The purpose of this trait is that it is declared as a supertrait of the traits that we don't want application code to implement (like "Proxied" and "MessageView"); application code can see those traits but not the supertrait, which enables them to use them but not implement them.
PiperOrigin-RevId: 657555025
- We introduce two new view types ProtoStringCow and ProtoBytesCow.
- In UPB, for cord field accessors we always return a Cow::Borrowed.
- In C++, for coed field accessors we check if the underlying absl::Cord is flat (contigous) and if so return a Cow::Borrowed. If it's not flat we copy the data to a ProtoString and return a Cow::Owned.
- We expect the absl::Cord to be flat almost all the time. We have experimentally verified that for small strings (<4 KiB) and less than 6 appends the cord is in fact flat [1].
- This change lifts the requirement of all ViewProxy types to be Copy. Our Cow types cannot be Copy because the owned types aren't copy.
[1] https://source.corp.google.com/piper///depot/google3/experimental/users/buchgr/cords/cords.cc
PiperOrigin-RevId: 655485943
Protobuf Team Bot
Jakob Buchgraber