Function EncodeSubstraitCall

cpp/src/arrow/engine/substrait/expression_internal.cc:1255–1292

}

Result<std::unique_ptr<substrait::Expression::ScalarFunction>> EncodeSubstraitCall(
    const SubstraitCall& call, ExtensionSet* ext_set,
    const ConversionOptions& conversion_options) {
  ARROW_ASSIGN_OR_RAISE(uint32_t anchor, ext_set->EncodeFunction(call.id()));
  auto scalar_fn = std::make_unique<substrait::Expression::ScalarFunction>();
  scalar_fn->set_function_reference(anchor);
  ARROW_ASSIGN_OR_RAISE(
      std::unique_ptr<substrait::Type> output_type,
      ToProto(*call.output_type(), call.output_nullable(), ext_set, conversion_options));
  scalar_fn->set_allocated_output_type(output_type.release());

  for (int i = 0; i < call.size(); i++) {
    substrait::FunctionArgument* arg = scalar_fn->add_arguments();
    if (call.HasEnumArg(i)) {
      ARROW_ASSIGN_OR_RAISE(std::string_view enum_val, call.GetEnumArg(i));
      arg->set_enum_(std::string(enum_val));
    } else if (call.HasValueArg(i)) {
      ARROW_ASSIGN_OR_RAISE(compute::Expression value_arg, call.GetValueArg(i));
      ARROW_ASSIGN_OR_RAISE(std::unique_ptr<substrait::Expression> value_expr,
                            ToProto(value_arg, ext_set, conversion_options));
      arg->set_allocated_value(value_expr.release());
    } else {
      return Status::Invalid("Call reported having ", call.size(),
                             " arguments but no argument could be found at index ", i);
    }
  }

  for (const auto& option : call.options()) {
    substrait::FunctionOption* fn_option = scalar_fn->add_options();
    fn_option->set_name(option.first);
    for (const auto& opt_val : option.second) {
      std::string* pref = fn_option->add_preference();
      *pref = opt_val;
    }
  }

  return scalar_fn;
}

Result<std::vector<std::unique_ptr<substrait::Expression>>> DatumToLiterals(
    const Datum& datum, ExtensionSet* ext_set,