vtkSingleton.h

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/*=========================================================================

  Library:   CTK

  Copyright (c) 2010  Kitware Inc.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

      http://www.commontk.org/LICENSE

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

=========================================================================*/

#ifndef __vtkSingleton_h
#define __vtkSingleton_h


//-----------------------------------------------------------------------------
#define VTK_SINGLETON_DECLARE(NAME)       \
typedef NAME Self;                        \
static NAME* Instance;                    \
static void classInitialize();            \
static void classFinalize();              \
friend class NAME##Initialize;

//-----------------------------------------------------------------------------
#define VTK_SINGLETON_DECLARE_INITIALIZER(EXPORT_DIRECTIVE,NAME)   \
class EXPORT_DIRECTIVE NAME##Initialize                            \
{                                                                  \
public:                                                            \
  typedef NAME##Initialize Self;                                   \
                                                                   \
  NAME##Initialize();                                              \
  ~NAME##Initialize();                                             \
private:                                                           \
  static unsigned int Count;                                       \
};                                                                 \
                                                                   \
static NAME##Initialize NAME##Initializer;


//-----------------------------------------------------------------------------
#define VTK_SINGLETON_INITIALIZER_CXX(NAME)      \
NAME##Initialize::NAME##Initialize()                \
{                                                   \
  if(++Self::Count == 1)                            \
    { NAME::classInitialize(); }                    \
}                                                   \
                                                    \
NAME##Initialize::~NAME##Initialize()               \
{                                                   \
  if(--Self::Count == 0)                            \
    { NAME::classFinalize(); }                      \
}                                                   \
                                                    \
unsigned int NAME##Initialize::Count;               \
NAME* NAME::Instance;

// TODO Would be great to have this macro working. that would avoid
// to duplicate the following lines over and over
//#define VTK_SINGLETON_GETINSTANCE_CXX(NAME)
/* Up the reference count so it behaves like New */
//NAME* NAME::New()
//{
//  NAME* instance = Self::GetInstance();
//  instance->Register(0);
//  return instance;
//}
//NAME* NAME::GetInstance()
//{
//  if(!Self::Instance)
//    {
    /* Try the factory first */
//    Self::Instance = (NAME*)vtkObjectFactory::CreateInstance(#NAME);
//
    /* if the factory did not provide one, then create it here*/
//    if(!Self::Instance)
//      {
      /* if the factory failed to create the object, */
      /* then destroy it now, as vtkDebugLeaks::ConstructClass */
      /* was called with "NAME", and not the real name of the class */
//#ifdef VTK_DEBUG_LEAKS
//      vtkDebugLeaks::DestructClass(#NAME);
//#endif
//      Self::Instance = new NAME;
//      }
//    }
//  return Self::Instance;
//}

//----------------------------------------------------------------------------
#define VTK_SINGLETON_CXX(NAME)                     \
void NAME::classInitialize()                        \
{                                                   \
  Self::Instance = NAME::GetInstance();             \
}                                                   \
                                                    \
void NAME::classFinalize()                          \
{                                                   \
  Self::Instance->Delete();                         \
  Self::Instance = 0;                               \
}                                                   \
                                                    \
VTK_SINGLETON_INITIALIZER_CXX(NAME)


#endif //__vtkSingleton_h