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#include <Functions/IFunction.h>
#include <Functions/FunctionFactory.h>
#include <DataTypes/DataTypeNullable.h>
#include <Core/ColumnNumbers.h>
#include <Columns/ColumnNullable.h>
namespace DB
{
namespace ErrorCodes
{
extern const int ILLEGAL_COLUMN;
}
namespace
{
/// 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(ContextPtr)
{
return std::make_shared<FunctionAssumeNotNull>();
}
std::string getName() const override
{
return name;
}
bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
size_t getNumberOfArguments() const override { return 1; }
bool useDefaultImplementationForNulls() const override { return false; }
bool useDefaultImplementationForConstants() const override { return true; }
ColumnNumbers getArgumentsThatDontImplyNullableReturnType(size_t /*number_of_arguments*/) const override { return {0}; }
DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
{
return removeNullable(arguments[0]);
}
ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t) const override
{
const ColumnPtr & col = arguments[0].column;
if (arguments[0].type->onlyNull() && !col->empty())
throw Exception(ErrorCodes::ILLEGAL_COLUMN, "Cannot create non-empty column with type Nothing");
if (const auto * nullable_col = checkAndGetColumn<ColumnNullable>(*col))
return nullable_col->getNestedColumnPtr();
else
return col;
}
};
}
REGISTER_FUNCTION(AssumeNotNull)
{
factory.registerFunction<FunctionAssumeNotNull>();
}
}
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