text: # -*- coding: utf-8 -*-
  #
  # diffoscope: in-depth comparison of files, archives, and directories
  #
  # Copyright © 2016 Chris Lamb <lamby@debian.org>
  #
  # diffoscope is free software: you can redistribute it and/or modify
  # it under the terms of the GNU General Public License as published by
  # the Free Software Foundation, either version 3 of the License, or
  # (at your option) any later version.
  #
  # diffoscope is distributed in the hope that it will be useful,
  # but WITHOUT ANY WARRANTY; without even the implied warranty of
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  # GNU General Public License for more details.
  #
  # You should have received a copy of the GNU General Public License
  # along with diffoscope.  If not, see <https://www.gnu.org/licenses/>.
  
  import logging
  
  from diffoscope.profiling import profile
  
  from .. import ComparatorManager
  
  logger = logging.getLogger(__name__)
  
  
  def try_recognize(file, cls, recognizes):
      if isinstance(file, cls):
          return True
  
      # Does this file class match?
      with profile('recognizes', file):
          # logger.debug("trying %s on %s", cls, file)
          if not recognizes(file):
              return False
  
      # Found a match; perform type magic
      logger.debug("Using %s for %s", cls.__name__, file.name)
      new_cls = type(cls.__name__, (cls, type(file)), {})
      file.__class__ = new_cls
  
      return True
  
  
  def specialize(file):
      for cls in ComparatorManager().classes:
          if try_recognize(file, cls, cls.recognizes):
              return file
  
      for cls in ComparatorManager().classes:
          if try_recognize(file, cls, cls.fallback_recognizes):
              logger.debug(
                  "File recognized by fallback. Magic says: %s",
                  file.magic_file_type,
              )
              return file
  
      logger.debug(
          "File not identified by any comparator. Magic says: %s",
          file.magic_file_type,
      )
  
      return file
  
  
  def is_direct_instance(file, cls):
      # is_direct_instance(<GzipFile>, GzipFile) == True, but
      # is_direct_instance(<IpkFile>, GzipFile) == False
      if not isinstance(file, cls):
          return False
      for c in ComparatorManager().classes:
          if c is not cls and isinstance(file, c):
              return False
      return True
  