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#pragma once
#include <base/types.h>
#include <IO/SeekableReadBuffer.h>
namespace DB
{
/** Allows to read from another SeekableReadBuffer up to `limit_size` bytes starting from `start_offset`.
* Note that the nested buffer may read slightly more data internally to fill its buffer.
*/
class LimitSeekableReadBuffer : public SeekableReadBuffer
{
public:
LimitSeekableReadBuffer(SeekableReadBuffer & in_, UInt64 start_offset_, UInt64 limit_size_);
LimitSeekableReadBuffer(std::unique_ptr<SeekableReadBuffer> in_, UInt64 start_offset_, UInt64 limit_size_);
/// Returns adjusted position, i.e. returns `3` if the position in the nested buffer is `start_offset + 3`.
off_t getPosition() override;
off_t seek(off_t off, int whence) override;
private:
std::unique_ptr<SeekableReadBuffer> in;
off_t min_offset;
off_t max_offset;
std::optional<off_t> need_seek;
bool nextImpl() override;
};
}
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