Method LookupValue

Common/Core/vtkVariantArray.cxx:908–976

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//------------------------------------------------------------------------------
vtkIdType vtkVariantArray::LookupValue(ValueType value)
{
  this->UpdateLookup();

  // First look into the cached updates, to see if there were any
  // cached changes. Find an equivalent element in the set of cached
  // indices for this value. Some of the indices may have changed
  // values since the cache was built, so we need to do this equality
  // check.
  typedef vtkVariantCachedUpdates::iterator CacheIterator;
  CacheIterator cached = this->Lookup->CachedUpdates.lower_bound(value),
                cachedEnd = this->Lookup->CachedUpdates.end();
  while (cached != cachedEnd)
  {
    // Check that we are still in the same equivalence class as the
    // value.
    if (value == (*cached).first)
    {
      // Check that the value in the original array hasn't changed.
      ValueType currentValue = this->GetValue(cached->second);
      if (value == currentValue)
      {
        return (*cached).second;
      }
    }
    else
    {
      break;
    }

    ++cached;
  }

  // Perform a binary search of the sorted array using STL equal_range.
  int numComps = this->Lookup->SortedArray->GetNumberOfComponents();
  vtkIdType numTuples = this->Lookup->SortedArray->GetNumberOfTuples();
  ValueType* ptr = this->Lookup->SortedArray->GetPointer(0);
  ValueType* ptrEnd = ptr + numComps * numTuples;
  ValueType* found = std::lower_bound(ptr, ptrEnd, value, vtkVariantLessThan());

  // Find an index with a matching value. Non-matching values might
  // show up here when the underlying value at that index has been
  // changed (so the sorted array is out-of-date).
  vtkIdType offset = static_cast<vtkIdType>(found - ptr);
  while (found != ptrEnd)
  {
    // Check whether we still have a value equivalent to what we're
    // looking for.
    if (value == *found)
    {
      // Check that the value in the original array hasn't changed.
      vtkIdType index = this->Lookup->IndexArray->GetId(offset);
      ValueType currentValue = this->GetValue(index);
      if (value == currentValue)
      {
        return index;
      }
    }