This is primarily for access to comments, which would be expected to be available in a protoc plugin.
The implementation has two fiddly aspects:
- We use a Lazy<T> to avoid building the map before cross-linking. An alternative would be to crosslink at the end of the constructor, and remove the calls to CrossLink elsewhere. This would be generally better IMO, but deviate from the Java code.
- The casts to IReadOnlyList<DescriptorBase> are unfortunate. They'll always work, because these lists are always ReadOnlyCollection<T> for a descriptor type... but we can't use IList<DescriptorBase> as that's not covariant, and it's annoyingly fiddly to change the field to be of type ReadOnlyCollection<T>.
- Change the default message hash code to 1 to be consistent with other code
- Change the empty list/map hash code to 0 as "empty map" is equivalent to "no map"
- Removed map fields from unittest_proto3.proto
- Created map_unittest_proto3.proto which is like map_unittest.proto but proto3-only
- Fixed factory methods in FieldCodec highlighted by using all field types :)
- Added tests for map serialization:
- Extra fields within entries
- Entries with value then key
- Non-contiguous entries for the same map
- Multiple entries for the same key
Changes to generated code coming in next commit
Joshua Haberman
Protobuf Team Bot
listonjesse
Brian Wignall
Xiang Dai
Jon Skeet
Jie Luo
Jon Skeet