first commit

xterminal/source/emitter/index.ts

@@ -0,0 +1,77 @@
+import Disposable from "../base/disposable";
+import type {
+    XEventEmitter as IEventEmitter,
+    IEventListener,
+    IEventName
+} from "../types";
+import type { IEmitterState } from "./interface";
+
+/**
+ * EventEmitter class
+ *
+ * https://nodejs.dev/api/events.html
+ *
+ * https://nodejs.dev/en/learn/the-nodejs-event-emitter/
+ */
+export default class XEventEmitter extends Disposable implements IEventEmitter {
+    // private store for states
+    #state: IEmitterState;
+
+    constructor() {
+        super();
+        this.#state = {
+            stack: [],
+            store: new Map()
+        };
+        this.register({ dispose: () => this.#state.store.clear() });
+    }
+
+    public on(eventName: IEventName, listener: IEventListener): void {
+        const store = this.#state.store;
+        if (store.has(eventName)) {
+            store.get(eventName)?.add(listener);
+        } else {
+            store.set(eventName, new Set([listener]));
+        }
+    }
+
+    public once(eventName: IEventName, listener: IEventListener): void {
+        const evlistener = (...args: unknown[]) => {
+            listener.call(undefined, ...args);
+            this.off(eventName, evlistener);
+        };
+        const store = this.#state.store;
+        if (store.has(eventName)) {
+            store.get(eventName)?.add(evlistener);
+        } else {
+            store.set(eventName, new Set([evlistener]));
+        }
+    }
+
+    public off(eventName: IEventName, listener: IEventListener): void {
+        const all = this.#state.store.get(eventName);
+        if (all) {
+            for (const fn of all) {
+                if (fn === listener) {
+                    all.delete(listener);
+                    break;
+                }
+            }
+        }
+    }
+
+    public emit(eventName: IEventName, ...args: unknown[]): void {
+        if (this.isDisposed) return;
+        const stack = this.#state.stack;
+        if (stack.includes(eventName)) return;
+        const listeners = this.#state.store.get(eventName);
+        if (listeners) {
+            stack.push(eventName);
+            for (const fn of listeners) {
+                fn.call(undefined, ...args);
+            }
+            stack.pop();
+        }
+        return;
+    }
+}

xterminal/source/emitter/interface.ts

@@ -0,0 +1,9 @@
+import type { IEventName, IEventListener } from "../types";
+
+/**
+ * State of the Event Emitter
+ */
+export type IEmitterState = {
+    store: Map<IEventName, Set<IEventListener>>;
+    stack: IEventName[];
+};