Function AccumulateSampleValues

Common/Core/vtkAbstractArray.cxx:727–769

template <typename T>
bool AccumulateSampleValues(T* array, int nc, vtkIdType begin, vtkIdType end,
  std::vector<std::set<T, CompareWithNaN<T>>>& uniques, std::set<std::vector<T>>& tupleUniques,
  unsigned int maxDiscreteValues)
{
  // number of discrete components remaining (tracked during iteration):
  int ndc = nc;
  std::pair<typename std::set<T>::iterator, bool> result;
  std::pair<typename std::set<std::vector<T>>::iterator, bool> tresult;
  std::vector<T> tuple;
  tuple.resize(nc);
  // Here we iterate over the components and add to their respective lists
  // of previously encountered values -- as long as there are not too many
  // values already in the list. We also accumulate each component's value
  // into a vtkVariantArray named tuple, which is added to the list of
  // unique vectors -- again assuming it is not already too long.
  for (vtkIdType i = begin; i < end && ndc; ++i)
  {
    // First, attempt a per-component insert.
    for (int j = 0; j < nc; ++j)
    {
      if (uniques[j].size() > maxDiscreteValues)
        continue;
      T& val(array[i * nc + j]);
      tuple[j] = val;
      result = uniques[j].insert(val);
      if (result.second)
      {
        if (uniques[j].size() == maxDiscreteValues + 1)
        {
          --ndc;
        }
      }
    }
    // Now, as long as no component has exceeded maxDiscreteValues unique
    // values, it is worth seeing whether the tuple as a whole is unique:
    if (nc > 1 && ndc == nc)
    {
      tresult = tupleUniques.insert(tuple);
      (void)tresult; // nice to have when debugging.
    }
  }
  return ndc == 0;
}

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template <typename U>