Program Listing for File callback_wrapper.hpp

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#ifndef FUSE_CORE__CALLBACK_WRAPPER_HPP_
#define FUSE_CORE__CALLBACK_WRAPPER_HPP_

#include <deque>
#include <functional>
#include <future>
#include <memory>

#include <rclcpp/rclcpp.hpp>

namespace fuse_core
{

class CallbackWrapperBase
{
public:
  virtual void call() = 0;
};

template<typename T>
class CallbackWrapper : public CallbackWrapperBase
{
public:
  using CallbackFunction = std::function<T(void)>;

  explicit CallbackWrapper(CallbackFunction callback)
  : callback_(callback)
  {
  }

  std::future<T> getFuture()
  {
    return promise_.get_future();
  }

  void call() override
  {
    promise_.set_value(callback_());
  }

private:
  CallbackFunction callback_;
  std::promise<T> promise_;
};

// Specialization to handle 'void' return types
// Specifically, promise_.set_value(callback_()) does not work if callback_() returns void.
template<>
inline void CallbackWrapper<void>::call()
{
  callback_();
  promise_.set_value();
}


class CallbackAdapter : public rclcpp::Waitable
{
public:
  explicit CallbackAdapter(std::shared_ptr<rclcpp::Context> context_ptr);

  size_t get_number_of_ready_guard_conditions() override;


  bool is_ready(rcl_wait_set_t * wait_set) override;


  void add_to_wait_set(rcl_wait_set_t * wait_set) override;

  std::shared_ptr<void> take_data() override;

  void execute(std::shared_ptr<void> & data) override;

  void addCallback(const std::shared_ptr<CallbackWrapperBase> & callback);

  void addCallback(std::shared_ptr<CallbackWrapperBase> && callback);

  void removeAllCallbacks();

private:
  rcl_guard_condition_t gc_;

  std::mutex queue_mutex_;
  std::deque<std::shared_ptr<CallbackWrapperBase>> callback_queue_;
};


}  // namespace fuse_core

#endif  // FUSE_CORE__CALLBACK_WRAPPER_HPP_