ClickHouse/dbms/include/DB/IO/IReadableWriteBuffer.h

33 lines
639 B
C++

#pragma once
#include <memory>
#include <DB/IO/ReadBuffer.h>
namespace DB
{
struct IReadableWriteBuffer
{
/// At the first time returns getReadBufferImpl(). Next calls return nullptr.
inline std::shared_ptr<ReadBuffer> tryGetReadBuffer()
{
if (!can_reread)
return nullptr;
can_reread = false;
return getReadBufferImpl();
}
virtual ~IReadableWriteBuffer() {}
protected:
/// Creates read buffer from current write buffer.
/// Returned buffer points to the first byte of original buffer.
/// Original stream becomes invalid.
virtual std::shared_ptr<ReadBuffer> getReadBufferImpl() = 0;
bool can_reread = true;
};
}