Add EventEmitter2

src/common/EventEmitter2.test.ts

@@ -0,0 +1,31 @@
+/**
+ * Copyright (c) 2019 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { assert } from 'chai';
+import { EventEmitter2 } from './EventEmitter2';
+
+describe('EventEmitter2', () => {
+  it('should fire listeners multiple times', () => {
+    const order: string[] = [];
+    const emitter = new EventEmitter2<number>();
+    emitter.event(data => order.push(data + 'a'));
+    emitter.event(data => order.push(data + 'b'));
+    emitter.fire(1);
+    emitter.fire(2);
+    assert.deepEqual(order, [ '1a', '1b', '2a', '2b' ]);
+  });
+
+  it('should not fire listeners once disposed', () => {
+    const order: string[] = [];
+    const emitter = new EventEmitter2<number>();
+    emitter.event(data => order.push(data + 'a'));
+    const disposeB = emitter.event(data => order.push(data + 'b'));
+    emitter.event(data => order.push(data + 'c'));
+    emitter.fire(1);
+    disposeB.dispose();
+    emitter.fire(2);
+    assert.deepEqual(order, [ '1a', '1b', '1c', '2a', '2c' ]);
+  });
+});

src/common/EventEmitter2.ts

@@ -0,0 +1,47 @@
+/**
+ * Copyright (c) 2019 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { IDisposable } from 'xterm';
+
+type Listener<T> = (e: T) => void;
+
+export interface IEvent<T> {
+  (listener: (e: T) => any): IDisposable;
+}
+
+export class EventEmitter2<T> {
+  private _listeners: Listener<T>[] = [];
+  private _event?: IEvent<T>;
+
+  public get event(): IEvent<T> {
+    if (!this._event) {
+      this._event = (listener: (e: T) => any) => {
+        this._listeners.push(listener);
+        const disposable = {
+          dispose: () => {
+            for (let i = 0; i < this._listeners.length; i++) {
+              if (this._listeners[i] === listener) {
+                this._listeners.splice(i, 1);
+                return;
+              }
+            }
+          }
+        };
+        return disposable;
+      };
+    }
+    return this._event;
+  }
+
+  public fire(data: T): void {
+    const queue: Listener<T>[] = [];
+    for (let i = 0; i < this._listeners.length; i++) {
+      queue.push(this._listeners[i]);
+    }
+    for (let i = 0; i < queue.length; i++) {
+      queue[i].call(undefined, data);
+    }
+  }
+}