Improve stocks2 performance

sky/sdk/lib/rendering/object.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 'dart:math' as math;
 import 'dart:sky' as sky;
 import 'dart:sky' show Point, Size, Rect, Color, Paint, Path;
 
 import '../base/hit_test.dart';
 import '../base/node.dart';
@@ skipping 113 matching lines @@
   void _cleanRelayoutSubtreeRootChildren() { } // workaround for lack of inter-class mixins in Dart
   void scheduleInitialLayout() {
     assert(attached);
     assert(parent == null);
     assert(_relayoutSubtreeRoot == null);
     _relayoutSubtreeRoot = this;
     _nodesNeedingLayout.add(this);
     scheduler.ensureVisualUpdate();
   }
   static void flushLayout() {
+    sky.tracing.begin('RenderObject.flushLayout');
     _debugDoingLayout = true;
-    List<RenderObject> dirtyNodes = _nodesNeedingLayout;
-    _nodesNeedingLayout = new List<RenderObject>();
-    dirtyNodes..sort((a, b) => a.depth - b.depth)..forEach((node) {
-      if (node._needsLayout && node.attached)
-        node.layoutWithoutResize();
-    });
-    _debugDoingLayout = false;
+    try {
+      List<RenderObject> dirtyNodes = _nodesNeedingLayout;
+      _nodesNeedingLayout = new List<RenderObject>();
+      dirtyNodes..sort((a, b) => a.depth - b.depth)..forEach((node) {
+        if (node._needsLayout && node.attached)
+          node.layoutWithoutResize();
+      });
+    } finally {
+      _debugDoingLayout = false;
+      sky.tracing.end('RenderObject.flushLayout');
+    }
   }
   void layoutWithoutResize() {
     try {
       assert(_relayoutSubtreeRoot == this);
       performLayout();
     } catch (e, stack) {
       print('Exception raised during layout of ${this}: ${e}');
       print(stack);
       return;
     }
@@ skipping 191 matching lines @@
     while (child.parentData.nextSibling != null) {
       assert(child.parentData.nextSibling != child);
       child = child.parentData.nextSibling;
       assert(child.parentData is ParentDataType);
     }
     return child == equals;
   }
 
   ChildType _firstChild;
   ChildType _lastChild;
-  void add(ChildType child, { ChildType before }) {
-    assert(child != this);
-    assert(before != this);
-    assert(child != before);
-    assert(child != _firstChild);
-    assert(child != _lastChild);
-    adoptChild(child);
+  void _addToChildList(ChildType child, { ChildType before }) {
     assert(child.parentData is ParentDataType);
     assert(child.parentData.nextSibling == null);
     assert(child.parentData.previousSibling == null);
     if (before == null) {
       // append at the end (_lastChild)
       child.parentData.previousSibling = _lastChild;
       if (_lastChild != null) {
         assert(_lastChild.parentData is ParentDataType);
         _lastChild.parentData.nextSibling = child;
       }
@@ skipping 19 matching lines @@
         child.parentData.nextSibling = before;
         // set up links from siblings to child
         assert(child.parentData.previousSibling.parentData is ParentDataType);
         assert(child.parentData.nextSibling.parentData is ParentDataType);
         child.parentData.previousSibling.parentData.nextSibling = child;
         child.parentData.nextSibling.parentData.previousSibling = child;
         assert(before.parentData.previousSibling == child);
       }
     }
   }
-  void remove(ChildType child) {
+  void add(ChildType child, { ChildType before }) {
+    assert(child != this);
+    assert(before != this);
+    assert(child != before);
+    assert(child != _firstChild);
+    assert(child != _lastChild);
+    adoptChild(child);
+    _addToChildList(child, before: before);
+  }
+  void _removeFromChildList(ChildType child) {
     assert(child.parentData is ParentDataType);
     assert(_debugUltimatePreviousSiblingOf(child, equals: _firstChild));
     assert(_debugUltimateNextSiblingOf(child, equals: _lastChild));
     if (child.parentData.previousSibling == null) {
       assert(_firstChild == child);
       _firstChild = child.parentData.nextSibling;
     } else {
       assert(child.parentData.previousSibling.parentData is ParentDataType);
       child.parentData.previousSibling.parentData.nextSibling = child.parentData.nextSibling;
     }
     if (child.parentData.nextSibling == null) {
       assert(_lastChild == child);
       _lastChild = child.parentData.previousSibling;
     } else {
       assert(child.parentData.nextSibling.parentData is ParentDataType);
       child.parentData.nextSibling.parentData.previousSibling = child.parentData.previousSibling;
     }
     child.parentData.previousSibling = null;
     child.parentData.nextSibling = null;
+  }
+  void remove(ChildType child) {
+    _removeFromChildList(child);
     dropChild(child);
   }
+  void move(ChildType child, { ChildType before }) {
+    assert(child != this);
+    assert(before != this);
+    assert(child != before);
+    assert(child.parent == this);
+    assert(child.parentData is ParentDataType);
+    if (child.parentData.nextSibling == before)
+      return;
+    _removeFromChildList(child);
+    _addToChildList(child, before: before);
+  }
   void redepthChildren() {
     ChildType child = _firstChild;
     while (child != null) {
       redepthChild(child);
       assert(child.parentData is ParentDataType);
       child = child.parentData.nextSibling;
     }
   }
   void attachChildren() {
     ChildType child = _firstChild;
@@ skipping 32 matching lines @@
     int count = 1;
     ChildType child = _firstChild;
     while (child != null) {
       result += '${prefix}child ${count}: ${child.toString(prefix)}';
       count += 1;
       child = child.parentData.nextSibling;
     }
     return result;
   }
 }