Add EventSource class.

source/engine/core/eventsource.js

@@ -0,0 +1,27 @@
+export class EventSource
+{
+    constructor ()
+    {
+        this.eventListeners = new Map ();
+    }
+
+    AddEventListener (name, listener)
+    {
+        if (!this.eventListeners.has (name)) {
+            this.eventListeners.set (name, []);
+        }
+        let listeners = this.eventListeners.get (name);
+        listeners.push (listener);
+    }
+
+    NotifyEventListeners (name, ...args)
+    {
+        if (!this.eventListeners.has (name)) {
+            return;
+        }
+        let listeners = this.eventListeners.get (name);
+        for (let listener of listeners) {
+            listener (...args);
+        }
+    }
+}

source/engine/main.js

@@ -1,4 +1,5 @@
 import { IsDefined, ValueOrDefault, CopyObjectAttributes, IsObjectEmpty, EscapeHtmlChars } from './core/core.js';
+import { EventSource } from './core/eventsource.js';
 import { TaskRunner, RunTaskAsync, RunTasks, RunTasksBatch, WaitWhile } from './core/taskrunner.js';
 import { Exporter } from './export/exporter.js';
 import { Exporter3dm } from './export/exporter3dm.js';
@@ -76,6 +77,7 @@ export {
     CopyObjectAttributes,
     IsObjectEmpty,
     EscapeHtmlChars,
+    EventSource,
     TaskRunner,
     RunTaskAsync,
     RunTasks,

test/tests/core_test.js

@@ -46,6 +46,24 @@ describe ('Core', function () {
         OV.CopyObjectAttributes (src, dest3);
         assert.deepStrictEqual (dest3, {a : null, b : null, c : 6});
     });
+
+    it ('Event Source', function () {
+        let es = new OV.EventSource ();
+        let sumValues = 0;
+        es.AddEventListener ('first_event', (x) => {
+            sumValues += x;
+        });
+        es.AddEventListener ('first_event', (x) => {
+            sumValues += 2 * x;
+        });
+        es.AddEventListener ('second_event', (x, y) => {
+            sumValues += 3 * x;
+            sumValues += 3 * y;
+        });
+        es.NotifyEventListeners ('first_event', 5);
+        es.NotifyEventListeners ('second_event', 10, 15);
+        assert.strictEqual (sumValues, 90);
+    });
 });
 
 }