wpi::ProtobufSerializable Concept Reference

Specifies that a type is capable of protobuf serialization and deserialization. More...

#include <wpi/protobuf/Protobuf.h>

Concept definition

template<typename T>
concept wpi::ProtobufSerializable =  requires(
    wpi::ProtoOutputStream<std::remove_cvref_t<T>>& ostream,
    wpi::ProtoInputStream<std::remove_cvref_t<T>>& istream, const T& value) {
  typename Protobuf<typename std::remove_cvref_t<T>>;
  {
    Protobuf<typename std::remove_cvref_t<T>>::Unpack(istream)
  } -> std::same_as<std::optional<typename std::remove_cvref_t<T>>>;
  {
    Protobuf<typename std::remove_cvref_t<T>>::Pack(ostream, value)
  } -> std::same_as<bool>;
  typename Protobuf<typename std::remove_cvref_t<T>>::MessageStruct;
  {
    Protobuf<typename std::remove_cvref_t<T>>::MessageStruct::msg_descriptor()
  } -> std::same_as<const pb_msgdesc_t*>;
  {
    Protobuf<typename std::remove_cvref_t<T>>::MessageStruct::msg_name()
  } -> std::same_as<std::string_view>;
  {
    Protobuf<typename std::remove_cvref_t<T>>::MessageStruct::file_descriptor()
  } -> std::same_as<pb_filedesc_t>;
}

Detailed Description

Specifies that a type is capable of protobuf serialization and deserialization.

This is designed for serializing complex flexible data structures using code generated from a .proto file. Serialization consists of writing values into a nanopb Stream and deserialization consists of reading values from nanopb Stream.

Implementations must define a template specialization for wpi::Protobuf with T being the type that is being serialized/deserialized, with the following static members (as enforced by this concept):

• using MessageStruct = nanopb_message_struct_here: typedef to the wpilib modified nanopb message struct
• std::optional<T> Unpack(wpi::ProtoInputStream<T>&): function for deserialization
• bool Pack(wpi::ProtoOutputStream<T>&, T&& value): function for serialization

As a suggestion, 2 extra type usings can be added to simplify the stream definitions, however these are not required.

• using InputStream = wpi::ProtoInputStream<T>;
• using OutputStream = wpi::ProtoOutputStream<T>;