mapnik/include/factory.hpp

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2005-06-14 17:06:59 +02:00
/* This file is part of Mapnik (c++ mapping toolkit)
* Copyright (C) 2005 Artem Pavlenko
*
* Mapnik is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
//$Id: factory.hpp 39 2005-04-10 20:39:53Z pavlenko $
#ifndef FACTORY_HPP
#define FACTORY_HPP
#include <stdexcept>
#include <map>
#include "utils.hpp"
namespace mapnik
{
template <typename key_type,
typename product_type>
class default_factory_error
{
public:
struct factory_exception : public std::exception
{
const char* what() const throw()
{
return "uknown object type";
}
};
static product_type* on_unknown_type(const key_type&)
{
return 0;
}
};
template
<
typename product_type,
typename key_type,
typename product_creator=product_type* (*)(),
template <typename,typename> class factory_error_policy=default_factory_error
>
class factory : public singleton<factory <product_type,key_type,product_creator,factory_error_policy> >,
factory_error_policy <key_type,product_type>
{
private:
typedef std::map<key_type,product_creator> product_map;
product_map map_;
public:
bool register_product(const key_type& key,product_creator creator)
{
return map_.insert(typename product_map::value_type(key,creator)).second;
}
bool unregister_product(const key_type& key)
{
return map_.erase(key)==1;
}
product_type* create_object(const key_type& key,const std::string& file)
{
typename product_map::const_iterator pos=map_.find(key);
if (pos!=map_.end())
{
return (pos->second)(file);
}
return on_unknown_type(key);
}
};
}
#endif //FACTORY_HPP