Generalize DispatchQueues to Dispatcher-protocol objects

.travis.yml

@@ -1,54 +1,39 @@
+addons:
+  # To enable build artifact collection on S3, change "artifacts_disabled" below to "artifacts".
+  # Then define ARTIFACTS_KEY, ARTIFACTS_SECRET, ARTIFACTS_REGION, and ARTIFACTS_BUCKET in the
+  # Travis environment. If you enable artifacts here but do not define the configuration
+  # parameters, some jobs will fail.
+  artifacts_disabled:
+    paths:
+      # Collect build directory contents and logs if configured to do so in the environment, 
+      # but skip the Promises/A+ products because there are a lot. Also omit some larger binaries.
+      - $(find /var/folders -name '*carthage-xcodebuild*' -print 2>/dev/null | tr "\n" ":")
+      - $(if [ `git ls-files -o | grep build.js | wc -l` -eq 0 ]; then git ls-files -o | grep -v x86_64- | tr "\n" ":" ; fi)
 stages:
   - name: lint
-    if: branch = master OR branch =~ ^\d+\.\d+\.\d+$
+    if: branch = master OR branch =~ ^\d+\.\d+\.\d+$ OR branch =~ concat("^(",env(TRAVIS_BRANCHES),")$")
   - name: compile
-    if: branch = master OR branch =~ ^\d+\.\d+\.\d+$
+    if: branch = master OR branch =~ ^\d+\.\d+\.\d+$ OR branch =~ concat("^(",env(TRAVIS_BRANCHES),")$")
   - name: test
-    if: branch = master OR branch =~ ^\d+\.\d+\.\d+$
+    if: branch = master OR branch =~ ^\d+\.\d+\.\d+$ OR branch =~ concat("^(",env(TRAVIS_BRANCHES),")$")
   - name: deploy
     if: branch =~ ^\d+\.\d+\.\d+$
+
 jobs:
   include:
-    - &carthage
-      stage: compile
-      osx_image: xcode8.3
-      name: Carthage / Xcode 8.3
-      os: osx
-      language: objective-c
-      script: carthage build --no-skip-current --configuration Release
-    - <<: *carthage
-      osx_image: xcode9.2
-      name: Carthage / Xcode 9.2
-    - <<: *carthage
-      osx_image: xcode9.4
-      name: Carthage / Xcode 9.4
-    - <<: *carthage
-      osx_image: xcode10.1
-      name: Carthage / Xcode 10.0
 
+    # Lint stage
     - &pod
       stage: lint
-      osx_image: xcode8.3
-      env: SWIFT=3.1
-      name: pod lib lint --swift-version=3.1
+      osx_image: xcode10.1
+      env: SWIFT=3.4
+      name: pod lib lint --swift-version=3.4
       os: osx
       cache: cocoapods
       language: objective-c
       before_install: mv .github/PromiseKit.podspec .
       install: gem install cocoapods --prerelease --version 1.6.0.beta.2
       script: pod lib lint --subspec=PromiseKit/CorePromise --fail-fast --swift-version=$SWIFT
-    - <<: *pod
-      osx_image: xcode9.2
-      env: SWIFT=3.2
-      name: pod lib lint --swift-version=3.2
-    - <<: *pod
-      osx_image: xcode9.4
-      env: SWIFT=3.3
-      name: pod lib lint --swift-version=3.3
-    - <<: *pod
-      osx_image: xcode10.1
-      env: SWIFT=3.4
-      name: pod lib lint --swift-version=3.4
     - <<: *pod
       osx_image: xcode9.2
       env: SWIFT=4.0
@@ -62,10 +47,25 @@ jobs:
       env: SWIFT=4.2
       name: pod lib lint --swift-version=4.2
 
+    # Compile stage - Carthage macOS builds
+    - &carthage
+      stage: compile
+      osx_image: xcode10.1
+      name: Carthage / Xcode 10.1 (Swift 3.4)
+      env: SWIFT_VERSION=3.4
+      os: osx
+      language: objective-c
+      script: carthage build --no-skip-current --configuration Release
+    - <<: *carthage
+      osx_image: xcode10.1
+      env: SWIFT_VERSION=4.2
+      name: Carthage / Xcode 10.1 (Swift 4.2)
+
+    # Compile and test stages - Linux builds
     - &linux
       stage: compile
-      env: SWIFT_BUILD_VERSION=3 SWIFT_VERSION=4.0.3
-      name: Linux / Swift 3.2
+      env: SWIFT_BUILD_VERSION=4 SWIFT_VERSION=4.2.1
+      name: Linux / Swift 4.2 (compile)
       os: linux
       dist: trusty
       sudo: required
@@ -74,29 +74,50 @@ jobs:
       install: swift build -Xswiftc -swift-version -Xswiftc $SWIFT_BUILD_VERSION
       script: "true"
     - <<: *linux
-      env: SWIFT_BUILD_VERSION=3 SWIFT_VERSION=4.1.2
-      name: Linux / Swift 3.3
+      name: Linux / Swift 4.2 (test)
+      stage: test
+      script: swift test -Xswiftc -swift-version -Xswiftc $SWIFT_BUILD_VERSION
     - <<: *linux
-      env: SWIFT_BUILD_VERSION=3 SWIFT_VERSION=4.2.1
-      name: Linux / Swift 3.4
+      name: Linux / Swift 4.1 (compile)
+      env: SWIFT_BUILD_VERSION=4 SWIFT_VERSION=4.1.2
+    - <<: *linux
+      stage: test
+      name: Linux / Swift 4.1 (test)
+      env: SWIFT_BUILD_VERSION=4 SWIFT_VERSION=4.1.2
+      script: swift test -Xswiftc -swift-version -Xswiftc $SWIFT_BUILD_VERSION
     - <<: *linux
+      name: Linux / Swift 4.0 (compile)
       env: SWIFT_BUILD_VERSION=4 SWIFT_VERSION=4.0.3
-      name: Linux / Swift 4.0
+    - <<: *linux
       stage: test
-      script: swift test -Xswiftc -swift-version -Xswiftc 4
+      name: Linux / Swift 4.0 (test)
+      env: SWIFT_BUILD_VERSION=4 SWIFT_VERSION=4.0.3
+      script: swift test -Xswiftc -swift-version -Xswiftc $SWIFT_BUILD_VERSION
     - <<: *linux
-      env: SWIFT_BUILD_VERSION=4 SWIFT_VERSION=4.1.2
-      name: Linux / Swift 4.1
+      name: Linux / Swift 3 on tools 4.2.1 (compile)
+      env: SWIFT_BUILD_VERSION=3 SWIFT_VERSION=4.2.1
     - <<: *linux
-      env: SWIFT_BUILD_VERSION=4 SWIFT_VERSION=4.2.1
-      name: Linux / Swift 4.2
       stage: test
-      script: swift test -Xswiftc -swift-version -Xswiftc 4
+      name: Linux / Swift 3 on tools 4.2.1 (test)
+      env: SWIFT_BUILD_VERSION=3 SWIFT_VERSION=4.2.1
+      script: swift test -Xswiftc -swift-version -Xswiftc $SWIFT_BUILD_VERSION
 
+    # Compile stage - SwiftPM builds
+    - &swiftpm
+      stage: compile
+      name: SwiftPM / macOS / Xcode 9.4
+      os: osx
+      osx_image: xcode9.4
+      script: swift build
+    - <<: *swiftpm
+      osx_image: xcode10.1
+      name: SwiftPM / macOS / Xcode 10.1
+
+    # Test stage - macOS, iOS, and tvOS
     - &test
       stage: test
-      osx_image: xcode8.3
-      name: macOS / Xcode 8.3
+      osx_image: xcode10.1
+      name: macOS / Xcode 10.1 (Swift 3)
       os: osx
       language: objective-c
       env: DST='platform=OS X,arch=x86_64'
@@ -110,31 +131,20 @@ jobs:
       after_success:
         bash <(curl -s https://codecov.io/bash)
     - <<: *test
-      name: macOS / Xcode 9.2
-      osx_image: xcode9.2
-      script:
-        xcodebuild -scheme PromiseKit -destination="$DST" -enableCodeCoverage YES SWIFT_VERSION=4 test | xcpretty
-    - <<: *test
-      name: macOS / Xcode 9.4
-      osx_image: xcode9.4
-      script:
-        xcodebuild -scheme PromiseKit -destination="$DST" -enableCodeCoverage YES SWIFT_VERSION=4 test | xcpretty
-    - <<: *test
-      name: macOS / Xcode 10.0
+      name: macOS / Xcode 10.1 (Swift 4)
       osx_image: xcode10.1
       script:
         xcodebuild -scheme PromiseKit -destination="$DST" -enableCodeCoverage YES SWIFT_VERSION=4 test | xcpretty
-
     - <<: *test
-      name: iOS / Xcode 10.0
+      name: iOS / Xcode 10.1
       osx_image: xcode10.1
       env: DST='OS=12.0,name=iPhone SE'
-
     - <<: *test
-      name: tvOS / Xcode 10.0
+      name: tvOS / Xcode 10.1
       env: DST='OS=12.0,name=Apple TV'
       osx_image: xcode10.1
 
+    # Test stage - Promises/A+
     - stage: test
       name: Promises/A+ (via WebKit JavaScript Bridge)
       language: objective-c
@@ -155,16 +165,7 @@ jobs:
           - Tests/JS-A+/build
           - Tests/JS-A+/node_modules
 
-    - &swiftpm
-      stage: compile
-      name: SwiftPM / macOS / Xcode 9.4
-      os: osx
-      osx_image: xcode9.4
-      script: swift build
-    - <<: *swiftpm
-      osx_image: xcode10.1
-      name: SwiftPM / macOS / Xcode 10.0
-
+    # Deployment stage 
     - stage: deploy
       script: |
         set -eo pipefail

PromiseKit.xcodeproj/project.pbxproj

@@ -80,6 +80,8 @@
 		63CF6D80203CD19200EC8927 /* ThenableTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 63CF6D7F203CD19200EC8927 /* ThenableTests.swift */; };
 		63D9B2EF203385FD0075C00B /* race.m in Sources */ = {isa = PBXBuildFile; fileRef = 63D9B2EE203385FD0075C00B /* race.m */; };
 		63D9B2F120338D5D0075C00B /* Deprecations.swift in Sources */ = {isa = PBXBuildFile; fileRef = 63D9B2F020338D5D0075C00B /* Deprecations.swift */; };
+		BB2524DE20D729A60010F7B0 /* Dispatcher.swift in Sources */ = {isa = PBXBuildFile; fileRef = BB2524DD20D729A60010F7B0 /* Dispatcher.swift */; };
+		BB4AF7C520D820700008333D /* DispatcherTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = BB4AF7C320D819360008333D /* DispatcherTests.swift */; };
 		C013F7382048E3B6006B57B1 /* MockNodeEnvironment.swift in Sources */ = {isa = PBXBuildFile; fileRef = C013F7372048E3B6006B57B1 /* MockNodeEnvironment.swift */; };
 		C013F73A2049076A006B57B1 /* JSPromise.swift in Sources */ = {isa = PBXBuildFile; fileRef = C013F7392049076A006B57B1 /* JSPromise.swift */; };
 		C013F73C20494291006B57B1 /* JSAdapter.swift in Sources */ = {isa = PBXBuildFile; fileRef = C013F73B20494291006B57B1 /* JSAdapter.swift */; };
@@ -223,6 +225,8 @@
 		63CF6D7F203CD19200EC8927 /* ThenableTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ThenableTests.swift; sourceTree = "<group>"; };
 		63D9B2EE203385FD0075C00B /* race.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; name = race.m; path = Sources/race.m; sourceTree = "<group>"; };
 		63D9B2F020338D5D0075C00B /* Deprecations.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = Deprecations.swift; path = Sources/Deprecations.swift; sourceTree = "<group>"; };
+		BB2524DD20D729A60010F7B0 /* Dispatcher.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = Dispatcher.swift; path = Sources/Dispatcher.swift; sourceTree = "<group>"; };
+		BB4AF7C320D819360008333D /* DispatcherTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DispatcherTests.swift; sourceTree = "<group>"; };
 		C013F7372048E3B6006B57B1 /* MockNodeEnvironment.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; name = MockNodeEnvironment.swift; path = "Tests/JS-A+/MockNodeEnvironment.swift"; sourceTree = "<group>"; };
 		C013F7392049076A006B57B1 /* JSPromise.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = JSPromise.swift; path = "Tests/JS-A+/JSPromise.swift"; sourceTree = "<group>"; };
 		C013F73B20494291006B57B1 /* JSAdapter.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = JSAdapter.swift; path = "Tests/JS-A+/JSAdapter.swift"; sourceTree = "<group>"; };
@@ -352,6 +356,7 @@
 				635D640D1D59635300BC0AF5 /* ZalgoTests.swift */,
 				639BF755203DF02C00FA577B /* Utilities.swift */,
 				085B96B121A6358900E5E22F /* LoggingTests.swift */,
+				BB4AF7C320D819360008333D /* DispatcherTests.swift */,
 			);
 			name = Core;
 			path = Tests/CorePromise;
@@ -443,6 +448,7 @@
 				63B18AEB1F2D205C00B79E37 /* CustomStringConvertible.swift */,
 				63D9B2F020338D5D0075C00B /* Deprecations.swift */,
 				085B96BE21A9B37C00E5E22F /* LogEvent.swift */,
+				BB2524DD20D729A60010F7B0 /* Dispatcher.swift */,
 			);
 			name = Sources.swift;
 			sourceTree = "<group>";
@@ -677,6 +683,7 @@
 				635D64221D59635300BC0AF5 /* ZalgoTests.swift in Sources */,
 				635D64271D59635300BC0AF5 /* RaceTests.swift in Sources */,
 				632FBBE51F33B338008F8FBB /* CatchableTests.swift in Sources */,
+				BB4AF7C520D820700008333D /* DispatcherTests.swift in Sources */,
 				63CF6D80203CD19200EC8927 /* ThenableTests.swift in Sources */,
 				635D642B1D59635300BC0AF5 /* StressTests.swift in Sources */,
 				630A805A203CEF6800D25F23 /* WhenTests.m in Sources */,
@@ -750,6 +757,7 @@
 				085B96BF21A9B37C00E5E22F /* LogEvent.swift in Sources */,
 				6330B5E11F2E991200D60528 /* Configuration.swift in Sources */,
 				63B912AA1F1D7B1300D49110 /* firstly.swift in Sources */,
+				BB2524DE20D729A60010F7B0 /* Dispatcher.swift in Sources */,
 				636A29211F1C1716001229C2 /* Thenable.swift in Sources */,
 				632FBBE31F33B273008F8FBB /* Catchable.swift in Sources */,
 				63B0AC851D595E6300FA21D9 /* dispatch_promise.m in Sources */,

Sources/Box.swift

@@ -82,20 +82,3 @@ final class EmptyBox<T>: Box<T> {
         }
     }
 }
-
-
-extension Optional where Wrapped: DispatchQueue {
-    @inline(__always)
-    func async(flags: DispatchWorkItemFlags?, _ body: @escaping() -> Void) {
-        switch self {
-        case .none:
-            body()
-        case .some(let q):
-            if let flags = flags {
-                q.async(flags: flags, execute: body)
-            } else {
-                q.async(execute: body)
-            }
-        }
-    }
-}