element-web/src/settings/WatchManager.js
Travis Ralston 93673eff12 Use a global WatchManager for settings
Fixes https://github.com/vector-im/riot-web/issues/8936

Watchers are now managed by the SettingsStore itself through a global/default watch manager. As per the included documentation, the watch manager dispatches updates to callbacks which are redirected by the SettingsStore for consumer safety.
2019-02-26 12:52:59 -07:00

61 lines
2.4 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, atLevel, newValueAtLevel) {
// Dev note: We could avoid raising changes for ultimately inconsequential changes, but
// we also don't have a reliable way to get the old value of a setting. Instead, we'll just
// let it fall through regardless and let the receiver dedupe if they want to.
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, atLevel, newValueAtLevel);
}
}
}