Synnefo » snf-ganeti

def UnescapeAndSplit(text, sep=","):

  """Split and unescape a string based on a given separator.

  This function splits a string based on a separator where the

  separator itself can be escape in order to be an element of the

  elements. The escaping rules are (assuming coma being the

  separator):

    - a plain , separates the elements

    - a sequence \\\\, (double backslash plus comma) is handled as a

      backslash plus a separator comma

    - a sequence \, (backslash plus comma) is handled as a

      non-separator comma

  @type text: string

  @param text: the string to split

  @type sep: string

  @param text: the separator

  @rtype: string

  @return: a list of strings

  """

  # we split the list by sep (with no escaping at this stage)

  slist = text.split(sep)

  # next, we revisit the elements and if any of them ended with an odd

  # number of backslashes, then we join it with the next

  rlist = []

  while slist:

    e1 = slist.pop(0)

    if e1.endswith("\\"):

      num_b = len(e1) - len(e1.rstrip("\\"))

      if num_b % 2 == 1:

        e2 = slist.pop(0)

        # here the backslashes remain (all), and will be reduced in

        # the next step

        rlist.append(e1 + sep + e2)

        continue

    rlist.append(e1)

  # finally, replace backslash-something with something

  rlist = [re.sub(r"\\(.)", r"\1", v) for v in rlist]

  return rlist

     TailFile, ForceDictType, SafeEncode, IsNormAbsPath, FormatTime, \

     UnescapeAndSplit

class TestUnescapeAndSplit(unittest.TestCase):

  """Testing case for UnescapeAndSplit"""

  def setUp(self):

    # testing more that one separator for regexp safety

    self._seps = [",", "+", "."]

  def testSimple(self):

    a = ["a", "b", "c", "d"]

    for sep in self._seps:

      self.failUnlessEqual(UnescapeAndSplit(sep.join(a), sep=sep), a)

  def testEscape(self):

    for sep in self._seps:

      a = ["a", "b\\" + sep + "c", "d"]

      b = ["a", "b" + sep + "c", "d"]

      self.failUnlessEqual(UnescapeAndSplit(sep.join(a), sep=sep), b)

  def testDoubleEscape(self):

    for sep in self._seps:

      a = ["a", "b\\\\", "c", "d"]

      b = ["a", "b\\", "c", "d"]

      self.failUnlessEqual(UnescapeAndSplit(sep.join(a), sep=sep), b)

  def testThreeEscape(self):

    for sep in self._seps:

      a = ["a", "b\\\\\\" + sep + "c", "d"]

      b = ["a", "b\\" + sep + "c", "d"]

      self.failUnlessEqual(UnescapeAndSplit(sep.join(a), sep=sep), b)