feat(element binder): Make ElementBinder non-recursive and create an external tree

Author: jbdeboer

lib/core_dom/compiler.dart

@@ -7,20 +7,20 @@ class Compiler implements Function {
 
   Compiler(this._perf, this._expando);
 
-  List<ElementBinder> _compileView(NodeCursor domCursor, NodeCursor templateCursor,
+  List<ElementBinderTreeRef> _compileView(NodeCursor domCursor, NodeCursor templateCursor,
                 ElementBinder existingElementBinder,
                 DirectiveMap directives) {
     if (domCursor.current == null) return null;
 
-    List<ElementBinder> elementBinders = null; // don't pre-create to create sparse tree and prevent GC pressure.
+    List<ElementBinderTreeRef> elementBinders = null; // don't pre-create to create sparse tree and prevent GC pressure.
 
     do {
+      var subtrees, binder;
+
       ElementBinder elementBinder = existingElementBinder == null
           ?  directives.selector(domCursor.current)
           : existingElementBinder;
 
-      elementBinder.offsetIndex = templateCursor.index;
-
       if (elementBinder.hasTemplate) {
         elementBinder.templateViewFactory = compileTransclusion(
             domCursor, templateCursor,
@@ -31,18 +31,20 @@ class Compiler implements Function {
         if (domCursor.descend()) {
           templateCursor.descend();
 
-          elementBinder.childElementBinders =
+          subtrees =
               _compileView(domCursor, templateCursor, null, directives);
 
           domCursor.ascend();
           templateCursor.ascend();
         }
       }
 
-      if (elementBinder.isUseful) {
-        if (elementBinders == null) elementBinders = [];
-        elementBinders.add(elementBinder);
+      if (elementBinder.hasDirectives) {
+        binder = elementBinder;
       }
+
+      if (elementBinders == null) elementBinders = [];
+      elementBinders.add(new ElementBinderTreeRef(templateCursor.index, new ElementBinderTree(binder, subtrees)));
     } while (templateCursor.moveNext() && domCursor.moveNext());
 
     return elementBinders;

lib/core_dom/element_binder.dart

@@ -30,8 +30,6 @@ class ElementBinder {
   ViewFactory templateViewFactory;
 
   DirectiveRef component;
-  var childElementBinders;
-  var offsetIndex;
 
   // Can be either COMPILE_CHILDREN or IGNORE_CHILDREN
   String childMode = NgAnnotation.COMPILE_CHILDREN;
@@ -46,8 +44,6 @@ class ElementBinder {
 
     decorators = other.decorators;
     component = other.component;
-    childElementBinders = other.childElementBinders;
-    offsetIndex = other.offsetIndex;
     childMode = other.childMode;
   }
 
@@ -92,8 +88,8 @@ class ElementBinder {
     return decorators;
   }
 
-  bool get isUseful {
-    return (_usableDirectiveRefs != null && _usableDirectiveRefs.length != 0) || childElementBinders != null;
+  bool get hasDirectives {
+    return (_usableDirectiveRefs != null && _usableDirectiveRefs.length != 0);
   }
 
   // DI visibility callback allowing node-local visibility.
@@ -378,3 +374,18 @@ class ElementBinder {
     });
   }
 }
+
+
+// Used for walking the DOM
+class ElementBinderTreeRef {
+  final int offsetIndex;
+  final ElementBinderTree subtree;
+
+  ElementBinderTreeRef(this.offsetIndex, this.subtree);
+}
+class ElementBinderTree {
+  ElementBinder binder;
+  List<ElementBinderTreeRef> subtrees;
+
+  ElementBinderTree(this.binder, this.subtrees);
+}

lib/core_dom/view_factory.dart

@@ -24,13 +24,13 @@ class BoundViewFactory {
  * [Compiler] as a result of compiling a template.
  */
 class ViewFactory implements Function {
-  final List<ElementBinder> elementBinders;
+  final List<ElementBinderTreeRef> elementBinders;
   final List<dom.Node> templateElements;
   final Profiler _perf;
   final Expando _expando;
 
   ViewFactory(this.templateElements, this.elementBinders, this._perf, this._expando) {
-    assert(elementBinders.forEach((ElementBinder eb) { assert(eb is ElementBinder); }) != true);
+    assert(elementBinders.forEach((ElementBinderTreeRef eb) { assert(eb is ElementBinderTreeRef); }) != true);
   }
 
   BoundViewFactory bind(Injector injector) =>
@@ -57,7 +57,9 @@ class ViewFactory implements Function {
       var eb = elementBinders[i];
       int index = eb.offsetIndex;
 
-      List childElementBinders = eb.childElementBinders;
+      ElementBinderTree tree = eb.subtree;
+
+      //List childElementBinders = eb.childElementBinders;
       int nodeListIndex = index + preRenderedIndexOffset;
       dom.Node node = nodeList[nodeListIndex];
 
@@ -73,10 +75,10 @@ class ViewFactory implements Function {
           parentNode.append(node);
         }
 
-        var childInjector = eb.bind(view, parentInjector, node);
+        var childInjector = tree.binder != null ? tree.binder.bind(view, parentInjector, node) : parentInjector;
 
-        if (childElementBinders != null) {
-          _link(view, node.nodes, childElementBinders, childInjector);
+        if (tree.subtrees != null) {
+          _link(view, node.nodes, tree.subtrees, childInjector);
         }
 
         if (fakeParent) {