Allow hydrating into as well as onto.

Author: back2dos

src/coconut/diffing/Root.hx

@@ -2,19 +2,25 @@ package coconut.diffing;
 
 import coconut.ui.internal.ImplicitContext;
 
+enum abstract Hydration(Int) {
+  var No;
+  var Into;
+  var Onto;
+}
+
 class Root<Native> extends Parent {
   final rendered:RCell<Native>;
 
-  public function new(parent, applicator:Applicator<Native>, ?content, hydrate:Bool) {
+  public function new(parent, applicator:Applicator<Native>, ?content, hydration = No) {
     super(new ImplicitContext());
-    var rendered = Parent.withLater(later -> new RCell(this, content, applicator.children(parent), later, hydrate));
+    var rendered = Parent.withLater(later -> new RCell(this, content, if (hydration == Onto) applicator.siblings(parent) else applicator.children(parent), later, hydration != No));
     this.rendered = rendered;
   }
 
   static final byParent = new Map<{}, Root<Dynamic>>();
   static public function fromNative<Native:{}>(parent:Native, applicator:Applicator<Native>):Root<Native>
     return cast switch byParent[parent] {
-      case null: byParent[parent] = new Root(parent, applicator, false);
+      case null: byParent[parent] = new Root(parent, applicator);
       case v: v;
     }
 

tests/TodoMvc.hx

@@ -119,7 +119,7 @@ class TodoMvc {
             @:privateAccess Renderer.BACKEND // meh
           #else DummyApplicator.INST #end,
           markup,
-          hydrate
+          if (hydrate) Into else No
         );
         if (hydrate) {
           asserts.assert(root.innerHTML == innerHTML);