forked from 0ad/0ad
68 lines
1.5 KiB
C++
68 lines
1.5 KiB
C++
//////////////////////////////////////////////////////////////////////////////
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// AUTHOR: Michael Reiland
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// FILENAME: Singleton.h
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// PURPOSE: Provides a base template class for Singletons
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//
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// USEAGE: class myClass : Singleton<myClass>{};
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//
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// INFO: This implementation was originally copied from:
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//
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// Enginuity, Part II
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// Memory Management, Error Logging, and Utility Classes;
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// or, How To Forget To Explode Your Underwear
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// by Richard "superpig" Fine
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//
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// hosted at Gamedev.net at
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// http://gamedev.net/reference/articles/article1954.asp
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//
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// MODIFIED: 07.09.2003 mreiland
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#ifndef _TEMPLATE_SINGLETON
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#define _TEMPLATE_SINGLETON
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#include "lib/debug.h"
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template<typename T>
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class Singleton
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{
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static T* ms_singleton;
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public:
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Singleton()
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{
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debug_assert( !ms_singleton );
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// use a cunning trick to get the singleton pointing to the start of
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// the whole, rather than the start of the Singleton part of the object
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uintptr_t offset = (uintptr_t)(T*)1 - (uintptr_t)(Singleton<T>*)(T*)1;
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ms_singleton = (T*)((uintptr_t)this + offset);
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}
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~Singleton()
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{
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debug_assert( ms_singleton );
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ms_singleton = 0;
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}
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static T& GetSingleton()
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{
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debug_assert( ms_singleton );
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return *ms_singleton;
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}
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static T* GetSingletonPtr()
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{
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debug_assert( ms_singleton );
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return ms_singleton;
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}
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static bool IsInitialised()
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{
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return (ms_singleton != 0);
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}
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};
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template <typename T>
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T* Singleton<T>::ms_singleton = 0;
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#endif
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