Refactor of PolymerExpressions. Adds "as" expressions.

pkg/polymer_expressions/lib/eval.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.
 
 library polymer_expressions.eval;
 
 import 'dart:async';
 import 'dart:collection';
 
 @MirrorsUsed(metaTargets: const [Reflectable, ObservableProperty],
@@ skipping 197 matching lines @@
       var classMirror = _modelMirror.type;
       if (getMemberMirror(classMirror, symbol) != null) {
         return model;
       }
     }
     if (parent != null) {
       return parent.ownerOf(name);
     }
   }
 
-  bool contains(String name) {
-    if (_variables.containsKey(name)) {
-      return true;
-    } else {
-      var symbol = new Symbol(name);
-      var classMirror = _modelMirror.type;
-      if (getMemberMirror(classMirror, symbol) != null) {
-        return true;
-      }
-    }
-    if (parent != null) {
-      return parent.contains(name);
-    }
-    return false;
-  }
 }
 
 Object _convert(v) {
   if (v is Stream) return new StreamBinding(v);
   return v;
 }
 
 abstract class ExpressionObserver<E extends Expression> implements Expression {
   final E _expr;
   ExpressionObserver _parent;
@@ skipping 40 matching lines @@
 }
 
 class Updater extends RecursiveVisitor {
   final Scope scope;
 
   Updater(this.scope);
 
   visitExpression(ExpressionObserver e) {
     e._observe(scope);
   }
-
-  visitInExpression(InObserver c) {
-    visit(c.right);
-    visitExpression(c);
-  }
 }
 
 class ObserverBuilder extends Visitor {
   final Scope scope;
   final Queue parents = new Queue();
 
   ObserverBuilder(this.scope);
 
   visitEmptyExpression(EmptyExpression e) => new EmptyObserver(e);
 
@@ skipping 74 matching lines @@
     var trueExpr = visit(o.trueExpr);
     var falseExpr = visit(o.falseExpr);
     var ternary = new TernaryObserver(o, condition, trueExpr, falseExpr);
     condition._parent = ternary;
     trueExpr._parent = ternary;
     falseExpr._parent = ternary;
     return ternary;
   }
 
   visitInExpression(InExpression i) {
-    // don't visit the left. It's an identifier, but we don't want to evaluate
-    // it, we just want to add it to the comprehension object
-    var left = visit(i.left);
-    var right = visit(i.right);
-    var inexpr = new InObserver(i, left, right);
-    right._parent = inexpr;
-    return inexpr;
+    throw "can't eval an in expression";

[Jennifer Messerly, 2014/01/31 02:48:50]

throw new UnsupportedError?

[justinfagnani, 2014/03/12 23:21:30]

Done.

   }
+
+  visitAsExpression(AsExpression i) {
+    throw "can't eval an as expression";
+  }
+
 }
 
 class EmptyObserver extends ExpressionObserver<EmptyExpression>
     implements EmptyExpression {
 
   EmptyObserver(EmptyExpression value) : super(value);
 
   _updateSelf(Scope scope) {
     _value = scope.model;
     // TODO(justin): listen for scope.model changes?
@@ skipping 259 matching lines @@
                 _invalidate(scope);
               }
             });
       }
     }
   }
 
   accept(Visitor v) => v.visitInvoke(this);
 }
 
-class InObserver extends ExpressionObserver<InExpression>
-    implements InExpression {
-  IdentifierObserver left;
-  ExpressionObserver right;
-
-  InObserver(Expression expr, this.left, this.right) : super(expr);
-
-  _updateSelf(Scope scope) {
-    Identifier identifier = left;
-    var iterable = right._value;
-
-    if (iterable is! Iterable && iterable != null) {
-      throw new EvalException("right side of 'in' is not an iterator");
-    }
-
-    if (iterable is ObservableList) {
-      _subscription = iterable.listChanges.listen((_) => _invalidate(scope));
-    }
-
-    // TODO: make Comprehension observable and update it
-    _value = new Comprehension(identifier.value, iterable);
-  }
-
-  accept(Visitor v) => v.visitInExpression(this);
-}
-
 _toBool(v) => (v == null) ? false : v;
 
 /** Call a [Function] or a [Method]. */
 // TODO(jmesserly): remove this once dartbug.com/13002 is fixed.
 // Just inline `_convert(Function.apply(...))` to the call site.
 Object call(Object receiver, List args) {
   var result;
   if (receiver is Method) {
     Method method = receiver;
     result = method.mirror.invoke(method.symbol, args, null).reflectee;
   } else {
     result = Function.apply(receiver, args, null);
   }
   return _convert(result);
 }
 
-/**
- * A comprehension declaration ("a in b"). [identifier] is the loop variable
- * that's added to the scope during iteration. [iterable] is the set of
- * objects to iterate over.
- */
-class Comprehension {
-  final String identifier;
-  final Iterable iterable;
-
-  Comprehension(this.identifier, Iterable iterable)
-      : iterable = (iterable != null) ? iterable : const [];
-}
-
 /** A method on a model object in a [Scope]. */
 class Method {
   final InstanceMirror mirror;
   final Symbol symbol;
 
   Method(this.mirror, this.symbol);
 
   /**
    * Support for calling single argument methods like [Filter]s.
    * This does not work for calls that need to pass more than one argument.
    */
   call(arg0) => mirror.invoke(symbol, [arg0], null).reflectee;
 }
 
 class EvalException implements Exception {
   final String message;
   EvalException(this.message);
   String toString() => "EvalException: $message";
 }