Date/Time Conversion

import re
from datetime import datetime


class BaseUtils(object):
    __DATE_REGEX = r"[/.]+"
    __dateRegex = re.compile(__DATE_REGEX)

    def __init__(self):
        pass

    def __transposeFromYMDHMS(self, value):
        return value

    def __transposeFromMDYHMS(self, value):
        m = value[:2]
        d = value[3:5]
        y = value[6:10]

        if len(value) > 10:
            value = "%s-%s-%s %s" % (y, m, d, value[11:])
        else:
            value = "%s-%s-%s 00:00:00" % (y, m, d)

        return value

    def __transposeFromDMYHMS(self, value):
        d = value[:2]
        m = value[3:5]
        y = value[6:10]

        if len(value) > 10:
            value = "%s-%s-%s %s" % (y, m, d, value[11:])
        else:
            value = "%s-%s-%s 00:00:00" % (y, m, d)

        return value

    def __transposeNonDelimiterYMDHMS(self, value):
        y = value[:4]
        m = value[4:6]
        d = value[6:8]
        H = value[8:10]
        M = value[10:12]

        if len(value) > 12:
            S = value[12:]
            value = "%s-%s-%s %s:%s:%s" % (y, m, d, H, M, S)
        else:
            value = "%s-%s-%s %s:%s:00" % (y, m, d, H, M)

        return value

    __FROM_DATE_FORMATS = {'yyyy-mm-dd hh:mm:ss': __transposeFromYMDHMS,
                           'mm-dd-yyyy hh:mm:ss': __transposeFromMDYHMS,
                           'dd-mm-yyyy hh:mm:ss': __transposeFromDMYHMS,
                           'yyyymmddHHMMSS': __transposeNonDelimiterYMDHMS}

    @classmethod
    def toDatetime(self, value, format='yyyy-mm-dd hh:mm:ss'):
        """
        Convert a string representation of a date and time to a python
        datetime object.

        @param value: The string value to convert.
        @keyword format: The format to convert from.
        @return: A Python datetime object.
        """
        format = self.__dateRegex.sub('-', format)

        try:
            value = self.__FROM_DATE_FORMATS[format](self, value)
            date, time = value.split(' ')
        except KeyError, e:
            msg = "Invalid date format should be one of %s." % \
                  self.__FROM_DATE_FORMATS.keys()
            raise KeyError(msg)

        try:
            return datetime(*[int(float(x)) for x in date.split("-")] +
                            [int(float(x)) for x in time.split(":")])
        except Exception, e:
            msg = "Invalid format for datetime %s, found: %s, %s" % \
                  (format, value, e)
            raise Exception(msg)