Implement attach view

src/Fabulous/Component.fs

@@ -304,7 +304,24 @@
             { Key = key
               Name = "Component"
               TargetType = typeof<Component>
-              AttachView = fun _ -> failwith "Component widget cannot be attached"
+              AttachView =
+                fun (widget, treeContext, _parentNode, view) ->
+                    match widget.ScalarAttributes with
+                    | ValueNone -> failwith "Component widget must have a body and a context"
+                    | ValueSome attrs ->
+                        let body =
+                            match Array.tryFind (fun (attr: ScalarAttribute) -> attr.Key = Component.Body.Key) attrs with
+                            | Some attr -> attr.Value :?> ComponentBody
+                            | None -> failwith "Component widget must have a body"
+
+                        let context =
+                            match Array.tryFind (fun (attr: ScalarAttribute) -> attr.Key = Component.Context.Key) attrs with
+                            | Some attr -> attr.Value :?> ComponentContext
+                            | None -> ComponentContext()
+
+                        let comp = new Component(treeContext, body, context)
+                        let node = comp.AttachView(view)
+                        node
               CreateView =
                 fun (widget, treeContext, _) ->
                     match widget.ScalarAttributes with

src/Fabulous/Memo.fs

@@ -89,6 +89,19 @@ module Memo =
                 // to pass it to reconciler later on
                 node.MemoizedWidget <- Some memoizedWidget
                 struct (node, view)
-          AttachView = fun (_widget, _context, _parentNode, _view) -> failwith "Memo widget cannot be attached" }
+          AttachView =
+            fun (widget, context, parentNode, view) ->
+                let memoData = getMemoData widget
+
+                let memoizedWidget = memoData.CreateWidget memoData.KeyData
+
+                let memoizedDef = WidgetDefinitionStore.get memoizedWidget.Key
+
+                let node = memoizedDef.AttachView(memoizedWidget, context, parentNode, view)
+
+                // store widget that was used to produce this node
+                // to pass it to reconciler later on
+                node.MemoizedWidget <- Some memoizedWidget
+                node }
 
     WidgetDefinitionStore.set MemoWidgetKey widgetDefinition