forked from mystiq/hydrogen-web
101 lines
3.1 KiB
TypeScript
101 lines
3.1 KiB
TypeScript
/*
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Copyright 2020 Bruno Windels <bruno@windels.cloud>
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Copyright 2021 Daniel Fedorin <danila.fedorin@gmail.com>
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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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type Handler<T> = (value?: T) => void;
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export class EventEmitter<T> {
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private _handlersByName: { [event in keyof T]?: Set<Handler<T[event]>> }
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constructor() {
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this._handlersByName = {};
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}
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emit<K extends keyof T>(name: K, value?: T[K]): void {
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const handlers = this._handlersByName[name];
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if (handlers) {
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handlers.forEach(h => h(value));
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}
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}
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disposableOn<K extends keyof T>(name: K, callback: Handler<T[K]>): () => void {
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this.on(name, 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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on<K extends keyof T>(name: K, callback: Handler<T[K]>): void {
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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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}
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off<K extends keyof T>(name: K, callback: Handler<T[K]>): void {
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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.size === 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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onFirstSubscriptionAdded<K extends keyof T>(name: K): void {}
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onLastSubscriptionRemoved<K extends keyof T>(name: K): void {}
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}
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export function tests() {
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return {
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test_on_off(assert) {
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let counter = 0;
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const e = new EventEmitter<{ change: never }>();
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const callback = () => counter += 1;
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e.on("change", callback);
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e.emit("change");
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e.off("change", callback);
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e.emit("change");
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assert.equal(counter, 1);
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},
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test_emit_value(assert) {
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let value = 0;
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const e = new EventEmitter<{ change: number }>();
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const callback = (v) => value = v;
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e.on("change", callback);
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e.emit("change", 5);
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e.off("change", callback);
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assert.equal(value, 5);
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},
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test_double_on(assert) {
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let counter = 0;
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const e = new EventEmitter<{ change: never }>();
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const callback = () => counter += 1;
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e.on("change", callback);
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e.on("change", callback);
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e.emit("change");
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e.off("change", callback);
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assert.equal(counter, 1);
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}
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};
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}
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