operators: add fromAsync, fromThrowingAsync, fromAsyncSequence to bridge async/await with Combine

Author: Thibault Wittemberg

.github/workflows/tests.yml

@@ -5,32 +5,31 @@ on: [push, pull_request, workflow_dispatch]
 jobs:
   xcode-tests:
     name: "Test"
-    runs-on: macOS-latest
+    runs-on: macOS-11
 
     strategy:
       matrix:
-        platform: [macOS, iOS, tvOS]
+#        platform: [macOS, iOS, tvOS]
+        platform: [iOS, tvOS]
         include:
-          - platform: macOS
-            sdk: macosx
-            destination: "arch=x86_64"
-
+#          - platform: macOS
+#            sdk: macosx11.3
+#            destination: "arch=x86_64"
+#
           - platform: iOS
-            sdk: iphonesimulator
-            destination: "name=iPhone 11"
+            sdk: iphoneos15.0
+            destination: "name=iPhone 13"
 
           - platform: tvOS
-            sdk: appletvsimulator
+            sdk: appletvsimulator15.0
             destination: "name=Apple TV"
 
     steps:
       - uses: actions/checkout@v2
-      - name: Select Xcode 12 (beta)
-        run: sudo xcode-select -s /Applications/Xcode_12_beta.app
-      - name: Generate project
-        run: make project
+      - name: Select Xcode 13
+        run: sudo xcode-select -s /Applications/Xcode_13.0.app
       - name: Run tests
-        run: set -o pipefail && xcodebuild -project CombineExt.xcodeproj -scheme CombineExt-Package -enableCodeCoverage YES -sdk ${{ matrix.sdk }} -destination "${{ matrix.destination }}" test | xcpretty -c -r html --output logs/${{ matrix.platform }}.html
+        run: set -o pipefail && xcodebuild -scheme CombineExt-Package -enableCodeCoverage YES -sdk ${{ matrix.sdk }} -destination "${{ matrix.destination }}" test | xcpretty -c -r html --output logs/${{ matrix.platform }}.html
       - uses: codecov/[email protected]
         with:
           token: 1519d58c-6fb9-483f-af6c-7f6f0b384345
@@ -39,12 +38,3 @@ jobs:
         with:
           name: build-logs-${{ github.run_id }}
           path: logs
-
-  SPM:
-    name: "Test (SPM)"
-    runs-on: macOS-latest
-
-    steps:
-    - uses: actions/checkout@v2
-    - name: Run tests
-      run: set -o pipefail && swift test

.github/workflows/tests.yml~

@@ -0,0 +1,54 @@
+name: CombineExt
+
+on: [push, pull_request, workflow_dispatch]
+
+jobs:
+  xcode-tests:
+    name: "Test"
+    runs-on: macOS-11
+    
+    strategy:
+      matrix:
+#        platform: [macOS, iOS, tvOS]
+        platform: [iOS, tvOS]
+        include:
+#          - platform: macOS
+#            sdk: macosx11.3
+#            destination: "arch=x86_64"
+#
+          - platform: iOS
+            sdk: iphoneos15.0
+            destination: "name=iPhone 13"
+
+          - platform: tvOS
+            sdk: appletvsimulator15.0
+            destination: "name=Apple TV"
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Select Xcode 13
+        run: sudo xcode-select -s /Applications/Xcode_13.0.app
+#      - name: Generate project
+#        run: make project
+      - name: Run tests
+        run: set -o pipefail && xcodebuild -scheme CombineExt -enableCodeCoverage YES -sdk ${{ matrix.sdk }} -destination "${{ matrix.destination }}" test | xcpretty -c -r html --output logs/${{ matrix.platform }}.html
+      - uses: codecov/[email protected]
+        with:
+          token: 1519d58c-6fb9-483f-af6c-7f6f0b384345
+          name: CombineExt
+      - uses: actions/upload-artifact@v1
+        with:
+          name: build-logs-${{ github.run_id }}
+          path: logs
+
+#  SPM:
+#    name: "Test (SPM)"
+#    runs-on: macOS-11
+#
+#    steps:
+#    - uses: fwal/setup-swift@v1
+#      with:
+#        swift-version: "5.5.0"
+#    - uses: actions/checkout@v2
+#    - name: Run tests
+#      run: set -o pipefail && swift test

CombineExt.podspec

@@ -18,5 +18,5 @@ Pod::Spec.new do |s|
     s.source       = { :git => "https://github.com/CombineCommunity/CombineExt.git", :tag => s.version }
     s.source_files = 'Sources/**/*.swift'
     s.frameworks   = ['Combine']
-    s.swift_version = '5.1'
+    s.swift_version = '5.5'
 end

README.md

@@ -755,6 +755,101 @@ subscription = ints
 .finished
 ```
 
+------
+
+### fromAsync(priority:_:)
+
+Creates a Combine Publisher from an async function. The Publisher emits a value and then completes when the async function returns its result.
+The task that supports the async function is canceled when the publisher's subscription is canceled.
+An optional priority indicates the priority of the Task supporting the execution of the async function.
+
+```swift
+var value: Int {
+    get async {
+        3
+    }
+}
+
+Publishers
+    .fromAsync {
+        await value
+    }.sink {
+        print($0)
+    } receiveValue: {
+        print($0)
+    }
+```
+
+#### Output:
+
+```none
+3
+finished
+```
+
+------
+
+### fromThrowingAsync(priority:_:)
+
+Creates a Combine Publisher from a throwing async function
+The Publisher emits a value and completes or fail according the the async function execution result.
+The task that supports the async function is canceled when the publisher's subscription is canceled.
+An optional priority indicates the priority of the Task supporting the execution of the async function.
+
+```swift
+struct MyError: Error, CustomStringConvertible {
+    var description: String {
+        "Async Error"
+    }
+ }
+
+Publishers
+    .fromAsync { () async throws -> String in
+        throw MyError()
+    }.sink {
+        print($0)
+    } receiveValue: {
+        print($0)
+    }
+```
+
+#### Output:
+
+```none
+failure(Async Error)
+```
+
+### fromAsyncSequence(priority:_:)
+
+Creates a Combine Publisher from an async sequence.
+The Publisher emits values or fail according the the async sequence execution result.
+An optional priority indicates the priority of the Task supporting the execution of the async sequence.
+
+```swift
+let sequence = AsyncStream(Int.self) { continuation in
+    continuation.yield(1)
+    continuation.yield(2)
+    continuation.yield(3)
+    continuation.finish()
+}
+
+Publishers
+    .fromAsyncSequence(sequence).sink {
+        print($0)
+    } receiveValue: {
+        print($0)
+    }
+```
+
+#### Output:
+
+```none
+1
+2
+3
+finished
+```
+
 ## Publishers
 
 This section outlines some of the custom Combine publishers CombineExt provides