1  import contextlib
       2  import os.path
       3  
       4  
       5  def resolve(source, filename):
       6      if _looks_like_filename(source):
       7          return _resolve_filename(source, filename)
       8  
       9      if isinstance(source, str):
      10          source = source.splitlines()
      11  
      12      # At this point "source" is not a str.
      13      if not filename:
      14          filename = None
      15      elif not isinstance(filename, str):
      16          raise TypeError(f'filename should be str (or None), got {filename!r}')
      17      else:
      18          filename, _ = _resolve_filename(filename)
      19      return source, filename
      20  
      21  
      22  @contextlib.contextmanager
      23  def good_file(filename, alt=None):
      24      if not _looks_like_filename(filename):
      25          raise ValueError(f'expected a filename, got {filename}')
      26      filename, _ = _resolve_filename(filename, alt)
      27      try:
      28          yield filename
      29      except Exception:
      30          if not os.path.exists(filename):
      31              raise FileNotFoundError(f'file not found: {filename}')
      32          raise  # re-raise
      33  
      34  
      35  def _looks_like_filename(value):
      36      if not isinstance(value, str):
      37          return False
      38      return value.endswith(('.c', '.h'))
      39  
      40  
      41  def _resolve_filename(filename, alt=None):
      42      if os.path.isabs(filename):
      43          ...
      44  #        raise NotImplementedError
      45      else:
      46          filename = os.path.join('.', filename)
      47  
      48      if not alt:
      49          alt = filename
      50      elif os.path.abspath(filename) == os.path.abspath(alt):
      51          alt = filename
      52      else:
      53          raise ValueError(f'mismatch: {filename} != {alt}')
      54      return filename, alt
      55  
      56  
      57  @contextlib.contextmanager
      58  def opened(source, filename=None):
      59      source, filename = resolve(source, filename)
      60      if isinstance(source, str):
      61          with open(source) as srcfile:
      62              yield srcfile, filename
      63      else:
      64          yield source, filename