view nearestaccumulator.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 NearestAccumulator : public Accumulator {
public:
  NearestAccumulator();
  ~NearestAccumulator();
  void add_point(adb_result_t *r);
  adb_query_results_t *get_points();
private:
  std::set< adb_result_t, adb_result_triple_lt > *set;
  std::set< adb_result_t, adb_result_qpos_lt > *points;
};

template <class T> NearestAccumulator<T>::NearestAccumulator()
  : set(0), points(0) {
  set = new std::set< adb_result_t, adb_result_triple_lt >;
  points = new std::set< adb_result_t, adb_result_qpos_lt >;
}

template <class T> NearestAccumulator<T>::~NearestAccumulator() {
  if(set) {
    delete set;
  }
  if(points) {
    delete points;
  }
}

template <class T> void NearestAccumulator<T>::add_point(adb_result_t *r) {
  if(!isnan(r->dist)) {
    if(set->find(*r) == set->end()) {
      set->insert(*r);

      std::set< adb_result_t, adb_result_qpos_lt >::iterator it;
      it = points->find(*r);
      if(it == points->end()) {
        points->insert(*r);
      } else if(T()(*(const adb_result_t *)r,(*it))) {
        points->erase(it);
        points->insert(*r);
      }
    }
  }
}

template <class T> adb_query_results_t *NearestAccumulator<T>::get_points() {
  unsigned int nresults = points->size();
  adb_query_results_t *r = (adb_query_results_t *) malloc(sizeof(adb_query_results_t));
  adb_result_t *rs = (adb_result_t *) calloc(nresults, sizeof(adb_result_t));
  r->nresults = nresults;
  r->results = rs;
  std::set< adb_result_t, adb_result_qpos_lt >::iterator it;
  unsigned int k = 0;
  for(it = points->begin(); it != points->end(); it++) {
    rs[k++] = *it;
  }
  return r;
}