Merge pull request #879 from Hixie/RenderBlockViewport

Abstract out syncChildren().

packages/flutter/lib/rendering/block.dart

@@ -272,7 +272,8 @@ class RenderBlockViewport extends RenderBlockBase {
       result = intrinsicCallback(constraints);
       if (result == null)
         result = constrainer(0.0);
-      assert(constrainer(result) == result);
+      else
+        result = constrainer(result);
     } finally {
       _inCallback = false;
     }

packages/flutter/lib/widgets/framework.dart

@@ -979,6 +979,7 @@ abstract class RenderObjectWrapper extends Widget {
   }
 
   void syncRenderObject(RenderObjectWrapper old) {
+    assert(old == null || old.renderObject == renderObject);
     ParentData parentData = null;
     Widget ancestor = parent;
     while (ancestor != null && ancestor is! RenderObjectWrapper) {
@@ -998,134 +999,8 @@ abstract class RenderObjectWrapper extends Widget {
     }
   }
 
-  void dependenciesChanged() {
-    // called by Inherited.sync()
-    syncRenderObject(this);
-  }
-
-  void remove() {
-    assert(renderObject != null);
-    _nodeMap.remove(renderObject);
-    super.remove();
-  }
-
-  void detachRenderObject() {
-    assert(_ancestor != null);
-    assert(renderObject != null);
-    _ancestor.detachChildRenderObject(this);
-  }
-
-}
-
-abstract class LeafRenderObjectWrapper extends RenderObjectWrapper {
-
-  LeafRenderObjectWrapper({ Key key }) : super(key: key);
-
-  void insertChildRenderObject(RenderObjectWrapper child, dynamic slot) {
-    assert(false);
-  }
-
-  void detachChildRenderObject(RenderObjectWrapper child) {
-    assert(false);
-  }
-
-}
-
-abstract class OneChildRenderObjectWrapper extends RenderObjectWrapper {
-
-  OneChildRenderObjectWrapper({ Key key, Widget child })
-    : _child = child, super(key: key);
-
-  Widget _child;
-  Widget get child => _child;
-
-  void walkChildren(WidgetTreeWalker walker) {
-    if (child != null)
-      walker(child);
-  }
-
-  void syncRenderObject(RenderObjectWrapper old) {
-    super.syncRenderObject(old);
-    Widget oldChild = old == null ? null : (old as OneChildRenderObjectWrapper).child;
-    Widget newChild = child;
-    _child = syncChild(newChild, oldChild, null);
-    assert((newChild == null && child == null) || (newChild != null && child.parent == this));
-    assert(oldChild == null || child == oldChild || oldChild.parent == null);
-  }
-
-  void insertChildRenderObject(RenderObjectWrapper child, dynamic slot) {
-    final renderObject = this.renderObject; // TODO(ianh): Remove this once the analyzer is cleverer
-    assert(renderObject is RenderObjectWithChildMixin);
-    assert(slot == null);
-    renderObject.child = child.renderObject;
-    assert(renderObject == this.renderObject); // TODO(ianh): Remove this once the analyzer is cleverer
-  }
-
-  void detachChildRenderObject(RenderObjectWrapper child) {
-    final renderObject = this.renderObject; // TODO(ianh): Remove this once the analyzer is cleverer
-    assert(renderObject is RenderObjectWithChildMixin);
-    assert(renderObject.child == child.renderObject);
-    renderObject.child = null;
-    assert(renderObject == this.renderObject); // TODO(ianh): Remove this once the analyzer is cleverer
-  }
-}
-
-abstract class MultiChildRenderObjectWrapper extends RenderObjectWrapper {
-
-  // In MultiChildRenderObjectWrapper subclasses, slots are the Widget
-  // nodes whose RenderObjects are to be used as the "insert before"
-  // sibling in ContainerRenderObjectMixin.add() calls
-
-  MultiChildRenderObjectWrapper({ Key key, List<Widget> children })
-    : this.children = children == null ? const [] : children,
-      super(key: key) {
-    assert(!_debugHasDuplicateIds());
-  }
-
-  final List<Widget> children;
-
-  void walkChildren(WidgetTreeWalker walker) {
-    for (Widget child in children)
-      walker(child);
-  }
-
-  void insertChildRenderObject(RenderObjectWrapper child, Widget slot) {
-    final renderObject = this.renderObject; // TODO(ianh): Remove this once the analyzer is cleverer
-    RenderObject nextSibling = slot != null ? slot.renderObject : null;
-    assert(nextSibling == null || nextSibling is RenderObject);
-    assert(renderObject is ContainerRenderObjectMixin);
-    renderObject.add(child.renderObject, before: nextSibling);
-    assert(renderObject == this.renderObject); // TODO(ianh): Remove this once the analyzer is cleverer
-  }
-
-  void detachChildRenderObject(RenderObjectWrapper child) {
-    final renderObject = this.renderObject; // TODO(ianh): Remove this once the analyzer is cleverer
-    assert(renderObject is ContainerRenderObjectMixin);
-    assert(child.renderObject.parent == renderObject);
-    renderObject.remove(child.renderObject);
-    assert(renderObject == this.renderObject); // TODO(ianh): Remove this once the analyzer is cleverer
-  }
-
-  bool _debugHasDuplicateIds() {
-    var idSet = new HashSet<Key>();
-    for (var child in children) {
-      assert(child != null);
-      if (child.key == null)
-        continue; // when these nodes are reordered, we just reassign the data
-
-      if (!idSet.add(child.key)) {
-        throw '''If multiple keyed nodes exist as children of another node, they must have unique keys. $this has duplicate child key "${child.key}".''';
-      }
-    }
-    return false;
-  }
-
-  void syncRenderObject(MultiChildRenderObjectWrapper old) {
-    super.syncRenderObject(old);
-
-    final ContainerRenderObjectMixin renderObject = this.renderObject; // TODO(ianh): Remove this once the analyzer is cleverer
-    assert(renderObject is ContainerRenderObjectMixin);
-    assert(old == null || old.renderObject == renderObject);
+  // for use by subclasses that manage their children using lists
+  void syncChildren(List<Widget> newChildren, List<Widget> oldChildren) {
 
     // This attempts to diff the new child list (this.children) with
     // the old child list (old.children), and update our renderObject
@@ -1158,8 +1033,9 @@ abstract class MultiChildRenderObjectWrapper extends RenderObjectWrapper {
     // 6. Sync null with any items in the list of keys that are still
     //    mounted.
 
-    final List<Widget> newChildren = children;
-    final List<Widget> oldChildren = old == null ? const <Widget>[] : old.children;
+    final ContainerRenderObjectMixin renderObject = this.renderObject; // TODO(ianh): Remove this once the analyzer is cleverer
+    assert(renderObject is ContainerRenderObjectMixin);
+
     int childrenTop = 0;
     int newChildrenBottom = newChildren.length-1;
     int oldChildrenBottom = oldChildren.length-1;
@@ -1260,6 +1136,133 @@ abstract class MultiChildRenderObjectWrapper extends RenderObjectWrapper {
     assert(renderObject == this.renderObject); // TODO(ianh): Remove this once the analyzer is cleverer
   }
 
+  void dependenciesChanged() {
+    // called by Inherited.sync()
+    syncRenderObject(this);
+  }
+
+  void remove() {
+    assert(renderObject != null);
+    _nodeMap.remove(renderObject);
+    super.remove();
+  }
+
+  void detachRenderObject() {
+    assert(_ancestor != null);
+    assert(renderObject != null);
+    _ancestor.detachChildRenderObject(this);
+  }
+
+}
+
+abstract class LeafRenderObjectWrapper extends RenderObjectWrapper {
+
+  LeafRenderObjectWrapper({ Key key }) : super(key: key);
+
+  void insertChildRenderObject(RenderObjectWrapper child, dynamic slot) {
+    assert(false);
+  }
+
+  void detachChildRenderObject(RenderObjectWrapper child) {
+    assert(false);
+  }
+
+}
+
+abstract class OneChildRenderObjectWrapper extends RenderObjectWrapper {
+
+  OneChildRenderObjectWrapper({ Key key, Widget child })
+    : _child = child, super(key: key);
+
+  Widget _child;
+  Widget get child => _child;
+
+  void walkChildren(WidgetTreeWalker walker) {
+    if (child != null)
+      walker(child);
+  }
+
+  void syncRenderObject(RenderObjectWrapper old) {
+    super.syncRenderObject(old);
+    Widget oldChild = old == null ? null : (old as OneChildRenderObjectWrapper).child;
+    Widget newChild = child;
+    _child = syncChild(newChild, oldChild, null);
+    assert((newChild == null && child == null) || (newChild != null && child.parent == this));
+    assert(oldChild == null || child == oldChild || oldChild.parent == null);
+  }
+
+  void insertChildRenderObject(RenderObjectWrapper child, dynamic slot) {
+    final renderObject = this.renderObject; // TODO(ianh): Remove this once the analyzer is cleverer
+    assert(renderObject is RenderObjectWithChildMixin);
+    assert(slot == null);
+    renderObject.child = child.renderObject;
+    assert(renderObject == this.renderObject); // TODO(ianh): Remove this once the analyzer is cleverer
+  }
+
+  void detachChildRenderObject(RenderObjectWrapper child) {
+    final renderObject = this.renderObject; // TODO(ianh): Remove this once the analyzer is cleverer
+    assert(renderObject is RenderObjectWithChildMixin);
+    assert(renderObject.child == child.renderObject);
+    renderObject.child = null;
+    assert(renderObject == this.renderObject); // TODO(ianh): Remove this once the analyzer is cleverer
+  }
+}
+
+abstract class MultiChildRenderObjectWrapper extends RenderObjectWrapper {
+
+  // In MultiChildRenderObjectWrapper subclasses, slots are the Widget
+  // nodes whose RenderObjects are to be used as the "insert before"
+  // sibling in ContainerRenderObjectMixin.add() calls
+
+  MultiChildRenderObjectWrapper({ Key key, List<Widget> children })
+    : this.children = children == null ? const [] : children,
+      super(key: key) {
+    assert(!_debugHasDuplicateIds());
+  }
+
+  final List<Widget> children;
+
+  void walkChildren(WidgetTreeWalker walker) {
+    for (Widget child in children)
+      walker(child);
+  }
+
+  void insertChildRenderObject(RenderObjectWrapper child, Widget slot) {
+    final renderObject = this.renderObject; // TODO(ianh): Remove this once the analyzer is cleverer
+    RenderObject nextSibling = slot != null ? slot.renderObject : null;
+    assert(nextSibling == null || nextSibling is RenderObject);
+    assert(renderObject is ContainerRenderObjectMixin);
+    renderObject.add(child.renderObject, before: nextSibling);
+    assert(renderObject == this.renderObject); // TODO(ianh): Remove this once the analyzer is cleverer
+  }
+
+  void detachChildRenderObject(RenderObjectWrapper child) {
+    final renderObject = this.renderObject; // TODO(ianh): Remove this once the analyzer is cleverer
+    assert(renderObject is ContainerRenderObjectMixin);
+    assert(child.renderObject.parent == renderObject);
+    renderObject.remove(child.renderObject);
+    assert(renderObject == this.renderObject); // TODO(ianh): Remove this once the analyzer is cleverer
+  }
+
+  bool _debugHasDuplicateIds() {
+    var idSet = new HashSet<Key>();
+    for (var child in children) {
+      assert(child != null);
+      if (child.key == null)
+        continue; // when these nodes are reordered, we just reassign the data
+
+      if (!idSet.add(child.key)) {
+        throw '''If multiple keyed nodes exist as children of another node, they must have unique keys. $this has duplicate child key "${child.key}".''';
+      }
+    }
+    return false;
+  }
+
+  void syncRenderObject(MultiChildRenderObjectWrapper old) {
+    super.syncRenderObject(old);
+    syncChildren(children, old == null ? const <Widget>[] : old.children);
+  }
+
 }
 
 class WidgetSkyBinding extends SkyBinding {