Method defaultImplementationForNulls

src/Functions/IFunction.cpp:204–234

ColumnPtr IExecutableFunction::defaultImplementationForNulls(
    const ColumnsWithTypeAndName & args, const DataTypePtr & result_type, size_t input_rows_count, bool dry_run) const
{
    if (args.empty() || !useDefaultImplementationForNulls())
        return nullptr;

    NullPresence null_presence = getNullPresense(args);

    if (null_presence.has_null_constant)
    {
        // Default implementation for nulls returns null result for null arguments,
        // so the result type must be nullable.
        if (!result_type->isNullable())
            throw Exception(ErrorCodes::LOGICAL_ERROR,
                            "Function {} with Null argument and default implementation for Nulls "
                            "is expected to return Nullable result, got {}", getName(), result_type->getName());

        return result_type->createColumnConstWithDefaultValue(input_rows_count);
    }

    if (null_presence.has_nullable)
    {
        ColumnsWithTypeAndName temporary_columns = createBlockWithNestedColumns(args);
        auto temporary_result_type = removeNullable(result_type);

        auto res = executeWithoutLowCardinalityColumns(temporary_columns, temporary_result_type, input_rows_count, dry_run);
        return wrapInNullable(res, args, result_type, input_rows_count);
    }

    return nullptr;
}

ColumnPtr IExecutableFunction::defaultImplementationForNothing(
    const ColumnsWithTypeAndName & args, const DataTypePtr & result_type, size_t input_rows_count) const