"""encoding.py - Encoding handler."""

import sys

_filesystemencoding = sys.getfilesystemencoding()


def to_unicode(string):
    """Convert <string> to unicode. First try the default filesystem
    encoding, and then fall back on some common encodings. If none
    of the convertions are successful, "???" is returned.
    """
    if isinstance(string, unicode):
        return string
    for encoding in (_filesystemencoding, 'utf-8', 'latin-1'):
        try:
            ustring = unicode(string, encoding)
            return ustring
        except (UnicodeError, LookupError):
            pass
    return u'???'