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

#pragma once

#include <DB/Core/Block.h>
#include <DB/Core/Names.h>
#include <DB/DataStreams/IRowOutputStream.h>


namespace DB
{

class WriteBuffer;
class Context;


/** Stream to output data in format "each value in separate row".
  * Usable to show few rows with many columns.
  */
class VerticalRowOutputStream : public IRowOutputStream
{
public:
	VerticalRowOutputStream(WriteBuffer & ostr_, const Block & sample_, const Context & context);

	void writeField(const IColumn & column, const IDataType & type, size_t row_num) override;
	void writeRowStartDelimiter() override;
	void writeRowBetweenDelimiter() override;

	void flush() override;

protected:
	virtual void writeValue(const IColumn & column, const IDataType & type, size_t row_num) const;

	WriteBuffer & ostr;
	const Block sample;
	size_t field_number = 0;
	size_t row_number = 0;

	using NamesAndPaddings = std::vector<String>;
	NamesAndPaddings names_and_paddings;
};


/** Same but values are printed without escaping.
  */
class VerticalRawRowOutputStream final : public VerticalRowOutputStream
{
public:
	VerticalRawRowOutputStream(WriteBuffer & ostr_, const Block & sample_, const Context & context)
		: VerticalRowOutputStream(ostr_, sample_, context) {}

protected:
	void writeValue(const IColumn & column, const IDataType & type, size_t row_num) const override;
};

}