[Effen] Move responsibility for inserting nodes to the OneChildListRenderNodeWrapper.

Before, OneChildListRenderNodeWrappers were responsible for removing
the child nodes' RenderCSS nodes from their containers, and for moving
those around when nodes were reordered. Now, they're also responsible
for adding them.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1145953003

sdk/lib/framework/fn.dart

@@ -6,6 +6,7 @@ library fn;
 
 import 'dart:async';
 import 'dart:collection';
+import 'dart:mirrors';
 import 'dart:sky' as sky;
 import 'reflect.dart' as reflect;
 import 'layout.dart';
@@ -41,7 +42,9 @@ abstract class UINode {
 
   bool get interchangeable => false; // if true, then keys can be duplicated
 
-  void _sync(UINode old, RenderCSSContainer host, RenderCSS insertBefore);
+  void _sync(UINode old, dynamic slot);
+  // 'slot' is the identifier that the parent RenderNodeWrapper uses to know
+  // where to put this descendant
 
   void _remove() {
     _defunct = true;
@@ -50,6 +53,13 @@ abstract class UINode {
   }
   void handleRemoved() { }
 
+  UINode findAncestor(Type targetType) {
+    var ancestor = _parent;
+    while (ancestor != null && !reflectClass(ancestor.runtimeType).isSubtypeOf(reflectClass(targetType)))
+      ancestor = ancestor._parent;
+    return ancestor;
+  }
+
   int _nodeDepth;
   void _ensureDepth() {
     if (_nodeDepth == null) {
@@ -85,9 +95,8 @@ abstract class UINode {
   }
 
   // Returns the child which should be retained as the child of this node.
-  UINode _syncChild(UINode node, UINode oldNode, RenderCSSContainer host,
-      RenderCSS insertBefore) {
-
+  UINode _syncChild(UINode node, UINode oldNode, dynamic slot) {
+    assert(node != null);
     assert(oldNode == null || node._key == oldNode._key);
 
     if (node == oldNode) {
@@ -104,7 +113,7 @@ abstract class UINode {
 
     if (node._willSync(oldNode)) {
       _traceSync(_SyncOperation.STATEFUL, node._key);
-      oldNode._sync(node, host, insertBefore);
+      oldNode._sync(node, slot);
       node._defunct = true;
       assert(oldNode._root is RenderCSS);
       return oldNode;
@@ -118,7 +127,7 @@ abstract class UINode {
     } else {
       _traceSync(_SyncOperation.STATELESS, node._key);
     }
-    node._sync(oldNode, host, insertBefore);
+    node._sync(oldNode, slot);
     if (oldNode != null)
       oldNode._defunct = true;
 
@@ -132,9 +141,9 @@ abstract class ContentNode extends UINode {
 
   ContentNode(UINode content) : this.content = content, super(key: content._key);
 
-  void _sync(UINode old, RenderCSSContainer host, RenderCSS insertBefore) {
+  void _sync(UINode old, dynamic slot) {
     UINode oldContent = old == null ? null : (old as ContentNode).content;
-    content = _syncChild(content, oldContent, host, insertBefore);
+    content = _syncChild(content, oldContent, slot);
     assert(content._root != null);
     _root = content._root;
   }
@@ -266,12 +275,11 @@ class EventListenerNode extends ContentNode  {
     }
   }
 
-  void _sync(UINode old, RenderCSSContainer host, RenderCSS insertBefore) {
+  void _sync(UINode old, dynamic slot) {
     for (var type in listeners.keys) {
       _ensureDocumentListener(type);
     }
-
-    super._sync(old, host, insertBefore);
+    super._sync(old, slot);
   }
 }
 
@@ -301,11 +309,15 @@ abstract class RenderNodeWrapper extends UINode {
   RenderCSS _createNode();
   RenderNodeWrapper get _emptyNode;
 
-  void _sync(UINode old, RenderCSSContainer host, RenderCSS insertBefore) {
+  void insert(RenderNodeWrapper child, dynamic slot);
+
+  void _sync(UINode old, dynamic slot) {
     if (old == null) {
       _root = _createNode();
       assert(_root != null);
-      host.add(_root, before: insertBefore);
+      var ancestor = findAncestor(RenderNodeWrapper);
+      if (ancestor is RenderNodeWrapper)
+        ancestor.insert(this, slot);
       old = _emptyNode;
     } else {
       _root = old._root;
@@ -364,6 +376,9 @@ final List<UINode> _emptyList = new List<UINode>();
 
 abstract class OneChildListRenderNodeWrapper extends RenderNodeWrapper {
 
+  // In OneChildListRenderNodeWrapper subclasses, slots are RenderCSS nodes
+  // to use as the "insert before" sibling in RenderCSSContainer.add() calls
+
   final List<UINode> children;
 
   OneChildListRenderNodeWrapper({
@@ -380,6 +395,11 @@ abstract class OneChildListRenderNodeWrapper extends RenderNodeWrapper {
     assert(!_debugHasDuplicateIds());
   }
 
+  void insert(RenderNodeWrapper child, dynamic slot) {
+    assert(slot == null || slot is RenderCSS);
+    _root.add(child._root, before: slot);
+  }
+
   void _remove() {
     assert(children != null);
     for (var child in children) {
@@ -423,7 +443,7 @@ abstract class OneChildListRenderNodeWrapper extends RenderNodeWrapper {
     UINode oldNode = null;
 
     void sync(int atIndex) {
-      children[atIndex] = _syncChild(currentNode, oldNode, _root, nextSibling);
+      children[atIndex] = _syncChild(currentNode, oldNode, nextSibling);
       assert(children[atIndex] != null);
     }
 
@@ -482,8 +502,10 @@ abstract class OneChildListRenderNodeWrapper extends RenderNodeWrapper {
       oldNodeIdMap[currentNode._key] = null; // mark it reordered
       assert(_root is RenderCSSContainer);
       assert(oldNode._root is RenderCSSContainer);
+
       old._root.remove(oldNode._root);
       _root.add(oldNode._root, before: nextSibling);
+
       return true;
     }
 
@@ -780,6 +802,7 @@ abstract class Component extends UINode {
   static Component _currentlyBuilding;
   List<Function> _mountCallbacks;
   List<Function> _unmountCallbacks;
+  dynamic _slot; // cached slot from the last time we were synced
 
   void onDidMount(Function fn) {
     if (_mountCallbacks == null)
@@ -852,12 +875,14 @@ abstract class Component extends UINode {
    * 3) Syncing against an old version
    *      assert(_built == null && old != null)
    */
-  void _sync(UINode old, RenderCSSContainer host, RenderCSS insertBefore) {
+  void _sync(UINode old, dynamic slot) {
     assert(!_defunct);
     assert(_built == null || old == null);
 
     Component oldComponent = old as Component;
 
+    _slot = slot;
+
     var oldBuilt;
     if (oldComponent == null) {
       oldBuilt = _built;
@@ -876,7 +901,7 @@ abstract class Component extends UINode {
     _currentlyBuilding = null;
     _currentOrder = lastOrder;
 
-    _built = _syncChild(_built, oldBuilt, host, insertBefore);
+    _built = _syncChild(_built, oldBuilt, slot);
     _dirty = false;
     _root = _built._root;
     assert(_root != null);
@@ -887,7 +912,8 @@ abstract class Component extends UINode {
       return;
 
     _trace('$_key rebuilding...');
-    _sync(null, _root.parent, _root.parent.childAfter(_root));
+    assert(_root != null);
+    _sync(null, _slot);
   }
 
   void scheduleBuild() {
@@ -920,7 +946,10 @@ abstract class App extends Component {
       return;
 
     _trace('$_key rebuilding...');
-    _sync(null, _host, _root);
+    _sync(null, null);
+    if (_root.parent == null)
+      _host.add(_root);
+    assert(_root.parent == _host);
   }
 }