singleton.cpp

来自「loki 程序库」· C++ 代码 · 共 51 行

////////////////////////////////////////////////////////////////////////////////
// The Loki Library
// Copyright (c) 2001 by Andrei Alexandrescu
// This code accompanies the book:
// Alexandrescu, Andrei. "Modern C++ Design: Generic Programming and Design 
//     Patterns Applied". Copyright (c) 2001. Addison-Wesley.
// Permission to use, copy, modify, distribute and sell this software for any 
//     purpose is hereby granted without fee, provided that the above copyright 
//     notice appear in all copies and that both that copyright notice and this 
//     permission notice appear in supporting documentation.
// The author or Addison-Wesley Longman make no representations about the 
//     suitability of this software for any purpose. It is provided "as is" 
//     without express or implied warranty.
////////////////////////////////////////////////////////////////////////////////

// Last update: June 20, 2001

#include "Singleton.h"

using namespace Loki::Private;

Loki::Private::TrackerArray Loki::Private::pTrackerArray = 0;
unsigned int Loki::Private::elements = 0;

////////////////////////////////////////////////////////////////////////////////
// function AtExitFn
// Ensures proper destruction of objects with longevity
////////////////////////////////////////////////////////////////////////////////

void Loki::Private::AtExitFn()
{
    assert(elements > 0 && pTrackerArray != 0);
    // Pick the element at the top of the stack
    LifetimeTracker* pTop = pTrackerArray[elements - 1];
    // Remove that object off the stack
    // Don't check errors - realloc with less memory 
    //     can't fail
    pTrackerArray = static_cast<TrackerArray>(std::realloc(
        pTrackerArray, sizeof(*pTrackerArray) * --elements));
    // Destroy the element
    delete pTop;
}

////////////////////////////////////////////////////////////////////////////////
// Change log:
// June 20, 2001: ported by Nick Thurn to gcc 2.95.3. Kudos, Nick!!!
// January 10, 2002: Fixed bug in call to realloc - credit due to Nigel Gent and
//      Eike Petersen
// May 08, 2002: Refixed bug in call to realloc
////////////////////////////////////////////////////////////////////////////////