75 lines
3 KiB
TypeScript
75 lines
3 KiB
TypeScript
/*
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Copyright 2019 New Vector Ltd.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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import { SettingLevel } from "./SettingLevel";
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export type CallbackFn = (changedInRoomId: string, atLevel: SettingLevel, newValAtLevel: any) => void;
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const IRRELEVANT_ROOM: string = null;
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/**
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* Generalized management class for dealing with watchers on a per-handler (per-level)
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* basis without duplicating code. Handlers are expected to push updates through this
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* class, which are then proxied outwards to any applicable watchers.
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*/
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export class WatchManager {
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private watchers = new Map<string, Map<string | symbol, CallbackFn[]>>(); // settingName -> roomId -> CallbackFn[]
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// Proxy for handlers to delegate changes to this manager
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public watchSetting(settingName: string, roomId: string | null, cb: CallbackFn) {
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if (!this.watchers.has(settingName)) this.watchers.set(settingName, new Map());
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if (!this.watchers.get(settingName).has(roomId)) this.watchers.get(settingName).set(roomId, []);
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this.watchers.get(settingName).get(roomId).push(cb);
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}
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// Proxy for handlers to delegate changes to this manager
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public unwatchSetting(cb: CallbackFn) {
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this.watchers.forEach((map) => {
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map.forEach((callbacks) => {
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let idx;
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while ((idx = callbacks.indexOf(cb)) !== -1) {
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callbacks.splice(idx, 1);
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}
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});
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});
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}
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public notifyUpdate(settingName: string, inRoomId: string | null, atLevel: SettingLevel, newValueAtLevel: any) {
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// Dev note: We could avoid raising changes for ultimately inconsequential changes, but
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// we also don't have a reliable way to get the old value of a setting. Instead, we'll just
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// let it fall through regardless and let the receiver dedupe if they want to.
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if (!this.watchers.has(settingName)) return;
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const roomWatchers = this.watchers.get(settingName);
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const callbacks = [];
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if (inRoomId !== null && roomWatchers.has(inRoomId)) {
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callbacks.push(...roomWatchers.get(inRoomId));
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}
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if (!inRoomId) {
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// Fire updates to all the individual room watchers too, as they probably care about the change higher up.
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callbacks.push(...Array.from(roomWatchers.values()).flat(1));
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} else if (roomWatchers.has(IRRELEVANT_ROOM)) {
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callbacks.push(...roomWatchers.get(IRRELEVANT_ROOM));
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}
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for (const callback of callbacks) {
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callback(inRoomId, atLevel, newValueAtLevel);
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}
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}
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}
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