PX4-Autopilot/src/platforms/px4_publisher.h

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/**
 * @file px4_publisher.h
 *
 * PX4 Publisher API, implements publishing of messages from a nodehandle
 */
#pragma once
#if defined(__PX4_ROS)
/* includes when building for ros */
#include "ros/ros.h"
#else
/* includes when building for NuttX */
#include <uORB/Publication.hpp>
#include <containers/List.hpp>
#endif

#include <platforms/px4_message.h>

namespace px4
{

/**
 * Untemplated publisher base class
 * */
class __EXPORT PublisherBase
{
public:
	PublisherBase() {};
	~PublisherBase() {};
};

/**
 * Publisher base class, templated with the message type
 * */
template <typename T>
class __EXPORT Publisher
{
public:
	Publisher() {};
	~Publisher() {};

	virtual int publish(const T &msg)  = 0;
};

#if defined(__PX4_ROS)
template <typename T>
class PublisherROS :
	public Publisher<T>
{
public:
	/**
	 * Construct Publisher by providing a ros::Publisher
	 * @param ros_pub the ros publisher which will be used to perform the publications
	 */
	PublisherROS(ros::NodeHandle *rnh) :
		Publisher<T>(),
		_ros_pub(rnh->advertise<typename std::remove_reference<decltype(((T*)nullptr)->data())>::type &>(T::handle(), kQueueSizeDefault))
	{}

	~PublisherROS() {};

	/** Publishes msg
	 * @param msg	    the message which is published to the topic
	 */
	int publish(const T &msg)
	{
		_ros_pub.publish(msg.data());
		return 0;
	}
protected:
	static const uint32_t kQueueSizeDefault = 1;		/**< Size of queue for ROS */
	ros::Publisher _ros_pub;	/**< Handle to the ros publisher */
};
#else
/**
 * Because we maintain a list of publishers we need a node class
 */
class __EXPORT PublisherNode :
	public ListNode<PublisherNode *>
{
public:
	PublisherNode() :
		ListNode()
	{}

	virtual ~PublisherNode() {}

	virtual void update() = 0;
};

template <typename T>
class __EXPORT PublisherUORB :
	public Publisher<T>,
	public PublisherNode

{
public:
	/**
	 * Construct Publisher by providing orb meta data
	 */
	PublisherUORB() :
		Publisher<T>(),
		PublisherNode(),
		_uorb_pub(new uORB::PublicationBase(T::handle()))
	{}

	~PublisherUORB() {
		delete _uorb_pub;
	};

	/** Publishes msg
	 * @param msg	    the message which is published to the topic
	 */
	int publish(const T &msg)
	{
		_uorb_pub->update((void *)&(msg.data()));
		return 0;
	}

	/**
	 * Empty callback for list traversal
	 */
	void update() {} ;
private:
	uORB::PublicationBase * _uorb_pub;	/**< Handle to the publisher */

};
#endif
}