text: # Copyright 2017 The Forseti Security Authors. All rights reserved.
  #
  # 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.
  
  """Regex utility module."""
  
  import re
  
  # pylint: disable=anomalous-backslash-in-string
  def escape_and_globify(pattern_string):
      """Given a pattern string with a glob, create actual regex pattern.
  
      To require > 0 length glob, change the "*" to ".+". This is to handle
      strings like "\*@company.com". (The actual regex would probably be
      ".\*@company.com", except that we don't want to match zero-length
      usernames before the "@".)
  
      Special case the pattern '*' to match 0 or more characters.
  
      Args:
          pattern_string (str): The pattern string of which to make a regex.
  
      Returns:
          str: The pattern string, escaped except for the "*", which is
              transformed into ".+" (match on one or more characters).
      """
      # pylint: enable=anomalous-backslash-in-string
      if pattern_string == '*':
          return '^.*$'
      return '^{}$'.format(re.escape(pattern_string).replace('\\*', '.+?'))
  