Function readConstantVector

bolt/serializers/PrestoSerializer.cpp:469–500

    bool useLosslessTimestamp);

void readConstantVector(
    ByteInputStream* source,
    const TypePtr& type,
    bolt::memory::MemoryPool* pool,
    VectorPtr& result,
    vector_size_t resultOffset,
    bool useLosslessTimestamp) {
  const auto size = source->read<int32_t>();
  std::vector<TypePtr> childTypes = {type};
  std::vector<VectorPtr> children{BaseVector::create(type, 0, pool)};
  readColumns(source, pool, childTypes, children, 0, useLosslessTimestamp);
  BOLT_CHECK_EQ(1, children[0]->size());

  // If there are no previous results, we output this as a constant. RowVectors
  // with top-level nulls can have child ConstantVector (even though they can't
  // have nulls explicitly set on them), so we don't need to try to apply
  // incomingNulls here.
  auto constantVector = BaseVector::wrapInConstant(size, 0, children[0]);

  if (resultOffset == 0) {
    result = std::move(constantVector);
  } else {
    result->resize(resultOffset + size);

    SelectivityVector rows(resultOffset + size, false);
    rows.setValidRange(resultOffset, resultOffset + size, true);
    rows.updateBounds();

    BaseVector::ensureWritable(rows, type, pool, result);
    result->copy(constantVector.get(), resultOffset, 0, size);
  }
}

void readDictionaryVector(
    ByteInputStream* source,