Add RenderObject.childCount

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 349 matching lines @@
       assert(nextSibling != this);
       assert(nextSibling.parentData.previousSibling == this);
       nextSibling.parentData.previousSibling = previousSibling;
     }
     previousSibling = null;
     nextSibling = null;
   }
 }
 
 abstract class ContainerRenderObjectMixin<ChildType extends RenderObject, ParentDataType extends ContainerParentDataMixin<ChildType>> implements RenderObject {
-  // abstract class that has only InlineNode children
 
   bool _debugUltimatePreviousSiblingOf(ChildType child, { ChildType equals }) {
     assert(child.parentData is ParentDataType);
     while (child.parentData.previousSibling != null) {
       assert(child.parentData.previousSibling != child);
       child = child.parentData.previousSibling;
       assert(child.parentData is ParentDataType);
     }
     return child == equals;
   }
   bool _debugUltimateNextSiblingOf(ChildType child, { ChildType equals }) {
     assert(child.parentData is ParentDataType);
     while (child.parentData.nextSibling != null) {
       assert(child.parentData.nextSibling != child);
       child = child.parentData.nextSibling;
       assert(child.parentData is ParentDataType);
     }
     return child == equals;
   }
 
+  int _childCount = 0;
+  int get childCount => _childCount;
+
   ChildType _firstChild;
   ChildType _lastChild;
   void _addToChildList(ChildType child, { ChildType before }) {
     assert(child.parentData is ParentDataType);
     assert(child.parentData.nextSibling == null);
     assert(child.parentData.previousSibling == null);
+
+    _childCount += 1;

[Hixie, 2015/06/26 18:04:33]

Since the rest of this function doesn't have paragraph breaks (and indeed, it's
in the same paragraph as the next function and the members defined before it),
it's weird to have newlines here.

[hansmuller, 2015/06/26 18:16:10]

Done.

+    assert(_childCount > 0);
+
     if (before == null) {
       // append at the end (_lastChild)
       child.parentData.previousSibling = _lastChild;
       if (_lastChild != null) {
         assert(_lastChild.parentData is ParentDataType);
         _lastChild.parentData.nextSibling = child;
       }
       _lastChild = child;
       if (_firstChild == null)
         _firstChild = child;
@@ skipping 34 matching lines @@
   }
   void addAll(List<ChildType> children) {
     if (children != null)
       for (ChildType child in children)
         add(child);
   }
   void _removeFromChildList(ChildType child) {
     assert(child.parentData is ParentDataType);
     assert(_debugUltimatePreviousSiblingOf(child, equals: _firstChild));
     assert(_debugUltimateNextSiblingOf(child, equals: _lastChild));
+
+    _childCount -= 1;
+    assert(_childCount > 0);
+

[Hixie, 2015/06/26 18:04:33]

ditto here

[hansmuller, 2015/06/26 18:16:10]

Done.

     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;
@@ skipping 64 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;
   }
 }