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

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#pragma once
#include <Poco/SharedPtr.h>
#include <DB/Core/Block.h>
#include <DB/IO/WriteBuffer.h>
#include <DB/DataStreams/IRowOutputStream.h>
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#include <DB/DataStreams/IProfilingBlockInputStream.h>
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namespace DB
{
/** Поток для вывода данных в формате JSON.
*/
class JSONRowOutputStream : public IRowOutputStream
{
public:
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JSONRowOutputStream(WriteBuffer & ostr_, const Block & sample_);
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void writeField(const Field & field) override;
void writeFieldDelimiter() override;
void writeRowStartDelimiter() override;
void writeRowEndDelimiter() override;
void writePrefix() override;
void writeSuffix() override;
void flush() override
{
ostr->next();
if (validating_ostr)
dst_ostr.next();
}
void setRowsBeforeLimit(size_t rows_before_limit_) override
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{
applied_limit = true;
rows_before_limit = rows_before_limit_;
}
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void setTotals(const Block & totals_) override { totals = totals_; }
void setExtremes(const Block & extremes_) override { extremes = extremes_; }
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String getContentType() const override { return "application/json; charset=UTF-8"; }
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protected:
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void writeRowsBeforeLimitAtLeast();
virtual void writeTotals();
virtual void writeExtremes();
WriteBuffer & dst_ostr;
std::unique_ptr<WriteBuffer> validating_ostr; /// Валидирует UTF-8 последовательности.
WriteBuffer * ostr;
size_t field_number = 0;
size_t row_count = 0;
bool applied_limit = false;
size_t rows_before_limit = 0;
NamesAndTypes fields;
Block totals;
Block extremes;
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};
}