feat: Adds documentation and removes some unused code.

Sources/ComposableSubscriber/Reducer+receive.swift

@@ -0,0 +1,149 @@
+import ComposableArchitecture
+
+extension Reducer {
+
+  /// A higher order reducer that sends a receive action on a trigger action.
+  ///
+  /// ## Example
+  /// ```swift
+  ///
+  /// @Reducer
+  /// struct MyFeature {
+  ///   ...
+  ///
+  ///   enum Action {
+  ///     case receive(TaskResult<Int>)
+  ///     case task
+  ///   }
+  ///
+  ///   @Dependency(\.numberClient) var numberClient
+  ///
+  ///   var body: some ReducerOf<Self> {
+  ///     Reduce { state, action in
+  ///       ...
+  ///     }
+  ///     .receive(on: \.task, with: \.receive) {
+  ///       try await numberClient.fetchCurrentNumber()
+  ///     }
+  ///   }
+  /// }
+  /// ```
+  ///
+  /// - Parameters:
+  ///   - triggerAction: The action that triggers calling the result handler.
+  ///   - receiveAction: The action that receives the task result.
+  ///   - resultHandler: The operations that is called that returns the value to be received.
+  ///
+  @inlinable
+  public func receive<TriggerAction, Value>(
+    on triggerAction: CaseKeyPath<Action, TriggerAction>,
+    with receiveAction: CaseKeyPath<Action, TaskResult<Value>>,
+    result resultHandler: @escaping @Sendable () async throws -> Value
+  ) -> _ReceiveOnTriggerReducer<Self, TriggerAction, Value, Value> {
+    .init(
+      parent: self,
+      triggerAction: { AnyCasePath(triggerAction).extract(from: $0) },
+      receiveOperation: .case(AnyCasePath(receiveAction), resultHandler)
+    )
+  }
+
+}
+
+extension Reducer where Action: ReceiveAction {
+  /// A higher order reducer that sends a receive action on a trigger action.
+  ///
+  /// ## Example
+  /// ```swift
+  ///
+  /// @Reducer
+  /// struct MyFeature {
+  ///   ...
+  ///
+  ///   enum Action: ReceiveAction {
+  ///     case receive(TaskResult<ReceiveAction>)
+  ///     case task
+  ///
+  ///     @CasePathable
+  ///     enum ReceiveAction {
+  ///       case currentNumber(Int)
+  ///       ...
+  ///     }
+  ///   }
+  ///
+  ///   @Dependency(\.numberClient) var numberClient
+  ///
+  ///   var body: some ReducerOf<Self> {
+  ///     Reduce { state, action in
+  ///       ...
+  ///     }
+  ///     .receive(on: \.task, case: \.currentNumber) {
+  ///       try await numberClient.fetchCurrentNumber()
+  ///     }
+  ///   }
+  /// }
+  /// ```
+  ///
+  /// - Parameters:
+  ///   - triggerAction: The action that triggers calling the result handler.
+  ///   - embedCasePath: The case path to embed the result into.
+  ///   - resultHandler: The operations that is called that returns the value to be received.
+  @inlinable
+  public func receive<TriggerAction, Value>(
+    on triggerAction: CaseKeyPath<Action, TriggerAction>,
+    case embedCasePath: CaseKeyPath<Action.ReceiveAction, Value>,
+    result resultHandler: @escaping @Sendable () async throws -> Value
+  ) -> _ReceiveOnTriggerReducer<Self, TriggerAction, Value, Action.ReceiveAction> {
+    .init(
+      parent: self,
+      triggerAction: { AnyCasePath(triggerAction).extract(from: $0) },
+      receiveOperation: .case(AnyCasePath(embedCasePath), resultHandler)
+    )
+
+  }
+}
+
+public struct _ReceiveOnTriggerReducer<
+  Parent: Reducer,
+  TriggerAction,
+  Value,
+  Result
+>: Reducer {
+
+  @usableFromInline
+  let parent: Parent
+
+  @usableFromInline
+  let triggerAction: @Sendable (Parent.Action) -> TriggerAction?
+
+  @usableFromInline
+  let receiveOperation:  ReceiveOperation<Parent.Action, Value, Result>
+
+  @usableFromInline
+  init(
+    parent: Parent,
+    triggerAction: @escaping @Sendable (Parent.Action) -> TriggerAction?,
+    receiveOperation: ReceiveOperation<Parent.Action, Value, Result>
+  ) {
+    self.parent = parent
+    self.triggerAction = triggerAction
+    self.receiveOperation = receiveOperation
+  }
+
+  @inlinable
+  public func reduce(
+    into state: inout Parent.State,
+    action: Parent.Action) -> Effect<Parent.Action>
+  {
+    let baseEffects = parent.reduce(into: &state, action: action)
+
+    guard triggerAction(action) != nil else {
+      return baseEffects
+    }
+
+    return .merge(
+      baseEffects,
+      .receive(operation: receiveOperation)
+    )
+  }
+}
+