element-web/src/settings/WatchManager.js
Travis Ralston 7ea4008daa Implement support for watching for changes in settings
This implements a dream of one day being able to listen for changes in a settings to react to them, regardless of which device actually changed the setting. The use case for this kind of thing is extremely limited, but when it is needed it should be more than powerful enough.
2019-02-22 17:09:07 -07:00

57 lines
2.1 KiB
JavaScript

/*
Copyright 2019 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.
*/
/**
* Generalized management class for dealing with watchers on a per-handler (per-level)
* basis without duplicating code. Handlers are expected to push updates through this
* class, which are then proxied outwards to any applicable watchers.
*/
export class WatchManager {
_watchers = {}; // { settingName: { roomId: callbackFns[] } }
// Proxy for handlers to delegate changes to this manager
watchSetting(settingName, roomId, cb) {
if (!this._watchers[settingName]) this._watchers[settingName] = {};
if (!this._watchers[settingName][roomId]) this._watchers[settingName][roomId] = [];
this._watchers[settingName][roomId].push(cb);
}
// Proxy for handlers to delegate changes to this manager
unwatchSetting(cb) {
for (const settingName of Object.keys(this._watchers)) {
for (const roomId of Object.keys(this._watchers[settingName])) {
let idx;
while ((idx = this._watchers[settingName][roomId].indexOf(cb)) !== -1) {
this._watchers[settingName][roomId].splice(idx, 1);
}
}
}
}
notifyUpdate(settingName, inRoomId, newValue) {
if (!this._watchers[settingName]) return;
const roomWatchers = this._watchers[settingName];
const callbacks = [];
if (inRoomId !== null && roomWatchers[inRoomId]) callbacks.push(...roomWatchers[inRoomId]);
if (roomWatchers[null]) callbacks.push(...roomWatchers[null]);
for (const callback of callbacks) {
callback(inRoomId, newValue);
}
}
}