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#include <Functions/IFunction.h>
#include <Functions/FunctionFactory.h>
#include <DataTypes/DataTypesNumber.h>
namespace DB
{
namespace
{
/** ignore(...) is a function that takes any arguments, and always returns 0.
*/
class FunctionIgnore : public IFunction
{
public:
static constexpr auto name = "ignore";
static FunctionPtr create(ContextPtr)
{
return std::make_shared<FunctionIgnore>();
}
bool isVariadic() const override
{
return true;
}
size_t getNumberOfArguments() const override
{
return 0;
}
bool useDefaultImplementationForNulls() const override { return false; }
bool isSuitableForConstantFolding() const override { return false; }
bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
/// We should never return LowCardinality result, cause we declare that result is always constant zero.
/// (in getResultIfAlwaysReturnsConstantAndHasArguments)
bool useDefaultImplementationForLowCardinalityColumns() const override { return false; }
bool useDefaultImplementationForSparseColumns() const override { return false; }
String getName() const override
{
return name;
}
DataTypePtr getReturnTypeImpl(const DataTypes & /*arguments*/) const override
{
return std::make_shared<DataTypeUInt8>();
}
ColumnPtr executeImpl(const ColumnsWithTypeAndName &, const DataTypePtr &, size_t input_rows_count) const override
{
return DataTypeUInt8().createColumnConst(input_rows_count, 0u);
}
};
}
REGISTER_FUNCTION(Ignore)
{
factory.registerFunction<FunctionIgnore>();
}
}
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