GelFactory.h

/********************************************************************/
/* Copyright (c) 2015 DG Technologies Inc. and Yuzi Mizuno          */
/* All rights reserved.                                             */
/********************************************************************/
#if !defined(MGINCLUDEGUARD_GELFACTORY__)
#define MGINCLUDEGUARD_GELFACTORY__
#include <map>
#include "mg/MGCL.h"

class MGGel;

struct MGGelFactoryBase
{
    virtual MGGel* create_gel() const = 0;
};

template <typename T>
struct MGGelFactoryT : public MGGelFactoryBase
{
    virtual T* create_gel() const
    {
        return new T;
    }
};


class MG_DLL_DECLR MGGelFactoryRegistry
{
public:
    typedef long KeyType;
    typedef std::map<KeyType, MGGelFactoryBase*> TypeMap;

    ~MGGelFactoryRegistry();

    static MGGelFactoryRegistry* get_instance();

    static bool is_valid();

    MGGel* create_gel(const KeyType& name) const;

    void register_factory(
        const KeyType& name,
        MGGelFactoryBase* factory);

    void unregister_factory(const KeyType& name);

    void unregister_factory(MGGelFactoryBase* factory);

private:
    MGGelFactoryRegistry();

    MGGelFactoryRegistry(const MGGelFactoryRegistry& other);
    MGGelFactoryRegistry& operator=(const MGGelFactoryRegistry& other);

    TypeMap m_map; 
};



template <typename T>
class MGAutoGelRegister
{
    MGGelFactoryRegistry* m_pRegistry; 
    MGGelFactoryT<T> m_factory; 

public:
    MGAutoGelRegister(const MGGelFactoryRegistry::KeyType& name)
         : m_pRegistry(MGGelFactoryRegistry::get_instance())
    {
        m_pRegistry->register_factory(name, &m_factory);
    }

    ~MGAutoGelRegister()
    {
        if(MGGelFactoryRegistry::is_valid()){
            m_pRegistry->unregister_factory(&m_factory);
        }
    }
};

#define GEL_REG_JOIN( s1, s2 ) GEL_REG_JOIN__( s1, s2 )
#define GEL_REG_JOIN__( s1, s2 ) s1##s2
#define GEL_REG_MAKE_UNIQUE_NAME( prefix ) GEL_REG_JOIN( prefix, __LINE__ )

#define AUTO_GEL_REGISTER(classname, gelname) \
    static MGAutoGelRegister<classname> \
        GEL_REG_MAKE_UNIQUE_NAME( glreg__ ) (gelname);

#endif // defined(MGINCLUDEGUARD_GELFACTORY__)