ClickHouse/dbms/include/DB/DataStreams/OneBlockInputStream.h

42 lines
721 B
C++

#pragma once
#include <DB/DataStreams/IProfilingBlockInputStream.h>
namespace DB
{
/** Поток блоков, из которого можно прочитать один блок.
* Также смотрите BlocksListBlockInputStream.
*/
class OneBlockInputStream : public IProfilingBlockInputStream
{
public:
OneBlockInputStream(const Block & block_) : block(block_) {}
String getName() const override { return "One"; }
String getID() const override
{
std::stringstream res;
res << this;
return res.str();
}
protected:
Block readImpl() override
{
if (has_been_read)
return Block();
has_been_read = true;
return block;
}
private:
Block block;
bool has_been_read = false;
};
}