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91 lines
2.5 KiB
C++
91 lines
2.5 KiB
C++
#pragma once
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#include <Formats/FormatFactory.h>
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#include <Processors/Formats/IOutputFormat.h>
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#include <string>
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namespace DB
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{
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struct RowOutputFormatParams
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{
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using WriteCallback = std::function<void(const Columns & columns,size_t row)>;
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// Callback used to indicate that another row is written.
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WriteCallback callback;
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};
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class WriteBuffer;
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/** Output format that writes data row by row.
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*/
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class IRowOutputFormat : public IOutputFormat
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{
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protected:
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DataTypes types;
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Serializations serializations;
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bool first_row = true;
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void consume(Chunk chunk) override;
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void consumeTotals(Chunk chunk) override;
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void consumeExtremes(Chunk chunk) override;
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void finalize() override;
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bool prefix_written = false;
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bool suffix_written = false;
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void writePrefixIfNot()
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{
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if (!prefix_written)
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writePrefix();
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prefix_written = true;
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}
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void writeSuffixIfNot()
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{
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if (!suffix_written)
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writeSuffix();
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suffix_written = true;
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}
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public:
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using Params = RowOutputFormatParams;
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IRowOutputFormat(const Block & header, WriteBuffer & out_, const Params & params_);
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/** Write a row.
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* Default implementation calls methods to write single values and delimiters
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* (except delimiter between rows (writeRowBetweenDelimiter())).
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*/
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virtual void write(const Columns & columns, size_t row_num);
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virtual void writeMinExtreme(const Columns & columns, size_t row_num);
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virtual void writeMaxExtreme(const Columns & columns, size_t row_num);
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virtual void writeTotals(const Columns & columns, size_t row_num);
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/** Write single value. */
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virtual void writeField(const IColumn & column, const ISerialization & serialization, size_t row_num) = 0;
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/** Write delimiter. */
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virtual void writeFieldDelimiter() {} /// delimiter between values
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virtual void writeRowStartDelimiter() {} /// delimiter before each row
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virtual void writeRowEndDelimiter() {} /// delimiter after each row
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virtual void writeRowBetweenDelimiter() {} /// delimiter between rows
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virtual void writePrefix() {} /// delimiter before resultset
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virtual void writeSuffix() {} /// delimiter after resultset
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virtual void writeBeforeTotals() {}
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virtual void writeAfterTotals() {}
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virtual void writeBeforeExtremes() {}
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virtual void writeAfterExtremes() {}
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virtual void writeLastSuffix() {} /// Write something after resultset, totals end extremes.
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private:
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Params params;
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};
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}
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