Roll polymer packages to version 0.3.4

pkg/polymer_expressions/lib/polymer_expressions.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.
 
 /**
  * A binding delegate used with Polymer elements that
  * allows for complex binding expressions, including
  * property access, function invocation,
  * list/map indexing, and two-way filtering.
  *
@@ skipping 79 matching lines @@
               ? model
               : _scopeFactory.modelScope(model: model, variables: globals);
           return new _Binding(bindExpr, scope);
         };
       } else {
         return (model, Node node, bool oneTime) {
           var scope = _scopes[node] = (model is Scope)
               ? model
               : _scopeFactory.modelScope(model: model, variables: globals);
           if (oneTime) {
-            return _Binding._oneTime(expr, scope, null);
+            return _Binding._oneTime(expr, scope);
           }
           return new _Binding(expr, scope);
         };
       }
     }
 
     // For regular bindings, not bindings on a template, the model is always
     // a Scope created by prepareInstanceModel
     _Converter converter = null;
     if (boundNode is Element && name == 'class') {
@@ skipping 132 matching lines @@
       } else {
         // only happens in bindings_test
         scope = _scopeFactory.modelScope(model: model, variables: globals);
       }
       return scope;
     } else {
       return _getContainingScope(node.parentNode, model);
     }
   }
 
+  /// Parse the expression string and return an expression tree.
+  static Expression getExpression(String exprString) =>
+      new Parser(exprString).parse();
+
+  /// Determines the value of evaluating [expr] on the given [model] and returns
+  /// either its value or a binding for it. If [oneTime] is true, it direclty
+  /// returns the value. Otherwise, when [oneTime] is false, it returns a
+  /// [Bindable] that besides evaluating the expression, it will also react to
+  /// observable changes from the model and update the value accordingly.
+  static getBinding(Expression expr, model, {Map<String, Object> globals,
+      oneTime: false}) {
+    if (globals == null) globals = new Map.from(DEFAULT_GLOBALS);
+    var scope = model is Scope ? model
+        : new Scope(model: model, variables: globals);
+    return oneTime ? _Binding._oneTime(expr, scope)
+        : new _Binding(expr, scope);
+  }
 }
 
 typedef Object _Converter(Object);
 
 class _Binding extends Bindable {
   final Scope _scope;
   final _Converter _converter;
   final Expression _expr;
 
   Function _callback;
   StreamSubscription _sub;
   ExpressionObserver _observer;
   var _value;
 
-  _Binding(this._expr, this._scope, [converter])
-      : _converter = converter == null ? _identity : converter;
+  _Binding(this._expr, this._scope, [this._converter]);
 
-  static Object _oneTime(Expression expr, Scope scope, _Converter converter) {
+  static Object _oneTime(Expression expr, Scope scope, [_Converter converter]) {
     try {
       var value = eval(expr, scope);
       return (converter == null) ? value : converter(value);
     } catch (e, s) {
       new Completer().completeError(
           "Error evaluating expression '$expr': $e", s);
     }
     return null;
   }
 
   bool _convertAndCheck(newValue, {bool skipChanges: false}) {
     var oldValue = _value;
-    _value = _converter(newValue);
+    _value = _converter == null ? newValue : _converter(newValue);
 
     if (!skipChanges && _callback != null && oldValue != _value) {
       _callback(_value);
       return true;
     }
     return false;
   }
 
   get value {
     // if there's a callback, then _value has been set, if not we need to
     // force an evaluation
     if (_callback != null) {
       _check(skipChanges: true);
       return _value;
     }
-    return _oneTime(_expr, _scope, _converter);
+    return _Binding._oneTime(_expr, _scope, _converter);
   }
 
   set value(v) {
     try {
       assign(_expr, v, _scope, checkAssignability: false);
     } catch (e, s) {
       new Completer().completeError(
           "Error evaluating expression '$_expr': $e", s);
     }
   }
@@ skipping 62 matching lines @@
  * Factory function used for testing.
  */
 class ScopeFactory {
   const ScopeFactory();
   modelScope({Object model, Map<String, Object> variables}) =>
       new Scope(model: model, variables: variables);
 
   childScope(Scope parent, String name, Object value) =>
       parent.childScope(name, value);
 }