64 lines
1.8 KiB
JavaScript
64 lines
1.8 KiB
JavaScript
/*
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* Copyright © 2020 Luciano Iam <oss@lucianoiam.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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export default class Observable {
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constructor () {
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this._observers = {};
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}
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addObserver (event, observer) {
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// event=undefined means the caller is interested in observing all events
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if (!(event in this._observers)) {
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this._observers[event] = [];
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}
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this._observers[event].push(observer);
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}
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removeObserver (event, observer) {
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// event=undefined means the caller is not interested in any event anymore
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if (typeof(event) == 'undefined') {
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for (const event in this._observers) {
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this.removeObserver(event, observer);
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}
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} else {
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const index = this._observers[event].indexOf(observer);
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if (index > -1) {
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this._observers[event].splice(index, 1);
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}
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}
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}
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notifyObservers (event, ...args) {
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// always notify observers that observe all events
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if (undefined in this._observers) {
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for (const observer of this._observers[undefined]) {
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observer(event, ...args);
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}
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}
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if (event in this._observers) {
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for (const observer of this._observers[event]) {
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observer(...args);
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}
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}
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}
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}
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