ClickHouse/src/Functions/bitmaskToList.cpp
2020-11-17 16:24:45 +03:00

133 lines
3.8 KiB
C++

#include <Functions/FunctionFactory.h>
#include <Functions/IFunctionImpl.h>
#include <Columns/ColumnString.h>
#include <Columns/ColumnVector.h>
#include <DataTypes/DataTypeString.h>
#include <IO/WriteBufferFromVector.h>
#include <IO/WriteHelpers.h>
namespace DB
{
namespace ErrorCodes
{
extern const int ILLEGAL_TYPE_OF_ARGUMENT;
extern const int ILLEGAL_COLUMN;
}
/** Function for an unusual conversion to a string:
*
* bitmaskToList - takes an integer - a bitmask, returns a string of degrees of 2 separated by a comma.
* for example, bitmaskToList(50) = '2,16,32'
*/
namespace
{
class FunctionBitmaskToList : public IFunction
{
public:
static constexpr auto name = "bitmaskToList";
static FunctionPtr create(const Context &) { return std::make_shared<FunctionBitmaskToList>(); }
String getName() const override
{
return name;
}
size_t getNumberOfArguments() const override { return 1; }
bool isInjective(const ColumnsWithTypeAndName &) const override { return true; }
DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
{
const DataTypePtr & type = arguments[0];
if (!isInteger(type))
throw Exception("Cannot format " + type->getName() + " as bitmask string", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
return std::make_shared<DataTypeString>();
}
bool useDefaultImplementationForConstants() const override { return true; }
ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t /*input_rows_count*/) const override
{
ColumnPtr res;
if (!((res = executeType<UInt8>(arguments))
|| (res = executeType<UInt16>(arguments))
|| (res = executeType<UInt32>(arguments))
|| (res = executeType<UInt64>(arguments))
|| (res = executeType<Int8>(arguments))
|| (res = executeType<Int16>(arguments))
|| (res = executeType<Int32>(arguments))
|| (res = executeType<Int64>(arguments))))
throw Exception("Illegal column " + arguments[0].column->getName()
+ " of argument of function " + getName(),
ErrorCodes::ILLEGAL_COLUMN);
return res;
}
private:
template <typename T>
inline static void writeBitmask(T x, WriteBuffer & out)
{
using UnsignedT = make_unsigned_t<T>;
UnsignedT u_x = x;
bool first = true;
while (u_x)
{
UnsignedT y = u_x & (u_x - 1);
UnsignedT bit = u_x ^ y;
u_x = y;
if (!first)
writeChar(',', out);
first = false;
writeIntText(T(bit), out);
}
}
template <typename T>
ColumnPtr executeType(const ColumnsWithTypeAndName & columns) const
{
if (const ColumnVector<T> * col_from = checkAndGetColumn<ColumnVector<T>>(columns[0].column.get()))
{
auto col_to = ColumnString::create();
const typename ColumnVector<T>::Container & vec_from = col_from->getData();
ColumnString::Chars & data_to = col_to->getChars();
ColumnString::Offsets & offsets_to = col_to->getOffsets();
size_t size = vec_from.size();
data_to.resize(size * 2);
offsets_to.resize(size);
WriteBufferFromVector<ColumnString::Chars> buf_to(data_to);
for (size_t i = 0; i < size; ++i)
{
writeBitmask<T>(vec_from[i], buf_to);
writeChar(0, buf_to);
offsets_to[i] = buf_to.count();
}
buf_to.finalize();
return col_to;
}
return nullptr;
}
};
}
void registerFunctionBitmaskToList(FunctionFactory & factory)
{
factory.registerFunction<FunctionBitmaskToList>();
}
}