ClickHouse/dbms/DataStreams/ExpressionBlockInputStream.h
Ivan 97f2a2213e
Move all folders inside /dbms one level up (#9974)
* Move some code outside dbms/src folder
* Fix paths
2020-04-02 02:51:21 +03:00

54 lines
1.3 KiB
C++

#pragma once
#include <DataStreams/IBlockInputStream.h>
namespace DB
{
class ExpressionActions;
/** Executes a certain expression over the block.
* The expression consists of column identifiers from the block, constants, common functions.
* For example: hits * 2 + 3, url LIKE '%yandex%'
* The expression processes each row independently of the others.
*/
class ExpressionBlockInputStream : public IBlockInputStream
{
public:
using ExpressionActionsPtr = std::shared_ptr<ExpressionActions>;
ExpressionBlockInputStream(const BlockInputStreamPtr & input, const ExpressionActionsPtr & expression_);
String getName() const override;
Block getTotals() override;
Block getHeader() const override;
protected:
bool initialized = false;
ExpressionActionsPtr expression;
Block readImpl() override;
private:
Block cached_header;
};
/// ExpressionBlockInputStream that could generate many out blocks for single input block.
class InflatingExpressionBlockInputStream : public ExpressionBlockInputStream
{
public:
InflatingExpressionBlockInputStream(const BlockInputStreamPtr & input, const ExpressionActionsPtr & expression_)
: ExpressionBlockInputStream(input, expression_)
{}
protected:
Block readImpl() override;
private:
ExtraBlockPtr not_processed;
size_t action_number = 0;
};
}