mirror of
https://github.com/libretro/scummvm.git
synced 2024-12-03 15:41:41 +00:00
107 lines
3.0 KiB
C++
107 lines
3.0 KiB
C++
/* ScummVM - Graphic Adventure Engine
|
|
*
|
|
* ScummVM is the legal property of its developers, whose names
|
|
* are too numerous to list here. Please refer to the COPYRIGHT
|
|
* file distributed with this source distribution.
|
|
*
|
|
* This program 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.
|
|
*
|
|
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
|
*
|
|
*/
|
|
|
|
#ifndef COMMON_SINGLETON_H
|
|
#define COMMON_SINGLETON_H
|
|
|
|
#include "common/noncopyable.h"
|
|
|
|
namespace Common {
|
|
|
|
/**
|
|
* Generic template base class for implementing the singleton design pattern.
|
|
*/
|
|
template<class T>
|
|
class Singleton : NonCopyable {
|
|
private:
|
|
Singleton<T>(const Singleton<T> &);
|
|
Singleton<T> &operator=(const Singleton<T> &);
|
|
|
|
/**
|
|
* The default object factory used by the template class Singleton.
|
|
* By specialising this template function, one can make a singleton use a
|
|
* custom object factory. For example, to support encapsulation, your
|
|
* singleton class might be pure virtual (or "abstract" in Java terminology),
|
|
* and you specialise makeInstance to return an instance of a subclass.
|
|
*/
|
|
//template<class T>
|
|
#if defined(__WINS__)
|
|
//FIXME verify if __WINS__ needs this still
|
|
public:
|
|
#endif
|
|
static T *makeInstance() {
|
|
return new T();
|
|
}
|
|
|
|
static void destroyInstance() {
|
|
delete _singleton;
|
|
_singleton = 0;
|
|
}
|
|
|
|
|
|
public:
|
|
static bool hasInstance() {
|
|
return _singleton != 0;
|
|
}
|
|
|
|
static T& instance() {
|
|
// TODO: We aren't thread safe. For now we ignore it since the
|
|
// only thing using this singleton template is the config manager,
|
|
// and that is first instantiated long before any threads.
|
|
// TODO: We don't leak, but the destruction order is nevertheless
|
|
// semi-random. If we use multiple singletons, the destruction
|
|
// order might become an issue. There are various approaches
|
|
// to solve that problem, but for now this is sufficient
|
|
if (!_singleton)
|
|
_singleton = T::makeInstance();
|
|
return *_singleton;
|
|
}
|
|
|
|
static void destroy() {
|
|
T::destroyInstance();
|
|
}
|
|
protected:
|
|
Singleton<T>() { }
|
|
#ifdef __SYMBIAN32__
|
|
virtual ~Singleton() { }
|
|
#else
|
|
virtual ~Singleton<T>() { }
|
|
#endif
|
|
|
|
typedef T SingletonBaseType;
|
|
|
|
static T *_singleton;
|
|
};
|
|
|
|
/**
|
|
* Note that you need to use this macro from the Common namespace.
|
|
*
|
|
* This is because C++ requires initial explicit specialization
|
|
* to be placed in the same namespace as the template.
|
|
*/
|
|
#define DECLARE_SINGLETON(T) \
|
|
template<> T *Singleton<T>::_singleton = 0
|
|
|
|
} // End of namespace Common
|
|
|
|
#endif
|