Current.h

// -*- C++ -*-
//
// Current.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_Current_H
#define ThePEG_Current_H
// This is the declaration of the Current class.

namespace ThePEG {

template <typename T>
class Current {

public:

  Current() : pushed(false) {}

  Current(const Current<T> &)
    : pushed(false) {}

  Current(T * t) : pushed(false) {
    if ( t ) {
      theStack.push_back(t);
      pushed = true;
    }
  }

  ~Current() {
    if ( pushed ) theStack.pop_back();
  }

public:

  static bool isVoid() {
    return theStack.empty() || !(theStack.back());
  }

  static T & current() {
    return *theStack.back();
  }

  T & operator*() const {
    return *theStack.back();
  }

  T * operator->() const {
    return theStack.back();
  }

  static T * ptr() {
    return theStack.back();
  }

  operator bool() const {
    return ptr();
  }

  bool operator!() const {
    return !ptr();
  }

private:

  static vector<T *> theStack;

  bool pushed;

private:

  Current<T> & operator=(const Current<T> &) = delete;

};

template <typename T>
std::vector<T *> ThePEG::Current<T>::theStack;

}

#endif /* ThePEG_Current_H */