Add observatory_pub_packages snapshot to third_party

observatory_pub_packages/template_binding/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 template_binding;
+
+/** Extensions to [Element]s that behave as templates. */
+class TemplateBindExtension extends NodeBindExtension {
+  var _model;
+  BindingDelegate _bindingDelegate;
+  _TemplateIterator _iterator;
+  bool _setModelScheduled = false;
+
+  Element _templateInstanceRef;
+
+  // Note: only used if `this is! TemplateElement`
+  DocumentFragment _content;
+  bool _templateIsDecorated;
+
+  HtmlDocument _stagingDocument;
+
+  _InstanceBindingMap _bindingMap;
+
+  Node _refContent;
+
+  TemplateBindExtension._(Element node) : super._(node);
+
+  Element get _node => super._node;
+
+  TemplateBindExtension get _self => _node is TemplateBindExtension
+      ? _node : this;
+
+  Bindable bind(String name, value, {bool oneTime: false}) {
+    if (name != 'ref') return super.bind(name, value, oneTime: oneTime);
+
+    var ref = oneTime ? value : value.open((ref) {
+      _node.attributes['ref'] = ref;
+      _refChanged();
+    });
+
+    _node.attributes['ref'] = ref;
+    _refChanged();
+    if (oneTime) return null;
+
+    if (bindings == null) bindings = {};
+    return bindings['ref'] = value;
+  }
+
+  _TemplateIterator _processBindingDirectives(_TemplateBindingMap directives) {
+    if (_iterator != null) _iterator._closeDependencies();
+
+    if (directives._if == null &&
+        directives._bind == null &&
+        directives._repeat == null) {
+
+      if (_iterator != null) {
+        _iterator.close();
+        _iterator = null;
+      }
+      return null;
+    }
+
+    if (_iterator == null) {
+      _iterator = new _TemplateIterator(this);
+    }
+
+    _iterator._updateDependencies(directives, model);
+
+    _templateObserver.observe(_node,
+        attributes: true, attributeFilter: ['ref']);
+
+    return _iterator;
+  }
+
+  /**
+   * Creates an instance of the template, using the provided [model] and
+   * optional binding [delegate].
+   *
+   * If [instanceBindings] is supplied, each [Bindable] in the returned
+   * instance will be added to the list. This makes it easy to close all of the
+   * bindings without walking the tree. This is not normally necessary, but is
+   * used internally by the system.
+   */
+  DocumentFragment createInstance([model, BindingDelegate delegate]) {
+    if (delegate == null) delegate = _bindingDelegate;
+    if (_refContent == null) _refContent = templateBind(_ref).content;
+
+    var content = _refContent;
+    if (content.firstChild == null) return _emptyInstance;
+
+    final map = _getInstanceBindingMap(content, delegate);
+    final staging = _getTemplateStagingDocument();
+    final instance = _stagingDocument.createDocumentFragment();
+
+    final instanceExt = new _InstanceExtension();
+    _instanceExtension[instance] = instanceExt
+      .._templateCreator = _node
+      .._protoContent = content;
+
+    final instanceRecord = new TemplateInstance(model);
+    nodeBindFallback(instance)._templateInstance = instanceRecord;
+
+    var i = 0;
+    bool collectTerminator = false;
+    for (var c = content.firstChild; c != null; c = c.nextNode, i++) {
+      // The terminator of the instance is the clone of the last child of the
+      // content. If the last child is an active template, it may produce
+      // instances as a result of production, so simply collecting the last
+      // child of the instance after it has finished producing may be wrong.
+      if (c.nextNode == null) collectTerminator = true;
+
+      final childMap = map != null ? map.getChild(i) : null;
+      var clone = _cloneAndBindInstance(c, instance, _stagingDocument,
+          childMap, model, delegate, instanceExt._bindings);
+
+      nodeBindFallback(clone)._templateInstance = instanceRecord;
+      if (collectTerminator) instanceExt._terminator = clone;
+    }
+
+    instanceRecord._firstNode = instance.firstChild;
+    instanceRecord._lastNode = instance.lastChild;
+
+    instanceExt._protoContent = null;
+    instanceExt._templateCreator = null;
+    return instance;
+  }
+
+  /** The data model which is inherited through the tree. */
+  get model => _model;
+
+  void set model(value) {
+    _model = value;
+    _ensureSetModelScheduled();
+  }
+
+  static Node _deepCloneIgnoreTemplateContent(Node node, stagingDocument) {
+    var clone = stagingDocument.importNode(node, false);
+    if (isSemanticTemplate(clone)) return clone;
+
+    for (var c = node.firstChild; c != null; c = c.nextNode) {
+      clone.append(_deepCloneIgnoreTemplateContent(c, stagingDocument));
+    }
+    return clone;
+  }
+
+  /**
+   * The binding delegate which is inherited through the tree. It can be used
+   * to configure custom syntax for `{{bindings}}` inside this template.
+   */
+  BindingDelegate get bindingDelegate => _bindingDelegate;
+
+
+  void set bindingDelegate(BindingDelegate value) {
+    if (_bindingDelegate != null) {
+      throw new StateError('Template must be cleared before a new '
+          'bindingDelegate can be assigned');
+    }
+    _bindingDelegate = value;
+
+    // Clear cached state based on the binding delegate.
+    _bindingMap = null;
+    if (_iterator != null) {
+      _iterator._initPrepareFunctions = false;
+      _iterator._instanceModelFn = null;
+      _iterator._instancePositionChangedFn = null;
+    }
+  }
+
+  _ensureSetModelScheduled() {
+    if (_setModelScheduled) return;
+    _decorate();
+    _setModelScheduled = true;
+    scheduleMicrotask(_setModel);
+  }
+
+  void _setModel() {
+    _setModelScheduled = false;
+    var map = _getBindings(_node, _bindingDelegate);
+    _processBindings(_node, map, _model);
+  }
+
+  _refChanged() {
+    if (_iterator == null || _refContent == templateBind(_ref).content) return;
+
+    _refContent = null;
+    _iterator._valueChanged(null);
+    _iterator._updateIteratedValue(this._iterator._getUpdatedValue());
+  }
+
+  void clear() {
+    _model = null;
+    _bindingDelegate = null;
+    if (bindings != null) {
+      var ref = bindings.remove('ref');
+      if (ref != null) ref.close();
+    }
+    _refContent = null;
+    if (_iterator == null) return;
+    _iterator._valueChanged(null);
+    _iterator.close();
+    _iterator = null;
+  }
+
+  /** Gets the template this node refers to. */
+  Element get _ref {
+    _decorate();
+
+    var ref = _searchRefId(_node, _node.attributes['ref']);
+    if (ref == null) {
+      ref = _templateInstanceRef;
+      if (ref == null) return _node;
+    }
+
+    var nextRef = templateBindFallback(ref)._ref;
+    return nextRef != null ? nextRef : ref;
+  }
+
+  /**
+   * Gets the content of this template.
+   */
+  DocumentFragment get content {
+    _decorate();
+    return _content != null ? _content : (_node as TemplateElement).content;
+  }
+
+  /**
+   * Ensures proper API and content model for template elements.
+   *
+   * [instanceRef] can be used to set the [Element.ref] property of [template],
+   * and use the ref's content will be used as source when createInstance() is
+   * invoked.
+   *
+   * Returns true if this template was just decorated, or false if it was
+   * already decorated.
+   */
+  static bool decorate(Element template, [Element instanceRef]) =>
+      templateBindFallback(template)._decorate(instanceRef);
+
+  bool _decorate([Element instanceRef]) {
+    // == true check because it starts as a null field.
+    if (_templateIsDecorated == true) return false;
+
+    _injectStylesheet();
+    _globalBaseUriWorkaround();
+
+    var templateElementExt = this;
+    _templateIsDecorated = true;
+    var isNativeHtmlTemplate = _node is TemplateElement;
+    final bootstrapContents = isNativeHtmlTemplate;
+    final liftContents = !isNativeHtmlTemplate;
+    var liftRoot = false;
+
+    if (!isNativeHtmlTemplate) {
+      if (_isAttributeTemplate(_node)) {
+        if (instanceRef != null) {
+          // Dart note: this is just an assert in JS.
+          throw new ArgumentError('instanceRef should not be supplied for '
+              'attribute templates.');
+        }
+        templateElementExt = templateBind(
+            _extractTemplateFromAttributeTemplate(_node));
+        templateElementExt._templateIsDecorated = true;
+        isNativeHtmlTemplate = templateElementExt._node is TemplateElement;
+        liftRoot = true;
+      } else if (_isSvgTemplate(_node)) {
+        templateElementExt = templateBind(
+            _extractTemplateFromSvgTemplate(_node));
+        templateElementExt._templateIsDecorated = true;
+        isNativeHtmlTemplate = templateElementExt._node is TemplateElement;
+      }
+    }
+
+    if (!isNativeHtmlTemplate) {
+      var doc = _getOrCreateTemplateContentsOwner(templateElementExt._node);
+      templateElementExt._content = doc.createDocumentFragment();
+    }
+
+    if (instanceRef != null) {
+      // template is contained within an instance, its direct content must be
+      // empty
+      templateElementExt._templateInstanceRef = instanceRef;
+    } else if (liftContents) {
+      _liftNonNativeChildrenIntoContent(templateElementExt, _node, liftRoot);
+    } else if (bootstrapContents) {
+      bootstrap(templateElementExt.content);
+    }
+
+    return true;
+  }
+
+  static final _contentsOwner = new Expando();
+  static final _ownerStagingDocument = new Expando();
+
+  // http://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/templates/index.html#dfn-template-contents-owner
+  static HtmlDocument _getOrCreateTemplateContentsOwner(Element template) {
+    var doc = template.ownerDocument;
+    if (doc.window == null) return doc;
+
+    var d = _contentsOwner[doc];
+    if (d == null) {
+      // TODO(arv): This should either be a Document or HTMLDocument depending
+      // on doc.
+      d = doc.implementation.createHtmlDocument('');
+      while (d.lastChild != null) {
+        d.lastChild.remove();
+      }
+      _contentsOwner[doc] = d;
+    }
+    return d;
+  }
+
+  HtmlDocument _getTemplateStagingDocument() {
+    if (_stagingDocument == null) {
+      var owner = _node.ownerDocument;
+      var doc = _ownerStagingDocument[owner];
+      if (doc == null) {
+        doc = owner.implementation.createHtmlDocument('');
+        _isStagingDocument[doc] = true;
+        _baseUriWorkaround(doc);
+        _ownerStagingDocument[owner] = doc;
+      }
+      _stagingDocument = doc;
+    }
+    return _stagingDocument;
+  }
+
+  // For non-template browsers, the parser will disallow <template> in certain
+  // locations, so we allow "attribute templates" which combine the template
+  // element with the top-level container node of the content, e.g.
+  //
+  //   <tr template repeat="{{ foo }}"" class="bar"><td>Bar</td></tr>
+  //
+  // becomes
+  //
+  //   <template repeat="{{ foo }}">
+  //   + #document-fragment
+  //     + <tr class="bar">
+  //       + <td>Bar</td>
+  //
+  static Element _extractTemplateFromAttributeTemplate(Element el) {
+    var template = el.ownerDocument.createElement('template');
+    el.parentNode.insertBefore(template, el);
+
+    for (var name in el.attributes.keys.toList()) {
+      switch (name) {
+        case 'template':
+          el.attributes.remove(name);
+          break;
+        case 'repeat':
+        case 'bind':
+        case 'ref':
+          template.attributes[name] = el.attributes.remove(name);
+          break;
+      }
+    }
+
+    return template;
+  }
+
+  static Element _extractTemplateFromSvgTemplate(Element el) {
+    var template = el.ownerDocument.createElement('template');
+    el.parentNode.insertBefore(template, el);
+    template.attributes.addAll(el.attributes);
+
+    el.attributes.clear();
+    el.remove();
+    return template;
+  }
+
+  static void _liftNonNativeChildrenIntoContent(TemplateBindExtension template,
+      Element el, bool useRoot) {
+
+    var content = template.content;
+    if (useRoot) {
+      content.append(el);
+      return;
+    }
+
+    var child;
+    while ((child = el.firstChild) != null) {
+      content.append(child);
+    }
+  }
+
+  /**
+   * This used to decorate recursively all templates from a given node.
+   *
+   * By default [decorate] will be called on templates lazily when certain
+   * properties such as [model] are accessed, but it can be run eagerly to
+   * decorate an entire tree recursively.
+   */
+  // TODO(rafaelw): Review whether this is the right public API.
+  static void bootstrap(Node content) {
+    void _bootstrap(template) {
+      if (!TemplateBindExtension.decorate(template)) {
+        bootstrap(templateBind(template).content);
+      }
+    }
+
+    // Need to do this first as the contents may get lifted if |node| is
+    // template.
+    // TODO(jmesserly): content is DocumentFragment or Element
+    var descendents =
+        (content as dynamic).querySelectorAll(_allTemplatesSelectors);
+    if (isSemanticTemplate(content)) {
+      _bootstrap(content);
+    }
+
+    descendents.forEach(_bootstrap);
+  }
+
+  static final String _allTemplatesSelectors =
+      'template, ' +
+      _SEMANTIC_TEMPLATE_TAGS.keys.map((k) => "$k[template]").join(", ");
+
+  static bool _initStyles;
+
+  // This is to replicate template_element.css
+  // TODO(jmesserly): move this to an opt-in CSS file?
+  static void _injectStylesheet() {
+    if (_initStyles == true) return;
+    _initStyles = true;
+
+    var style = new StyleElement()
+        ..text = '$_allTemplatesSelectors { display: none; }';
+    document.head.append(style);
+  }
+
+  static bool _initBaseUriWorkaround;
+
+  static void _globalBaseUriWorkaround() {
+    if (_initBaseUriWorkaround == true) return;
+    _initBaseUriWorkaround = true;
+
+    var t = document.createElement('template');
+    if (t is TemplateElement) {
+      var d = t.content.ownerDocument;
+      if (d.documentElement == null) {
+        d.append(d.createElement('html')).append(d.createElement('head'));
+      }
+      // don't patch this if TemplateBinding.js already has.
+      if (d.head.querySelector('base') == null) {
+        _baseUriWorkaround(d);
+      }
+    }
+  }
+
+  // TODO(rafaelw): Remove when fix for
+  // https://codereview.chromium.org/164803002/
+  // makes it to Chrome release.
+  static void _baseUriWorkaround(HtmlDocument doc) {
+    BaseElement base = doc.createElement('base');
+    base.href = document.baseUri;
+    doc.head.append(base);
+  }
+
+  static final _templateObserver = new MutationObserver((records, _) {
+    for (MutationRecord record in records) {
+      templateBindFallback(record.target)._refChanged();
+    }
+  });
+
+}
+
+final DocumentFragment _emptyInstance = () {
+  var empty = new DocumentFragment();
+  _instanceExtension[empty] = new _InstanceExtension();
+  return empty;
+}();
+
+// TODO(jmesserly): if we merged with wtih TemplateInstance, it seems like it
+// would speed up some operations (e.g. _getInstanceRoot wouldn't need to walk
+// the parent chain).
+class _InstanceExtension {
+  final List _bindings = [];
+  Node _terminator;
+  Element _templateCreator;
+  DocumentFragment _protoContent;
+}
+
+// TODO(jmesserly): this is private in JS but public for us because pkg:polymer
+// uses it.
+List getTemplateInstanceBindings(DocumentFragment fragment) {
+  var ext = _instanceExtension[fragment];
+  return ext != null ? ext._bindings : ext;
+}
+
+/// Gets the root of the current node's parent chain
+_getFragmentRoot(Node node) {
+  var p;
+  while ((p = node.parentNode) != null) {
+    node = p;
+  }
+  return node;
+}
+
+Node _searchRefId(Node node, String id) {
+  if (id == null || id == '') return null;
+
+  final selector = '#$id';
+  while (true) {
+    node = _getFragmentRoot(node);
+
+    Node ref = null;
+
+    _InstanceExtension instance = _instanceExtension[node];
+    if (instance != null && instance._protoContent != null) {
+      ref = instance._protoContent.querySelector(selector);
+    } else if (_hasGetElementById(node)) {
+      ref = (node as dynamic).getElementById(id);
+    }
+
+    if (ref != null) return ref;
+
+    if (instance == null) return null;
+    node = instance._templateCreator;
+    if (node == null) return null;
+  }
+}
+
+_getInstanceRoot(node) {
+  while (node.parentNode != null) {
+    node = node.parentNode;
+  }
+  _InstanceExtension instance = _instanceExtension[node];
+  return instance != null && instance._templateCreator != null ? node : null;
+}
+
+// Note: JS code tests that getElementById is present. We can't do that
+// easily, so instead check for the types known to implement it.
+bool _hasGetElementById(Node node) =>
+    node is Document || node is ShadowRoot || node is SvgSvgElement;
+
+final Expando<_InstanceExtension> _instanceExtension = new Expando();
+
+final _isStagingDocument = new Expando();