enclosure_deleter.h

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* Author: Eitan Marder-Eppstein
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#include <boost/shared_ptr.hpp>

#ifndef ACTIONLIB__ENCLOSURE_DELETER_H_
#define ACTIONLIB__ENCLOSURE_DELETER_H_

namespace actionlib
{

/*
 * This allows the creation of a shared pointer to a section
 * of an already reference counted structure. For example,
 * if in the following picture Enclosure is reference counted with
 * a boost::shared_ptr and you want to return a boost::shared_ptr
 * to the Member that is referenced counted along with Enclosure objects
 *
 * Enclosure ---------------  <--- Already reference counted
 * -----Member <------- A member of enclosure objects, eg. Enclosure.Member
 */
template<class Enclosure>
class EnclosureDeleter
{
public:
  EnclosureDeleter(const boost::shared_ptr<Enclosure> & enc_ptr)
  : enc_ptr_(enc_ptr) {}

  template<class Member>
  void operator()(Member *)
  {
    enc_ptr_.reset();
  }

private:
  boost::shared_ptr<Enclosure> enc_ptr_;
};

template<class Enclosure, class Member>
boost::shared_ptr<Member> share_member(boost::shared_ptr<Enclosure> enclosure, Member & member)
{
  EnclosureDeleter<Enclosure> d(enclosure);
  boost::shared_ptr<Member> p(&member, d);
  return p;
}

}  // namespace actionlib

#endif  // ACTIONLIB__ENCLOSURE_DELETER_H_