is accepted, but ignored.
+
+    Raise ValueError if the input is well formatted but not a valid datetime.
+    Return None if the input isn't well formatted.
+    """
+    match = datetime_re.match(value)
+    if match:
+        kw = match.groupdict()
+        if kw['microsecond']:
+            kw['microsecond'] = kw['microsecond'].ljust(6, '0')
+        tzinfo = kw.pop('tzinfo')
+        if tzinfo == 'Z':
+            tzinfo = utc
+        elif tzinfo is not None:
+            offset = 60 * int(tzinfo[1:3]) + int(tzinfo[4:6])
+            if tzinfo[0] == '-':
+                offset = -offset
+            tzinfo = FixedOffset(offset)
+        kw = dict((k, int(v)) for k, v in kw.iteritems() if v is not None)
+        kw['tzinfo'] = tzinfo
+        return datetime.datetime(**kw)