Starting Settings modules + implemented basic events for ECMAScript <=> Qt compat.

common/src/events.mjs

@@ -0,0 +1,96 @@
+/**
+ *  LogarithmPlotter - 2D plotter software to make BODE plots, sequences and distribution functions.
+ *  Copyright (C) 2021-2024  Ad5001
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/**
+ * We do not inherit the DOM's Event, because not only the DOM part is unnecessary,
+ * but also because it does not exist within Qt environments.
+ */
+
+
+export class BaseEvent {
+    /**
+     * @property {string} name - Name of the event.
+     */
+    constructor(name) {
+        this.name = name
+    }
+}
+
+
+/**
+ * Base class for all classes which can emit events.
+ */
+export class BaseEventEmitter {
+    static emits = []
+    
+    /** @type {Record<string, function[]>} */
+    #listeners = {}
+    
+    constructor() {
+        for(const eventType of this.constructor.emits) {
+            this.#listeners[eventType] = new Set()
+        }
+    }
+    
+    /**
+     * Adds a listener to an event that can be emitted by this object.
+     * 
+     * @param {string} eventType - Name of the event to listen to. Throws an error if this object does not emit this kind of event.
+     * @param {function(BaseEvent)} eventListener - The function to be called back when the event is emitted.
+     */
+    addEventListener(eventType, eventListener) {
+        if(!this.emits.includes(eventType)) {
+            const className = this.constructor.name
+            const eventTypes = this.constructor.emits.join(", ")
+            throw new Error(`Cannot listen to unknown event ${eventType} in class ${className}. ${className} only emits: ${eventTypes}`)
+        }
+        if(!this.#listeners[eventType].has(eventListener))
+            this.#listeners[eventType].add(eventListener)
+    }
+    
+    /**
+     * Remvoes a listener from an event that can be emitted by this object.
+     * 
+     * @param {string} eventType - Name of the event that was listened to. Throws an error if this object does not emit this kind of event.
+     * @param {function(BaseEvent)} eventListener - The function previously registered as a listener.
+     * @returns {boolean} True if the listener was removed, false if it was not found.
+     */
+    removeEventListener(eventType, eventListener) {
+        if(!this.emits.includes(eventType)) {
+            const className = this.constructor.name
+            const eventTypes = this.constructor.emits.join(", ")
+            throw new Error(`Cannot listen to unknown event ${eventType} in class ${className}. ${className} only emits: ${eventTypes}`)
+        }
+        return this.#listeners[eventType].delete(eventListener)
+        
+    }
+    
+    /**
+     * Emits an event to all of its listeners.
+     * 
+     * @param {BaseEvent} e
+     */
+    emit(e) {
+        if(!(e instanceof BaseEvent))
+            throw new Error("Cannot emit non event object.")
+        if(!this.emits.includes(e.name))
+            throw new Error(`Cannot emit event '${e.name}' from class ${this.constructor.name}. ${this.constructor.name} can only emits: ${this.constructor.emits.join(", ")}.`)
+        for(const listener of this.#listeners[e.name])
+            listener(e)
+    }
+}