sds-json-protobuf

simple data struct serialization library for C++. With this library you can serialize and deserialize C++ structs directly to JSON or protobuf.

#include <person.pb.h>

auto john = PhoneBook::Person{
        .name  = "John Doe",
        .id    = 1234,
        .email = "jdoe@example.com",
    };
auto json   = sds::json::serialize( john );
auto person = sds::json::deserialize< PhoneBook::Person >( json );
//- person is now john

goal

goal of this library is to make JSON and protobuf part of the C++ language itself.

reason

There are literally a tons of JSON C++ libraries but most of them are designed in a way that the user needs to construct the json Object via some API and for serialization and deserialization there is a lot of boilerplate code like type/schema checking, to_json, from_json, macros... All this is needed to be done by the user, and it usually ends up with a conversion to some C++ struct.

SDS works the other way around, from C++ struct to JSON or protobuf. With this approach user can focus only on the data, C++ struct, which is much more natural and sds will handle all the boring stuff like serialization/deserialization and type/schema checking.

about

SDS is an alternative implementation of protobuf for C++. This is not an plugin for protoc but an replacement for protoc, so you don't need protobuf or protoc installed to use it. Serialization and deserialization to JSON or protobuf is compatible with protoc, in other words, data serialized with code generated by sds-protoc can be deserialized by code generated by protoc and vice versa.

Usage

Cheat sheet

# add this repo to your project
add_subdirectory(external/sds-proto)
# compile proto files to C++
sds_protobuf_generate(PROTO_SRCS PROTO_HDRS ${CMAKE_SOURCE_DIR}/proto/person.proto)
# add generated files to your project
add_executable(myapp ${PROTO_SRCS} ${PROTO_HDRS})
# `sds-proto` is an interface library
# the main purpose is to update include path of `myapp` 
target_link_libraries(myapp PUBLIC sds-proto)

1. define a schema for you data in a person.proto file

package PhoneBook;

message Person {
  string name = 1;
  int32 id = 2;  // Unique ID number for this person.
  string email = 3;

  enum PhoneType {
    MOBILE = 0;
    HOME = 1;
    WORK = 2;
  }

  message PhoneNumber {
    required string number = 1; // phone number is always required
    PhoneType type = 2;
  }
  // all registered phones
  repeated PhoneNumber phones = 4;
}

2. compile person.proto with sds-protoc into person.pb.h and person.pb.cc

sds_protobuf_generate(PROTO_SRCS PROTO_HDRS ${CMAKE_SOURCE_DIR}/proto/person.proto)

observe the beautifully generated person.pb.h and person.pb.cc

namespace PhoneBook
{
struct Person {
    enum class PhoneType : int32_t {
        MOBILE = 0,
        HOME   = 1,
        WORK   = 2,
    };
    struct PhoneNumber {
        // phone number is always required
        std::string number;
        std::optional< PhoneType > type;
    };
    std::optional< std::string > name;
    // Unique ID number for this person.
    std::optional< int32_t > id;
    std::optional< std::string > email;
    // all registered phones
    std::vector< PhoneNumber > phones;
};
}// namespace PhoneBook

3. use Person struct natively and de/serialize

#include <person.pb.h>

auto john = PhoneBook::Person{
        .name  = "John Doe",
        .id    = 1234,
        .email = "jdoe@example.com",
    };
auto json   = sds::json::serialize( john );
auto person = sds::json::deserialize< PhoneBook::Person >( json );
//- person is now john

example

navigate to the example directory.

status

project is in an early stage of development, expect bugs, API changes and definitely do NOT use it in production, yet.

• Make it work
• Make it right
• Make it fast

roadmap

• parser for proto files (supported syntax: proto2 and proto3)
• compile proto message to C++ data struct
• generate json de/serializer for generated C++ data struct (serialized json has to be compatible with GPB)
• generate protobuf de/serializer for generated C++ data struct (serialized pb has to be compatible with GPB)