feat(core): introduced lucene style search

ts/classes.watcher.ts

@@ -0,0 +1,37 @@
+import { SmartDataDbDoc } from './classes.doc.js';
+import * as plugins from './plugins.js';
+
+/**
+ * a wrapper for the native mongodb cursor. Exposes better
+ */
+export class SmartdataDbWatcher<T = any> {
+  // STATIC
+  public readyDeferred = plugins.smartpromise.defer();
+
+  // INSTANCE
+  private changeStream: plugins.mongodb.ChangeStream<T>;
+
+  public changeSubject = new plugins.smartrx.rxjs.Subject<T>();
+  constructor(
+    changeStreamArg: plugins.mongodb.ChangeStream<T>,
+    smartdataDbDocArg: typeof SmartDataDbDoc
+  ) {
+    this.changeStream = changeStreamArg;
+    this.changeStream.on('change', async (item: any) => {
+      if (!item.fullDocument) {
+        this.changeSubject.next(null);
+        return;
+      }
+      this.changeSubject.next(
+        smartdataDbDocArg.createInstanceFromMongoDbNativeDoc(item.fullDocument) as any as T
+      );
+    });
+    plugins.smartdelay.delayFor(0).then(() => {
+      this.readyDeferred.resolve();
+    });
+  }
+
+  public async close() {
+    await this.changeStream.close();
+  }
+}