PX4-Autopilot/src/modules/uORB/Publication.hpp

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/**
 * @file Publication.h
 *
 */

#pragma once

#include <assert.h>

#include <uORB/uORB.h>
#include <containers/List.hpp>


namespace uORB
{

/**
 * Base publication warapper class, used in list traversal
 * of various publications.
 */
class __EXPORT PublicationBase
{
public:

	/**
	 * Constructor
	 *
	 *
	 * @param meta The uORB metadata (usually from the ORB_ID()
	 * 	macro) for the topic.
	 */
	PublicationBase(const struct orb_metadata *meta) :
		_meta(meta),
		_handle(-1) {
	}

	/**
	 * Update the struct
	 * @param data The uORB message struct we are updating.
	 */
	void update(void * data) {
		if (_handle > 0) {
			orb_publish(getMeta(), getHandle(), data);
		} else {
			setHandle(orb_advertise(getMeta(), data));
		}
	}

	/**
	 * Deconstructor
	 */
	virtual ~PublicationBase() {
		orb_unsubscribe(getHandle());
	}
// accessors
	const struct orb_metadata *getMeta() { return _meta; }
	int getHandle() { return _handle; }
protected:
// accessors
	void setHandle(orb_advert_t handle) { _handle = handle; }
// attributes
	const struct orb_metadata *_meta;
	orb_advert_t _handle;
};

/**
 * alias class name so it is clear that the base class
 * can be used by itself if desired
 */
typedef PublicationBase PublicationTiny;

/**
 * The publication base class as a list node.
 */
class __EXPORT PublicationNode :
	public PublicationBase,
	public ListNode<PublicationNode *>
{
public:
	/**
	 * Constructor
	 *
	 *
	 * @param meta The uORB metadata (usually from the ORB_ID()
	 * 	macro) for the topic.
	 * @param list 	A pointer to a list of subscriptions
	 * 	that this should be appended to.
	 */
	PublicationNode(const struct orb_metadata *meta,
		List<PublicationNode *> * list=nullptr) :
		PublicationBase(meta) {
		if (list != nullptr) list->add(this);
	}

	/**
	 * This function is the callback for list traversal
	 * updates, a child class must implement it.
	 */
	virtual void update() = 0;
};

/**
 * Publication wrapper class
 */
template<class T>
class Publication :
	public T, // this must be first!
	public PublicationNode
{
public:
	/**
	 * Constructor
	 *
	 * @param meta The uORB metadata (usually from
	 * 	the ORB_ID() macro) for the topic.
	 * @param list A list interface for adding to
	 * 	list during construction
	 */
	Publication(const struct orb_metadata *meta,
		List<PublicationNode *> * list=nullptr);

	/**
	 * Deconstructor
	 **/
	virtual ~Publication();

	/*
	 * XXX
	 * This function gets the T struct, assuming
	 * the struct is the first base class, this
	 * should use dynamic cast, but doesn't
	 * seem to be available
	 */
	void *getDataVoidPtr();

	/**
	 * Create an update function that uses the embedded struct.
	 */
	void update() {
		PublicationBase::update(getDataVoidPtr());
	}
};

} // namespace uORB