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#pragma once
#include <Functions/IFunction.h>
#include <Columns/ColumnTuple.h>
#include <DataTypes/DataTypeTuple.h>
#include <Functions/FunctionFactory.h>
#include <Interpreters/Context.h>
namespace DB
{
namespace ErrorCodes
{
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
}
/** tuple(x, y, ...) is a function that allows you to group several columns
* tupleElement(tuple, n) is a function that allows you to retrieve a column from tuple.
*/
class FunctionTuple : public IFunction
{
public:
static constexpr auto name = "tuple";
/// maybe_unused: false-positive
[[ maybe_unused ]] static FunctionPtr create(ContextPtr) { return std::make_shared<FunctionTuple>(); }
String getName() const override { return name; }
bool isVariadic() const override { return true; }
size_t getNumberOfArguments() const override { return 0; }
bool isInjective(const ColumnsWithTypeAndName &) const override { return true; }
bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
bool useDefaultImplementationForNulls() const override { return false; }
/// tuple(..., Nothing, ...) -> Tuple(..., Nothing, ...)
bool useDefaultImplementationForNothing() const override { return false; }
bool useDefaultImplementationForConstants() const override { return true; }
bool useDefaultImplementationForLowCardinalityColumns() const override { return false; }
DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
{
if (arguments.empty())
throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH, "Function {} requires at least one argument.", getName());
return std::make_shared<DataTypeTuple>(arguments);
}
ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t /*input_rows_count*/) const override
{
size_t tuple_size = arguments.size();
Columns tuple_columns(tuple_size);
for (size_t i = 0; i < tuple_size; ++i)
{
/** If tuple is mixed of constant and not constant columns,
* convert all to non-constant columns,
* because many places in code expect all non-constant columns in non-constant tuple.
*/
tuple_columns[i] = arguments[i].column->convertToFullColumnIfConst();
}
return ColumnTuple::create(tuple_columns);
}
};
}
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