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template_binding/lib/src/node.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 template_binding;
-
-/** Extensions to the [Node] API. */
-class NodeBindExtension {
-  final Node _node;
-  final JsObject _js;
-
-  NodeBindExtension._(node)
-      : _node = node,
-        _js = new JsObject.fromBrowserObject(node);
-
-  /**
-   * Gets the data bindings that are associated with this node, if any.
-   *
-   * This starts out null, and if [enableBindingsReflection] is enabled, calls
-   * to [bind] will initialize this field and the binding.
-   */
-  // Dart note: in JS this has a trailing underscore, meaning "private".
-  // But in dart if we made it _bindings, it wouldn't be accessible at all.
-  // It is unfortunately needed to implement Node.bind correctly.
-  Map<String, Bindable> get bindings {
-    var b = _js['bindings_'];
-    if (b == null) return null;
-    // TODO(jmesserly): should cache this for identity.
-    return new _NodeBindingsMap(_node, b);
-  }
-  
-  set bindings(Map<String, Bindable> value) {
-    if (value == null) {
-      _js.deleteProperty('bindings_');
-      return;
-    }
-    var b = bindings;
-    if (b == null) {
-      _js['bindings_'] = new JsObject.jsify({});
-      b = bindings;
-    }
-    b.addAll(value);
-  }
-
-  /**
-   * Binds the attribute [name] to [value]. [value] can be a simple value when
-   * [oneTime] is true, or a [Bindable] like [PathObserver].
-   * Returns the [Bindable] instance.
-   */
-  Bindable bind(String name, value, {bool oneTime: false}) {
-    name = _dartToJsName(_node, name);
-
-    if (!oneTime && value is Bindable) {
-      value = bindableToJsObject(value);
-    }
-    return jsObjectToBindable(_js.callMethod('bind', [name, value, oneTime]));
-  }
-
-  /**
-   * Called when all [bind] calls are finished for a given template expansion.
-   */
-  bindFinished() => _js.callMethod('bindFinished');
-
-  // Note: confusingly this is on NodeBindExtension because it can be on any
-  // Node. It's really an API added by TemplateBinding. Therefore it stays
-  // implemented in Dart because TemplateBinding still is.
-  TemplateInstance _templateInstance;
-
-  /** Gets the template instance that instantiated this node, if any. */
-  TemplateInstance get templateInstance =>
-      _templateInstance != null ? _templateInstance :
-      (_node.parent != null ? nodeBind(_node.parent).templateInstance : null);
-}
-
-class _NodeBindingsMap extends MapBase<String, Bindable> {
-  final Node _node;
-  final JsObject _bindings;
-
-  _NodeBindingsMap(this._node, this._bindings);
-
-  // TODO(jmesserly): this should be lazy
-  Iterable<String> get keys =>
-      js.context['Object'].callMethod('keys', [_bindings]).map(
-          (name) => _jsToDartName(_node, name));
-
-  Bindable operator[](String name) =>
-      jsObjectToBindable(_bindings[_dartToJsName(_node, name)]);
-
-  operator[]=(String name, Bindable value) {
-    _bindings[_dartToJsName(_node, name)] = bindableToJsObject(value);
-  }
-
-  @override Bindable remove(String name) {
-    name = _dartToJsName(_node, name);
-    var old = this[name];
-    _bindings.deleteProperty(name);
-    return old;
-  }
-
-  @override void clear() {
-    // Notes: this implementation only works because our "keys" returns a copy.
-    // We could also make it O(1) by assigning a new JS object to the bindings_
-    // property, if performance is an issue.
-    keys.forEach(remove);
-  }
-}
-
-// TODO(jmesserly): perhaps we should switch Dart's Node.bind API back to
-// 'textContent' for consistency? This only affects the raw Node.bind API when
-// called on Text nodes, which is unlikely to be used except by TemplateBinding.
-// Seems like a lot of magic to support it. I don't think Node.bind promises any
-// strong relationship between properties and [name], so textContent seems fine.
-String _dartToJsName(Node node, String name) {
-  if (node is Text && name == 'text') name = 'textContent';
-  return name;
-}
-
-
-String _jsToDartName(Node node, String name) {
-  if (node is Text && name == 'textContent') name = 'text';
-  return name;
-}
-
-
-/// Given a bindable [JsObject], wraps it in a Dart [Bindable].
-/// See [bindableToJsObject] to go in the other direction.
-Bindable jsObjectToBindable(JsObject obj) {
-  if (obj == null) return null;
-  var b = obj['__dartBindable'];
-  // For performance, unwrap the Dart bindable if we find one.
-  // Note: in the unlikely event some code messes with our __dartBindable
-  // property we can simply fallback to a _JsBindable wrapper.
-  return b is Bindable ? b : new _JsBindable(obj);
-}
-
-class _JsBindable extends Bindable {
-  final JsObject _js;
-  _JsBindable(JsObject obj) : _js = obj;
-
-  open(callback) => _js.callMethod('open',
-      [Zone.current.bindUnaryCallback(callback)]);
-
-  close() => _js.callMethod('close');
-
-  get value => _js.callMethod('discardChanges');
-
-  set value(newValue) {
-    _js.callMethod('setValue', [newValue]);
-  }
-
-  deliver() => _js.callMethod('deliver');
-}
-
-/// Given a [bindable], create a JS object proxy for it.
-/// This is the inverse of [jsObjectToBindable].
-JsObject bindableToJsObject(Bindable bindable) {
-  if (bindable is _JsBindable) return bindable._js;
-
-  var zone = Zone.current;
-  inZone(f) => zone.bindCallback(f, runGuarded: false);
-  inZoneUnary(f) => zone.bindUnaryCallback(f, runGuarded: false);
-
-  return new JsObject.jsify({
-    'open': inZoneUnary(
-        (callback) => bindable.open((x) => callback.apply([x]))),
-    'close': inZone(() => bindable.close()),
-    'discardChanges': inZone(() => bindable.value),
-    'setValue': inZoneUnary((x) => bindable.value = x),
-    // NOTE: this is not used by Node.bind, but it's used by Polymer:
-    // https://github.com/Polymer/polymer-dev/blob/ba2b68fe5a5721f60b5994135f3270e63588809a/src/declaration/properties.js#L130
-    // Technically this works because 'deliver' is on PathObserver and
-    // CompoundObserver. But ideally Polymer-JS would not assume that.
-    'deliver': inZone(() => bindable.deliver()),
-    // Save this so we can return it from [jsObjectToBindable]
-    '__dartBindable': bindable
-  });
-}
-
-/** Information about the instantiated template. */
-class TemplateInstance {
-  // TODO(rafaelw): firstNode & lastNode should be read-synchronous
-  // in cases where script has modified the template instance boundary.
-
-  /** The first node of this template instantiation. */
-  Node get firstNode => _firstNode;
-
-  /**
-   * The last node of this template instantiation.
-   * This could be identical to [firstNode] if the template only expanded to a
-   * single node.
-   */
-  Node get lastNode => _lastNode;
-
-  /** The model used to instantiate the template. */
-  final model;
-
-  Node _firstNode, _lastNode;
-
-  TemplateInstance(this.model);
-}