Introduce a LeafRenderObjectWrapper abstract class so that RenderObjectWrappers that are leaves don…

sky/sdk/lib/widgets/basic.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'package:vector_math/vector_math.dart';
 
 import '../painting/text_style.dart';
 import '../rendering/block.dart';
 import '../rendering/box.dart';
 import '../rendering/flex.dart';
@@ skipping 328 matching lines @@
     root.alignItems = alignItems;
   }
 
 }
 
 class Flexible extends ParentDataNode {
   Flexible({ String key, Widget child, int flex: 1 })
     : super(child, new FlexBoxParentData()..flex = flex, key: key);
 }
 
-class Inline extends RenderObjectWrapper {
+class Inline extends LeafRenderObjectWrapper {
   Inline({ String key, this.text }) : super(key: key);
 
   RenderParagraph get root => super.root;
   RenderParagraph createNode() => new RenderParagraph(text);
 
   final InlineBase text;
 
   void syncRenderObject(Widget old) {
     super.syncRenderObject(old);
     root.inline = text;
   }
 
-  void insertChildRoot(RenderObjectWrapper child, dynamic slot) {
-    assert(false);
-    // Inline does not support having children currently
-  }
-
 }
 
 class Text extends Component {
-  Text(data, { String key, TextStyle this.style }) : data = data, super(key: key);
+  Text(data, { String key, TextStyle this.style }) : super(key: key);
   final String data;
   final TextStyle style;
   bool get interchangeable => true;
   Widget build() {
     InlineBase text = new InlineText(data);
     if (style != null) text = new InlineStyle(style, [text]);
     return new Inline(text: text);
   }
 }
 
-class Image extends RenderObjectWrapper {
+class Image extends LeafRenderObjectWrapper {
 
   Image({
-    String key,
-    this.src,
+    src,
     this.size
-  }) : super(key: key);
+  }) : src = src,
+       super(key: src) {
+    assert(src != null);
+  }
 
   RenderImage get root => super.root;
   RenderImage createNode() => new RenderImage(this.src, this.size);
 
   final String src;
   final Size size;
 
   void syncRenderObject(Widget old) {
     super.syncRenderObject(old);
     root.src = src;
     root.requestedSize = size;
   }
 
-  void insertChildRoot(RenderObjectWrapper child, dynamic slot) {
-    assert(false);
-    // Image does not support having children currently
-  }
-
 }
 
-class WidgetToRenderBoxAdapter extends RenderObjectWrapper {
+class WidgetToRenderBoxAdapter extends LeafRenderObjectWrapper {
 
   WidgetToRenderBoxAdapter(RenderBox renderBox)
-    : this.renderBox = renderBox,
+    : renderBox = renderBox,
       super(key: renderBox.hashCode.toString());
 
   RenderBox get root => super.root;
   RenderBox createNode() => this.renderBox;
 
   final RenderBox renderBox;
 
   void syncRenderObject(Widget old) {
     super.syncRenderObject(old);
     if (old != null) {
       assert(old is WidgetToRenderBoxAdapter);
       assert(root == old.root);
     }
   }
 
-  void insertChildRoot(RenderObjectWrapper child, dynamic slot) {
-    assert(false);
-    // WidgetToRenderBoxAdapter cannot have Widget children; by
-    // definition, it is the transition out of the Widget world.
-  }
-
   void remove() {
     parent.detachChildRoot(this);
     super.remove();
   }
 
 }