Function ToProto

cpp/src/arrow/engine/substrait/expression_internal.cc:1131–1151

}  // namespace

Result<std::unique_ptr<substrait::Expression::Literal>> ToProto(
    const Datum& datum, ExtensionSet* ext_set,
    const ConversionOptions& conversion_options) {
  if (!datum.is_scalar()) {
    return Status::NotImplemented("representing ", datum.ToString(),
                                  " as a substrait::Expression::Literal");
  }

  auto out = std::make_unique<substrait::Expression::Literal>();

  if (datum.scalar()->is_valid) {
    RETURN_NOT_OK(
        (ScalarToProtoImpl{out.get(), ext_set, conversion_options})(*datum.scalar()));
  } else {
    ARROW_ASSIGN_OR_RAISE(auto type, ToProto(*datum.type(), /*nullable=*/true, ext_set,
                                             conversion_options));
    out->set_allocated_null(type.release());
  }

  return out;
}

namespace {