Merge remote-tracking branch 'origin/main' into jquadri/workflow-observers

* origin/main:
  [chore]: refactor some internal actions to use existential any (#190)

Author: jamieQ

Diff for: Workflow/Sources/SubtreeManager.swift

@@ -130,7 +130,7 @@ extension WorkflowNode {
 
 extension WorkflowNode.SubtreeManager {
     enum Output {
-        case update(AnyWorkflowAction<WorkflowType>, source: WorkflowUpdateDebugInfo.Source)
+        case update(any WorkflowAction<WorkflowType>, source: WorkflowUpdateDebugInfo.Source)
         case childDidUpdate(WorkflowUpdateDebugInfo)
     }
 }
@@ -209,7 +209,7 @@ extension WorkflowNode.SubtreeManager {
                 /// Update the existing child
                 existing.update(
                     workflow: workflow,
-                    outputMap: { AnyWorkflowAction(outputMap($0)) },
+                    outputMap: { outputMap($0) },
                     eventPipe: eventPipe
                 )
                 child = existing
@@ -218,7 +218,7 @@ extension WorkflowNode.SubtreeManager {
                 /// This spins up a new workflow node, etc to host the newly created child.
                 child = ChildWorkflow<Child>(
                     workflow: workflow,
-                    outputMap: { AnyWorkflowAction(outputMap($0)) },
+                    outputMap: { outputMap($0) },
                     eventPipe: eventPipe,
                     key: key,
                     parentSession: session,
@@ -333,7 +333,7 @@ extension WorkflowNode.SubtreeManager {
         var observerInfo: ObserverInfo?
 
         func handle(action: Action) {
-            let output = Output.update(AnyWorkflowAction(action), source: .external)
+            let output = Output.update(action, source: .external)
 
             if let observerInfo = observerInfo {
                 observerInfo.observer.workflowDidReceiveAction(
@@ -456,11 +456,11 @@ extension WorkflowNode.SubtreeManager {
 
     fileprivate final class ChildWorkflow<W: Workflow>: AnyChildWorkflow {
         private let node: WorkflowNode<W>
-        private var outputMap: (W.Output) -> AnyWorkflowAction<WorkflowType>
+        private var outputMap: (W.Output) -> any WorkflowAction<WorkflowType>
 
         init(
             workflow: W,
-            outputMap: @escaping (W.Output) -> AnyWorkflowAction<WorkflowType>,
+            outputMap: @escaping (W.Output) -> any WorkflowAction<WorkflowType>,
             eventPipe: EventPipe,
             key: String,
             parentSession: WorkflowSession?,
@@ -489,7 +489,11 @@ extension WorkflowNode.SubtreeManager {
             return node.render(isRootNode: false)
         }
 
-        func update(workflow: W, outputMap: @escaping (W.Output) -> AnyWorkflowAction<WorkflowType>, eventPipe: EventPipe) {
+        func update(
+            workflow: W,
+            outputMap: @escaping (W.Output) -> any WorkflowAction<WorkflowType>,
+            eventPipe: EventPipe
+        ) {
             self.outputMap = outputMap
             self.eventPipe = eventPipe
             node.update(workflow: workflow)

Diff for: Workflow/Sources/WorkflowNode.swift

@@ -79,17 +79,15 @@ final class WorkflowNode<WorkflowType: Workflow> {
         let output: Output
 
         switch subtreeOutput {
-        case .update(let event, let source):
-            let actionObserverCompletion = observer?.workflowWillApplyAction(
-                event,
-                workflow: workflow,
-                state: state,
-                session: session
+        case .update(let action, let source):
+            /// 'Opens' the existential `any WorkflowAction<WorkflowType>` value
+            /// allowing the underlying conformance to be applied to the Workflow's State
+            let outputEvent = openAndApply(
+                action,
+                to: &state,
+                observerInfo: observer.map { ($0, workflow, session) }
             )
 
-            /// Apply the update to the current state
-            let outputEvent = event.apply(toState: &state)
-
             /// Finally, we tell the outside world that our state has changed (including an output event if it exists).
             output = Output(
                 outputEvent: outputEvent,
@@ -99,8 +97,6 @@ final class WorkflowNode<WorkflowType: Workflow> {
                 )
             )
 
-            actionObserverCompletion?(state, outputEvent)
-
         case .childDidUpdate(let debugInfo):
             output = Output(
                 outputEvent: nil,
@@ -181,3 +177,34 @@ extension WorkflowNode {
         var debugInfo: WorkflowUpdateDebugInfo
     }
 }
+
+private extension WorkflowNode {
+    /// Applies an appropriate `WorkflowAction` to advance the underlying Workflow `State`
+    /// - Parameters:
+    ///   - action: The `WorkflowAction` to apply
+    ///   - state: The `State` to which the action will be applied
+    ///   - observerInfo: Optional observation info to notify registered `WorkflowObserver`s
+    /// - Returns: An optional `Output` produced by the action application
+    func openAndApply<A: WorkflowAction>(
+        _ action: A,
+        to state: inout WorkflowType.State,
+        observerInfo: (WorkflowObserver, WorkflowType, WorkflowSession)?
+    ) -> WorkflowType.Output? where A.WorkflowType == WorkflowType {
+        let output: WorkflowType.Output?
+
+        let observerCompletion = observerInfo.flatMap { observer, workflow, session in
+            observer.workflowWillApplyAction(
+                action,
+                workflow: workflow,
+                state: state,
+                session: session
+            )
+        }
+        defer { observerCompletion?(state, output) }
+
+        /// Apply the action to the current state
+        output = action.apply(toState: &state)
+
+        return output
+    }
+}

Diff for: Workflow/Tests/SubtreeManagerTests.swift

@@ -72,7 +72,7 @@ final class SubtreeManagerTests: XCTestCase {
         manager.onUpdate = {
             switch $0 {
             case .update(let event, _):
-                events.append(event)
+                events.append(AnyWorkflowAction(event))
             default:
                 break
             }