def url_decode_stream(stream, charset='utf-8', decode_keys=False,
                      include_empty=True, errors='replace', separator='&',
                      cls=None, limit=None, return_iterator=False):
    """Works like :func:`url_decode` but decodes a stream.  The behavior
    of stream and limit follows functions like
    :func:`~werkzeug.wsgi.make_line_iter`.  The generator of pairs is
    directly fed to the `cls` so you can consume the data while it's
    parsed.

    .. versionadded:: 0.8

    :param stream: a stream with the encoded querystring
    :param charset: the charset of the query string.
    :param decode_keys: set to `True` if you want the keys to be decoded
                        as well.
    :param include_empty: Set to `False` if you don't want empty values to
                          appear in the dict.
    :param errors: the decoding error behavior.
    :param separator: the pair separator to be used, defaults to ``&``
    :param cls: an optional dict class to use.  If this is not specified
                       or `None` the default :class:`MultiDict` is used.
    :param limit: the content length of the URL data.  Not necessary if
                  a limited stream is provided.
    :param return_iterator: if set to `True` the `cls` argument is ignored
                            and an iterator over all decoded pairs is
                            returned
    """
    if return_iterator:
        cls = lambda x: x
    elif cls is None:
        cls = MultiDict
    pair_iter = make_chunk_iter(stream, separator, limit)
    return cls(_url_decode_impl(pair_iter, charset, decode_keys,
                                include_empty, errors))