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#ifndef IMAGE_IO_BASE_ISTREAM_DATA_SOURCE_H_ // NOLINT
#define IMAGE_IO_BASE_ISTREAM_DATA_SOURCE_H_ // NOLINT
#include <iostream>
#include <memory>
#include <utility>
#include "image_io/base/data_source.h"
namespace photos_editing_formats {
namespace image_io {
/// A DataSource that obtains data from an istream.
class IStreamDataSource : public DataSource {
public:
/// Constructs an IStreamDataSource using the given istream.
/// @param istram_ptr The istream from which to read.
explicit IStreamDataSource(std::unique_ptr<std::istream> istream_ptr)
: istream_(std::move(istream_ptr)) {}
void Reset() override;
std::shared_ptr<DataSegment> GetDataSegment(size_t begin,
size_t min_size) override;
TransferDataResult TransferData(const DataRange& data_range, size_t best_size,
DataDestination* data_destination) override;
private:
/// The worker function to create a DataSegment and fill it with the given
/// number of bytes read from the istream, starting at the given location.
/// @param begin The location in the istream at which to start reading.
/// @param count The number of bytes to read.
/// @return A DataSegment pointer, or nullptr if the read failed.
std::shared_ptr<DataSegment> Read(size_t begin, size_t count);
private:
/// The istream from which to read.
std::unique_ptr<std::istream> istream_;
/// The current data segment that was read in the GetDataSegment() function.
std::shared_ptr<DataSegment> current_data_segment_;
};
} // namespace image_io
} // namespace photos_editing_formats
#endif // IMAGE_IO_BASE_ISTREAM_DATA_SOURCE_H_ // NOLINT
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