Merge pull request #211 from wwt/Issue-96

Add the ability to abandon workflow when a publisher emits a value

Author: Tyler-Keith-Thompson

Sources/SwiftCurrent_SwiftUI/Views/WorkflowLauncher.swift

@@ -6,6 +6,7 @@
 //  Copyright © 2021 WWT and Tyler Thompson. All rights reserved.
 //
 
+import Combine
 import SwiftUI
 import SwiftCurrent
 
@@ -15,6 +16,7 @@ public struct WorkflowLauncher<Content: _WorkflowItemProtocol>: View {
     public typealias WorkflowInput = Content.FlowRepresentableType.WorkflowInput
 
     @WorkflowBuilder private var content: Content
+    @State private var abandonOnPublisher: AnyPublisher<Void, Never> = Empty(completeImmediately: false).eraseToAnyPublisher()
     @State private var onFinish = [(AnyWorkflow.PassedArgs) -> Void]()
     @State private var onAbandon = [() -> Void]()
     @State private var shouldEmbedInNavView = false
@@ -38,6 +40,7 @@ public struct WorkflowLauncher<Content: _WorkflowItemProtocol>: View {
             }
         }
         .onChange(of: isLaunched) { if $0 == false { resetWorkflow() } }
+        .onReceive(abandonOnPublisher) { launcher.workflow.abandon() }
     }
 
     private var workflowContent: some View {
@@ -61,14 +64,19 @@ public struct WorkflowLauncher<Content: _WorkflowItemProtocol>: View {
         self.content = content()
     }
 
-    private init(current: Self, shouldEmbedInNavView: Bool, onFinish: [(AnyWorkflow.PassedArgs) -> Void], onAbandon: [() -> Void]) {
+    private init(current: Self,
+                 abandonOnPublisher: AnyPublisher<Void, Never> = Empty(completeImmediately: false).eraseToAnyPublisher(),
+                 shouldEmbedInNavView: Bool,
+                 onFinish: [(AnyWorkflow.PassedArgs) -> Void],
+                 onAbandon: [() -> Void]) {
         _model = current._model
         _launcher = current._launcher
         content = current.content
         _isLaunched = current._isLaunched
-        _shouldEmbedInNavView = State(initialValue: shouldEmbedInNavView)
-        _onFinish = State(initialValue: onFinish)
-        _onAbandon = State(initialValue: onAbandon)
+        _shouldEmbedInNavView = State(wrappedValue: shouldEmbedInNavView)
+        _onFinish = State(wrappedValue: onFinish)
+        _onAbandon = State(wrappedValue: onAbandon)
+        _abandonOnPublisher = State(wrappedValue: abandonOnPublisher)
     }
 
     private func resetWorkflow() {
@@ -92,6 +100,14 @@ public struct WorkflowLauncher<Content: _WorkflowItemProtocol>: View {
         return Self(current: self, shouldEmbedInNavView: shouldEmbedInNavView, onFinish: onFinish, onAbandon: onAbandon)
     }
 
+    func abandonOn<P: Publisher>(_ publisher: P) -> Self where P.Failure == Never {
+        Self(current: self,
+             abandonOnPublisher: publisher.map { _ in () }.eraseToAnyPublisher(),
+             shouldEmbedInNavView: shouldEmbedInNavView,
+             onFinish: onFinish,
+             onAbandon: onAbandon)
+    }
+
     func embedInNavigationView() -> Self {
         Self(current: self, shouldEmbedInNavView: true, onFinish: onFinish, onAbandon: onAbandon)
     }

Sources/SwiftCurrent_SwiftUI/Views/WorkflowView.swift

@@ -6,6 +6,7 @@
 //  Copyright © 2022 WWT and Tyler Thompson. All rights reserved.
 //  
 
+import Combine
 import SwiftUI
 import SwiftCurrent
 
@@ -202,6 +203,11 @@ public struct WorkflowView<Content: View>: View {
         Self(self, newContent: _content.wrappedValue.onAbandon(closure: closure))
     }
 
+    /// Subscribers to a combine publisher, when a value is emitted the workflow will abandon.
+    public func abandonOn<WI: _WorkflowItemProtocol, P: Publisher>(_ publisher: P) -> Self where Content == WorkflowLauncher<WI>, P.Failure == Never {
+        Self(self, newContent: _content.wrappedValue.abandonOn(publisher))
+    }
+
     /// Wraps content in a NavigationView.
     public func embedInNavigationView<WI: _WorkflowItemProtocol>() -> Self where Content == WorkflowLauncher<WI> {
         Self(self, newContent: _content.wrappedValue.embedInNavigationView())

Tests/SwiftCurrent_SwiftUITests/SwiftCurrent_SwiftUITests.swift

@@ -8,6 +8,7 @@
 
 import XCTest
 import SwiftUI
+import Combine
 import ViewInspector
 
 import SwiftCurrent
@@ -529,6 +530,32 @@ final class SwiftCurrent_SwiftUIConsumerTests: XCTestCase {
         wait(for: [expectOnAbandon1, expectOnAbandon2], timeout: TestConstant.timeout)
     }
 
+    func testWorkflowCanAbandonFromAPublisher() async throws {
+        let publisher = PassthroughSubject<Void, Never>()
+        struct FR1: View, FlowRepresentable, Inspectable {
+            var _workflowPointer: AnyFlowRepresentable?
+            var body: some View { Text("FR1 type") }
+        }
+        let isLaunched = Binding(wrappedValue: true)
+        let expectOnAbandon = expectation(description: "OnAbandon called")
+        let launcher = try await MainActor.run {
+            WorkflowView(isLaunched: isLaunched) {
+                WorkflowItem(FR1.self)
+            }
+            .onAbandon {
+                XCTAssertFalse(isLaunched.wrappedValue)
+                expectOnAbandon.fulfill()
+            }
+            .abandonOn(publisher)
+        }.hostAndInspect(with: \.inspection)
+
+        XCTAssertEqual(try launcher.find(FR1.self).text().string(), "FR1 type")
+        publisher.send()
+        XCTAssertThrowsError(try launcher.find(FR1.self))
+
+        wait(for: [expectOnAbandon], timeout: TestConstant.timeout)
+    }
+
     func testWorkflowCanHaveModifiers() async throws {
         struct FR1: View, FlowRepresentable, Inspectable {
             var _workflowPointer: AnyFlowRepresentable?