59 lines
1.6 KiB
JavaScript
59 lines
1.6 KiB
JavaScript
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/*
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Copyright 2020 The Matrix.org Foundation C.I.C.
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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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class EventEmitter {
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constructor() {
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this._handlersByName = {};
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}
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emit(name, ...values) {
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const handlers = this._handlersByName[name];
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if (handlers) {
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for(const h of handlers) {
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h(...values);
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}
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}
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}
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on(name, callback) {
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let handlers = this._handlersByName[name];
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if (!handlers) {
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this.onFirstSubscriptionAdded(name);
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this._handlersByName[name] = handlers = new Set();
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}
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handlers.add(callback);
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return () => {
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this.off(name, callback);
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}
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}
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off(name, callback) {
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const handlers = this._handlersByName[name];
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if (handlers) {
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handlers.delete(callback);
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if (handlers.length === 0) {
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delete this._handlersByName[name];
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this.onLastSubscriptionRemoved(name);
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}
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}
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}
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}
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export class ViewModel extends EventEmitter {
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emitChange() {
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this.emit("change");
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}
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}
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