Add observatory_pub_packages snapshot to third_party

observatory_pub_packages/polymer/deserialize.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.deserialize;
+
+import 'dart:convert' show JSON;
+
+final _typeHandlers = {
+  String: (x, _) => x,
+  Null: (x, _) => x,
+  DateTime: (x, def) {
+    // TODO(jmesserly): shouldn't need to try-catch here
+    // See: https://code.google.com/p/dart/issues/detail?id=1878
+    try {
+      return DateTime.parse(x);
+    } catch (e) {
+      return def;
+    }
+  },
+  bool: (x, _) => x != 'false',
+  int: (x, def) => int.parse(x, onError: (_) => def),
+  double: (x, def) => double.parse(x, (_) => def),
+};
+
+/// Convert representation of [value] based on [type] and [currentValue].
+Object deserializeValue(String value, Object currentValue, Type type) {
+  var handler = _typeHandlers[type];
+  if (handler != null) return handler(value, currentValue);
+
+  try {
+    // If the string is an object, we can parse is with the JSON library.
+    // include convenience replace for single-quotes. If the author omits
+    // quotes altogether, parse will fail.
+    return JSON.decode(value.replaceAll("'", '"'));
+
+    // TODO(jmesserly): deserialized JSON is not assignable to most objects in
+    // Dart. We should attempt to convert it appropriately.
+  } catch(e) {
+    // The object isn't valid JSON, return the raw value
+    return value;
+  }
+}