includes/image_io/base/ostream_data_destination.h

#ifndef IMAGE_IO_BASE_OSTREAM_DATA_DESTINATION_H_  // NOLINT
#define IMAGE_IO_BASE_OSTREAM_DATA_DESTINATION_H_  // NOLINT

#include <iostream>
#include <memory>
#include <string>
#include <utility>

#include "image_io/base/data_destination.h"

namespace photos_editing_formats {
namespace image_io {

/// A DataDestination that writes its output to an ostream.
class OStreamDataDestination : public DataDestination {
 public:
  /// Constructs an OStreamDataDestination using the given ostream.
  /// @param ostream_ptr The ostream to which data is written.
  explicit OStreamDataDestination(std::unique_ptr<std::ostream> ostream_ptr)
      : ostream_(std::move(ostream_ptr)),
        bytes_transferred_(0),
        has_error_(false) {}

  /// @param name A name to associate with the ostream. Used for error messages.
  void SetName(const std::string& name) { name_ = name; }

  /// @return The name associated with the ostream.
  const std::string& GetName() const { return name_; }

  /// @return The number of bytes written to the ostream.
  size_t GetBytesTransferred() const override { return bytes_transferred_; }

  /// @return True if errors were encountered while writing to the ostream.
  bool HasError() const { return has_error_; }

  void StartTransfer() override;
  TransferStatus Transfer(const DataRange& transfer_range,
                          const DataSegment& data_segment) override;
  void FinishTransfer() override;

 private:
  /// The ostream written to.
  std::unique_ptr<std::ostream> ostream_;

  /// The number of bytes written so far.
  size_t bytes_transferred_;

  /// A (file) name to associate with the ostream, used with error messages.
  std::string name_;

  /// If true indicates an error has occurred writing to the ostream.
  bool has_error_;
};

}  // namespace image_io
}  // namespace photos_editing_formats

#endif // IMAGE_IO_BASE_OSTREAM_DATA_DESTINATION_H_  // NOLINT