asyncapi_gencpp

C++ code generator for serializing and deserializing Async API components and messages based on a specification file.

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README

asyncapi_gencpp

C++ code generator for serializing and deserializing Async API components and messages based on a specification file.

The generator is implemented as as python3 script with the following usage:

usage: asyncapi_gencpp.py [-h] spec prefix outdir

positional arguments:
  spec        AsyncAPI specification file
  prefix      Include file prefix
  outdir      Output directory

The script will generate C++ data structures and code for parsing and writing the JSON objects described in the components and messages sections of the asyncapi spec file. Low level JSON parsing code is handled using the header only nlohmann json library.

The generated objects are returned as std::optional<> to deal with parsing failures, and so will be dependent on C++17.

The generator can also be used directly in cmake using a provided macro.

Example Usage:

asyncapi.yaml

components:
  schemas:
    pose:
      type: object
      properties:
        position:
          $ref: '#/components/schemas/vector3'
        orientation:
          type: object
          properties:
            - w:
              type: number
            - x:
              type: number
            - y:
              type: number
            - z:
              type: number
          required:
            - w
            - x
            - y
            - z
      required:
        - position
        - orientation
    vector3:
      type: object
      properties:
        x:
          type: number
        y:
          type: number
        z:
          type: number
      required:
        - x
        - y
        - z

CMakeLists.txt

project(example)
find_package(asyncapi_gencpp REQUIRED)

# asyncapi_gencpp macro provided via find_package(asyncapi_gencpp)
asyncapi_gencpp(${PROJECT_SOURCE_DIR}/api/asyncapi.yaml ${PROJECT_NAME}/msg ${CMAKE_CURRENT_BINARY_DIR}/include)

add_executable(main src/main.cpp)
add_dependencies(main ${PROJECT_NAME}_gencpp)

main.cpp

#include <iostream>
#include <example/msg/messages.h>  // This header includes all of the includes for the generated code, but individual
                                   // message headers can also be include as needed.

int main(int argc, char **argv) {

  // serialize to JSON
  example::msg::Pose pose;
  pose.position.x = 0.0;
  pose.position.y = 0.0;
  pose.position.z = 0.0;
  pose.orientation.w = 1.0;
  pose.orientation.x = 0.0;
  pose.orientation.y = 0.0;
  pose.orientation.z = 0.0;
  std::string json_string = pose.dump();

  // deserialize from JSON
  auto pose2 = example::msg::Pose::fromJson(json_string);
  if (pose2) {
    std::cout << "position: \n";
    std::cout << " x: " << pose2->position.x << "\n";
    std::cout << " y: " << pose2->position.y << "\n";
    std::cout << " z: " << pose2->position.z << "\n";
    std::cout << "orientation: \n";
    std::cout << " w: " << pose2->orientation.w << "\n";
    std::cout << " x: " << pose2->orientation.x << "\n";
    std::cout << " y: " << pose2->orientation.y << "\n";
    std::cout << " z: " << pose2->orientation.z << "\n";
  }

  return 0;
}

For a more complete example see the rpad library.

ROS Support

This library is agnostic to ROS, but is packaged to work in a ROS1 or ROS2 workspace.