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#include <Functions/IFunction.h>
#include <Functions/FunctionFactory.h>
#include <Functions/FunctionHelpers.h>
#include <DataTypes/DataTypesNumber.h>
#include <Columns/ColumnsNumber.h>
#include <Columns/ColumnDecimal.h>
#include <base/extended_types.h>
#include <base/itoa.h>
namespace DB
{
namespace ErrorCodes
{
extern const int ILLEGAL_TYPE_OF_ARGUMENT;
extern const int ILLEGAL_COLUMN;
}
namespace
{
/// Returns number of decimal digits you need to represent the value.
/// For Decimal values takes in account their scales: calculates result over underlying int type which is (value * scale).
/// countDigits(42) = 2, countDigits(42.000) = 5, countDigits(0.04200) = 4.
/// I.e. you may check decimal overflow for Decimal64 with 'countDecimal(x) > 18'. It's a slow variant of isDecimalOverflow().
class FunctionCountDigits : public IFunction
{
public:
static constexpr auto name = "countDigits";
static FunctionPtr create(ContextPtr)
{
return std::make_shared<FunctionCountDigits>();
}
String getName() const override { return name; }
bool useDefaultImplementationForConstants() const override { return true; }
size_t getNumberOfArguments() const override { return 1; }
bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
{
WhichDataType which_first(arguments[0]->getTypeId());
if (!which_first.isInt() && !which_first.isUInt() && !which_first.isDecimal())
throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Illegal type {} of argument of function {}",
arguments[0]->getName(), getName());
return std::make_shared<DataTypeUInt8>(); /// Up to 255 decimal digits.
}
ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t input_rows_count) const override
{
const auto & src_column = arguments[0];
if (!src_column.column)
throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Illegal column while execute function {}", getName());
auto result_column = ColumnUInt8::create();
auto call = [&](const auto & types) -> bool
{
using Types = std::decay_t<decltype(types)>;
using Type = typename Types::RightType;
using ColVecType = ColumnVectorOrDecimal<Type>;
if (const ColVecType * col_vec = checkAndGetColumn<ColVecType>(src_column.column.get()))
{
execute<Type>(*col_vec, *result_column, input_rows_count);
return true;
}
throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Illegal column while execute function {}", getName());
};
TypeIndex dec_type_idx = src_column.type->getTypeId();
if (!callOnBasicType<void, true, false, true, false>(dec_type_idx, call))
throw Exception(ErrorCodes::ILLEGAL_COLUMN, "Wrong call for {} with {}", getName(), src_column.type->getName());
return result_column;
}
private:
template <typename T, typename ColVecType>
static void execute(const ColVecType & col, ColumnUInt8 & result_column, size_t rows_count)
{
using NativeT = make_unsigned_t<NativeType<T>>;
const auto & src_data = col.getData();
auto & dst_data = result_column.getData();
dst_data.resize(rows_count);
for (size_t i = 0; i < rows_count; ++i)
{
if constexpr (is_decimal<T>)
{
auto value = src_data[i].value;
if (unlikely(value < 0))
dst_data[i] = digits10<NativeT>(-static_cast<NativeT>(value));
else
dst_data[i] = digits10<NativeT>(value);
}
else
{
auto value = src_data[i];
if (unlikely(value < 0))
dst_data[i] = digits10<NativeT>(-static_cast<NativeT>(value));
else
dst_data[i] = digits10<NativeT>(value);
}
}
}
};
}
REGISTER_FUNCTION(CountDigits)
{
factory.registerFunction<FunctionCountDigits>();
}
}
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