Function Visit

cpp/src/arrow/compute/expression.cc:1532–1562

    }

    Status Visit(const Expression& expr) {
      if (auto lit = expr.literal()) {
        if (!lit->is_scalar()) {
          return Status::NotImplemented("Serialization of non-scalar literals");
        }
        ARROW_ASSIGN_OR_RAISE(auto value, AddScalar(*lit->scalar()));
        metadata_->Append("literal", std::move(value));
        return Status::OK();
      }

      if (auto ref = expr.field_ref()) {
        return VisitFieldRef(*ref);
      }

      auto call = CallNotNull(expr);
      metadata_->Append("call", call->function_name);

      for (const auto& argument : call->arguments) {
        RETURN_NOT_OK(Visit(argument));
      }

      if (call->options) {
        ARROW_ASSIGN_OR_RAISE(auto options_scalar,
                              internal::FunctionOptionsToStructScalar(*call->options));
        ARROW_ASSIGN_OR_RAISE(auto value, AddScalar(*options_scalar));
        metadata_->Append("options", std::move(value));
      }

      metadata_->Append("end", call->function_name);
      return Status::OK();
    }

    Result<std::shared_ptr<RecordBatch>> operator()(const Expression& expr) {
      RETURN_NOT_OK(Visit(expr));