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 */