quick functions for dealing with zipfiles, which might be zipped with or without a leading prefix.

zipfun.py

def filenames_has_directory(filenames, directory):
    """if this appears to be a directory, great
        treat directories as / instead of os.path, because we write with '/'
    """
    if directory[-1] != '/':
        directory = directory + '/'
    directory_len = len(directory)
    for fname in filenames:
        if fname[:directory_len] == directory:
            return True
    return False


def filenames_all_directory(filenames):
    """if this is all in a directory, returns the directory
        otherwise, returns false
        treat directories as / instead of os.path, because we write with '/'
    """
    is_dir = False
    shortest = min(filenames, key=len)
    if shortest[-1] == '/':
        shortest_len = len(shortest)
        for i in filenames:
            bad = False
            if i[:shortest_len] != shortest:
                bad = True
        if not bad:
            is_dir = shortest
    return is_dir


class ZipfileNamedList(object):
    """
        wraps a list of files from a zipfile.
    """

    _common_directory = None
    filenames_archived = None       ## what is actually in the archive
    filenames_unmasked = None       ## list of files without the prefix

    def __init__(self, filenames_archived ):
        self.filenames_archived = filenames_archived
        self._common_directory = filenames_all_directory( filenames_archived )
        if self._common_directory:
            _common_directory_len = len(self._common_directory)
            self.filenames_unmasked = [ i[_common_directory_len:] for i in self.filenames_archived ]
                
    def has_file( self, unmasked_filename ):
        """expects:  the desired filename in an archive (without possible prefixes)
            returns: the actual filename in an archive (includes prefixes), or False
        """
        if self._common_directory:
            if unmasked_filename in self.filenames_unmasked:
                masked_name = "%s%s" % ( self._common_directory, unmasked_filename )
                return masked_name
            return False
        if unmasked_filename in self.filenames_archived:
            return unmasked_filename
        return False
        
    def has_directory( self, unmasked_directory ):
        """expects:  the desired directory in an archive
            returns: True or False
        """
        masked_name = unmasked_directory if not self._common_directory else "%s%s" % ( self._common_directory, unmasked_directory )
        return filenames_has_directory( self.filenames_archived , masked_name )