add reload method and hold(value:) modifier

Sources/UIComponent/Core/Model/Component/Component+Modifier.swift

@@ -227,3 +227,24 @@ extension Component {
         VisibleBoundsObserverComponent(child: self, onVisibleBoundsChanged: callback)
     }
 }
+
+extension Component {
+    /// A block that can be captured inside `layout` or `build` method to trigger a reload on the linked componentView
+    public var reload: () -> Void {
+        guard let componentView = currentComponentView() else {
+            assertionFailure("reloadComponent should only be captured within `layout` or `build` method")
+            return {}
+        }
+        return { [weak componentView] in
+            componentView?.reloadData()
+        }
+    }
+}
+
+extension Component {
+    /// Hold any value while the Component is displayed
+    /// - Parameter value: value to be holding
+    public func hold(value: Any) -> Component {
+        HoldValueComponent(child: self, value: value)
+    }
+}

Sources/UIComponent/Core/Util/HoldValueComponent.swift

@@ -0,0 +1,21 @@
+//
+//  File.swift
+//  
+//
+//  Created by Luke Zhao on 3/14/23.
+//
+
+import Foundation
+
+struct HoldValueComponent: Component {
+    let child: Component
+    let value: Any
+    func layout(_ constraint: Constraint) -> RenderNode {
+        HoldValueRenderNode(child: child.layout(constraint), value: value)
+    }
+}
+
+struct HoldValueRenderNode: WrapperRenderNode {
+    let child: RenderNode
+    let value: Any?
+}

Sources/UIComponent/Core/Util/WrapperRenderNode.swift

@@ -0,0 +1,26 @@
+//
+//  File.swift
+//  
+//
+//  Created by Luke Zhao on 3/14/23.
+//
+
+import Foundation
+
+public protocol WrapperRenderNode: RenderNode {
+    var child: RenderNode { get }
+}
+
+public extension WrapperRenderNode {
+    var size: CGSize {
+        child.size
+    }
+
+    var positions: [CGPoint] {
+        [.zero]
+    }
+
+    var children: [RenderNode] {
+        [child]
+    }
+}