text: // Licensed to the Apache Software Foundation (ASF) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The ASF licenses this file
  // to you under the Apache License, Version 2.0 (the
  // "License"); you may not use this file except in compliance
  // with the License.  You may obtain a copy of the License at
  //
  //   http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing,
  // software distributed under the License is distributed on an
  // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  // KIND, either express or implied.  See the License for the
  // specific language governing permissions and limitations
  // under the License.
  
  #include "./arrow_types.h"
  
  #if defined(ARROW_R_WITH_ARROW)
  #include <arrow/ipc/writer.h>
  #include <arrow/type.h>
  #include <arrow/util/key_value_metadata.h>
  
  // [[arrow::export]]
  std::shared_ptr<arrow::Schema> schema_(
      const std::vector<std::shared_ptr<arrow::Field>>& fields) {
    return arrow::schema(fields);
  }
  
  // [[arrow::export]]
  std::string Schema__ToString(const std::shared_ptr<arrow::Schema>& s) {
    return s->ToString();
  }
  
  // [[arrow::export]]
  int Schema__num_fields(const std::shared_ptr<arrow::Schema>& s) {
    return s->num_fields();
  }
  
  // [[arrow::export]]
  std::shared_ptr<arrow::Field> Schema__field(const std::shared_ptr<arrow::Schema>& s,
                                              int i) {
    if (i >= s->num_fields() || i < 0) {
      cpp11::stop("Invalid field index for schema.");
    }
  
    return s->field(i);
  }
  
  // [[arrow::export]]
  std::shared_ptr<arrow::Field> Schema__GetFieldByName(
      const std::shared_ptr<arrow::Schema>& s, std::string x) {
    return s->GetFieldByName(x);
  }
  
  // [[arrow::export]]
  cpp11::list Schema__fields(const std::shared_ptr<arrow::Schema>& schema) {
    return arrow::r::to_r_list(schema->fields());
  }
  
  // [[arrow::export]]
  std::vector<std::string> Schema__field_names(
      const std::shared_ptr<arrow::Schema>& schema) {
    return schema->field_names();
  }
  
  // [[arrow::export]]
  bool Schema__HasMetadata(const std::shared_ptr<arrow::Schema>& schema) {
    return schema->HasMetadata();
  }
  
  // [[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;
  }
  
  // [[arrow::export]]
  std::shared_ptr<arrow::Schema> Schema__WithMetadata(
      const std::shared_ptr<arrow::Schema>& schema, cpp11::strings metadata) {
    auto values = cpp11::as_cpp<std::vector<std::string>>(metadata);
    auto names = cpp11::as_cpp<std::vector<std::string>>(metadata.attr("names"));
  
    auto kv =
        std::make_shared<arrow::KeyValueMetadata>(std::move(names), std::move(values));
    return schema->WithMetadata(std::move(kv));
  }
  
  // [[arrow::export]]
  cpp11::writable::raws Schema__serialize(const std::shared_ptr<arrow::Schema>& schema) {
    auto out = ValueOrStop(arrow::ipc::SerializeSchema(*schema));
    auto n = out->size();
    return cpp11::writable::raws(out->data(), out->data() + n);
  }
  
  // [[arrow::export]]
  bool Schema__Equals(const std::shared_ptr<arrow::Schema>& schema,
                      const std::shared_ptr<arrow::Schema>& other, bool check_metadata) {
    return schema->Equals(*other, check_metadata);
  }
  
  // [[arrow::export]]
  std::shared_ptr<arrow::Schema> arrow__UnifySchemas(
      const std::vector<std::shared_ptr<arrow::Schema>>& schemas) {
    return ValueOrStop(arrow::UnifySchemas(schemas));
  }
  
  #endif
  