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Unified Diff: pkg/template_binding/lib/src/node_binding.dart

Issue 50203004: port TemplateBinding to ed3266266e751b5ab1f75f8e0509d0d5f0ef35d8 (Closed) Base URL: https://dart.googlecode.com/svn/branches/bleeding_edge/dart
Patch Set: Created 7 years, 2 months ago
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Index: pkg/template_binding/lib/src/node_binding.dart
diff --git a/pkg/template_binding/lib/src/node_binding.dart b/pkg/template_binding/lib/src/node_binding.dart
new file mode 100644
index 0000000000000000000000000000000000000000..95c5e00dd5ee999e2fca097f21cc17171252498a
--- /dev/null
+++ b/pkg/template_binding/lib/src/node_binding.dart
@@ -0,0 +1,92 @@
+// 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.
+
+library template_binding.src.node_binding;
+
+import 'dart:async' show StreamSubscription;
+import 'dart:html' show Node;
+import 'package:observe/observe.dart' show PathObserver, CompoundPathObserver;
+
+/** Test only method. Not re-exported. */
+getObserverForTest(NodeBinding binding) => binding._observer;
+
+/**
+ * A data binding on a [Node].
+ * See [NodeBindExtension.bindings] and [NodeBindExtension.bind].
+ */
+abstract class NodeBinding {
+ Node _node;
+ var _model;
+
+ // TODO(jmesserly): need common interface for PathObserver,
+ // CompoundPathObserver.
+ var _observer;
+ StreamSubscription _pathSub;
+
+ /** The property of [node] which will be data bound. */
+ final String property;
+
+ /** The property of [node] which will be data bound. */
+ final String path;
+
+ /** The node that has [property] which will be data bound. */
+ Node get node => _node;
+
+ /** The bound data model. */
+ get model => _model;
+
+ /** True if this binding has been [closed]. */
+ bool get closed => _node == null;
+
+ /** The value at the [path] on [model]. */
+ get value => _observer.value;
+
+ set value(newValue) {
+ _observer.value = newValue;
+ }
+
+ NodeBinding(this._node, this.property, this._model, [String path])
+ : path = path != null ? path : '' {
+
+ // Fast path if we're observing "value"
+ if ((model is PathObserver || model is CompoundPathObserver) &&
+ path == 'value') {
+
+ _observer = model;
+ } else {
+ // Create the path observer
+ _observer = new PathObserver(model, this.path);
+ }
+
+ _pathSub = _observer.changes.listen((r) => valueChanged(value));
+ valueChanged(value);
+ }
+
+ /** Called when [value] changes to update the [node]. */
+ // TODO(jmesserly): the impl in template_binding uses reflection to set the
+ // property, but that isn't used except for specific known fields like
+ // "textContent", so I'm overridding this in the subclasses instead.
+ void valueChanged(newValue);
+
+ /** Called to sanitize the value before it is assigned into the property. */
+ sanitizeBoundValue(value) => value == null ? '' : '$value';
+
+ /**
+ * Called by [NodeBindExtension.unbind] to close this binding and unobserve
+ * the [path].
+ *
+ * This can be overridden in subclasses, but they must call `super.close()`
+ * to free associated resources. They must also check [closed] and return
+ * immediately if already closed.
+ */
+ void close() {
+ if (closed) return;
+
+ if (_pathSub != null) _pathSub.cancel();
+ _pathSub = null;
+ _observer = null;
+ _node = null;
+ _model = null;
+ }
+}
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