static.h

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/*
Copyright (C) 2001-2006, William Joseph.
All Rights Reserved.

This file is part of GtkRadiant.

GtkRadiant 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
(at your option) any later version.

GtkRadiant 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 GtkRadiant; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

#if !defined(INCLUDED_GENERIC_STATIC_H)
#define INCLUDED_GENERIC_STATIC_H


#include <cstddef>

class Null {
};

template < typename Type, typename Context = Null >
class Static {
    static Type m_instance;
public:
    static Type& instance() {
        return m_instance;
    }
};

template<typename Type, typename Context>
Type Static<Type, Context>::m_instance;


template < typename Type, typename Context = Null >
class LazyStatic {
    static Type* m_instance; // this will be initialised to 0 by the CRT, according to the c++ standard
public:
    static Type& instance() {
        if (m_instance == 0) {
            m_instance = new Type; // allocate using 'new' to get the correct alignment
        }
        return *m_instance;
    }
};

template<typename Type, typename Context>
Type* LazyStatic<Type, Context>::m_instance;


template < typename Type, typename Context = Null >
class CountedStatic {
    static std::size_t m_refcount; // this will be initialised to 0 by the CRT, according to the c++ standard
    static Type* m_instance;
public:
    static Type& instance() {
        return *m_instance;
    }
    static void capture() {
        if (++m_refcount == 1) {
            m_instance = new Type; // allocate using 'new' to get the correct alignment
        }
    }
    static void release() {
        if (--m_refcount == 0) {
            delete m_instance;
        }
    }
};

template<typename Type, typename Context>
std::size_t CountedStatic<Type, Context>::m_refcount; // this will be initialised to 0 by the CRT, according to the c++ standard
template<typename Type, typename Context>
Type* CountedStatic<Type, Context>::m_instance;

template < typename Type, typename Context = Null >
class SmartStatic {
public:
    SmartStatic() {
        CountedStatic<Type, Context>::capture();
    }
    ~SmartStatic() {
        CountedStatic<Type, Context>::release();
    }
    Type& instance() {
        return CountedStatic<Type, Context>::instance();
    }
};


#endif