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"""Utilities for use with the base interface of RPC Framework."""

import collections

from grpc.framework.interfaces.base import base


class _Completion(base.Completion,
                  collections.namedtuple('_Completion', ('terminal_metadata',
                                                         'code', 'message',))):
    """A trivial implementation of base.Completion."""


class _Subscription(base.Subscription,
                    collections.namedtuple('_Subscription', (
                        'kind', 'termination_callback', 'allowance', 'operator',
                        'protocol_receiver',))):
    """A trivial implementation of base.Subscription."""


_NONE_SUBSCRIPTION = _Subscription(base.Subscription.Kind.NONE, None, None,
                                   None, None)


def completion(terminal_metadata, code, message):
    """Creates a base.Completion aggregating the given operation values.

  Args:
    terminal_metadata: A terminal metadata value for an operaton.
    code: A code value for an operation.
    message: A message value for an operation.

  Returns:
    A base.Completion aggregating the given operation values.
  """
    return _Completion(terminal_metadata, code, message)


def full_subscription(operator, protocol_receiver):
    """Creates a "full" base.Subscription for the given base.Operator.

  Args:
    operator: A base.Operator to be used in an operation.
    protocol_receiver: A base.ProtocolReceiver to be used in an operation.

  Returns:
    A base.Subscription of kind base.Subscription.Kind.FULL wrapping the given
      base.Operator and base.ProtocolReceiver.
  """
    return _Subscription(base.Subscription.Kind.FULL, None, None, operator,
                         protocol_receiver)
