ClickHouse/src/Functions/FunctionCustomWeekToSomething.h

#pragma once
#include <Functions/IFunctionCustomWeek.h>

namespace DB
{

namespace ErrorCodes
{
    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
}


/// See CustomWeekTransforms.h
template <typename ToDataType, typename Transform>
class FunctionCustomWeekToSomething : public IFunctionCustomWeek<Transform>
{
public:
    static FunctionPtr create(ContextPtr) { return std::make_shared<FunctionCustomWeekToSomething>(); }

    DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
    {
        this->checkArguments(arguments, /*is_result_type_date_or_date32*/ false, Transform::value_may_be_string);
        return std::make_shared<ToDataType>();
    }

    ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, size_t input_rows_count) const override
    {
        const IDataType * from_type = arguments[0].type.get();
        WhichDataType which(from_type);

        if (which.isDate())
            return CustomWeekTransformImpl<DataTypeDate, ToDataType>::execute(arguments, result_type, input_rows_count, Transform{});
        else if (which.isDate32())
            return CustomWeekTransformImpl<DataTypeDate32, ToDataType>::execute(arguments, result_type, input_rows_count, Transform{});
        else if (which.isDateTime())
            return CustomWeekTransformImpl<DataTypeDateTime, ToDataType>::execute(arguments, result_type, input_rows_count, Transform{});
        else if (which.isDateTime64())
            return CustomWeekTransformImpl<DataTypeDateTime64, ToDataType>::execute(arguments, result_type, input_rows_count,
                TransformDateTime64<Transform>{assert_cast<const DataTypeDateTime64 *>(from_type)->getScale()});
        else if (Transform::value_may_be_string && which.isString())
            return CustomWeekTransformImpl<DataTypeString, ToDataType>::execute(arguments, result_type, input_rows_count, Transform{});
        else
            throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT,
                "Illegal type {} of argument of function {}",
                arguments[0].type->getName(), this->getName());
    }

};

}