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#include <Functions/IFunction.h>
#include <Functions/FunctionFactory.h>
#include <DataTypes/DataTypeString.h>
#include <DataTypes/DataTypeNullable.h>
#include <DataTypes/DataTypeDateTime.h>
#include <Common/DateLUTImpl.h>
#include <Core/Field.h>
namespace DB
{
namespace ErrorCodes
{
extern const int BAD_ARGUMENTS;
}
namespace
{
/** timezoneOf(x) - get the name of the timezone of DateTime data type.
* Example: Pacific/Pitcairn.
*/
class FunctionTimezoneOf : public IFunction
{
public:
static constexpr auto name = "timezoneOf";
String getName() const override { return name; }
static FunctionPtr create(ContextPtr) { return std::make_unique<FunctionTimezoneOf>(); }
size_t getNumberOfArguments() const override { return 1; }
bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
DataTypePtr getReturnTypeImpl(const DataTypes & types) const override
{
DataTypePtr type_no_nullable = removeNullable(types[0]);
if (isDateTime(type_no_nullable) || isDateTime64(type_no_nullable))
return std::make_shared<DataTypeString>();
else
throw Exception(ErrorCodes::BAD_ARGUMENTS, "Bad argument for function {}, should be DateTime or DateTime64", name);
}
bool useDefaultImplementationForNulls() const override { return false; }
bool useDefaultImplementationForLowCardinalityColumns() const override { return false; }
ColumnNumbers getArgumentsThatDontImplyNullableReturnType(size_t /*number_of_arguments*/) const override { return {0}; }
ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t input_rows_count) const override
{
DataTypePtr type_no_nullable = removeNullable(arguments[0].type);
return DataTypeString().createColumnConst(input_rows_count,
dynamic_cast<const TimezoneMixin &>(*type_no_nullable).getTimeZone().getTimeZone());
}
ColumnPtr getConstantResultForNonConstArguments(const ColumnsWithTypeAndName & arguments, const DataTypePtr &) const override
{
DataTypePtr type_no_nullable = removeNullable(arguments[0].type);
return DataTypeString().createColumnConst(1,
dynamic_cast<const TimezoneMixin &>(*type_no_nullable).getTimeZone().getTimeZone());
}
};
}
REGISTER_FUNCTION(TimezoneOf)
{
factory.registerFunction<FunctionTimezoneOf>();
factory.registerAlias("timeZoneOf", "timezoneOf");
}
}
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