ClickHouse/dbms/src/DataStreams/ExpressionBlockInputStream.cpp

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#include <Interpreters/ExpressionActions.h>
#include <DataStreams/ExpressionBlockInputStream.h>
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namespace DB
{
ExpressionBlockInputStream::ExpressionBlockInputStream(const BlockInputStreamPtr & input, const ExpressionActionsPtr & expression_)
: expression(expression_)
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{
children.push_back(input);
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cached_header = children.back()->getHeader();
expression->execute(cached_header, true);
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}
String ExpressionBlockInputStream::getName() const { return "Expression"; }
Block ExpressionBlockInputStream::getTotals()
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{
totals = children.back()->getTotals();
expression->executeOnTotals(totals);
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return totals;
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}
Block ExpressionBlockInputStream::getHeader() const
{
return cached_header.cloneEmpty();
}
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Block ExpressionBlockInputStream::readImpl()
{
Block res = children.back()->read();
if (res)
expression->execute(res);
return res;
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}
}