121 lines
2.4 KiB
C++
121 lines
2.4 KiB
C++
//This file is part of Photon (http://photon.sourceforge.net)
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//Copyright (C) 2004-2005 James Turk
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//
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// Author:
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// James Turk (jpt2433@rit.edu)
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//
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// Version:
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// $Id: Singleton.hpp,v 1.8 2005/07/18 06:18:51 cozman Exp $
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#ifndef PHOTON_UTIL_SINGLETON_HPP
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#define PHOTON_UTIL_SINGLETON_HPP
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#include <boost/utility.hpp>
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#include "exceptions.hpp"
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namespace photon
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{
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namespace util
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{
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// Class: Singleton
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// Template class for singleton pattern. Is non-copyable to enforce correct
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// behavior.
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//
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// Defining a Singleton:
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// (code)
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// class YourClass : public Singleton<Class>
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// {
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// // class definition
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// };
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// (end)
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//
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// Using The Singleton:
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// (code)
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// new YourClass;
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// YourClass& yc(YourClass::getInstance());
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//
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// // use yc
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//
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// YourClass::destroy();
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// (end)
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template<class T>
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class Singleton : public boost::noncopyable
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{
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public:
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// Function: initialize
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// Initialize the instance of the singleton, can be done explicitly if
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// order of construction matters. Will be done on first call to
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// getInstance otherwise.
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static void initialize();
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// Function: destroy
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// Destroy the instance of the singleton, can be done explicitly if order
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// of destruction matters. Will be done automatically if not done.
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static void destroy();
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// Function: getInstance
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// Get a reference to the instance of the derived class.
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static T& getInstance();
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protected:
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Singleton();
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virtual ~Singleton(); // allow inheritance
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private:
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static T* instance_;
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};
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// template implementation
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template<class T>
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Singleton<T>::Singleton()
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{
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if(instance_ != 0)
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{
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throw PreconditionException("Attempt to double-initialize singleton.");
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}
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instance_ = static_cast<T*>(this); // cast self to type of T*
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}
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template<class T>
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Singleton<T>::~Singleton()
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{
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}
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template<class T>
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void Singleton<T>::destroy()
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{
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if(instance_ == 0)
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{
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throw PreconditionException("Attempt to destroy null singleton.");
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}
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if(instance_)
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{
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delete instance_;
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instance_ = 0;
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}
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}
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template<class T>
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T& Singleton<T>::getInstance()
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{
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if(instance_ == 0)
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{
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throw PreconditionException("Attempt to access null singleton.");
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}
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return *instance_; //return dereferenced instance
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}
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template<class T>
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T* Singleton<T>::instance_(0);
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}
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}
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#endif //PHOTON_UTIL_SINGLETON_HPP
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