Function Schema__metadata

r/src/schema.cpp:110–130

[[arrow::export]]

// [[arrow::export]]
cpp11::writable::list Schema__metadata(const std::shared_ptr<arrow::Schema>& schema) {
  auto meta = schema->metadata();
  int64_t n = 0;
  if (schema->HasMetadata()) {
    n = meta->size();
  }

  cpp11::writable::list out(n);
  std::vector<std::string> names_out(n);

  for (int i = 0; i < n; i++) {
    auto key = meta->key(i);
    out[i] = cpp11::as_sexp(meta->value(i));
    if (key == "r") {
      Rf_classgets(out[i], arrow::r::data::classes_metadata_r);
    }
    names_out[i] = key;
  }
  out.names() = names_out;
  return out;
}

std::shared_ptr<arrow::KeyValueMetadata> strings_to_kvm(cpp11::strings metadata) {
  auto values = cpp11::as_cpp<std::vector<std::string>>(metadata);