Add a DateTimeRule to default serialization

pkg/serialization/lib/src/serialization_rule.dart

 // Copyright (c) 2012, 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.
 
 part of serialization;
 
 // TODO(alanknight): We should have an example and tests for subclassing
 // serialization rule rather than using the hard-coded ClosureToMap rule. And
 // possibly an abstract superclass that's designed to be subclassed that way.
 /**
@@ skipping 474 matching lines @@
 /** A hard-coded rule for serializing Symbols. */
 class SymbolRule extends CustomRule {
   bool appliesTo(instance, _) => instance is Symbol;
   getState(instance) => [MirrorSystem.getName(instance)];
   create(state) => new Symbol(state[0]);
   void setState(symbol, state) {}
   int get dataLength => 1;
   bool get hasVariableLengthEntries => false;
 }
 
+/** A hard-coded rule for DateTime. */
+class DateTimeRule extends CustomRule {
+  bool appliesTo(instance, _) => instance is DateTime;
+  List getState(DateTime date) => [date.millisecondsSinceEpoch, date.isUtc];
+  create(List state) =>
+      new DateTime.fromMillisecondsSinceEpoch(state[0], isUtc: state[1]);
+  void setState(date, state) {}
+  // Let the system know we don't have to store a length for these.
+  int get dataLength => 2;
+  bool get hasVariableLengthEntries => false;
+}
+
 /** Create a lazy list/map that will inflate its items on demand in [r]. */
 _lazy(l, Reader r) {
   if (l is List) return new _LazyList(l, r);
   if (l is Map) return new _LazyMap(l, r);
   throw new SerializationException("Invalid type: must be Map or List - $l");
 }
 
 /**
  * This provides an implementation of Map that wraps a list which may
  * contain references to (potentially) non-inflated objects. If these
@@ skipping 49 matching lines @@
   operator [](x) => _reader.inflateReference(_raw[x]);
 
   int get length => _raw.length;
   bool get isEmpty => _raw.isEmpty;
   get first => _reader.inflateReference(_raw.first);
   get last => _reader.inflateReference(_raw.last);
 
   // These operations, and other inherited methods that iterate over the whole
   // list will work, but may be expensive, and are probably
   // best avoided.
-  List get _inflated => _raw.map(_reader.inflateReference);
+  Iterable get _inflated => _raw.map(_reader.inflateReference);
   Iterator get iterator => _inflated.iterator;
   indexOf(x, [pos = 0]) => _inflated.toList().indexOf(x);
   lastIndexOf(x, [pos]) => _inflated.toList().lastIndexOf(x);
   sublist(start, [end]) => _inflated.sublist(start, end);
 
   Map<int, dynamic> asMap() => _inflated.asMap();
 
   // These operations are all invalid
   _throw() {
     throw new UnsupportedError("Not modifiable");
@@ skipping 14 matching lines @@
   removeWhere(x) => _throw();
   retainWhere(x) => _throw();
   replaceRange(x, y, z) => _throw();
   getRange(x, y) => _throw();
   setRange(x, y, z, [a = 0]) => _throw();
   setAll(x, y) => _throw();
   removeRange(x, y) => _throw();
   get reversed => _throw();
   void set length(x) => _throw();
 }