feat(CombineBridge): Draft implementation

Package.swift

@@ -39,6 +39,7 @@ let package = Package(
             ],
             swiftSettings: [.define("WASI", .when(platforms: [.wasi]))]
         ),
+        .target(name: "OpenCombineBridge", dependencies: ["OpenCombine"]),
         .target(name: "OpenCombineDispatch", dependencies: ["OpenCombine"]),
         .target(
             name: "OpenCombineFoundation",

Sources/OpenCombineBridge/Cancellable+Adapter.swift

@@ -0,0 +1,37 @@
+#if canImport(Combine) && canImport(OpenCombine)
+import Combine
+import OpenCombine
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+private struct CancellableAdapter: OpenCombine.Cancellable, Combine.Cancellable {
+  public init(_ cancellable: OpenCombine.Cancellable) {
+    self._cancel = cancellable.cancel
+  }
+
+  public init(_ cancellable: Combine.Cancellable) {
+    self._cancel = cancellable.cancel
+  }
+
+  private init(cancel: @escaping () -> Void) {
+    self._cancel = cancel
+  }
+
+  private let _cancel: () -> Void
+
+  func cancel() { _cancel() }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension OpenCombine.Cancellable {
+  public var combine: OpenCombine.Cancellable {
+    CancellableAdapter(self)
+  }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension Combine.Cancellable {
+  public var ocombine: OpenCombine.Cancellable {
+    CancellableAdapter(self)
+  }
+}
+#endif

Sources/OpenCombineBridge/CombineIdentifier+Adapter.swift

@@ -0,0 +1,67 @@
+#if canImport(Combine) && canImport(OpenCombine)
+import Combine
+import OpenCombine
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+private func _rawValue(for id: Combine.CombineIdentifier) -> UInt64 {
+  Mirror(reflecting: id).children.first(where: { $0.label == "rawValue" })!.value as! UInt64
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+private func _rawValue(for id: OpenCombine.CombineIdentifier) -> UInt64 {
+  Mirror(reflecting: id).children.first(where: { $0.label == "rawValue" })!.value as! UInt64
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+private struct _CombineIdentifierProxy {
+  init(_ object: OpenCombine.CustomCombineIdentifierConvertible) {
+    self.init(object.combineIdentifier)
+  }
+
+  init(_ object: Combine.CustomCombineIdentifierConvertible) {
+    self.init(object.combineIdentifier)
+  }
+
+  init(_ combineIdentifier: OpenCombine.CombineIdentifier) {
+    self.init(rawValue: _rawValue(for: combineIdentifier))
+  }
+
+  init(_ combineIdentifier: Combine.CombineIdentifier) {
+    self.init(rawValue: _rawValue(for: combineIdentifier))
+  }
+
+  init(rawValue: UInt64) {
+    self.rawValue = rawValue
+  }
+
+  var rawValue: UInt64
+
+  var combine: Combine.CombineIdentifier {
+    return copyValue(
+      of: self,
+      as: Combine.CombineIdentifier()
+    )
+  }
+
+  var ocombine: OpenCombine.CombineIdentifier {
+    return copyValue(
+      of: self,
+      as: OpenCombine.CombineIdentifier()
+    )
+  }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension OpenCombine.CombineIdentifier {
+  public var combine: Combine.CombineIdentifier {
+    _CombineIdentifierProxy(self).combine
+  }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension Combine.CombineIdentifier {
+  public var ocombine: OpenCombine.CombineIdentifier {
+    _CombineIdentifierProxy(self).ocombine
+  }
+}
+#endif

Sources/OpenCombineBridge/Helpers/CopyValue.swift

@@ -0,0 +1,9 @@
+import Foundation
+
+func copyValue<Source, Destination>(of source: Source, as destination: Destination) -> Destination {
+  var value = source
+  var buffer = destination
+  let data = Data(bytes: &value, count: MemoryLayout<Source>.size)
+  _ = withUnsafeMutableBytes(of: &buffer, { data.copyBytes(to: $0) })
+  return buffer
+}

Sources/OpenCombineBridge/Publisher+Adapter.swift

@@ -0,0 +1,35 @@
+#if canImport(Combine) && canImport(OpenCombine)
+import Combine
+import OpenCombine
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+public struct PublisherAdapter<Publisher> {
+  internal init(_ publisher: Publisher) {
+    self.publisher = publisher
+  }
+
+  let publisher: Publisher
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension PublisherAdapter: Combine.Publisher where Publisher: OpenCombine.Publisher {
+  public typealias Output = Publisher.Output
+  public typealias Failure = Publisher.Failure
+
+  public func receive<S>(subscriber: S)
+  where S: Combine.Subscriber, Publisher.Failure == S.Failure, Publisher.Output == S.Input {
+    publisher.receive(subscriber: SubscriberAdapter.subscriber(subscriber))
+  }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension PublisherAdapter: OpenCombine.Publisher where Publisher: Combine.Publisher {
+  public typealias Output = Publisher.Output
+  public typealias Failure = Publisher.Failure
+
+  public func receive<S>(subscriber: S)
+  where S: OpenCombine.Subscriber, Publisher.Failure == S.Failure, Publisher.Output == S.Input {
+    publisher.receive(subscriber: SubscriberAdapter.subscriber(subscriber))
+  }
+}
+#endif

Sources/OpenCombineBridge/Subject+Adapter.swift

@@ -0,0 +1,65 @@
+#if canImport(Combine) && canImport(OpenCombine)
+import Combine
+import OpenCombine
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+public final class SubjectAdapter<Subject> {
+  internal init(_ subject: Subject) {
+    self.subject = subject
+  }
+
+  let subject: Subject
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension SubjectAdapter: Combine.Publisher where Subject: OpenCombine.Publisher {
+  public typealias Output = Subject.Output
+  public typealias Failure = Subject.Failure
+
+  public func receive<S>(subscriber: S)
+  where S: Combine.Subscriber, Subject.Failure == S.Failure, Subject.Output == S.Input {
+    subject.receive(subscriber: SubscriberAdapter.subscriber(subscriber))
+  }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension SubjectAdapter: OpenCombine.Publisher where Subject: Combine.Publisher {
+  public typealias Output = Subject.Output
+  public typealias Failure = Subject.Failure
+
+  public func receive<S>(subscriber: S)
+  where S: OpenCombine.Subscriber, Subject.Failure == S.Failure, Subject.Output == S.Input {
+    subject.receive(subscriber: SubscriberAdapter.subscriber(subscriber))
+  }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension SubjectAdapter: Combine.Subject where Subject: OpenCombine.Subject {
+  public func send(_ value: Subject.Output) {
+    subject.send(value)
+  }
+
+  public func send(completion: Combine.Subscribers.Completion<Subject.Failure>) {
+    subject.send(completion: completion.ocombine)
+  }
+
+  public func send(subscription: Combine.Subscription) {
+    subject.send(subscription: SubscriptionAdapter.subscription(subscription))
+  }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension SubjectAdapter: OpenCombine.Subject where Subject: Combine.Subject {
+  public func send(_ value: Subject.Output) {
+    subject.send(value)
+  }
+
+  public func send(completion: OpenCombine.Subscribers.Completion<Subject.Failure>) {
+    subject.send(completion: completion.combine)
+  }
+
+  public func send(subscription: OpenCombine.Subscription) {
+    subject.send(subscription: SubscriptionAdapter.subscription(subscription))
+  }
+}
+#endif

Sources/OpenCombineBridge/Subscriber+Adapter.swift

@@ -0,0 +1,94 @@
+#if canImport(Combine) && canImport(OpenCombine)
+import Combine
+import OpenCombine
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+public struct SubscriberAdapter<Subscriber> {
+  internal init(_ subscriber: Subscriber) {
+    self.subscriber = subscriber
+  }
+
+  public let subscriber: Subscriber
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension SubscriberAdapter where Subscriber: OpenCombine.Subscriber {
+  public static func subscriber(
+    _ subscriber: Subscriber
+  ) -> SubscriberAdapter<Subscriber> {
+    SubscriberAdapter<Subscriber>(subscriber)
+  }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension SubscriberAdapter where Subscriber: Combine.Subscriber {
+  public static func subscriber(
+    _ subscriber: Subscriber
+  ) -> SubscriberAdapter<Subscriber> {
+    SubscriberAdapter<Subscriber>(subscriber)
+  }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension SubscriberAdapter: Combine.CustomCombineIdentifierConvertible
+where Subscriber: OpenCombine.CustomCombineIdentifierConvertible {
+  public var combineIdentifier: Combine.CombineIdentifier {
+    subscriber.combineIdentifier.combine
+  }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension SubscriberAdapter: OpenCombine.CustomCombineIdentifierConvertible
+where Subscriber: Combine.CustomCombineIdentifierConvertible {
+  public var combineIdentifier: OpenCombine.CombineIdentifier {
+    subscriber.combineIdentifier.ocombine
+  }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension SubscriberAdapter: OpenCombine.Subscriber
+where Subscriber: Combine.Subscriber {
+  public typealias Input = Subscriber.Input
+  public typealias Failure = Subscriber.Failure
+
+  public var combineIdentifier: OpenCombine.CombineIdentifier {
+    subscriber.combineIdentifier.ocombine
+  }
+
+  public func receive(subscription: OpenCombine.Subscription) {
+    subscriber.receive(subscription: SubscriptionAdapter.subscription(subscription))
+  }
+
+  public func receive(_ input: Subscriber.Input) -> OpenCombine.Subscribers.Demand {
+    return subscriber.receive(input).ocombine
+  }
+
+  public func receive(completion: OpenCombine.Subscribers.Completion<Subscriber.Failure>) {
+    subscriber.receive(completion: completion.combine)
+  }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension SubscriberAdapter: Combine.Subscriber
+where Subscriber: OpenCombine.Subscriber {
+  public typealias Input = Subscriber.Input
+  public typealias Failure = Subscriber.Failure
+
+  public var combineIdentifier: Combine.CombineIdentifier {
+    subscriber.combineIdentifier.combine
+  }
+
+  public func receive(subscription: Combine.Subscription) {
+    subscriber.receive(subscription: SubscriptionAdapter.subscription(subscription))
+  }
+
+  public func receive(_ input: Subscriber.Input) -> Combine.Subscribers.Demand {
+    return subscriber.receive(input).combine
+  }
+
+  public func receive(completion: Combine.Subscribers.Completion<Subscriber.Failure>) {
+    subscriber.receive(completion: completion.ocombine)
+  }
+}
+
+#endif

Sources/OpenCombineBridge/Subscribers.Completion+Adapter.swift

@@ -0,0 +1,28 @@
+#if canImport(Combine) && canImport(OpenCombine)
+import Combine
+import OpenCombine
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension OpenCombine.Subscribers.Completion {
+  public var combine: Combine.Subscribers.Completion<Failure> {
+    switch self {
+    case .finished:
+      return .finished
+    case .failure(let error):
+      return .failure(error)
+    }
+  }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension Combine.Subscribers.Completion {
+  public var ocombine: OpenCombine.Subscribers.Completion<Failure> {
+    switch self {
+    case .finished:
+      return .finished
+    case .failure(let error):
+      return .failure(error)
+    }
+  }
+}
+#endif

Sources/OpenCombineBridge/Subscribers.Demand+Adapter.swift

@@ -0,0 +1,34 @@
+#if canImport(Combine) && canImport(OpenCombine)
+import Combine
+import OpenCombine
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+private func _rawValue(for demand: Combine.Subscribers.Demand) -> UInt {
+  Mirror(reflecting: demand).children.first(where: { $0.label == "rawValue" })!.value as! UInt
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+private func _rawValue(for demand: OpenCombine.Subscribers.Demand) -> UInt {
+  Mirror(reflecting: demand).children.first(where: { $0.label == "rawValue" })!.value as! UInt
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension OpenCombine.Subscribers.Demand {
+  public var combine: Combine.Subscribers.Demand {
+    copyValue(
+      of: self,
+      as: Combine.Subscribers.Demand.none
+    )
+  }
+}
+
+@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+extension Combine.Subscribers.Demand {
+  public var ocombine: OpenCombine.Subscribers.Demand {
+    copyValue(
+      of: self,
+      as: OpenCombine.Subscribers.Demand.none
+    )
+  }
+}
+#endif