Remove Comprehension type in polymer 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';
 
 import 'package:observe/observe.dart';
@@ skipping 190 matching lines @@
   Object operator[](String name) {
     if (name == 'this') return model;
     var symbol = smoke.nameToSymbol(name);
     if (model == null || symbol == null) {
       throw new EvalException("variable '$name' not found");
     }
     return _convert(smoke.read(model, symbol));
   }
 
   Object _isModelProperty(String name) => name != 'this';
+
+  String toString() => "[model: $model]";
 }
 
 /**
  * A scope that holds a reference to a single variable. Polymer expressions
  * introduce variables to the scope one at a time. Each time a variable is
  * added, a new [_LocalVariableScope] is created.
  */
 class _LocalVariableScope extends Scope {
   final Scope parent;
   final String varName;
@@ skipping 11 matching lines @@
   Object operator[](String name) {
     if (varName == name) return _convert(value);
     if (parent != null) return parent[name];
     throw new EvalException("variable '$name' not found");
   }
 
   bool _isModelProperty(String name) {
     if (varName == name) return false;
     return parent == null ? false : parent._isModelProperty(name);
   }
+
+  String toString() => "$parent > [local: $varName]";
 }
 
 /** A scope that holds a reference to a global variables. */
 class _GlobalsScope extends Scope {
   final _ModelScope parent;
   final Map<String, Object> variables;
 
   _GlobalsScope(this.variables, this.parent) : super._() {
     if (variables.containsKey('this')) {
       throw new EvalException("'this' cannot be used as a variable name.");
     }
   }
 
   Object get model => parent != null ? parent.model : null;
 
   Object operator[](String name) {
     if (variables.containsKey(name)) return _convert(variables[name]);
     if (parent != null) return parent[name];
     throw new EvalException("variable '$name' not found");
   }
 
   bool _isModelProperty(String name) {
     if (variables.containsKey(name)) return false;
     return parent == null ? false : parent._isModelProperty(name);
   }
+
+  String toString() => "$parent > [global: ${variables.keys}]";
 }
 
 Object _convert(v) => v is Stream ? new StreamBinding(v) : v;
 
 abstract class ExpressionObserver<E extends Expression> implements Expression {
   final E _expr;
   ExpressionObserver _parent;
 
   StreamSubscription _subscription;
   Object _value;
@@ skipping 446 matching lines @@
     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

[Jennifer Messerly, 2014/05/30 22:55:10]

does this TODO need to stick around?

[Siggi Cherem (dart-lang), 2014/05/31 00:56:17]

Yes, but there was already an equivalent TODO in _LocalVariableScope, which is
where this would also be implemented :-)

-    _value = new Comprehension(identifier.value, iterable);
+    var name = identifier.value;
+    _value = iterable == null ? const [] :
+        iterable.map((i) => scope.childScope(name, i)).toList(growable: false);
   }
 
   accept(Visitor v) => v.visitInExpression(this);
 }
 
 _toBool(v) => (v == null) ? false : v;
 
-/**
- * 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 [];
-}
-
 class EvalException implements Exception {
   final String message;
   EvalException(this.message);
   String toString() => "EvalException: $message";
 }