view dbaccumulator.h @ 457:823bca1e10f5 api-inversion

Sketch out a "query state" structure.

As yet it's completely unused, but the intention is that accumulated
state will be collected into one of these structures for each query, and
then passed around, to help reduce the need for silly arglists.  It's
possible that this structure will also grow a pointer to the adb itself,
and be the thing passed to the LSH callback; we'll see how that
develops.

template <class T> class DBAccumulator : public Accumulator {
public:
  DBAccumulator(unsigned int pointNN);
  ~DBAccumulator();
  void add_point(adb_result_t *r);
  adb_query_results_t *get_points();
private:
  unsigned int pointNN;
  std::priority_queue< adb_result_t, std::vector<adb_result_t>, T > *queue;
  std::set< adb_result_t, adb_result_triple_lt > *set;
};

template <class T> DBAccumulator<T>::DBAccumulator(unsigned int pointNN)
  : pointNN(pointNN), queue(0), set(0) {
  queue = new std::priority_queue< adb_result_t, std::vector<adb_result_t>, T>;
  set = new std::set<adb_result_t, adb_result_triple_lt>;
}

template <class T> DBAccumulator<T>::~DBAccumulator() {
  if(queue) {
    delete queue;
  }
  if(set) {
    delete set;
  }
}

template <class T> void DBAccumulator<T>::add_point(adb_result_t *r) {
  if(!isnan(r->dist)) {
    if(set->find(*r) == set->end()) {
      set->insert(*r);
      queue->push(*r);
      if(queue->size() > pointNN) {
        queue->pop();
      }
    }
  }
}

template <class T> adb_query_results_t *DBAccumulator<T>::get_points() {
  unsigned int size = queue->size();
  adb_query_results_t *r = (adb_query_results_t *) malloc(sizeof(adb_query_results_t));
  adb_result_t *rs = (adb_result_t *) calloc(size, sizeof(adb_result_t));
  r->nresults = size;
  r->results = rs;

  for(unsigned int k = 0; k < size; k++) {
    rs[k] = queue->top();
    queue->pop();
  }
  return r;
}