cpp/src/arrow/testing/json_integration.h

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// to you under the Apache License, Version 2.0 (the
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//
//   http://www.apache.org/licenses/LICENSE-2.0
//
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// specific language governing permissions and limitations
// under the License.

// Implement Arrow JSON serialization format for integration tests

#pragma once

#include <memory>
#include <string>

#include "arrow/status.h"
#include "arrow/testing/visibility.h"

namespace arrow {

class Buffer;
class MemoryPool;
class RecordBatch;
class Schema;

namespace io {
class ReadableFile;
}  // namespace io

namespace testing {

/// \class IntegrationJsonWriter
/// \brief Write the JSON representation of an Arrow record batch file or stream
///
/// This is used for integration testing
class ARROW_TESTING_EXPORT IntegrationJsonWriter {
 public:
  ~IntegrationJsonWriter();

  /// \brief Create a new JSON writer that writes to memory
  ///
  /// \param[in] schema the schema of record batches
  /// \param[out] out the returned writer object
  /// \return Status
  static Status Open(const std::shared_ptr<Schema>& schema,
                     std::unique_ptr<IntegrationJsonWriter>* out);

  /// \brief Append a record batch
  Status WriteRecordBatch(const RecordBatch& batch);

  /// \brief Finish the JSON payload and return as a std::string
  ///
  /// \param[out] result the JSON as as a std::string
  /// \return Status
  Status Finish(std::string* result);

 private:
  explicit IntegrationJsonWriter(const std::shared_ptr<Schema>& schema);

  // Hide RapidJSON details from public API
  class Impl;
  std::unique_ptr<Impl> impl_;
};

/// \class IntegrationJsonReader
/// \brief Read the JSON representation of an Arrow record batch file or stream
///
/// This is used for integration testing
class ARROW_TESTING_EXPORT IntegrationJsonReader {
 public:
  ~IntegrationJsonReader();

  /// \brief Create a new JSON reader
  ///
  /// \param[in] pool a MemoryPool to use for buffer allocations
  /// \param[in] data a Buffer containing the JSON data
  /// \param[out] reader the returned reader object
  /// \return Status
  static Status Open(MemoryPool* pool, const std::shared_ptr<Buffer>& data,
                     std::unique_ptr<IntegrationJsonReader>* reader);

  /// \brief Create a new JSON reader that uses the default memory pool
  ///
  /// \param[in] data a Buffer containing the JSON data
  /// \param[out] reader the returned reader object
  /// \return Status
  static Status Open(const std::shared_ptr<Buffer>& data,
                     std::unique_ptr<IntegrationJsonReader>* reader);

  /// \brief Create a new JSON reader from a file
  ///
  /// \param[in] pool a MemoryPool to use for buffer allocations
  /// \param[in] in_file a ReadableFile containing JSON data
  /// \param[out] reader the returned reader object
  /// \return Status
  static Status Open(MemoryPool* pool, const std::shared_ptr<io::ReadableFile>& in_file,
                     std::unique_ptr<IntegrationJsonReader>* reader);

  /// \brief Return the schema read from the JSON
  std::shared_ptr<Schema> schema() const;

  /// \brief Return the number of record batches
  int num_record_batches() const;

  /// \brief Read a particular record batch from the file
  ///
  /// \param[in] i the record batch index, does not boundscheck
  /// \param[out] batch the read record batch
  Status ReadRecordBatch(int i, std::shared_ptr<RecordBatch>* batch) const;

 private:
  IntegrationJsonReader(MemoryPool* pool, const std::shared_ptr<Buffer>& data);

  // Hide RapidJSON details from public API
  class Impl;
  std::unique_ptr<Impl> impl_;
};

}  // namespace testing
}  // namespace arrow