Roll Observatory packages and add a roll script

packages/polymer_expressions/benchmark/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.benchmark.eval;
+
+import 'package:benchmark_harness/benchmark_harness.dart';
+import 'package:polymer_expressions/parser.dart' show parse;
+import 'package:polymer_expressions/eval.dart' show eval, Scope;
+
+class Foo {
+  final Bar bar;
+  Foo(this.bar);
+}
+
+class Bar {
+  String baz;
+  Bar(this.baz);
+}
+
+class EvalBenchmark extends BenchmarkBase {
+  final expr;
+  final scope;
+
+  EvalBenchmark(String name, String expr, {Object model, Map variables})
+      : expr = parse(expr),
+        scope = new Scope(model: model, variables: variables),
+        super('$name: $expr ');
+
+  run() {
+    var value = eval(expr, scope);
+  }
+
+}
+
+double total = 0.0;
+
+benchmark(String name, String expr, {Object model, Map variables}) {
+  var score = new EvalBenchmark(name, expr, model: model, variables: variables)
+      .measure();
+  print("$name $expr: $score us");
+  total += score;
+}
+
+main() {
+
+  benchmark('Constant', '1');
+  benchmark('Top-level Name', 'foo',
+      variables: {'foo': new Foo(new Bar('hello'))});
+  benchmark('Model field', 'bar',
+      model: new Foo(new Bar('hello')));
+  benchmark('Path', 'foo.bar.baz',
+      variables: {'foo': new Foo(new Bar('hello'))});
+  benchmark('Map', 'm["foo"]',
+      variables: {'m': {'foo': 1}});
+  benchmark('Equality', '"abc" == "123"');
+  print('total: $total us');
+
+}