From 54701bd5f43d5664dea506c7d8641d709faf2c3a Mon Sep 17 00:00:00 2001
From: dougzilla32 <dougstein@gmail.com>
Date: Sun, 7 Oct 2018 14:49:29 +0900
Subject: [PATCH 1/2] 'Cancel' for PromiseKit -- provides the ability to cancel
 promises and promise chains

---
 Cartfile                     |  4 +++-
 Cartfile.resolved            |  2 +-
 Sources/BFTask+Promise.swift | 23 +++++++++++++++++++++--
 Tests/TestBolts.swift        | 28 ++++++++++++++++++++++++++++
 4 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/Cartfile b/Cartfile
index cf08ba9..e4e8729 100644
--- a/Cartfile
+++ b/Cartfile
@@ -1,2 +1,4 @@
-github "mxcl/PromiseKit" ~> 6.0
+#github "mxcl/PromiseKit" ~> 6.0
+github "dougzilla32/PromiseKit" "CoreCancel"
+
 github "BoltsFramework/Bolts-ObjC" ~> 1.9
diff --git a/Cartfile.resolved b/Cartfile.resolved
index cc39392..9991ce5 100644
--- a/Cartfile.resolved
+++ b/Cartfile.resolved
@@ -1,2 +1,2 @@
 github "BoltsFramework/Bolts-ObjC" "1.9.0"
-github "mxcl/PromiseKit" "6.3.3"
+github "dougzilla32/PromiseKit" "087b3cf470890ff9ea841212e2f3e285fecf3988"
diff --git a/Sources/BFTask+Promise.swift b/Sources/BFTask+Promise.swift
index de78655..0311251 100644
--- a/Sources/BFTask+Promise.swift
+++ b/Sources/BFTask+Promise.swift
@@ -9,8 +9,9 @@ extension Promise {
      */
     public func then<U>(on q: DispatchQueue? = conf.Q.map, body: @escaping (T) -> BFTask<U>) -> Promise<U?> {
         return then(on: q) { tee -> Promise<U?> in
+            let tokenSource = BFCancellationTokenSource()
             let task = body(tee)
-            return Promise<U?> { seal in
+            return Promise<U?>(cancellableTask: tokenSource) { seal in
                 task.continueWith(block: { task in
                     if task.isCompleted {
                         seal.fulfill(task.result)
@@ -20,8 +21,26 @@ extension Promise {
                         seal.reject(PMKError.invalidCallingConvention)
                     }
                     return nil
-                })
+                }, cancellationToken: tokenSource.token)
             }
         }
     }
 }
+
+/// Extend BFCancellationTokenSource to be a CancellableTask
+extension BFCancellationTokenSource: CancellableTask {
+    public var isCancelled: Bool {
+        return token.isCancellationRequested
+    }
+}
+
+//////////////////////////////////////////////////////////// Cancellable wrapper
+
+extension CancellablePromise {
+    /**
+     The provided closure is executed when this cancellable promise is resolved.
+     */
+    public func then<U>(on q: DispatchQueue? = conf.Q.map, body: @escaping (T) -> BFTask<U>) -> CancellablePromise<U?> {
+        return cancellable(promise.then(on: q, body: body), cancelContext: self.cancelContext)
+    }
+}
diff --git a/Tests/TestBolts.swift b/Tests/TestBolts.swift
index 6985661..1a63e40 100644
--- a/Tests/TestBolts.swift
+++ b/Tests/TestBolts.swift
@@ -21,3 +21,31 @@ class TestBolts: XCTestCase {
         waitForExpectations(timeout: 1)
     }
 }
+
+//////////////////////////////////////////////////////////// Cancellation
+
+extension TestBolts {
+    func testCancel() {
+        let ex = expectation(description: "")
+
+        let value = { NSString(string: "1") }
+        var task: BFTask<NSString>?
+        
+        let p = firstly { () -> CancellablePromise<Void> in
+            return CancellablePromise()
+        }
+        p.then { _ -> BFTask<NSString> in
+            task = BFTask(result: value())
+            p.cancel()
+            return task!
+        }.done { obj in
+            XCTAssertEqual(obj, value())
+            XCTFail()
+        }.catch(policy: .allErrors) {
+            $0.isCancelled ? ex.fulfill() : XCTFail()
+        }
+
+        waitForExpectations(timeout: 1)
+    }
+}
+

From 19e89ecf993577dd5b2fb7181961d59d977c11be Mon Sep 17 00:00:00 2001
From: dougzilla32 <dougstein@gmail.com>
Date: Tue, 16 Oct 2018 11:53:03 +0900
Subject: [PATCH 2/2] 'Cancel' for PromiseKit -- remove cancellable wrappers
 (they are unnecessary)

---
 Sources/BFTask+Promise.swift | 2 --
 1 file changed, 2 deletions(-)

diff --git a/Sources/BFTask+Promise.swift b/Sources/BFTask+Promise.swift
index 0311251..96b943a 100644
--- a/Sources/BFTask+Promise.swift
+++ b/Sources/BFTask+Promise.swift
@@ -34,8 +34,6 @@ extension BFCancellationTokenSource: CancellableTask {
     }
 }
 
-//////////////////////////////////////////////////////////// Cancellable wrapper
-
 extension CancellablePromise {
     /**
      The provided closure is executed when this cancellable promise is resolved.