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- # 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 enum import Enum, auto
- from typing import TYPE_CHECKING, Optional
- if TYPE_CHECKING:
- from synapse.server import HomeServer
- logger = logging.getLogger(__name__)
- class MatchChange(Enum):
- no_change = auto()
- now_true = auto()
- now_false = auto()
- class StateDeltasHandler:
- def __init__(self, hs: "HomeServer"):
- self.store = hs.get_datastores().main
- async def _get_key_change(
- self,
- prev_event_id: Optional[str],
- event_id: Optional[str],
- key_name: str,
- public_value: str,
- ) -> MatchChange:
- """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`).
- """
- prev_event = None
- event = None
- if prev_event_id:
- prev_event = await self.store.get_event(prev_event_id, allow_none=True)
- if event_id:
- event = await 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 MatchChange.no_change
- 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 MatchChange.now_true
- elif value != public_value and prev_value == public_value:
- return MatchChange.now_false
- else:
- return MatchChange.no_change
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