blocxx

GlobalPtr.hpp

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00001 /*******************************************************************************
00002 * Copyright (C) 2005, Quest Software, Inc. All rights reserved.
00003 * Copyright (C) 2006, Novell, Inc. All rights reserved.
00004 * 
00005 * Redistribution and use in source and binary forms, with or without
00006 * modification, are permitted provided that the following conditions are met:
00007 * 
00008 *     * Redistributions of source code must retain the above copyright notice,
00009 *       this list of conditions and the following disclaimer.
00010 *     * Redistributions in binary form must reproduce the above copyright
00011 *       notice, this list of conditions and the following disclaimer in the
00012 *       documentation and/or other materials provided with the distribution.
00013 *     * Neither the name of 
00014 *       Quest Software, Inc., 
00015 *       nor Novell, Inc., 
00016 *       nor the names of its contributors or employees may be used to 
00017 *       endorse or promote products derived from this software without 
00018 *       specific prior written permission.
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00020 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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00032 
00033 
00038 #ifndef BLOCXX_GLOBAL_PTR_HPP_INCLUDE_GUARD_
00039 #define BLOCXX_GLOBAL_PTR_HPP_INCLUDE_GUARD_
00040 #include "blocxx/BLOCXX_config.h"
00041 #include "blocxx/ThreadOnce.hpp"
00042 #include "blocxx/SafeBool.hpp"
00043 
00044 namespace BLOCXX_NAMESPACE
00045 {
00050    template <typename T>
00051    struct DefaultConstructorFactory
00052    {
00053       static T* create()
00054       {
00055          return new T;
00056       }
00057    };
00058 
00082    template <typename T, typename FactoryT = DefaultConstructorFactory<T> >
00083    class GlobalPtr
00084    {
00085    private:
00086       struct InitPtr
00087       {
00088          InitPtr(T*& p)
00089          : m_p(p)
00090          {}
00091          T*& m_p;
00092 
00093          void operator()()
00094          {
00095             m_p = static_cast<T*>(FactoryT::create());
00096          }
00097       };
00098 
00099    public:
00105       T* get() const
00106       {
00107          callOnce(m_onceFlag, InitPtr(m_p));
00108 
00109          return m_p;
00110       }
00111 
00118       T* set(T* newP)
00119       {
00120          T* oldP = get();
00121          m_p = newP;
00122          return oldP;
00123       }
00124 
00125       BLOCXX_SAFE_BOOL_IMPL(GlobalPtr, T*, GlobalPtr::m_p, get() != 0);
00126 
00127       T & operator*() const
00128       {
00129          return *get();
00130       }
00131       T * operator->() const
00132       {
00133          return get();
00134       }
00135       
00136 
00137       // These members should be treated as private. They aren't marked private because if they are, POD initializaer syntax can't be used.
00138       mutable T* m_p;
00139       mutable OnceFlag m_onceFlag;
00140    };
00141 
00146 #define BLOCXX_GLOBAL_PTR_INIT { 0, BLOCXX_ONCE_INIT }
00147 
00148 
00149 } // end namespace BLOCXX_NAMESPACE
00150 
00151 
00152 #endif
00153 
00154