HoldFlag.h

// -*- C++ -*-
//
// HoldFlag.h is a part of ThePEG - Toolkit for HEP Event Generation
// Copyright (C) 1999-2019 Leif Lonnblad
//
// ThePEG is licenced under version 3 of the GPL, see COPYING for details.
// Please respect the MCnet academic guidelines, see GUIDELINES for details.
//
#ifndef ThePEG_HoldFlag_H
#define ThePEG_HoldFlag_H
// This is the declaration of the HoldFlag class.
 
namespace ThePEG {
 
template <typename T = bool>
class HoldFlag {
 
public:
 
  HoldFlag(T & newFlag, const T & holdFlag)
    : theFlag(newFlag), oldFlag(holdFlag) { std::swap(theFlag, oldFlag); }
 
  HoldFlag(T & newFlag, const T & holdFlag, const T & finalFlag)
    : theFlag(newFlag), oldFlag(holdFlag) 
  {
    std::swap(theFlag, oldFlag);
    oldFlag = finalFlag;
  }
 
  ~HoldFlag() { std::swap(theFlag, oldFlag); }
 
private:
 
  T & theFlag;
 
  T oldFlag;
 
  HoldFlag();
 
  HoldFlag(const HoldFlag &);
 
  HoldFlag & operator=(const HoldFlag &) = delete;
 
};
 
template <>
class HoldFlag<bool> {
 
public:
 
  HoldFlag(bool & newFlag, bool holdFlag = true)
    : theFlag(newFlag), oldFlag(newFlag) { theFlag = holdFlag; }
 
  HoldFlag(bool & newFlag, bool holdFlag, bool finalFlag)
    : theFlag(newFlag), oldFlag(finalFlag) { theFlag = holdFlag; }
 
  ~HoldFlag() { theFlag = oldFlag; }
 
private:
 
  bool & theFlag;
 
  bool oldFlag;
 
  HoldFlag();
 
  HoldFlag(const HoldFlag &);
 
  HoldFlag & operator=(const HoldFlag &) = delete;
 
};
 
}
 
#endif /* ThePEG_HoldFlag_H */