ClickHouse/src/Functions/date_trunc.cpp

#include <Columns/ColumnConst.h>
#include <Columns/ColumnString.h>
#include <Columns/ColumnsNumber.h>
#include <DataTypes/DataTypeDate.h>
#include <DataTypes/DataTypeDateTime.h>
#include <DataTypes/DataTypeInterval.h>
#include <Functions/DateTimeTransforms.h>
#include <Functions/FunctionFactory.h>


namespace DB
{
namespace ErrorCodes
{
    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
    extern const int BAD_ARGUMENTS;
}

namespace
{

class FunctionDateTrunc : public IFunction
{
public:
    static constexpr auto name = "dateTrunc";

    explicit FunctionDateTrunc(ContextPtr context_) : context(context_) { }

    static FunctionPtr create(ContextPtr context) { return std::make_shared<FunctionDateTrunc>(context); }

    String getName() const override { return name; }

    bool isVariadic() const override { return true; }
    bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
    size_t getNumberOfArguments() const override { return 0; }

    DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
    {
        /// The first argument is a constant string with the name of datepart.

        intermediate_type_is_date = false;
        String datepart_param;
        auto check_first_argument = [&]
        {
            const ColumnConst * datepart_column = checkAndGetColumnConst<ColumnString>(arguments[0].column.get());
            if (!datepart_column)
                throw Exception(
                    ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT,
                    "First argument for function {} must be constant string: "
                    "name of datepart",
                    getName());

            datepart_param = datepart_column->getValue<String>();
            if (datepart_param.empty())
                throw Exception(
                    ErrorCodes::BAD_ARGUMENTS, "First argument (name of datepart) for function {} cannot be empty", getName());

            if (!IntervalKind::tryParseString(datepart_param, datepart_kind))
                throw Exception(ErrorCodes::BAD_ARGUMENTS, "{} doesn't look like datepart name in {}", datepart_param, getName());

            intermediate_type_is_date = (datepart_kind == IntervalKind::Year) || (datepart_kind == IntervalKind::Quarter)
                || (datepart_kind == IntervalKind::Month) || (datepart_kind == IntervalKind::Week);
        };

        bool second_argument_is_date = false;
        auto check_second_argument = [&]
        {
            if (!isDate(arguments[1].type) && !isDateTime(arguments[1].type) && !isDateTime64(arguments[1].type))
                throw Exception(
                    ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT,
                    "Illegal type {} of 2nd argument of function {}. "
                    "Should be a date or a date with time",
                    arguments[1].type->getName(),
                    getName());

            second_argument_is_date = isDate(arguments[1].type);

            if (second_argument_is_date
                && ((datepart_kind == IntervalKind::Hour) || (datepart_kind == IntervalKind::Minute)
                    || (datepart_kind == IntervalKind::Second)))
                throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Illegal type Date of argument for function {}", getName());
        };

        auto check_timezone_argument = [&]
        {
            if (!WhichDataType(arguments[2].type).isString())
                throw Exception(
                    ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT,
                    "Illegal type {} of argument of function {}. "
                    "This argument is optional and must be a constant string with timezone name",
                    arguments[2].type->getName(),
                    getName());
        };

        if (arguments.size() == 2)
        {
            check_first_argument();
            check_second_argument();
        }
        else if (arguments.size() == 3)
        {
            check_first_argument();
            check_second_argument();
            check_timezone_argument();
        }
        else
        {
            throw Exception(
                ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH,
                "Number of arguments for function {} doesn't match: passed {}, should be 2 or 3",
                getName(),
                arguments.size());
        }

        return std::make_shared<DataTypeDateTime>(extractTimeZoneNameFromFunctionArguments(arguments, 2, 1));
    }

    bool useDefaultImplementationForConstants() const override { return true; }
    ColumnNumbers getArgumentsThatAreAlwaysConstant() const override { return {0, 2}; }

    ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, size_t input_rows_count) const override
    {
        ColumnsWithTypeAndName temp_columns(arguments.size());
        temp_columns[0] = arguments[1];

        const UInt16 interval_value = 1;
        const ColumnPtr interval_column = ColumnConst::create(ColumnInt64::create(1, interval_value), input_rows_count);
        temp_columns[1] = {interval_column, std::make_shared<DataTypeInterval>(datepart_kind), ""};

        auto to_start_of_interval = FunctionFactory::instance().get("toStartOfInterval", context);

        ColumnPtr truncated_column;
        auto date_type = std::make_shared<DataTypeDate>();

        if (arguments.size() == 2)
            truncated_column = to_start_of_interval->build(temp_columns)
                                    ->execute(temp_columns, intermediate_type_is_date ? date_type : result_type, input_rows_count);
        else
        {
            temp_columns[2] = arguments[2];
            truncated_column = to_start_of_interval->build(temp_columns)
                                    ->execute(temp_columns, intermediate_type_is_date ? date_type : result_type, input_rows_count);
        }

        if (!intermediate_type_is_date)
            return truncated_column;

        ColumnsWithTypeAndName temp_truncated_column(1);
        temp_truncated_column[0] = {truncated_column, date_type, ""};

        auto to_date_time_or_default = FunctionFactory::instance().get("toDateTime", context);
        return to_date_time_or_default->build(temp_truncated_column)->execute(temp_truncated_column, result_type, input_rows_count);
    }

    bool hasInformationAboutMonotonicity() const override { return true; }

    Monotonicity getMonotonicityForRange(const IDataType &, const Field &, const Field &) const override
    {
        return {.is_monotonic = true, .is_always_monotonic = true};
    }

private:
    ContextPtr context;
    mutable IntervalKind::Kind datepart_kind = IntervalKind::Kind::Second;
    mutable bool intermediate_type_is_date = false;
};

}


REGISTER_FUNCTION(DateTrunc)
{
    factory.registerFunction<FunctionDateTrunc>();

    /// Compatibility alias.
    factory.registerAlias("DATE_TRUNC", "dateTrunc", FunctionFactory::CaseInsensitive);
}

}