compat.py 文件源码

def _escape_strings(val):
        """If val is pure ascii, returns it as a str().  Otherwise, escapes
        bytes objects into a sequence of escaped bytes:

        b'\xc3\xb4\xc5\xd6' -> u'\\xc3\\xb4\\xc5\\xd6'

        and escapes unicode objects into a sequence of escaped unicode
        ids, e.g.:

        '4\\nV\\U00043efa\\x0eMXWB\\x1e\\u3028\\u15fd\\xcd\\U0007d944'

        note:
           the obvious "v.decode('unicode-escape')" will return
           valid utf-8 unicode if it finds them in bytes, but we
           want to return escaped bytes for any byte, even if they match
           a utf-8 string.

        """
        if isinstance(val, bytes):
            if val:
                # source: http://goo.gl/bGsnwC
                encoded_bytes, _ = codecs.escape_encode(val)
                return encoded_bytes.decode('ascii')
            else:
                # empty bytes crashes codecs.escape_encode (#1087)
                return ''
        else:
            return val.encode('unicode_escape').decode('ascii')