Function reorderInputChannels

bolt/exec/WindowBuild.cpp:38–85

namespace {
std::tuple<std::vector<column_index_t>, std::vector<column_index_t>, RowTypePtr>
reorderInputChannels(
    const RowTypePtr& inputType,
    const std::vector<core::FieldAccessTypedExprPtr>& partitionKeys,
    const std::vector<core::FieldAccessTypedExprPtr>& sortingKeys) {
  const auto size = inputType->size();

  std::vector<column_index_t> channels;
  std::vector<column_index_t> inversedChannels;
  std::vector<std::string> names;
  std::vector<TypePtr> types;
  channels.reserve(size);
  inversedChannels.resize(size);
  names.reserve(size);
  types.reserve(size);

  std::unordered_set<std::string> keyNames;

  auto appendChannel =
      [&inputType, &channels, &inversedChannels, &names, &types](
          column_index_t channel) {
        channels.push_back(channel);
        inversedChannels[channel] = channels.size() - 1;
        names.push_back(inputType->nameOf(channel));
        types.push_back(inputType->childAt(channel));
      };

  for (const auto& key : partitionKeys) {
    auto channel = exprToChannel(key.get(), inputType);
    appendChannel(channel);
    keyNames.insert(key->name());
  }

  for (const auto& key : sortingKeys) {
    auto channel = exprToChannel(key.get(), inputType);
    appendChannel(channel);
    keyNames.insert(key->name());
  }

  for (auto i = 0; i < size; ++i) {
    if (keyNames.count(inputType->nameOf(i)) == 0) {
      appendChannel(i);
    }
  }

  return std::make_tuple(
      channels, inversedChannels, ROW(std::move(names), std::move(types)));
}

// Returns a [start, end) slice of the 'types' vector.
std::vector<TypePtr>