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

62 lines
1.8 KiB
C++

#include <Functions/IFunction.h>
#include <Functions/FunctionHelpers.h>
#include <Functions/FunctionFactory.h>
#include <DataTypes/DataTypeNullable.h>
#include <Core/ColumnNumbers.h>
#include <Columns/ColumnNullable.h>
namespace DB
{
/// Implements the function assumeNotNull which takes 1 argument and works as follows:
/// - if the argument is a nullable column, return its embedded column;
/// - otherwise return the original argument.
/// NOTE: assumeNotNull may not be called with the NULL value.
class FunctionAssumeNotNull : public IFunction
{
public:
static constexpr auto name = "assumeNotNull";
static FunctionPtr create(const Context &)
{
return std::make_shared<FunctionAssumeNotNull>();
}
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 removeNullable(arguments[0]);
}
void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t) override
{
const ColumnPtr & col = block.getByPosition(arguments[0]).column;
ColumnPtr & res_col = block.getByPosition(result).column;
if (col->isColumnNullable())
{
const ColumnNullable & nullable_col = static_cast<const ColumnNullable &>(*col);
res_col = nullable_col.getNestedColumnPtr();
}
else
res_col = col;
}
};
void registerFunctionAssumeNotNull(FunctionFactory & factory)
{
factory.registerFunction<FunctionAssumeNotNull>();
}
}