ClickHouse/dbms/src/AggregateFunctions/AggregateFunctionGroupArray.cpp

#include <AggregateFunctions/AggregateFunctionFactory.h>
#include <AggregateFunctions/AggregateFunctionGroupArray.h>
#include <AggregateFunctions/Helpers.h>
#include <AggregateFunctions/FactoryHelpers.h>
#include <DataTypes/DataTypeDate.h>
#include <DataTypes/DataTypeDateTime.h>


namespace DB
{

namespace ErrorCodes
{
    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
}

namespace
{

template <template <typename, typename> class AggregateFunctionTemplate, typename Data, typename ... TArgs>
static IAggregateFunction * createWithNumericOrTimeType(const IDataType & argument_type, TArgs && ... args)
{
    if (typeid_cast<const DataTypeDate *>(&argument_type)) return new AggregateFunctionTemplate<UInt16, Data>(std::forward<TArgs>(args)...);
    if (typeid_cast<const DataTypeDateTime *>(&argument_type)) return new AggregateFunctionTemplate<UInt32, Data>(std::forward<TArgs>(args)...);
    return createWithNumericType<AggregateFunctionTemplate, Data, TArgs...>(argument_type, std::forward<TArgs>(args)...);
}


template <typename has_limit, typename ... TArgs>
inline AggregateFunctionPtr createAggregateFunctionGroupArrayImpl(const DataTypePtr & argument_type, TArgs ... args)
{
    if (auto res = createWithNumericOrTimeType<GroupArrayNumericImpl, has_limit>(*argument_type, argument_type, std::forward<TArgs>(args)...))
        return AggregateFunctionPtr(res);

    if (typeid_cast<const DataTypeString *>(argument_type.get()))
        return std::make_shared<GroupArrayGeneralListImpl<GroupArrayListNodeString, has_limit::value>>(std::forward<TArgs>(args)...);

    return std::make_shared<GroupArrayGeneralListImpl<GroupArrayListNodeGeneral, has_limit::value>>(std::forward<TArgs>(args)...);
};


static AggregateFunctionPtr createAggregateFunctionGroupArray(const std::string & name, const DataTypes & argument_types, const Array & parameters)
{
    assertUnary(name, argument_types);

    bool limit_size = false;
    UInt64 max_elems = std::numeric_limits<UInt64>::max();

    if (parameters.empty())
    {
        // no limit
    }
    else if (parameters.size() == 1)
    {
        auto type = parameters[0].getType();
        if (type != Field::Types::Int64  && type != Field::Types::UInt64)
               throw Exception("Parameter for aggregate function " + name + " should be positive number", ErrorCodes::BAD_ARGUMENTS);

        if ((type == Field::Types::Int64  && parameters[0].get<Int64>() < 0) ||
            (type == Field::Types::UInt64 && parameters[0].get<UInt64>() == 0))
            throw Exception("Parameter for aggregate function " + name + " should be positive number", ErrorCodes::BAD_ARGUMENTS);

        limit_size = true;
        max_elems = parameters[0].get<UInt64>();
    }
    else
        throw Exception("Incorrect number of parameters for aggregate function " + name + ", should be 0 or 1",
            ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);

    if (!limit_size)
        return createAggregateFunctionGroupArrayImpl<std::false_type>(argument_types[0]);
    else
        return createAggregateFunctionGroupArrayImpl<std::true_type>(argument_types[0], max_elems);
}

}


void registerAggregateFunctionGroupArray(AggregateFunctionFactory & factory)
{
    factory.registerFunction("groupArray", createAggregateFunctionGroupArray);
}

}