From 361a53befa3d0a1ac4bab5b6690ef4c6ae301628 Mon Sep 17 00:00:00 2001
From: Ben Lesh <blesh@netflix.com>
Date: Wed, 5 Aug 2015 23:49:45 -0700
Subject: [PATCH] feat(operator): add toPromise operator. closes #159

---
 spec/operators/toPromise-spec.js | 22 ++++++++++++++++++++++
 src/Observable.ts                |  3 ++-
 src/Rx.ts                        |  2 ++
 src/operators/toPromise.ts       |  8 ++++++++
 4 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 spec/operators/toPromise-spec.js
 create mode 100644 src/operators/toPromise.ts

diff --git a/spec/operators/toPromise-spec.js b/spec/operators/toPromise-spec.js
new file mode 100644
index 0000000000..fc8323503a
--- /dev/null
+++ b/spec/operators/toPromise-spec.js
@@ -0,0 +1,22 @@
+/* globals describe, it, expect */
+var Rx = require('../../dist/cjs/Rx');
+var promise = require('promise');
+var Observable = Rx.Observable;
+
+describe('Observable.prototype.toPromise()', function () {
+  it('should convert an Observable to a promise of its last value', function (done) {
+    Observable.of(1, 2, 3).toPromise(promise).then(function (x) {
+      expect(x).toBe(3);
+      done();
+    });
+  });
+  
+  it('should handle errors properly', function (done) {
+    Observable.throw('bad').toPromise(promise).then(function () {
+      throw 'should not be called';
+    }, function (err) {
+      expect(err).toBe('bad');
+      done();
+    });
+  });
+});
\ No newline at end of file
diff --git a/src/Observable.ts b/src/Observable.ts
index 52bb680a2a..2c9813a1bf 100644
--- a/src/Observable.ts
+++ b/src/Observable.ts
@@ -129,7 +129,8 @@ export default class Observable<T> {
   take: (count: number) => Observable<T>;
   takeUntil: (observable: Observable<any>) => Observable<T>;
   partition: (predicate: (x: T) => boolean) => Observable<T>[];
-
+  toPromise: (PromiseCtor: PromiseConstructor) => Promise<T>;
+  
   observeOn: (scheduler: Scheduler, delay?: number) => Observable<T>;
   subscribeOn: (scheduler: Scheduler, delay?: number) => Observable<T>;
 
diff --git a/src/Rx.ts b/src/Rx.ts
index da6e2a3ef6..3d82fdaed2 100644
--- a/src/Rx.ts
+++ b/src/Rx.ts
@@ -122,8 +122,10 @@ observableProto.observeOn = observeOn;
 observableProto.subscribeOn = subscribeOn;
 
 import partition from './operators/partition';
+import toPromise from './operators/toPromise';
 
 observableProto.partition = partition;
+observableProto.toPromise = toPromise;
 
 import _catch from './operators/catch';
 import retryWhen from './operators/retryWhen';
diff --git a/src/operators/toPromise.ts b/src/operators/toPromise.ts
new file mode 100644
index 0000000000..b880a32326
--- /dev/null
+++ b/src/operators/toPromise.ts
@@ -0,0 +1,8 @@
+import Subscriber from '../Subscriber';
+
+export default function toPromise<T>(PromiseCtor: PromiseConstructor = Promise): Promise<T> {
+  return new PromiseCtor((resolve, reject) => {
+    let value: any;
+    this.subscribe(x => value = x, err => reject(err), () => resolve(value));
+  });
+}
\ No newline at end of file