Add observatory_pub_packages snapshot to third_party

observatory_pub_packages/template_binding/src/template_iterator.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;
+
+// This code is a port of what was formerly known as Model-Driven-Views, now
+// located at:
+//     https://github.com/polymer/TemplateBinding
+//     https://github.com/polymer/NodeBind
+
+// TODO(jmesserly): not sure what kind of boolean conversion rules to
+// apply for template data-binding. HTML attributes are true if they're
+// present. However Dart only treats "true" as true. Since this is HTML we'll
+// use something closer to the HTML rules: null (missing) and false are false,
+// everything else is true.
+// See: https://github.com/polymer/TemplateBinding/issues/59
+bool _toBoolean(value) => null != value && false != value;
+
+// Dart note: this was added to decouple the MustacheTokens.parse function from
+// the rest of template_binding.
+_getDelegateFactory(name, node, delegate) {
+  if (delegate == null) return null;
+  return (pathString) => delegate.prepareBinding(pathString, name, node);
+}
+
+_InstanceBindingMap _getBindings(Node node, BindingDelegate delegate) {
+  if (node is Element) {
+    return _parseAttributeBindings(node, delegate);
+  }
+
+  if (node is Text) {
+    var tokens = MustacheTokens.parse(node.text,
+        _getDelegateFactory('text', node, delegate));
+    if (tokens != null) return new _InstanceBindingMap(['text', tokens]);
+  }
+
+  return null;
+}
+
+void _addBindings(Node node, model, [BindingDelegate delegate]) {
+  final bindings = _getBindings(node, delegate);
+  if (bindings != null) {
+    _processBindings(node, bindings, model);
+  }
+
+  for (var c = node.firstChild; c != null; c = c.nextNode) {
+    _addBindings(c, model, delegate);
+  }
+}
+
+MustacheTokens _parseWithDefault(Element element, String name,
+    BindingDelegate delegate) {
+
+  var v = element.attributes[name];
+  if (v == '') v = '{{}}';
+  return MustacheTokens.parse(v, _getDelegateFactory(name, element, delegate));
+}
+
+_InstanceBindingMap _parseAttributeBindings(Element element,
+    BindingDelegate delegate) {
+
+  var bindings = null;
+  var ifFound = false;
+  var bindFound = false;
+  var isTemplateNode = isSemanticTemplate(element);
+
+  element.attributes.forEach((name, value) {
+    // Allow bindings expressed in attributes to be prefixed with underbars.
+    // We do this to allow correct semantics for browsers that don't implement
+    // <template> where certain attributes might trigger side-effects -- and
+    // for IE which sanitizes certain attributes, disallowing mustache
+    // replacements in their text.
+    while (name[0] == '_') {
+      name = name.substring(1);
+    }
+
+    if (isTemplateNode &&
+        (name == 'bind' || name == 'if' || name == 'repeat')) {
+      return;
+    }
+
+    var tokens = MustacheTokens.parse(value,
+        _getDelegateFactory(name, element, delegate));
+    if (tokens != null) {
+      if (bindings == null) bindings = [];
+      bindings..add(name)..add(tokens);
+    }
+  });
+
+  if (isTemplateNode) {
+    if (bindings == null) bindings = [];
+    var result = new _TemplateBindingMap(bindings)
+        .._if = _parseWithDefault(element, 'if', delegate)
+        .._bind = _parseWithDefault(element, 'bind', delegate)
+        .._repeat = _parseWithDefault(element, 'repeat', delegate);
+
+    // Treat <template if> as <template bind if>
+    if (result._if != null && result._bind == null && result._repeat == null) {
+      result._bind = MustacheTokens.parse('{{}}',
+          _getDelegateFactory('bind', element, delegate));
+    }
+
+    return result;
+  }
+
+  return bindings == null ? null : new _InstanceBindingMap(bindings);
+}
+
+_processOneTimeBinding(String name, MustacheTokens tokens, Node node, model) {
+
+  if (tokens.hasOnePath) {
+    var delegateFn = tokens.getPrepareBinding(0);
+    var value = delegateFn != null ? delegateFn(model, node, true) :
+        tokens.getPath(0).getValueFrom(model);
+    return tokens.isSimplePath ? value : tokens.combinator(value);
+  }
+
+  // Tokens uses a striding scheme to essentially store a sequence of structs in
+  // the list. See _MustacheTokens for more information.
+  var values = new List(tokens.length);
+  for (int i = 0; i < tokens.length; i++) {
+    Function delegateFn = tokens.getPrepareBinding(i);
+    values[i] = delegateFn != null ?
+        delegateFn(model, node, false) :
+        tokens.getPath(i).getValueFrom(model);
+  }
+  return tokens.combinator(values);
+}
+
+_processSinglePathBinding(String name, MustacheTokens tokens, Node node,
+    model) {
+  Function delegateFn = tokens.getPrepareBinding(0);
+  var observer = delegateFn != null ?
+      delegateFn(model, node, false) :
+      new PathObserver(model, tokens.getPath(0));
+
+  return tokens.isSimplePath ? observer :
+      new ObserverTransform(observer, tokens.combinator);
+}
+
+_processBinding(String name, MustacheTokens tokens, Node node, model) {
+  if (tokens.onlyOneTime) {
+    return _processOneTimeBinding(name, tokens, node, model);
+  }
+  if (tokens.hasOnePath) {
+    return _processSinglePathBinding(name, tokens, node, model);
+  }
+
+  var observer = new CompoundObserver();
+
+  for (int i = 0; i < tokens.length; i++) {
+    bool oneTime = tokens.getOneTime(i);
+    Function delegateFn = tokens.getPrepareBinding(i);
+
+    if (delegateFn != null) {
+      var value = delegateFn(model, node, oneTime);
+      if (oneTime) {
+        observer.addPath(value);
+      } else {
+        observer.addObserver(value);
+      }
+      continue;
+    }
+
+    PropertyPath path = tokens.getPath(i);
+    if (oneTime) {
+      observer.addPath(path.getValueFrom(model));
+    } else {
+      observer.addPath(model, path);
+    }
+  }
+
+  return new ObserverTransform(observer, tokens.combinator);
+}
+
+void _processBindings(Node node, _InstanceBindingMap map, model,
+    [List<Bindable> instanceBindings]) {
+
+  final bindings = map.bindings;
+  final nodeExt = nodeBind(node);
+  for (var i = 0; i < bindings.length; i += 2) {
+    var name = bindings[i];
+    var tokens = bindings[i + 1];
+
+    var value = _processBinding(name, tokens, node, model);
+    var binding = nodeExt.bind(name, value, oneTime: tokens.onlyOneTime);
+    if (binding != null && instanceBindings != null) {
+      instanceBindings.add(binding);
+    }
+  }
+
+  nodeExt.bindFinished();
+  if (map is! _TemplateBindingMap) return;
+
+  final templateExt = nodeBindFallback(node);
+  templateExt._model = model;
+
+  var iter = templateExt._processBindingDirectives(map);
+  if (iter != null && instanceBindings != null) {
+    instanceBindings.add(iter);
+  }
+}
+
+
+// Note: this doesn't really implement most of Bindable. See:
+// https://github.com/Polymer/TemplateBinding/issues/147
+class _TemplateIterator extends Bindable {
+  final TemplateBindExtension _templateExt;
+
+  final List<DocumentFragment> _instances = [];
+
+  /** A copy of the last rendered [_presentValue] list state. */
+  final List _iteratedValue = [];
+
+  List _presentValue;
+
+  bool _closed = false;
+
+  // Dart note: instead of storing these in a Map like JS, or using a separate
+  // object (extra memory overhead) we just inline the fields.
+  var _ifValue, _value;
+
+  // TODO(jmesserly): lots of booleans in this object. Bitmask?
+  bool _hasIf, _hasRepeat;
+  bool _ifOneTime, _oneTime;
+
+  StreamSubscription _listSub;
+
+  bool _initPrepareFunctions = false;
+  PrepareInstanceModelFunction _instanceModelFn;
+  PrepareInstancePositionChangedFunction _instancePositionChangedFn;
+
+  _TemplateIterator(this._templateExt);
+
+  open(callback) => throw new StateError('binding already opened');
+  get value => _value;
+
+  Element get _templateElement => _templateExt._node;
+
+  void _closeDependencies() {
+    if (_ifValue is Bindable) {
+      _ifValue.close();
+      _ifValue = null;
+    }
+    if (_value is Bindable) {
+      _value.close();
+      _value = null;
+    }
+  }
+
+  void _updateDependencies(_TemplateBindingMap directives, model) {
+    _closeDependencies();
+
+    final template = _templateElement;
+
+    _hasIf = directives._if != null;
+    _hasRepeat = directives._repeat != null;
+
+    var ifValue = true;
+    if (_hasIf) {
+      _ifOneTime = directives._if.onlyOneTime;
+      _ifValue = _processBinding('if', directives._if, template, model);
+      ifValue = _ifValue;
+
+      // oneTime if & predicate is false. nothing else to do.
+      if (_ifOneTime && !_toBoolean(ifValue)) {
+        _valueChanged(null);
+        return;
+      }
+
+      if (!_ifOneTime) {
+        ifValue = (ifValue as Bindable).open(_updateIfValue);
+      }
+    }
+
+    if (_hasRepeat) {
+      _oneTime = directives._repeat.onlyOneTime;
+      _value = _processBinding('repeat', directives._repeat, template, model);
+    } else {
+      _oneTime = directives._bind.onlyOneTime;
+      _value = _processBinding('bind', directives._bind, template, model);
+    }
+
+    var value = _value;
+    if (!_oneTime) {
+      value = _value.open(_updateIteratedValue);
+    }
+
+    if (!_toBoolean(ifValue)) {
+      _valueChanged(null);
+      return;
+    }
+
+    _updateValue(value);
+  }
+
+  /// Gets the updated value of the bind/repeat. This can potentially call
+  /// user code (if a bindingDelegate is set up) so we try to avoid it if we
+  /// already have the value in hand (from Observer.open).
+  Object _getUpdatedValue() {
+    var value = _value;
+    // Dart note: x.discardChanges() is x.value in Dart.
+    if (!_toBoolean(_oneTime)) value = value.value;
+    return value;
+  }
+
+  void _updateIfValue(ifValue) {
+    if (!_toBoolean(ifValue)) {
+      _valueChanged(null);
+      return;
+    }
+    _updateValue(_getUpdatedValue());
+  }
+
+  void _updateIteratedValue(value) {
+    if (_hasIf) {
+      var ifValue = _ifValue;
+      if (!_ifOneTime) ifValue = (ifValue as Bindable).value;
+      if (!_toBoolean(ifValue)) {
+        _valueChanged([]);
+        return;
+      }
+    }
+
+    _updateValue(value);
+  }
+
+  void _updateValue(Object value) {
+    if (!_hasRepeat) value = [value];
+    _valueChanged(value);
+  }
+
+  void _valueChanged(Object value) {
+    if (value is! List) {
+      if (value is Iterable) {
+        // Dart note: we support Iterable by calling toList.
+        // But we need to be careful to observe the original iterator if it
+        // supports that.
+        value = (value as Iterable).toList();
+      } else {
+        value = [];
+      }
+    }
+
+    if (identical(value, _iteratedValue)) return;
+
+    _unobserve();
+    _presentValue = value;
+
+    if (value is ObservableList && _hasRepeat && !_oneTime) {
+      // Make sure any pending changes aren't delivered, since we're getting
+      // a snapshot at this point in time.
+      value.discardListChages();
+      _listSub = value.listChanges.listen(_handleSplices);
+    }
+
+    _handleSplices(ObservableList.calculateChangeRecords(
+        _iteratedValue != null ? _iteratedValue : [],
+        _presentValue != null ? _presentValue : []));
+  }
+
+  Node _getLastInstanceNode(int index) {
+    if (index == -1) return _templateElement;
+    // TODO(jmesserly): we could avoid this expando lookup by caching the
+    // instance extension instead of the instance.
+    var instance = _instanceExtension[_instances[index]];
+    var terminator = instance._terminator;
+    if (terminator == null) return _getLastInstanceNode(index - 1);
+
+    if (!isSemanticTemplate(terminator) ||
+        identical(terminator, _templateElement)) {
+      return terminator;
+    }
+
+    var subtemplateIterator = templateBindFallback(terminator)._iterator;
+    if (subtemplateIterator == null) return terminator;
+
+    return subtemplateIterator._getLastTemplateNode();
+  }
+
+  Node _getLastTemplateNode() => _getLastInstanceNode(_instances.length - 1);
+
+  void _insertInstanceAt(int index, DocumentFragment fragment) {
+    var previousInstanceLast = _getLastInstanceNode(index - 1);
+    var parent = _templateElement.parentNode;
+
+    _instances.insert(index, fragment);
+    parent.insertBefore(fragment, previousInstanceLast.nextNode);
+  }
+
+  DocumentFragment _extractInstanceAt(int index) {
+    var previousInstanceLast = _getLastInstanceNode(index - 1);
+    var lastNode = _getLastInstanceNode(index);
+    var parent = _templateElement.parentNode;
+    var instance = _instances.removeAt(index);
+
+    while (lastNode != previousInstanceLast) {
+      var node = previousInstanceLast.nextNode;
+      if (node == lastNode) lastNode = previousInstanceLast;
+
+      instance.append(node..remove());
+    }
+
+    return instance;
+  }
+
+  void _handleSplices(List<ListChangeRecord> splices) {
+    if (_closed || splices.isEmpty) return;
+
+    final template = _templateElement;
+
+    if (template.parentNode == null) {
+      close();
+      return;
+    }
+
+    ObservableList.applyChangeRecords(_iteratedValue, _presentValue, splices);
+
+    final delegate = _templateExt.bindingDelegate;
+
+    // Dart note: the JavaScript code relies on the distinction between null
+    // and undefined to track whether the functions are prepared. We use a bool.
+    if (!_initPrepareFunctions) {
+      _initPrepareFunctions = true;
+      final delegate = _templateExt._self.bindingDelegate;
+      if (delegate != null) {
+        _instanceModelFn = delegate.prepareInstanceModel(template);
+        _instancePositionChangedFn =
+            delegate.prepareInstancePositionChanged(template);
+      }
+    }
+
+    // Instance Removals.
+    var instanceCache = new HashMap(equals: identical);
+    var removeDelta = 0;
+    for (var splice in splices) {
+      for (var model in splice.removed) {
+        var instance = _extractInstanceAt(splice.index + removeDelta);
+        if (instance != _emptyInstance) {
+          instanceCache[model] = instance;
+        }
+      }
+
+      removeDelta -= splice.addedCount;
+    }
+
+    for (var splice in splices) {
+      for (var addIndex = splice.index;
+          addIndex < splice.index + splice.addedCount;
+          addIndex++) {
+
+        var model = _iteratedValue[addIndex];
+        DocumentFragment instance = instanceCache.remove(model);
+        if (instance == null) {
+          try {
+            if (_instanceModelFn != null) {
+              model = _instanceModelFn(model);
+            }
+            if (model == null) {
+              instance = _emptyInstance;
+            } else {
+              instance = _templateExt.createInstance(model, delegate);
+            }
+          } catch (e, s) {
+            // Dart note: we propagate errors asynchronously here to avoid
+            // disrupting the rendering flow. This is different than in the JS
+            // implementation but it should probably be fixed there too. Dart
+            // hits this case more because non-existing properties in
+            // [PropertyPath] are treated as errors, while JS treats them as
+            // null/undefined.
+            // TODO(sigmund): this should be a synchronous throw when this is
+            // called from createInstance, but that requires enough refactoring
+            // that it should be done upstream first. See dartbug.com/17789.
+            new Completer().completeError(e, s);
+            instance = _emptyInstance;
+          }
+        }
+
+        _insertInstanceAt(addIndex, instance);
+      }
+    }
+
+    for (var instance in instanceCache.values) {
+      _closeInstanceBindings(instance);
+    }
+
+    if (_instancePositionChangedFn != null) _reportInstancesMoved(splices);
+  }
+
+  void _reportInstanceMoved(int index) {
+    var instance = _instances[index];
+    if (instance == _emptyInstance) return;
+
+    _instancePositionChangedFn(nodeBind(instance).templateInstance, index);
+  }
+
+  void _reportInstancesMoved(List<ListChangeRecord> splices) {
+    var index = 0;
+    var offset = 0;
+    for (var splice in splices) {
+      if (offset != 0) {
+        while (index < splice.index) {
+          _reportInstanceMoved(index);
+          index++;
+        }
+      } else {
+        index = splice.index;
+      }
+
+      while (index < splice.index + splice.addedCount) {
+        _reportInstanceMoved(index);
+        index++;
+      }
+
+      offset += splice.addedCount - splice.removed.length;
+    }
+
+    if (offset == 0) return;
+
+    var length = _instances.length;
+    while (index < length) {
+      _reportInstanceMoved(index);
+      index++;
+    }
+  }
+
+  void _closeInstanceBindings(DocumentFragment instance) {
+    var bindings = _instanceExtension[instance]._bindings;
+    for (var binding in bindings) binding.close();
+  }
+
+  void _unobserve() {
+    if (_listSub == null) return;
+    _listSub.cancel();
+    _listSub = null;
+  }
+
+  void close() {
+    if (_closed) return;
+
+    _unobserve();
+    _instances.forEach(_closeInstanceBindings);
+    _instances.clear();
+    _closeDependencies();
+    _templateExt._iterator = null;
+    _closed = true;
+  }
+}
+
+// Dart note: the JavaScript version just puts an expando on the array.
+class _BoundNodes {
+  final List<Node> nodes;
+  final List<Bindable> instanceBindings;
+  _BoundNodes(this.nodes, this.instanceBindings);
+}