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- # -*- coding: utf-8 -*-
- # Copyright 2018 New Vector Ltd
- #
- # Licensed under the Apache License, Version 2.0 (the "License");
- # you may not use this file except in compliance with the License.
- # You may obtain a copy of the License at
- #
- # http://www.apache.org/licenses/LICENSE-2.0
- #
- # Unless required by applicable law or agreed to in writing, software
- # distributed under the License is distributed on an "AS IS" BASIS,
- # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- # See the License for the specific language governing permissions and
- # limitations under the License.
- import logging
- from twisted.internet import defer
- logger = logging.getLogger(__name__)
- class StateDeltasHandler(object):
- def __init__(self, hs):
- self.store = hs.get_datastore()
- @defer.inlineCallbacks
- def _get_key_change(self, prev_event_id, event_id, key_name, public_value):
- """Given two events check if the `key_name` field in content changed
- from not matching `public_value` to doing so.
- For example, check if `history_visibility` (`key_name`) changed from
- `shared` to `world_readable` (`public_value`).
- Returns:
- None if the field in the events either both match `public_value`
- or if neither do, i.e. there has been no change.
- True if it didnt match `public_value` but now does
- False if it did match `public_value` but now doesn't
- """
- prev_event = None
- event = None
- if prev_event_id:
- prev_event = yield self.store.get_event(prev_event_id, allow_none=True)
- if event_id:
- event = yield self.store.get_event(event_id, allow_none=True)
- if not event and not prev_event:
- logger.debug("Neither event exists: %r %r", prev_event_id, event_id)
- return None
- prev_value = None
- value = None
- if prev_event:
- prev_value = prev_event.content.get(key_name)
- if event:
- value = event.content.get(key_name)
- logger.debug("prev_value: %r -> value: %r", prev_value, value)
- if value == public_value and prev_value != public_value:
- return True
- elif value != public_value and prev_value == public_value:
- return False
- else:
- return None
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