ClickHouse/dbms/src/AggregateFunctions/AggregateFunctionFactory.cpp

#include <DB/AggregateFunctions/AggregateFunctionCount.h>
#include <DB/AggregateFunctions/AggregateFunctionSum.h>

#include <DB/AggregateFunctions/AggregateFunctionFactory.h>


namespace DB
{


AggregateFunctionFactory::AggregateFunctionFactory()
{
}


AggregateFunctionPtr AggregateFunctionFactory::get(const String & name, const DataTypes & argument_types) const
{
	if (name == "count")
	{
		return new AggregateFunctionCount;
	}
	else if (name == "sum")
	{
		if (argument_types.size() != 1)
			throw Exception("Incorrect number of arguments for aggregate function " + name, ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

		String argument_type_name = argument_types[0]->getName();
		
		if (argument_type_name == "UInt8" || argument_type_name == "UInt16"
			|| argument_type_name == "UInt32" || argument_type_name == "UInt64"
			|| argument_type_name == "VarUInt")
			return new AggregateFunctionSum<UInt64>;
		else if (argument_type_name == "Int8" || argument_type_name == "Int16"
			|| argument_type_name == "Int32" || argument_type_name == "Int64"
			|| argument_type_name == "VarInt")
			return new AggregateFunctionSum<Int64>;
		else if (argument_type_name == "Float32" || argument_type_name == "Float64")
			return new AggregateFunctionSum<Float64>;
		else
			throw Exception("Illegal type " + argument_type_name + " of argument for aggregate function " + name, ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
	}
	else
		throw Exception("Unknown aggregate function " + name, ErrorCodes::UNKNOWN_AGGREGATE_FUNCTION);
}


AggregateFunctionPtr AggregateFunctionFactory::getByTypeID(const String & type_id) const
{
	if (type_id == "count")
		return new AggregateFunctionCount;
	else if (0 == type_id.compare(0, strlen("sum_"), "sum_"))
	{
		if (0 == type_id.compare(strlen("sum_"), strlen("UInt64"), "UInt64"))
			return new AggregateFunctionSum<UInt64>;
		else if (0 == type_id.compare(strlen("sum_"), strlen("Int64"), "Int64"))
			return new AggregateFunctionSum<Int64>;
		else if (0 == type_id.compare(strlen("sum_"), strlen("Float64"), "Float64"))
			return new AggregateFunctionSum<Float64>;
		else
			throw Exception("Unknown type id of aggregate function " + type_id, ErrorCodes::UNKNOWN_AGGREGATE_FUNCTION);
	}
	else
		throw Exception("Unknown type id of aggregate function " + type_id, ErrorCodes::UNKNOWN_AGGREGATE_FUNCTION);
}


AggregateFunctionPtr AggregateFunctionFactory::tryGet(const String & name, const DataTypes & argument_types) const
{
	AggregateFunctionPtr res;

	try
	{
		return get(name, argument_types);
	}
	catch (const DB::Exception & e)
	{
		if (e.code() == ErrorCodes::UNKNOWN_AGGREGATE_FUNCTION)
			return NULL;
		else
			throw;
	}
}


}