From e2e89548dc1e91fd7cbaca25c80fa487e9b6233c Mon Sep 17 00:00:00 2001
From: Ben Lesh <blesh@netflix.com>
Date: Tue, 13 Oct 2015 15:51:28 -0700
Subject: [PATCH] perf(filter): add fast-path for filtering scalar observables

---
 src/observables/ScalarObservable.ts | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/observables/ScalarObservable.ts b/src/observables/ScalarObservable.ts
index 8e754b95f4..867c5cae69 100644
--- a/src/observables/ScalarObservable.ts
+++ b/src/observables/ScalarObservable.ts
@@ -62,4 +62,15 @@ export default class ScalarObservable<T> extends Observable<T> {
       return new ScalarObservable(project.call(thisArg || this, this.value, 0));
     }
   }
+
+  filter(select: (x: T, ix?: number) => boolean, thisArg?: any): Observable<T> {
+    let result = tryCatch(select).call(thisArg || this, this.value, 0);
+    if (result === errorObject) {
+      return new ErrorObservable(errorObject.e);
+    } else if (result) {
+      return this;
+    } else {
+      return new EmptyObservable();
+    }
+  }
 }