ClickHouse/src/Functions/blockNumber.cpp
2021-06-01 15:20:52 +03:00

69 lines
1.4 KiB
C++

#include <Functions/IFunction.h>
#include <Functions/FunctionFactory.h>
#include <DataTypes/DataTypesNumber.h>
#include <Columns/ColumnsNumber.h>
#include <atomic>
namespace DB
{
namespace
{
/** Incremental columns number among calls of this function. */
class FunctionBlockNumber : public IFunction
{
private:
mutable std::atomic<size_t> columns_number{0};
public:
static constexpr auto name = "blockNumber";
static FunctionPtr create(ContextPtr)
{
return std::make_shared<FunctionBlockNumber>();
}
/// Get the function name.
String getName() const override
{
return name;
}
bool isStateful() const override
{
return true;
}
size_t getNumberOfArguments() const override
{
return 0;
}
bool isDeterministic() const override { return false; }
bool isDeterministicInScopeOfQuery() const override
{
return false;
}
DataTypePtr getReturnTypeImpl(const DataTypes & /*arguments*/) const override
{
return std::make_shared<DataTypeUInt64>();
}
ColumnPtr executeImpl(const ColumnsWithTypeAndName &, const DataTypePtr &, size_t input_rows_count) const override
{
size_t current_columns_number = columns_number++;
return ColumnUInt64::create(input_rows_count, current_columns_number);
}
};
}
void registerFunctionBlockNumber(FunctionFactory & factory)
{
factory.registerFunction<FunctionBlockNumber>();
}
}