ClickHouse/src/IO/SeekableReadBuffer.h

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#pragma once
#include <IO/ReadBuffer.h>
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namespace DB
{
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class SeekableReadBuffer : public ReadBuffer
{
public:
SeekableReadBuffer(Position ptr, size_t size)
: ReadBuffer(ptr, size) {}
SeekableReadBuffer(Position ptr, size_t size, size_t offset)
: ReadBuffer(ptr, size, offset) {}
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/**
* Shifts buffer current position to given offset.
* @param off Offset.
* @param whence Seek mode (@see SEEK_SET, @see SEEK_CUR).
* @return New position from the begging of underlying buffer / file.
*/
virtual off_t seek(off_t off, int whence) = 0;
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/**
* Keep in mind that seekable buffer may encounter eof() once and the working buffer
* may get into inconsistent state. Don't forget to reset it on the first nextImpl()
* after seek().
*/
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/**
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* @return Offset from the begin of the underlying buffer / file corresponds to the buffer current position.
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*/
virtual off_t getPosition() = 0;
};
}