[mdv] implement Node.createBinding and Node.createBindings

pkg/mdv/lib/src/template.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of mdv;
 
 /** Extensions to [Element]s that behave as templates. */
 class _TemplateExtension extends _ElementExtension {
   var _model;
   BindingDelegate _bindingDelegate;
   _TemplateIterator _templateIterator;
   bool _scheduled = false;
 
   _TemplateExtension(Element node) : super(node);
 
-  void bind(String name, model, String path) {
+  Element get node => super.node;
+
+  NodeBinding createBinding(String name, model, String path) {
     switch (name) {
       case 'bind':
       case 'repeat':
       case 'if':
         if (_templateIterator == null) {
           _templateIterator = new _TemplateIterator(node);
         }
-        _templateIterator.inputs.bind(name, model, path);
-        return;
+        // TODO(jmesserly): why do we do this here and nowhere else?
+        if (path == null) path = '';
+        return new _TemplateBinding(node, name, model, path);
       default:
-        super.bind(name, model, path);
+        return super.createBinding(name, model, path);
     }
   }
 
-  void unbind(String name) {
-    switch (name) {
-      case 'bind':
-      case 'repeat':
-      case 'if':
-        if (_templateIterator != null) {
-          _templateIterator.inputs.unbind(name);
-        }
-        return;
-      default:
-        super.unbind(name);
-    }
-  }
-
-  void unbindAll() {
-    unbind('bind');
-    unbind('repeat');
-    unbind('if');
-    super.unbindAll();
-  }
-
   /**
    * Creates an instance of the template.
    */
   DocumentFragment createInstance(model, BindingDelegate delegate) {
     var template = node.ref;
     if (template == null) template = node;
 
     var instance = _createDeepCloneAndDecorateTemplates(
         template.ref.content, delegate);
 
@@ skipping 29 matching lines @@
     if (_scheduled) return;
     _scheduled = true;
     runAsync(_setModel);
   }
 
   void _setModel() {
     _scheduled = false;
     _addBindings(node, _model, _bindingDelegate);
   }
 }
+
+class _TemplateBinding extends NodeBinding {
+  // TODO(jmesserly): MDV uses TemplateIterator as the node, see:
+  // https://github.com/Polymer/mdv/issues/127
+  _TemplateBinding(node, name, model, path)
+      : super(node, name, model, path) {
+    _mdv(node)._templateIterator.inputs.bind(property, model, path);
+  }
+
+  // These are no-ops because we don't use the underlying PathObserver.
+  void _observePath() {}
+  void boundValueChanged(newValue) {}
+
+  void close() {
+    if (closed) return;
+    var templateIterator = _mdv(node)._templateIterator;
+    if (templateIterator != null) templateIterator.inputs.unbind(property);
+    super.close();
+  }
+}