Event/DecayChain/include/DecayChain/Element/ReferenceCount.h

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#ifndef DCHAIN_REFERENCECOUNT_H
#define DCHAIN_REFERENCECOUNT_H
// -*- C++ -*-
//
// Package:     DChain
// Module:      ReferenceCount
//
// Description: Base class for classes that need reference counting
//
// Usage:
//   ReferenceCount()  - default constructor
//   ~ReferenceCount() - destructor
//   addLink()  - record that another object points to this object
//   dropLink() - record that an object no longer points to this object
//
// Author:      Simon Patton
// Created:     Fri May 17 08:01:51 EDT 1996
// $Id: ReferenceCount.h,v 1.1.1.1 2009/03/03 06:06:56 maqm Exp $
//
// Revision history
//
// $Log: ReferenceCount.h,v $
// Revision 1.1.1.1  2009/03/03 06:06:56  maqm
// first import of DecayChain
//
// Revision 1.1  2006/01/11 20:28:09  cdj
// massive class renaming, addition of [] for selection and unit tests
//
// Revision 1.4  2004/05/12 20:12:52  ryd
// Added missing #include
//
// Revision 1.3  2004/05/11 02:39:17  ryd
// Change reference count to UInt32 and throw exception if count exceeds maximum
//
// Revision 1.2  2003/05/15 19:56:01  cdj
// revamped memory handling so always use a ReferenceHolder to deal with the reference counting
//
// Revision 1.1.1.1  2000/12/18 22:16:49  cdj
// imported DChain
//
// Revision 1.2  1998/08/21 00:46:09  sjp
// removed unnecessary include
//
// Revision 1.1  1998/08/19 20:56:46  sjp
// New heder for reference counting class
//
// Revision 1.1  1998/08/17 23:59:22  sjp
// New file to make libraries standalone
//
 
// system include files
#include <stdint.h>
 
// user include files
// #include "DecayChain/util/DAException.h"
 
// forward declarations
namespace dchain {
 
  /*
  class TooManyReferencesException : public DAException
  {
     public:
        TooManyReferencesException():DAException("Too many references to object in a DChain
  list.\n check sizes of list that you multiply."){}
  };
  */
 
  class ReferenceCount {
  public:
    // Constructors and destructor
    ReferenceCount();
    virtual ~ReferenceCount() {}
 
    // const member functions
    void addLink() const;
    void dropLink() const;
 
  private:
    // Constructors and destructor
    ReferenceCount( const ReferenceCount& ); // stop default
 
    // assignment operator(s)
    const ReferenceCount& operator=( const ReferenceCount& ); // stop default
 
    // data members
    mutable uint32_t m_linkCount;
  };
 
  // inline function definitions
 
  //
  // constructors and destructor
  //
 
  inline ReferenceCount::ReferenceCount() : m_linkCount( 0 ) {}
 
  //
  // member functions
  //
 
  inline void ReferenceCount::addLink() const {
    // if (m_linkCount==0xFFFFFFFF) {
    //    throw TooManyReferencesException();
    // }
    ++m_linkCount;
  }
 
  inline void ReferenceCount::dropLink() const {
    --m_linkCount;
    if ( 0 == m_linkCount )
    {
      // It is necessary to throw away the 'const' so that the object
      //   can be deleted
      delete const_cast<ReferenceCount*>( this );
    }
  }
} // namespace dchain
#endif // DCHAIN_REFERENCECOUNT_H