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from mod_pywebsocket import common
from mod_pywebsocket.extensions import _available_processors
from mod_pywebsocket.extensions import ExtensionProcessorInterface
from mod_pywebsocket import util


class DeflateStreamExtensionProcessor(ExtensionProcessorInterface):
    """WebSocket DEFLATE stream extension processor.

    Specification:
    Section 9.2.1 in
    http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-10
    """

    def __init__(self, request):
        ExtensionProcessorInterface.__init__(self, request)
        self._logger = util.get_class_logger(self)

    def name(self):
        return common.DEFLATE_STREAM_EXTENSION

    def _get_extension_response_internal(self):
        if len(self._request.get_parameter_names()) != 0:
            return None

        self._logger.debug(
            'Enable %s extension', common.DEFLATE_STREAM_EXTENSION)

        return common.ExtensionParameter(common.DEFLATE_STREAM_EXTENSION)

    def _setup_stream_options_internal(self, stream_options):
        stream_options.deflate_stream = True


_available_processors[common.DEFLATE_STREAM_EXTENSION] = (
    DeflateStreamExtensionProcessor)


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