Function DatumToLiterals

cpp/src/arrow/engine/substrait/expression_internal.cc:1294–1341

}

Result<std::vector<std::unique_ptr<substrait::Expression>>> DatumToLiterals(
    const Datum& datum, ExtensionSet* ext_set,
    const ConversionOptions& conversion_options) {
  std::vector<std::unique_ptr<substrait::Expression>> literals;

  auto ScalarToLiteralExpr = [&](const std::shared_ptr<Scalar>& scalar)
      -> Result<std::unique_ptr<substrait::Expression>> {
    ARROW_ASSIGN_OR_RAISE(std::unique_ptr<substrait::Expression::Literal> literal,
                          ToProto(scalar, ext_set, conversion_options));
    auto literal_expr = std::make_unique<substrait::Expression>();
    literal_expr->set_allocated_literal(literal.release());
    return literal_expr;
  };

  switch (datum.kind()) {
    case Datum::Kind::SCALAR: {
      ARROW_ASSIGN_OR_RAISE(auto literal_expr, ScalarToLiteralExpr(datum.scalar()));
      literals.push_back(std::move(literal_expr));
      break;
    }
    case Datum::Kind::ARRAY: {
      std::shared_ptr<Array> values = datum.make_array();
      for (int64_t i = 0; i < values->length(); i++) {
        ARROW_ASSIGN_OR_RAISE(std::shared_ptr<Scalar> scalar, values->GetScalar(i));
        ARROW_ASSIGN_OR_RAISE(auto literal_expr, ScalarToLiteralExpr(scalar));
        literals.push_back(std::move(literal_expr));
      }
      break;
    }
    case Datum::Kind::CHUNKED_ARRAY: {
      std::shared_ptr<ChunkedArray> values = datum.chunked_array();
      for (const auto& chunk : values->chunks()) {
        for (int64_t i = 0; i < chunk->length(); i++) {
          ARROW_ASSIGN_OR_RAISE(std::shared_ptr<Scalar> scalar, chunk->GetScalar(i));
          ARROW_ASSIGN_OR_RAISE(auto literal_expr, ScalarToLiteralExpr(scalar));
          literals.push_back(std::move(literal_expr));
        }
      }
      break;
    }
    case Datum::Kind::RECORD_BATCH:
    case Datum::Kind::TABLE:
    case Datum::Kind::NONE:
      return Status::Invalid("Expected a literal or an array of literals, got ",
                             datum.ToString());
  }
  return literals;
}

}  // namespace