ClickHouse/dbms/include/DB/AggregateFunctions/AggregateFunctionSum.h

97 lines
2.3 KiB
C++

#pragma once
#include <DB/IO/WriteHelpers.h>
#include <DB/IO/ReadHelpers.h>
#include <DB/DataTypes/DataTypesNumberFixed.h>
#include <DB/AggregateFunctions/IUnaryAggregateFunction.h>
namespace DB
{
template <typename T> struct AggregateFunctionSumTraits;
template <> struct AggregateFunctionSumTraits<UInt64>
{
static DataTypePtr getReturnType() { return new DataTypeUInt64; }
static void write(UInt64 x, WriteBuffer & buf) { writeVarUInt(x, buf); }
static void read(UInt64 & x, ReadBuffer & buf) { readVarUInt(x, buf); }
};
template <> struct AggregateFunctionSumTraits<Int64>
{
static DataTypePtr getReturnType() { return new DataTypeInt64; }
static void write(Int64 x, WriteBuffer & buf) { writeVarInt(x, buf); }
static void read(Int64 & x, ReadBuffer & buf) { readVarInt(x, buf); }
};
template <> struct AggregateFunctionSumTraits<Float64>
{
static DataTypePtr getReturnType() { return new DataTypeFloat64; }
static void write(Float64 x, WriteBuffer & buf) { writeFloatBinary(x, buf); }
static void read(Float64 & x, ReadBuffer & buf) { readFloatBinary(x, buf); }
};
/// Считает сумму чисел. Параметром шаблона может быть UInt64, Int64 или Float64.
template <typename T>
class AggregateFunctionSum : public IUnaryAggregateFunction
{
private:
T sum;
public:
AggregateFunctionSum() : sum(0) {}
String getName() const { return "sum"; }
String getTypeID() const { return "sum_" + TypeName<T>::get(); }
AggregateFunctionPlainPtr cloneEmpty() const
{
return new AggregateFunctionSum<T>;
}
DataTypePtr getReturnType() const
{
return AggregateFunctionSumTraits<T>::getReturnType();
}
void setArgument(const DataTypePtr & argument)
{
if (!argument->isNumeric())
throw Exception("Illegal type " + argument->getName() + " of argument for aggregate function " + getName(),
ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
}
void addOne(const Field & value)
{
sum += get<T>(value);
}
void merge(const IAggregateFunction & rhs)
{
sum += static_cast<const AggregateFunctionSum<T> &>(rhs).sum;
}
void serialize(WriteBuffer & buf) const
{
AggregateFunctionSumTraits<T>::write(sum, buf);
}
void deserializeMerge(ReadBuffer & buf)
{
T tmp;
AggregateFunctionSumTraits<T>::read(tmp, buf);
sum += tmp;
}
Field getResult() const
{
return sum;
}
};
}