ClickHouse/base/poco/Foundation/include/Poco/DynamicFactory.h

//
// DynamicFactory.h
//
// Library: Foundation
// Package: Core
// Module:  DynamicFactory
//
// Definition of the DynamicFactory class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_DynamicFactory_INCLUDED
#define Foundation_DynamicFactory_INCLUDED


#include <map>
#include <memory>
#include "Poco/Exception.h"
#include "Poco/Foundation.h"
#include "Poco/Instantiator.h"
#include "Poco/Mutex.h"


namespace Poco
{


template <class Base>
class DynamicFactory
/// A factory that creates objects by class name.
{
public:
    typedef AbstractInstantiator<Base> AbstractFactory;

    DynamicFactory()
    /// Creates the DynamicFactory.
    {
    }

    ~DynamicFactory()
    /// Destroys the DynamicFactory and deletes the instantiators for
    /// all registered classes.
    {
        for (typename FactoryMap::iterator it = _map.begin(); it != _map.end(); ++it)
        {
            delete it->second;
        }
    }

    Base * createInstance(const std::string & className) const
    /// Creates a new instance of the class with the given name.
    /// The class must have been registered with registerClass.
    /// If the class name is unknown, a NotFoundException is thrown.
    {
        FastMutex::ScopedLock lock(_mutex);

        typename FactoryMap::const_iterator it = _map.find(className);
        if (it != _map.end())
            return it->second->createInstance();
        else
            throw NotFoundException(className);
    }

    template <class C>
    void registerClass(const std::string & className)
    /// Registers the instantiator for the given class with the DynamicFactory.
    /// The DynamicFactory takes ownership of the instantiator and deletes
    /// it when it's no longer used.
    /// If the class has already been registered, an ExistsException is thrown
    /// and the instantiator is deleted.
    {
        registerClass(className, new Instantiator<C, Base>);
    }

    void registerClass(const std::string & className, AbstractFactory * pAbstractFactory)
    /// Registers the instantiator for the given class with the DynamicFactory.
    /// The DynamicFactory takes ownership of the instantiator and deletes
    /// it when it's no longer used.
    /// If the class has already been registered, an ExistsException is thrown
    /// and the instantiator is deleted.
    {
        poco_check_ptr(pAbstractFactory);

        FastMutex::ScopedLock lock(_mutex);

#ifndef POCO_ENABLE_CPP11
        std::auto_ptr<AbstractFactory> ptr(pAbstractFactory);
#else
        std::unique_ptr<AbstractFactory> ptr(pAbstractFactory);
#endif // POCO_ENABLE_CPP11

        typename FactoryMap::iterator it = _map.find(className);
        if (it == _map.end())
            _map[className] = ptr.release();
        else
            throw ExistsException(className);
    }

    void unregisterClass(const std::string & className)
    /// Unregisters the given class and deletes the instantiator
    /// for the class.
    /// Throws a NotFoundException if the class has not been registered.
    {
        FastMutex::ScopedLock lock(_mutex);

        typename FactoryMap::iterator it = _map.find(className);
        if (it != _map.end())
        {
            delete it->second;
            _map.erase(it);
        }
        else
            throw NotFoundException(className);
    }

    bool isClass(const std::string & className) const
    /// Returns true iff the given class has been registered.
    {
        FastMutex::ScopedLock lock(_mutex);

        return _map.find(className) != _map.end();
    }

private:
    DynamicFactory(const DynamicFactory &);
    DynamicFactory & operator=(const DynamicFactory &);

    typedef std::map<std::string, AbstractFactory *> FactoryMap;

    FactoryMap _map;
    mutable FastMutex _mutex;
};


} // namespace Poco


#endif // Foundation_DynamicFactory_INCLUDED