query_results_impl.hpp

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 /*
 * Copyright (c) 2008, Willow Garage, Inc.
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namespace mongo_ros
{

using std::vector;
using std::string;

template <class M>
ResultIterator<M>::ResultIterator
(boost::shared_ptr<mongo::DBClientConnection> conn,
 const string& ns, const mongo::Query& query,
 boost::shared_ptr<mongo::GridFS> gfs,
 const bool metadata_only) :
  metadata_only_(metadata_only),
  cursor_(new Cursor(conn->query(ns, query))),
  gfs_(gfs)
{
  if ((*cursor_)->more())
    next_ = (*cursor_)->nextSafe();
}

template <class M>
ResultIterator<M>::ResultIterator () :
  metadata_only_(false)
{
}

template <class M>
ResultIterator<M>::ResultIterator (const ResultIterator<M>& res) :
  metadata_only_(res.metadata_only_), cursor_(res.cursor_),
  next_(res.next_), gfs_(res.gfs_)
{
}

template <class M>
void ResultIterator<M>::increment ()
{
  ROS_ASSERT (next_);
  if ((*cursor_)->more())
    next_ = (*cursor_)->nextSafe();
  else
    next_.reset();
}

template <class M>
typename MessageWithMetadata<M>::ConstPtr
ResultIterator<M>::dereference () const
{
  ROS_ASSERT (next_);
  // Get the raw message if necessary, else
  // use a default constructed one
  typename MessageWithMetadata<M>::Ptr m(new MessageWithMetadata<M>(next_->copy()));
  if (!metadata_only_)
  {
    mongo::OID blob_id;
    (*next_)["blob_id"].Val(blob_id);
    mongo::BSONObj q = BSON ("_id" << blob_id);
    mongo::GridFile f = gfs_->findFile(q);
    ROS_ASSERT(f.exists());
    std::stringstream ss (std::ios_base::out);
    f.write(ss);
    std::string str = ss.str();

    uint8_t* buf = (uint8_t*) str.c_str();
    ros::serialization::IStream istream(buf, str.size());
    ros::serialization::Serializer<M>::read(istream, *m);
  }

  return m;
}

template <class M>
bool ResultIterator<M>::equal (const ResultIterator<M>& other) const
{
  // Incomplete; the only case we care about is whether we're at the end yet
  if (next_ && other.next_)
    ROS_WARN ("Unexpected case of equality check of two not-past-the-end "
              "iterators in ResultIterator");
  return (!next_ && !other.next_);
}


} // namespace