Add generic types for strong mode

lib/src/protobuf/field_info.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 protobuf;
 
 /**
  * An object representing a protobuf message field.
  */
-class FieldInfo {
+class FieldInfo<T> {
   final String name;
   final int tagNumber;
   final int index; // index of the field's value. Null for extensions.
   final int type;
 
   // Constructs the default value of a field.
   // (Only used for repeated fields where check is null.)
   final MakeDefaultFunc makeDefault;
 
   // Creates an empty message or group when decoding a message.
@@ skipping 18 matching lines @@
     assert(type != 0);
     assert(!_isGroupOrMessage(type) || subBuilder != null);
     assert(!_isEnum(type) || valueOf != null);
   }
 
   FieldInfo.repeated(this.name, this.tagNumber, this.index, int type,
       CheckFunc check, this.subBuilder,
       [this.valueOf])
       : this.type = type,
         this.check = check,
-        this.makeDefault = (() => new PbList(check: check)) {
+        this.makeDefault = (() => new PbList<T>(check: check)) {

[skybrian, 2016/04/01 18:01:40]

This is a bit inconsistent.

For a non-repeated field, T is the field's type.
For a repeated field, T is the *base type* and List<T> is the field type. (But
it's really a PbList or perhaps some other kind of list if a mixin overrides
it.)

Similarly for extensions. As a result, we can't really write generic methods
that work uniformly with non-repeated and repeated fields. (There are internal
methods that work that way, but they are currently untyped.)

I think I'm just going to live with it for now.

     assert(name != null);
     assert(tagNumber != null);
     assert(_isRepeated(type));
     assert(check != null);
     assert(!_isEnum(type) || valueOf != null);
   }
 
   static MakeDefaultFunc findMakeDefault(int type, dynamic defaultOrMaker) {
     if (defaultOrMaker == null) return PbFieldType._defaultForType(type);
     if (defaultOrMaker is MakeDefaultFunc) return defaultOrMaker;
@@ skipping 54 matching lines @@
       // Recurse on each item in the list.
       int position = 0;
       for (GeneratedMessage message in list) {
         message._fieldSet
             ._appendInvalidFields(problems, '$prefix$name[$position].');
         position++;
       }
     }
   }
 
+  /// Creates a repeated field to be attached to the given message.
+  ///
+  /// Delegates actual list creation to the message, so that it can
+  /// be overridden by a mixin.
+  List<T> _createRepeatedField(GeneratedMessage m) {
+    assert(isRepeated);
+    return m.createRepeatedField/*<T>*/(tagNumber, this);
+  }
+
   String toString() => name;
 }