Index: sky/sdk/lib/framework/node.dart |
diff --git a/sky/sdk/lib/framework/node.dart b/sky/sdk/lib/framework/node.dart |
deleted file mode 100644 |
index 8e772a9d3be4b79a5da20c790d06046a567d92be..0000000000000000000000000000000000000000 |
--- a/sky/sdk/lib/framework/node.dart |
+++ /dev/null |
@@ -1,82 +0,0 @@ |
-class AbstractNode { |
- |
- // AbstractNode represents a node in a tree. |
- // The AbstractNode protocol is as follows: |
- // - When a subclass is changing the parent of a child, it should |
- // call either parent.adoptChild(child) or parent.dropChild(child) |
- // as appropriate. Subclasses should expose an API for |
- // manipulating the tree if you want to (e.g. a setter for a |
- // 'child' property, or an 'add()' method to manipulate a list). |
- // - You can see the current parent by querying 'parent'. |
- // - You can see the current attachment state by querying |
- // 'attached'. The root of any tree that is to be considered |
- // attached should be manually attached by calling 'attach()'. |
- // Other than that, don't call 'attach()' or 'detach()'. This is |
- // all managed automatically assuming you call the 'adoptChild()' |
- // and 'dropChild()' methods appropriately. |
- // - Subclasses that have children must override 'attach()' and |
- // 'detach()' as described below. |
- // - Nodes always have a 'depth' greater than their ancestors'. |
- // There's no guarantee regarding depth between siblings. The |
- // depth of a node is used to ensure that nodes are processed in |
- // depth order. The 'depth' of a child can be more than one |
- // greater than the 'depth' of the parent, because the 'depth' |
- // values are never decreased: all that matters is that it's |
- // greater than the parent. Consider a tree with a root node A, a |
- // child B, and a grandchild C. Initially, A will have 'depth' 0, |
- // B 'depth' 1, and C 'depth' 2. If C is moved to be a child of A, |
- // sibling of B, then the numbers won't change. C's 'depth' will |
- // still be 2. This is all managed automatically assuming you call |
- // 'adoptChild()' and 'dropChild()' appropriately. |
- |
- int _depth = 0; |
- int get depth => _depth; |
- void redepthChild(AbstractNode child) { // internal, do not call |
- assert(child._attached == _attached); |
- if (child._depth <= _depth) { |
- child._depth = _depth + 1; |
- child.redepthChildren(); |
- } |
- } |
- void redepthChildren() { // internal, do not call |
- // override this in subclasses with child nodes |
- // simply call redepthChild(child) for each child |
- } |
- |
- bool _attached = false; |
- bool get attached => _attached; |
- void attach() { |
- // override this in subclasses with child nodes |
- // simply call attach() for each child then call your superclass |
- _attached = true; |
- attachChildren(); |
- } |
- attachChildren() { } // workaround for lack of inter-class mixins in Dart |
- void detach() { |
- // override this in subclasses with child nodes |
- // simply call detach() for each child then call your superclass |
- _attached = false; |
- detachChildren(); |
- } |
- detachChildren() { } // workaround for lack of inter-class mixins in Dart |
- |
- AbstractNode _parent; |
- AbstractNode get parent => _parent; |
- void adoptChild(AbstractNode child) { // only for use by subclasses |
- assert(child != null); |
- assert(child._parent == null); |
- child._parent = this; |
- if (attached) |
- child.attach(); |
- redepthChild(child); |
- } |
- void dropChild(AbstractNode child) { // only for use by subclasses |
- assert(child != null); |
- assert(child._parent == this); |
- assert(child.attached == attached); |
- child._parent = null; |
- if (attached) |
- child.detach(); |
- } |
- |
-} |