ClickHouse/dbms/src/AggregateFunctions/AggregateFunctionCombinatorFactory.h

#pragma once

#include <AggregateFunctions/IAggregateFunctionCombinator.h>

#include <ext/singleton.h>

#include <string>
#include <unordered_map>


namespace DB
{

/** Create aggregate function combinator by matching suffix in aggregate function name.
  */
class AggregateFunctionCombinatorFactory final: public ext::singleton<AggregateFunctionCombinatorFactory>
{
public:
    /// Not thread safe. You must register before using tryGet.
    void registerCombinator(const AggregateFunctionCombinatorPtr & value);

    /// Example: if the name is 'avgIf', it will return combinator -If.
    AggregateFunctionCombinatorPtr tryFindSuffix(const std::string & name) const;

private:
    std::unordered_map<std::string, AggregateFunctionCombinatorPtr> dict;
};

}