Method apply

bolt/functions/prestosql/TransformValues.cpp:50–108

  }

  void apply(
      const SelectivityVector& rows,
      std::vector<VectorPtr>& args,
      const TypePtr& outputType,
      exec::EvalCtx& context,
      VectorPtr& result) const override {
    BOLT_CHECK_EQ(args.size(), 2);

    // Flatten input map.
    exec::LocalDecodedVector mapDecoder(context, *args[0], rows);
    auto& decodedMap = *mapDecoder.get();

    auto flatMap = flattenMap(rows, args[0], decodedMap);

    std::vector<VectorPtr> lambdaArgs = {
        flatMap->mapKeys(), flatMap->mapValues()};
    auto numValues = flatMap->mapValues()->size();

    SelectivityVector validRowsInReusedResult =
        toElementRows<MapVector>(numValues, rows, flatMap.get());

    VectorPtr transformedValues;

    auto elementToTopLevelRows = getElementToTopLevelRows(
        numValues, rows, flatMap.get(), context.pool());

    // Loop over lambda functions and apply these to values of the map.
    // In most cases there will be only one function and the loop will run once.
    auto it = args[1]->asUnchecked<FunctionVector>()->iterator(&rows);
    while (auto entry = it.next()) {
      auto valueRows =
          toElementRows<MapVector>(numValues, *entry.rows, flatMap.get());
      auto wrapCapture = toWrapCapture<MapVector>(
          numValues, entry.callable, *entry.rows, flatMap);

      entry.callable->apply(
          valueRows,
          &validRowsInReusedResult,
          wrapCapture,
          &context,
          lambdaArgs,
          elementToTopLevelRows,
          &transformedValues);
    }

    // Set nulls for rows not present in 'rows'.
    BufferPtr newNulls = addNullsForUnselectedRows(flatMap, rows);

    auto localResult = std::make_shared<MapVector>(
        flatMap->pool(),
        outputType,
        std::move(newNulls),
        flatMap->size(),
        flatMap->offsets(),
        flatMap->sizes(),
        flatMap->mapKeys(),
        transformedValues);
    context.moveOrCopyResult(localResult, rows, result);