ClickHouse/dbms/src/Formats/IRowInputStream.h
2018-12-06 20:20:17 +03:00

51 lines
1.5 KiB
C++

#pragma once
#include <boost/noncopyable.hpp>
#include <memory>
#include <string>
#include <Columns/IColumn.h>
namespace DB
{
/// Contains extra information about read data.
struct RowReadExtension
{
/// IRowInputStream.read() output. It contains non zero for columns that actually read from the source and zero otherwise.
/// It's used to attach defaults for partially filled rows.
std::vector<UInt8> read_columns;
};
/** Interface of stream, that allows to read data by rows.
*/
class IRowInputStream : private boost::noncopyable
{
public:
/** Read next row and append it to the columns.
* If no more rows - return false.
*/
virtual bool read(MutableColumns & columns, RowReadExtension & extra) = 0;
virtual void readPrefix() {} /// delimiter before begin of result
virtual void readSuffix() {} /// delimiter after end of result
/// Skip data until next row.
/// This is intended for text streams, that allow skipping of errors.
/// By default - throws not implemented exception.
virtual bool allowSyncAfterError() const { return false; }
virtual void syncAfterError();
/// In case of parse error, try to roll back and parse last one or two rows very carefully
/// and collect as much as possible diagnostic information about error.
/// If not implemented, returns empty string.
virtual std::string getDiagnosticInfo() { return {}; }
virtual ~IRowInputStream() {}
};
using RowInputStreamPtr = std::shared_ptr<IRowInputStream>;
}