[WIP DNR] Decoration Views

ListableUI/Sources/Decoration/AnyDecoration.swift

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+//
+//  AnyDecoration.swift
+//  ListableUI
+//
+//  Created by Goose on 7/24/25.
+//
+
+import Foundation
+import UIKit
+
+
+public protocol AnyDecoration : AnyDecorationConvertible, AnyDecoration_Internal
+{
+    var anyContent : Any { get }
+
+    var sizing : Sizing { get set }
+    var layouts : DecorationLayouts { get set }
+
+    var reappliesToVisibleView: ReappliesToVisibleView { get }
+}
+
+
+public protocol AnyDecoration_Internal
+{
+    var layouts : DecorationLayouts { get }
+
+    func apply(
+        to decorationView : UIView,
+        for reason : ApplyReason,
+        with info : ApplyDecorationContentInfo
+    )
+
+    func anyIsEquivalent(to other : AnyDecoration) -> Bool
+
+    func newPresentationDecorationState(
+        kind : SupplementaryKind,
+        performsContentCallbacks : Bool
+    ) -> Any
+}

ListableUI/Sources/Decoration/AnyDecorationConvertible.swift

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+//
+//  AnyDecorationConvertible.swift
+//  ListableUI
+//
+//  Created by Goose on 7/24/25.
+//
+
+import Foundation
+
+
+/// A type which can be converted into a `Decoration`, so you
+/// do not need to explicitly wrap / convert your `DecorationContent`
+/// in a `Decoration` when providing a decoration to a list or section:
+///
+/// ```
+/// Section("id") { section in
+///     section.decoration = MyDecorationContent(backgroundColor: .red)
+/// }
+///
+/// struct MyDecorationContent : DecorationContent {
+///    var backgroundColor : UIColor
+///    ...
+/// }
+/// ```
+///
+/// Only two types conform to this protocol:
+///
+/// ### `Decoration`
+/// The `Decoration` conformance simply returns self.
+///
+/// ### `DecorationContent`
+/// The `DecorationContent` conformance returns `Decoration(self)`,
+/// utilizing the default values from the `Decoration` initializer.
+///
+public protocol AnyDecorationConvertible {
+
+    /// Converts the object into a type-erased `AnyDecoration` instance.
+    func asAnyDecoration() -> AnyDecoration
+}

ListableUI/Sources/Decoration/Decoration.swift

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+//
+//  Decoration.swift
+//  ListableUI
+//
+//  Created by Goose on 7/24/25.
+//
+
+import UIKit
+
+
+public struct Decoration<Content:DecorationContent> : AnyDecoration
+{
+    public var content : Content
+
+    public var sizing : Sizing
+    public var layouts : DecorationLayouts
+
+    public typealias OnTap = () -> ()
+    public var onTap : OnTap?
+
+    public var onDisplay : OnDisplay.Callback?
+    public var onEndDisplay : OnEndDisplay.Callback?
+
+    public var debuggingIdentifier : String? = nil
+
+    internal let reuseIdentifier : ReuseIdentifier<Content>
+
+    //
+    // MARK: Initialization
+    //
+
+    public typealias Configure = (inout Decoration) -> ()
+
+    public init(
+        _ content : Content,
+        configure : Configure
+    ) {
+        self.init(content)
+
+        configure(&self)
+    }
+
+    public init(
+        _ content : Content,
+        sizing : Sizing? = nil,
+        layouts : DecorationLayouts? = nil,
+        onTap : OnTap? = nil,
+        onDisplay : OnDisplay.Callback? = nil,
+        onEndDisplay : OnEndDisplay.Callback? = nil
+    ) {
+        assertIsValueType(Content.self)
+
+        self.content = content
+
+        let defaults = self.content.defaultDecorationProperties
+
+        self.sizing = sizing ?? defaults.sizing ?? .thatFits(.noConstraint)
+        self.layouts = layouts ?? defaults.layouts ?? .init()
+        self.onTap = onTap ?? defaults.onTap
+        self.onDisplay = onDisplay
+        self.onEndDisplay = onEndDisplay
+        self.debuggingIdentifier = defaults.debuggingIdentifier
+
+        self.reuseIdentifier = ReuseIdentifier.identifier(for: Content.self)
+    }
+
+    // MARK: AnyDecoration
+
+    public var anyContent: Any {
+        self.content
+    }
+
+    public var reappliesToVisibleView: ReappliesToVisibleView {
+        self.content.reappliesToVisibleView
+    }
+
+    // MARK: AnyDecorationConvertible
+
+    public func asAnyDecoration() -> AnyDecoration {
+        self
+    }
+
+    // MARK: AnyDecoration_Internal
+
+    public func apply(
+        to anyView : UIView,
+        for reason : ApplyReason,
+        with info : ApplyDecorationContentInfo
+    ) {
+        let view = anyView as! DecorationContentView<Content>
+
+        let views = DecorationContentViews<Content>(view: view)
+
+        self.content.apply(
+            to: views,
+            for: reason,
+            with: info
+        )
+    }
+
+    public func anyIsEquivalent(to other : AnyDecoration) -> Bool
+    {
+        guard let other = other as? Decoration<Content> else {
+            return false
+        }
+
+        return self.content.isEquivalent(to: other.content)
+    }
+
+    public func newPresentationDecorationState(
+        kind : SupplementaryKind,
+        performsContentCallbacks : Bool
+    ) -> Any
+    {
+        return PresentationState.DecorationState(
+            self,
+            kind: kind,
+            performsContentCallbacks: performsContentCallbacks
+        )
+    }
+}
+
+
+extension DecorationContent {
+
+    /// Identical to `Decoration.init` which takes in a `DecorationContent`,
+    /// except you can call this on the `DecorationContent` itself, instead of wrapping it,
+    /// to avoid additional nesting, and to hoist your content up in your code.
+    ///
+    /// ```
+    /// Section("id") { section in
+    ///     section.decoration = MyDecorationContent(
+    ///         backgroundColor: .red
+    ///     )
+    ///     .with(
+    ///         sizing: .thatFits(.noConstraint),
+    ///     )
+    ///
+    /// struct MyDecorationContent : DecorationContent {
+    ///    var backgroundColor : UIColor
+    ///    ...
+    /// }
+    /// ```
+    public func with(
+        sizing : Sizing? = nil,
+        layouts : DecorationLayouts? = nil,
+        onTap : Decoration<Self>.OnTap? = nil
+    ) -> Decoration<Self>
+    {
+        Decoration(
+            self,
+            sizing: sizing,
+            layouts: layouts,
+            onTap: onTap
+        )
+    }
+}
+
+
+extension Decoration : SignpostLoggable
+{
+    var signpostInfo : SignpostLoggingInfo {
+        SignpostLoggingInfo(
+            identifier: self.debuggingIdentifier,
+            instanceIdentifier: nil
+        )
+    }
+}

ListableUI/Sources/Decoration/DecorationCallbacks.swift

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+//
+//  HeaderFooterCallbacks.swift
+//  ListableUI
+//
+//  Created by Kyle Van Essen on 4/3/25.
+//
+
+import Foundation
+
+
+extension Decoration {
+
+    /// Value passed to the `onDisplay` callback for `HeaderFooter`.
+    public struct OnDisplay
+    {
+        public typealias Callback = (OnDisplay) -> ()
+
+        public var decoration : Decoration
+
+        public var isFirstDisplay : Bool
+    }
+
+    /// Value passed to the `onEndDisplay` callback for `HeaderFooter`.
+    public struct OnEndDisplay
+    {
+        public typealias Callback = (OnEndDisplay) -> ()
+
+        public var decoration : Decoration
+
+        public var isFirstEndDisplay : Bool
+    }
+}
+