object_factory.h

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 * Copyright 2008-2009  Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
 * Copyright 2008-2009  David G. Lowe (lowe@cs.ubc.ca). All rights reserved.
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#ifndef FLANN_OBJECT_FACTORY_H_
#define FLANN_OBJECT_FACTORY_H_
 
#include <map>
 
namespace flann
{
 
class CreatorNotFound
{
};
 
template<typename BaseClass,
         typename UniqueIdType,
         typename ObjectCreator = BaseClass* (*)()>
class ObjectFactory
{
    typedef ObjectFactory<BaseClass,UniqueIdType,ObjectCreator> ThisClass;
    typedef std::map<UniqueIdType, ObjectCreator> ObjectRegistry;
 
    // singleton class, private constructor
    ObjectFactory() {}
 
public:
 
    bool subscribe(UniqueIdType id, ObjectCreator creator)
    {
        if (object_registry.find(id) != object_registry.end()) return false;
 
        object_registry[id] = creator;
        return true;
    }
 
    bool unregister(UniqueIdType id)
    {
        return object_registry.erase(id) == 1;
    }
 
    ObjectCreator create(UniqueIdType id)
    {
        typename ObjectRegistry::const_iterator iter = object_registry.find(id);
 
        if (iter == object_registry.end()) {
            throw CreatorNotFound();
        }
 
        return iter->second;
    }
 
    static ThisClass& instance()
    {
        static ThisClass the_factory;
        return the_factory;
    }
private:
    ObjectRegistry object_registry;
};
 
}
 
#endif /* FLANN_OBJECT_FACTORY_H_ */