Method load_as_tuple

plugins/experimental/txn_box/plugin/src/Extractor.cc:316–351

}

Errata
FeatureGroup::load_as_tuple(Config &cfg, YAML::Node const &node, std::initializer_list<FeatureGroup::Descriptor> const &ex_keys)
{
  unsigned idx    = 0;
  unsigned n_keys = ex_keys.size();
  unsigned n_elts = node.size();
  ExprInfo info[n_keys];

  // No dependency in tuples, can just walk the keys and load them.
  for (auto const &key : ex_keys) {
    if (idx >= n_elts) {
      if (key._flags[REQUIRED]) {
        return Errata(S_ERROR, R"(The list was {} elements long but {} are required.)", n_elts, n_keys);
      }
      continue; // it was optional, skip it and keep checking for REQUIRED keys.
    }

    auto &&[expr, errata] = cfg.parse_expr(node[idx]);
    if (!errata.is_ok()) {
      return std::move(errata);
    }
    info[idx]._name = key._name;
    info[idx]._expr = std::move(expr); // safe because of the @c reserve
    ++idx;
  }
  // Localize feature info, now that the size is determined.
  _expr_info   = cfg.alloc_span<ExprInfo>(idx);
  index_type i = 0;
  for (auto &item : _expr_info) {
    new (&item) ExprInfo{std::move(info[i++])};
  }
  // No dependencies for tuple loads.
  // No feature data because no dependencies.

  return {};
}

Feature
FeatureGroup::extract(Context &ctx, swoc::TextView const &name)