Add a DateTimeRule to default serialization

pkg/serialization/lib/src/serialization_rule.dart

Index: pkg/serialization/lib/src/serialization_rule.dart
diff --git a/pkg/serialization/lib/src/serialization_rule.dart b/pkg/serialization/lib/src/serialization_rule.dart
index 53c0f72990a54f60d76ce129fca8f2ac24c3800a..cad1f18603627d656edcc384d53fef8108c20d3f 100644
--- a/pkg/serialization/lib/src/serialization_rule.dart
+++ b/pkg/serialization/lib/src/serialization_rule.dart
@@ -492,6 +492,32 @@ class SymbolRule extends CustomRule {
   bool get hasVariableLengthEntries => false;
 }
 
+/** A hard-coded rule for DateTime. */
+class DateTimeRule extends CustomRule {
+  /** A helper to make it easier to create dates either locally or UTC. */
+  static DateTime makeUtc(year, month, day, hour, minute, second, millisecond)
+      => new DateTime.utc(year, month, day, hour, minute, second, millisecond);
+  /** A helper to make it easier to create dates either locally or UTC. */
+  static DateTime makeLocal(year, month, day, hour, minute, second, millisecond)
+      => new DateTime(year, month, day, hour, minute, second, millisecond);
+
+  bool appliesTo(instance, _) => instance is DateTime;
+
+  List<int> getState(DateTime date) =>
+      [date.year, date.month, date.day, date.hour, date.minute,

[Jennifer Messerly, 2013/05/14 23:18:33]

alternatively, just store millisecondsSinceEpoch and isUtc?

[Alan Knight, 2013/05/14 23:32:55]

Doh! That's much simpler. Done.

+          date.second, date.millisecond, date.isUtc];
+
+  create(List<int> state) {
+    var creation = state.last ? makeUtc : makeLocal;
+    return Function.apply(creation, state.take(7).toList());

[Jennifer Messerly, 2013/05/14 23:18:33]

TIL: we have Function.apply :)

[Alan Knight, 2013/05/14 23:32:55]

But now I don't get to use it :-(

+  }
+
+  void setState(date, state) {}
+  // Let the system know we don't have to store a length for these.
+  int get dataLength => 8;
+  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);
@@ -561,7 +587,7 @@ class _LazyList extends IterableBase implements List {
   // 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);