gz/transport/RepHandler.hh

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/*
 * Copyright (C) 2014 Open Source Robotics Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
*/
 
#ifndef GZ_TRANSPORT_REPHANDLER_HH_
#define GZ_TRANSPORT_REPHANDLER_HH_
 
#ifdef _MSC_VER
#pragma warning(push, 0)
#endif
#include <google/protobuf/message.h>
#ifdef _MSC_VER
#pragma warning(pop)
#endif
 
#if GOOGLE_PROTOBUF_VERSION > 2999999 && GOOGLE_PROTOBUF_VERSION < 4022000
#include <google/protobuf/stubs/casts.h>
#endif
 
#include <functional>
#include <iostream>
#include <memory>
#include <string>
 
#include "gz/transport/config.hh"
#include "gz/transport/Export.hh"
#include "gz/transport/TransportTypes.hh"
#include "gz/transport/Uuid.hh"
 
namespace ignition::transport
{
  // Inline bracket to help doxygen filtering.
  inline namespace IGNITION_TRANSPORT_VERSION_NAMESPACE {
  //
  class IGNITION_TRANSPORT_VISIBLE IRepHandler
  {
    public: IRepHandler()
      : hUuid(Uuid().ToString())
    {
    }
 
    public: virtual ~IRepHandler() = default;
 
    public: virtual bool RunLocalCallback(const transport::ProtoMsg &_msgReq,
                                          transport::ProtoMsg &_msgRep) = 0;
 
    public: virtual bool RunCallback(const std::string &_req,
                                     std::string &_rep) = 0;
 
    public: std::string HandlerUuid() const
    {
      return this->hUuid;
    }
 
    public: virtual std::string ReqTypeName() const = 0;
 
    public: virtual std::string RepTypeName() const = 0;
 
#ifdef _WIN32
// Disable warning C4251 which is triggered by
// std::string
#pragma warning(push)
#pragma warning(disable: 4251)
#endif
    protected: std::string hUuid;
#ifdef _WIN32
#pragma warning(pop)
#endif
  };
 
  // the service call. 'Rep' is the protobuf message type that will be filled
  template <typename Req, typename Rep> class RepHandler
    : public IRepHandler
  {
    // Documentation inherited.
    public: RepHandler() = default;
 
    public: void SetCallback(
      const std::function<bool(const Req &, Rep &)> &_cb)
    {
      this->cb = _cb;
    }
 
    // Documentation inherited.
    public: bool RunLocalCallback(const transport::ProtoMsg &_msgReq,
                                  transport::ProtoMsg &_msgRep)
    {
      // Execute the callback (if existing)
      if (!this->cb)
      {
        std::cerr << "RepHandler::RunLocalCallback() error: "
                  << "Callback is NULL" << std::endl;
        return false;
      }
 
 
#if GOOGLE_PROTOBUF_VERSION >= 5028000
      const auto msgReq =
        google::protobuf::DynamicCastMessage<Req>(&_msgReq);
      auto msgRep =
          google::protobuf::DynamicCastMessage<Rep>(&_msgRep);
#elif GOOGLE_PROTOBUF_VERSION >= 4022000
      auto msgReq =
        google::protobuf::internal::DownCast<const Req*>(&_msgReq);
      auto msgRep = google::protobuf::internal::DownCast<Rep*>(&_msgRep);
#elif GOOGLE_PROTOBUF_VERSION > 2999999
      auto msgReq = google::protobuf::down_cast<const Req*>(&_msgReq);
      auto msgRep = google::protobuf::down_cast<Rep*>(&_msgRep);
#else
      auto msgReq =
        google::protobuf::internal::down_cast<const Req*>(&_msgReq);
      auto msgRep = google::protobuf::internal::down_cast<Rep*>(&_msgRep);
#endif
 
      // Verify the dynamically casted messages are valid
      if (msgReq == nullptr || msgRep == nullptr)
      {
        if (msgReq == nullptr)
        {
          if (_msgReq.GetDescriptor() != nullptr)
          {
            std::cerr << "RepHandler::RunLocalCallback() error: "
                      << "Failed to cast the request of the type "
                      << _msgReq.GetDescriptor()->full_name()
                      << " to the specified type" << '\n';
          }
          else
          {
            std::cerr << "RepHandler::RunLocalCallback() error: "
                      << "Failed to cast the request of an unknown type"
                      << " to the specified type" << '\n';
          }
        }
        if (msgRep == nullptr)
        {
          if (_msgRep.GetDescriptor() != nullptr)
          {
            std::cerr << "RepHandler::RunLocalCallback() error: "
                      << "Failed to cast the response of the type "
                      << _msgRep.GetDescriptor()->full_name()
                      << " to the specified type" << '\n';
          }
          else
          {
            std::cerr << "RepHandler::RunLocalCallback() error: "
                      << "Failed to cast the response of an unknown type"
                      << " to the specified type" << '\n';
          }
        }
        std::cerr.flush();
        return false;
      }
 
      return this->cb(*msgReq, *msgRep);
    }
 
    // Documentation inherited.
    public: bool RunCallback(const std::string &_req,
                             std::string &_rep)
    {
      // Check if we have a callback registered.
      if (!this->cb)
      {
        std::cerr << "RepHandler::RunCallback() error: "
                  << "Callback is NULL" << std::endl;
        return false;
      }
 
      // Instantiate the specific protobuf message associated to this topic.
      auto msgReq = this->CreateMsg(_req);
      if (!msgReq)
      {
        return false;
      }
 
      Rep msgRep;
      if (!this->cb(*msgReq, msgRep))
        return false;
 
      if (!msgRep.SerializeToString(&_rep))
      {
        std::cerr << "RepHandler::RunCallback(): Error serializing the "
                  << "response" << std::endl;
        return false;
      }
 
      return true;
    }
 
    // Documentation inherited.
    public: virtual std::string ReqTypeName() const
    {
      return std::string(Req().GetTypeName());
    }
 
    // Documentation inherited.
    public: virtual std::string RepTypeName() const
    {
      return std::string(Rep().GetTypeName());
    }
 
    private: std::shared_ptr<Req> CreateMsg(const std::string &_data) const
    {
      // Instantiate a specific protobuf message
      std::shared_ptr<Req> msgPtr(new Req());
 
      // Create the message using some serialized data
      if (!msgPtr->ParseFromString(_data))
      {
        std::cerr << "RepHandler::CreateMsg() error: ParseFromString failed"
                  << std::endl;
      }
 
      return msgPtr;
    }
 
    private: std::function<bool(const Req &, Rep &)> cb;
  };
  }
}
 
#endif