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209 lines
5.4 KiB
C++
209 lines
5.4 KiB
C++
#pragma once
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#include "../acl_cpp_define.hpp"
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#include <assert.h>
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#include "noncopyable.hpp"
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// singleton.hpp
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//
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// Copyright David Abrahams 2006. Original version
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//
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// Copyright Robert Ramey 2007. Changes made to permit
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// application throughout the serialization library.
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//
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// Distributed under the Boost
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// Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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// The intention here is to define a template which will convert
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// any class into a singleton with the following features:
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//
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// a) initialized before first use.
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// b) thread-safe for const access to the class
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// c) non-locking
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//
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// In order to do this,
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// a) Initialize dynamically when used.
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// b) Require that all singletons be initialized before main
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// is called or any entry point into the shared library is invoked.
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// This guarentees no race condition for initialization.
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// In debug mode, we assert that no non-const functions are called
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// after main is invoked.
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namespace acl {
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#if defined(_WIN32) || defined(_WIN64)
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# pragma warning(push)
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# pragma warning(disable : 4511 4512)
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#endif
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//////////////////////////////////////////////////////////////////////
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// Provides a dynamically-initialized (singleton) instance of T in a
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// way that avoids LNK1179 on vc6. See http://tinyurl.com/ljdp8 or
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// http://lists.boost.org/Archives/boost/2006/05/105286.php for
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// details.
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//
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// singletons created by this code are guarenteed to be unique
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// within the executable or shared library which creates them.
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// This is sufficient and in fact ideal for the serialization library.
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// The singleton is created when the module is loaded and destroyed
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// when the module is unloaded.
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// This base class has two functions.
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// First it provides a module handle for each singleton indicating
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// the executable or shared library in which it was created. This
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// turns out to be necessary and sufficient to implement the tables
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// used by serialization library.
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// Second, it provides a mechanism to detect when a non-const function
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// is called after initialization.
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// make a singleton to lock/unlock all singletons for alteration.
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// The intent is that all singletons created/used by this code
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// are to be initialized before main is called. A test program
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// can lock all the singletons when main is entereed. This any
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// attempt to retieve a mutable instances while locked will
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// generate a assertion if compiled for debug.
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class singleton_module : public noncopyable
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{
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public:
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static void lock()
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{
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get_lock() = true;
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}
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static void unlock()
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{
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get_lock() = false;
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}
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static bool is_locked() {
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return get_lock();
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}
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private:
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static bool& get_lock()
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{
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static bool lock_ = false;
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return lock_;
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}
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};
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template<class T>
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class singleton_wrapper : public T
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{
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public:
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static bool destroyed_;
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~singleton_wrapper()
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{
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destroyed_ = true;
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}
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};
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template<class T>
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bool singleton_wrapper< T >::destroyed_ = false;
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/**
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* <20><><EFBFBD><EFBFBD>ģ<EFBFBD><C4A3><EFBFBD>࣬<EFBFBD><E0A3AC>VC2010<31><30>GCC<43><43><EFBFBD><EFBFBD>ʱ<EFBFBD><CAB1><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> main <20><><EFBFBD><EFBFBD>֮ǰ<D6AE><C7B0>ִ<EFBFBD>У<EFBFBD>
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* <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>̰߳<DFB3>ȫ<EFBFBD>ģ<EFBFBD><C4A3><EFBFBD><EFBFBD><EFBFBD> VC2003 <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD> release <20>汾ʱ<E6B1BE>Ҵ<EFBFBD><D2B4><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ż<EFBFBD>
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* <20><><EFBFBD>أ<EFBFBD><D8A3><EFBFBD><EFBFBD>п<EFBFBD><D0BF><EFBFBD><EFBFBD><EFBFBD><EFBFBD>̲߳<DFB3><CCB2><EFBFBD>ȫ<EFBFBD>ģ<EFBFBD><C4A3><EFBFBD>ʱ<EFBFBD><CAB1><EFBFBD>ܱ<EFBFBD>֤<EFBFBD><D6A4><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ĺ<EFBFBD><C4B9>캯<EFBFBD><ECBAAF><EFBFBD><EFBFBD>
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* main ֮ǰִ<C7B0><D6B4>.
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* ʹ<>þ<EFBFBD><C3BE><EFBFBD><EFBFBD><EFBFBD><EFBFBD>£<EFBFBD>
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* class singleton_test : public acl::singleton<singlegon_test>
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* {
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* public:
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* singleton_test() {}
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* ~singleton_test() {}
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* singleton_test& init() { return *this; }
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* };
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* int main()
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* {
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* singleton_test& test = singleton_test::get_instance();
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* test.init();
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* ...
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* return 0;
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* }
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*/
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template <class T>
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class singleton : public singleton_module
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{
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public:
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static T& get_instance()
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{
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static singleton_wrapper< T > t;
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// refer to instance, causing it to be instantiated (and
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// initialized at startup on working compilers)
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assert(!singleton_wrapper< T >::destroyed_);
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use(instance_);
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return static_cast<T &>(t);
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}
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static bool is_destroyed()
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{
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return singleton_wrapper< T >::destroyed_;
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}
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private:
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static T& instance_;
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// include this to provoke instantiation at pre-execution time
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static void use(T const &) {}
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};
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template<class T>
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T& singleton< T >::instance_ = singleton< T >::get_instance();
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//////////////////////////////////////////////////////////////////////////
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/**
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* <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><CAB5><EFBFBD><EFBFBD> VC2003 <20><> release <20><><EFBFBD><EFBFBD>ʱ<EFBFBD><CAB1><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ż<EFBFBD><C5BB><EFBFBD><EFBFBD>أ<EFBFBD><D8A3><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ܱ<EFBFBD>֤<EFBFBD><D6A4><EFBFBD><EFBFBD>
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* <20>Ĺ<EFBFBD><C4B9>캯<EFBFBD><ECBAAF><EFBFBD><EFBFBD><EFBFBD><EFBFBD> main ִ<>У<EFBFBD><D0A3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> VC2003 <20>±<EFBFBD><C2B1>뵥<EFBFBD><EBB5A5><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڶ<EFBFBD><DAB6><EFBFBD><EFBFBD>߳<EFBFBD><DFB3><EFBFBD>
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* <20><><EFBFBD>õ<EFBFBD><C3B5><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʱ<EFBFBD><CAB1><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD><CAB9><EFBFBD><EFBFBD><EFBFBD>µĵ<C2B5><C4B5><EFBFBD>ģ<EFBFBD><C4A3><EFBFBD>࣬ʾ<E0A3AC><CABE><EFBFBD><EFBFBD><EFBFBD>£<EFBFBD>
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* class singleton_test
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* {
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* public:
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* singleton_test() {}
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* ~singleton_test() {}
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* singleton_test& init() { return *this; }
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* };
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* int main()
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* {
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* singleton_test& test = acl::singleton2<singleton_test>::get_instance();
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* test.init();
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* ...
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* return 0;
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* }
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*
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*/
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template <typename T>
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struct singleton2
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{
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private:
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struct object_creator
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{
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object_creator() { singleton2<T>::get_instance(); }
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inline void do_nothing() const {};
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};
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static object_creator create_object;
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public:
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typedef T object_type;
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static object_type & get_instance()
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{
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static object_type obj;
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create_object.do_nothing();
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return obj;
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}
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};
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template <typename T>
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typename singleton2<T>::object_creator singleton2<T>::create_object;
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#if defined(_WIN32) || defined(_WIN64)
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#pragma warning(pop)
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#endif
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} // namespace acl
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