#!/usr/bin/python2.5

#

# Copyright 2008 the Melange authors.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

#   http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

"""Common helper functions.

"""

__authors__ = [

  '"Pawel Solyga" <pawel.solyga@gmail.com>',

  ]

import re

LINKNAME_PATTERN = r'''(?x)

    ^

    [0-9a-z]   # start with ASCII digit or lowercase

    (

     [0-9a-z]  # additional ASCII digit or lowercase

     |         # -OR-

     _[0-9a-z] # underscore and ASCII digit or lowercase

    )*         # zero or more of OR group

    $

'''

LINKNAME_REGEX = re.compile(LINKNAME_PATTERN)

def isLinkNameFormatValid(link_name):

  """Returns True if link_name is in a valid format.

  Args:

    link_name: link name used in URLs for identification

  """

  if LINKNAME_REGEX.match(link_name):

    return True

  return False