Implement scene and app

README.md

@@ -31,7 +31,7 @@ _Meta_ follows the following principles:
 It knows the following layers of UI:
 
 - An app is the entry point of the executable, containing the windows.
-- A window is a container holding one or multiple views.
+- A scene element is a template for a container holding one or multiple views (e.g. a window).
 - A view is a part of the actual UI inside a window, another view or a menu.
 - A menu is a list of buttons, other menus, and views. Certain views (such as menu buttons) allow menus to be used.
 

Sources/Meta.docc/Meta.md

@@ -13,6 +13,6 @@ _Meta_ follows the following principles:
 It knows the following layers of UI:
 
 - An app is the entry point of the executable, containing the windows.
-- A window is a container holding one or multiple views.
+- A scene element is a template for a container holding one or multiple views (e.g. a window).
 - A view is a part of the actual UI inside a window, another view or a menu.
 - A menu is a list of buttons, other menus, and views. Certain views (such as menu buttons) allow menus to be used.

Sources/Model/Data Flow/StateManager.swift

@@ -14,6 +14,8 @@ public enum StateManager {
     public static var blockUpdates = false
     /// Whether to save state.
     public static var saveState = true
+    /// The application identifier.
+    static var appID: String?
     /// The functions handling view updates.
     static var updateHandlers: [(Bool) -> Void] = []
     /// The state.
@@ -35,7 +37,7 @@ public enum StateManager {
         func contains(id: UUID) -> Bool {
             ids.first == id || ids.second == id
         }
-        
+
         /// Change the identifier to a new one.
         /// - Parameter newID: The new identifier.
         mutating func changeID(new newID: UUID) {

Sources/Model/User Interface/App/App.swift

@@ -0,0 +1,79 @@
+//
+//  App.swift
+//  Meta
+//
+//  Created by david-swift on 01.07.24.
+//
+
+/// A structure conforming to `App` is the entry point of your app.
+///
+/// ```swift
+/// @main
+/// struct Test: App {
+///
+///     let id = "io.github.AparokshaUI.TestApp"
+///
+///     var scene: Scene {
+///         WindowScene()
+///     }
+///
+/// }
+/// ```
+///
+public protocol App {
+
+    /// The app storage typ.
+    associatedtype Storage: AppStorage
+
+    /// The app's application ID.
+    var id: String { get }
+    /// The app's scene.
+    @SceneBuilder var scene: Scene { get }
+    // swiftlint:disable implicitly_unwrapped_optional
+    /// The app storage.
+    var app: Storage! { get set }
+    // swiftlint:enable implicitly_unwrapped_optional
+
+    /// An app has to have an `init()` initializer.
+    init()
+
+}
+
+extension App {
+
+    /// The application's entry point.
+    public static func main() {
+        let app = setupApp()
+        app.app.run {
+            for element in app.scene {
+                element.setupInitialContainers(app: app.app)
+            }
+        }
+    }
+
+    /// Initialize and get the app with the app storage.
+    ///
+    /// To run the app, call the ``AppStorage/run(automaticSetup:manualSetup:)`` function.
+    public static func setupApp() -> Self {
+        var appInstance = self.init()
+        appInstance.app = Storage(id: appInstance.id) { appInstance }
+        StateManager.addUpdateHandler { force in
+            var removeIndices: [Int] = []
+            for (index, element) in appInstance.app.sceneStorage.enumerated() {
+                if element.destroy {
+                    removeIndices.insert(index, at: 0)
+                } else if let scene = appInstance.scene.first(
+                    where: { $0.id == element.id }
+                ) as? Storage.SceneElementType as? SceneElement {
+                    scene.update(element, app: appInstance.app, updateProperties: force)
+                }
+            }
+            for index in removeIndices {
+                appInstance.app.sceneStorage.remove(at: index)
+            }
+        }
+        StateManager.appID = appInstance.id
+        return appInstance
+    }
+
+}

Sources/Model/User Interface/App/AppStorage.swift

@@ -0,0 +1,67 @@
+//
+//  AppStorage.swift
+//  Meta
+//
+//  Created by david-swift on 01.07.24.
+//
+
+/// The app storage protocol.
+public protocol AppStorage: AnyObject {
+
+    /// The type of scene elements (which should be backend-specific).
+    associatedtype SceneElementType
+    /// The type of widget elements (which should be backend-specific).
+    associatedtype WidgetType
+
+    /// The scene.
+    var app: () -> any App { get }
+
+    /// The scene storage.
+    var sceneStorage: [SceneStorage] { get set }
+
+    /// Initialize the app storage.
+    /// - Parameters:
+    ///     - id: The app's identifier.
+    ///     - app: Get the application.
+    init(id: String, app: @escaping () -> any App)
+
+    /// Run the application.
+    /// - Parameter setup: A closure that is expected to be executed right at the beginning.
+    func run(setup: @escaping () -> Void)
+
+    /// Terminate the application.
+    func quit()
+
+}
+
+extension AppStorage {
+
+    /// Focus the scene element with a certain id (if supported). Create the element if it doesn't already exist.
+    /// - Parameter id: The element's id.
+    public func showSceneElement(_ id: String) {
+        sceneStorage.last { $0.id == id && !$0.destroy }?.show() ?? addSceneElement(id)
+    }
+
+    /// Add a new scene element with the content of the scene element with a certain id.
+    /// - Parameter id: The element's id.
+    public func addSceneElement(_ id: String) {
+        if let element = app().scene.last(where: { $0.id == id }) {
+            let container = element.container(app: self)
+            sceneStorage.append(container)
+            showSceneElement(id)
+        }
+    }
+
+    /// Focus the window with a certain id (if supported). Create the window if it doesn't already exist.
+    /// - Parameter id: The window's id.
+    public func showWindow(_ id: String) {
+        showSceneElement(id)
+    }
+
+    /// Add a new window with the content of the window template with a certain id.
+    /// - Parameter id: The window template's id.
+    public func addWindow(_ id: String) {
+        addSceneElement(id)
+    }
+
+}

Sources/Model/User Interface/Scene/SceneBuilder.swift

@@ -0,0 +1,68 @@
+//
+//  SceneBuilder.swift
+//  Meta
+//
+//  Created by david-swift on 30.06.24.
+//
+
+import Foundation
+
+/// The ``SceneBuilder`` is a result builder for scenes.
+@resultBuilder
+public enum SceneBuilder {
+
+    /// A component used in the ``SceneBuilder``.
+    public enum Component {
+
+        /// A scene as a component.
+        case element(_: any SceneElement)
+        /// An array of components as a component.
+        case components(_: [Self])
+
+    }
+
+    /// Build combined results from statement blocks.
+    /// - Parameter components: The components.
+    /// - Returns: The components in a component.
+    public static func buildBlock(_ elements: Component...) -> Component {
+        .components(elements)
+    }
+
+    /// Translate an element into a ``SceneBuilder.Component``.
+    /// - Parameter element: The element to translate.
+    /// - Returns: A component created from the element.
+    public static func buildExpression(_ element: any SceneElement) -> Component {
+        .element(element)
+    }
+
+    /// Translate an array of elements into a ``SceneBuilder.Component``.
+    /// - Parameter elements: The elements to translate.
+    /// - Returns: A component created from the element.
+    public static func buildExpression(_ elements: [any SceneElement]) -> Component {
+        var components: [Component] = []
+        for element in elements {
+            components.append(.element(element))
+        }
+        return .components(components)
+    }
+
+    /// Fetch a component.
+    /// - Parameter component: A component.
+    /// - Returns: The component.
+    public static func buildExpression(_ component: Component) -> Component {
+        component
+    }
+
+    /// Convert a component to an array of elements.
+    /// - Parameter component: The component to convert.
+    /// - Returns: The generated array of elements.
+    public static func buildFinalResult(_ component: Component) -> Scene {
+        switch component {
+        case let .element(element):
+            return [element]
+        case let .components(components):
+            return components.flatMap { buildFinalResult($0) }
+        }
+    }
+
+}

Sources/Model/User Interface/Scene/SceneElement.swift

@@ -0,0 +1,28 @@
+//
+//  SceneElement.swift
+//  Meta
+//
+//  Created by david-swift on 30.06.24.
+//
+
+/// A structure conforming to `SceneElement` can be added to an app's `scene` property.
+public protocol SceneElement {
+
+    /// The window type's identifier.
+    var id: String { get }
+    /// Set up the initial scene storages.
+    /// - Parameter app: The app storage.
+    func setupInitialContainers<Storage>(app: Storage) where Storage: AppStorage
+    /// The scene storage.
+    /// - Parameter app: The app storage.
+    func container<Storage>(app: Storage) -> SceneStorage where Storage: AppStorage
+    /// Update the stored content.
+    /// - Parameters:
+    ///     - storage: The storage to update.
+    ///     - updateProperties: Whether to update the view's properties.
+    func update<Storage>(_ storage: SceneStorage, app: Storage, updateProperties: Bool) where Storage: AppStorage
+
+}
+
+/// `Scene` is an array of scene elements.
+public typealias Scene = [any SceneElement]

Sources/Model/User Interface/Scene/SceneStorage.swift

@@ -0,0 +1,55 @@
+//
+//  SceneStorage.swift
+//  Meta
+//
+//  Created by david-swift on 30.06.24.
+//
+
+/// Store a reference to a rendered scene element in a view storage.
+public class SceneStorage {
+
+    /// The scene element's identifier.
+    public var id: String
+    /// The pointer.
+    ///
+    /// It can be a C pointer, a Swift class, or other information depending on the backend,
+    /// or it can be left out.
+    public var pointer: Any?
+    /// The scene element's view content.
+    public var content: [String: [ViewStorage]]
+    /// Various properties of a scene element.
+    public var fields: [String: Any] = [:]
+    /// Whether the reference to the window should disappear in the next update.
+    public var destroy = false
+    /// Show the scene element (including moving into the foreground, if possible).
+    public var show: () -> Void
+
+    /// The pointer as an opaque pointer, as this may be needed with backends interoperating with C or C++.
+    public var opaquePointer: OpaquePointer? {
+        get {
+            pointer as? OpaquePointer
+        }
+        set {
+            pointer = newValue
+        }
+    }
+
+    /// Initialize a scene storage.
+    /// - Parameters:
+    ///   - id: The scene element's identifier.
+    ///   - pointer: The pointer to the widget, its type depends on the backend.
+    ///   - content: The view's content for container widgets.
+    ///   - show: Function called when the scene element should be displayed.
+    public init(
+        id: String,
+        pointer: Any?,
+        content: [String: [ViewStorage]] = [:],
+        show: @escaping () -> Void
+    ) {
+        self.id = id
+        self.pointer = pointer
+        self.content = content
+        self.show = show
+    }
+
+}

Sources/Model/User Interface/View/ViewBuilder.swift

@@ -56,7 +56,7 @@ public enum ViewBuilder {
     /// Convert a component to an array of elements.
     /// - Parameter component: The component to convert.
     /// - Returns: The generated array of elements.
-    public static func buildFinalResult(_ component: Component) -> [AnyView] {
+    public static func buildFinalResult(_ component: Component) -> Body {
         switch component {
         case let .element(element):
             return [element]

Tests/DemoApp/DemoApp.swift

@@ -3,16 +3,44 @@ import Meta
 import Observation
 import SampleBackends
 
+@main
+struct TestExecutable {
+
+    public static func main() {
+        DemoApp.main()
+        sleep(2)
+    }
+
+}
+
+@available(macOS 14, *)
+@available(iOS 17, *)
+struct DemoApp: App {
+
+    typealias Storage = Backend1.Backend1App
+    let id = "io.github.AparokshaUI.DemoApp"
+    var app: Backend1.Backend1App!
+
+    var scene: Scene {
+        Backend1.Window("main", spawn: 1) {
+            DemoView(app: app)
+        }
+    }
+
+}
+
 @available(macOS 14, *)
 @available(iOS 17, *)
 struct DemoView: View {
 
     @State private var model = TestModel()
+    var app: Backend1.Backend1App
 
     var view: Body {
         Backend1.TestWidget1()
         Backend1.Button(model.test) {
             model.test = "\(Int.random(in: 1...10))"
+            app.addSceneElement("main")
         }
         TestView()
         testContent
@@ -51,26 +79,3 @@ class TestModel {
 
 }
 
-@main
-@available(macOS 14, *)
-@available(iOS 17, *)
-struct DemoApp {
-
-    static func main() {
-        let backendType = Backend1.BackendWidget.self
-
-        let storage = DemoView().storage(modifiers: [], type: backendType)
-        for round in 0...2 {
-            print("#\(round)")
-            DemoView().updateStorage(storage, modifiers: [], updateProperties: true, type: backendType)
-        }
-
-        StateManager.addUpdateHandler { force in
-            print("#*")
-            DemoView().updateStorage(storage, modifiers: [], updateProperties: force, type: backendType)
-        }
-
-        sleep(2)
-    }
-
-}

Tests/SampleBackends/Backend1.swift

@@ -70,7 +70,67 @@ public enum Backend1 {
 
     }
 
+    public struct Window: BackendSceneElement {
+
+        public var id: String
+        var spawn: Int
+        var content: Body
+
+        public init(_ id: String, spawn: Int, @ViewBuilder content: () -> Body) {
+            self.id = id
+            self.spawn = spawn
+            self.content = content()
+        }
+
+        public func setupInitialContainers<Storage>(app: Storage) where Storage: AppStorage {
+            for _ in 0..<spawn {
+                app.sceneStorage.append(container(app: app))
+            }
+        }
+
+        public func container<Storage>(app: Storage) -> SceneStorage where Storage: AppStorage {
+            print("Show \(id)")
+            let viewStorage = content.storage(modifiers: [], type: Storage.WidgetType.self)
+            return .init(id: id, pointer: nil, content: [.mainContent : [viewStorage]]) {
+                print("Make visible")
+            }
+        }
+
+        public func update<Storage>(_ storage: SceneStorage, app: Storage, updateProperties: Bool) where Storage: AppStorage {
+            print("Update \(id)")
+            guard let viewStorage = storage.content[.mainContent]?.first else {
+                return
+            }
+            content.updateStorage(viewStorage, modifiers: [], updateProperties: updateProperties, type: Storage.WidgetType.self)
+        }
+
+    }
+
     public protocol BackendWidget: Widget { }
 
+    public protocol BackendSceneElement: SceneElement { }
+
+    public class Backend1App: AppStorage {
+
+        public typealias SceneElementType = BackendSceneElement
+        public typealias WidgetType = BackendWidget
+
+        public var app: () -> any App
+        public var sceneStorage: [SceneStorage] = []
+
+        public required init(id: String, app: @escaping () -> any App) {
+            self.app = app
+        }
+
+        public func run(setup: @escaping () -> Void) {
+            setup()
+        }
+
+        public func quit() {
+            fatalError("Quit")
+        }
+
+    }
+
 }
 

Tests/SampleBackends/Backend2.swift

@@ -40,4 +40,28 @@ public enum Backend2 {
 
     public protocol BackendWidget: Widget { }
 
+    public protocol BackendSceneElement: SceneElement { }
+
+    public class Backend2App: AppStorage {
+
+        public typealias SceneElementType = BackendSceneElement
+        public typealias WidgetType = BackendWidget
+
+        public var app: () -> any App
+        public var sceneStorage: [SceneStorage] = []
+
+        public required init(id: String, app: @escaping () -> any App) {
+            self.app = app
+        }
+
+        public func run(setup: @escaping () -> Void) {
+            setup()
+        }
+
+        public func quit() {
+            fatalError("Quit")
+        }
+
+    }
+
 }