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#include <Columns/ColumnString.h>
#include <DataTypes/DataTypeString.h>
#include <IO/WriteHelpers.h>
#include <Functions/FunctionFactory.h>
namespace DB
{
namespace ErrorCodes
{
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
extern const int ILLEGAL_TYPE_OF_ARGUMENT;
}
class FunctionMonthName : public IFunction
{
public:
static constexpr auto name = "monthName";
static constexpr auto month_str = "month";
static FunctionPtr create(ContextPtr context) { return std::make_shared<FunctionMonthName>(context); }
explicit FunctionMonthName(ContextPtr context_)
: function_resolver(FunctionFactory::instance().get("dateName", std::move(context_)))
{}
String getName() const override { return name; }
bool useDefaultImplementationForConstants() const override { return true; }
bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
size_t getNumberOfArguments() const override { return 1; }
DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
{
if (arguments.size() != 1)
throw Exception(
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH,
"Number of arguments for function {} doesn't match: passed {}, should be 1",
getName(),
arguments.size());
WhichDataType argument_type(arguments[0].type);
if (!argument_type.isDate() && !argument_type.isDateTime() && !argument_type.isDateTime64())
throw Exception(
ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT,
"Illegal type of argument of function {}, should be Date, DateTime or DateTime64",
getName());
return std::make_shared<DataTypeString>();
}
ColumnPtr executeImpl(
const ColumnsWithTypeAndName & arguments,
const DataTypePtr & result_type,
size_t input_rows_count) const override
{
auto month_column = DataTypeString().createColumnConst(arguments[0].column->size(), month_str);
ColumnsWithTypeAndName temporary_columns
{
ColumnWithTypeAndName(month_column, std::make_shared<DataTypeString>(), ""),
arguments[0]
};
auto date_name_func = function_resolver->build(temporary_columns);
return date_name_func->execute(temporary_columns, result_type, input_rows_count);
}
private:
FunctionOverloadResolverPtr function_resolver;
};
REGISTER_FUNCTION(MonthName)
{
factory.registerFunction<FunctionMonthName>({}, FunctionFactory::CaseInsensitive);
}
}
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