ISubscriberMiddleware.h

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// Copyright (c) 2026 Computer Vision Center (CVC) at the Universitat Autonoma de Barcelona (UAB).
// This work is licensed under the terms of the MIT license.
// For a copy, see <https://opensource.org/licenses/MIT>.
 
#pragma once
 
#include <string>
 
#include "carla/ros2/middleware/QosProfile.h"
 
namespace carla {
namespace ros2 {
 
/// Type-erased abstract interface for a subscriber middleware.
/// Concrete implementations write received messages directly into the caller-provided
/// storage (message_ptr / new_message_flag) to avoid an extra copy.
///
/// Contract: when an implementation establishes its process-wide transport
/// context (a DDS DomainParticipant, a Zenoh session, ...) it must honor
/// carla::ros2::MiddlewareConfig::GetDomainId(), mapping kUnsetDomainId to its
/// own native default. This keeps the ROS 2 domain id configurable and
/// middleware-agnostic (see MiddlewareConfig.h).
class ISubscriberMiddleware {
 public:
  virtual ~ISubscriberMiddleware() = default;
 
  /// Initialize the underlying middleware entities.
  /// The middleware writes incoming messages to *message_ptr and sets *new_message_flag = true.
  /// @param topic_name       Full topic name.
  /// @param message_ptr      Pointer to the message storage owned by the caller.
  /// @param new_message_flag Pointer to the new-message flag owned by the caller.
  /// @return true on success.
  virtual bool Init(
      const std::string& topic_name,
      void* message_ptr,
      bool* new_message_flag) = 0;
 
  /// Initialize with an explicit per-topic QoS profile (see QosProfile.h).
  /// The default implementation ignores the profile and falls back to the
  /// QoS-less Init so test fakes and QoS-agnostic middlewares keep working;
  /// concrete backends override this to honor the profile.
  virtual bool Init(
      const std::string& topic_name,
      void* message_ptr,
      bool* new_message_flag,
      const QosProfile& qos) {
    (void)qos;
    return Init(topic_name, message_ptr, new_message_flag);
  }
 
  /// @return true if at least one publisher is matched.
  virtual bool IsAlive() const = 0;
 
  /// @return The topic name this subscriber is bound to.
  virtual std::string GetTopicName() const = 0;
};
 
} // namespace ros2
} // namespace carla