ClickHouse/dbms/src/Functions/toNullable.cpp
2018-09-08 04:24:09 +03:00

50 lines
1.3 KiB
C++

#include <Functions/IFunction.h>
#include <Functions/FunctionHelpers.h>
#include <Functions/FunctionFactory.h>
#include <DataTypes/DataTypeNullable.h>
#include <Columns/ColumnNullable.h>
#include <Core/ColumnNumbers.h>
namespace DB
{
/// If value is not Nullable or NULL, wraps it to Nullable.
class FunctionToNullable : public IFunction
{
public:
static constexpr auto name = "toNullable";
static FunctionPtr create(const Context &)
{
return std::make_shared<FunctionToNullable>();
}
std::string getName() const override
{
return name;
}
size_t getNumberOfArguments() const override { return 1; }
bool useDefaultImplementationForNulls() const override { return false; }
bool useDefaultImplementationForConstants() const override { return true; }
DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
{
return makeNullable(arguments[0]);
}
void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t) override
{
block.getByPosition(result).column = makeNullable(block.getByPosition(arguments[0]).column);
}
};
void registerFunctionToNullable(FunctionFactory & factory)
{
factory.registerFunction<FunctionToNullable>();
}
}