CdaggerC_Iterator_SingleI.h

#ifndef QNANO_NEW_CDAGGERC_ITERATOR_SINGLEI_DEFINED_H
#define QNANO_NEW_CDAGGERC_ITERATOR_SINGLEI_DEFINED_H

#include "manybody/Fermion_Double_Index.h"
#include <iostream>
#include <cstdlib>

class CdaggerC_Iterator_SingleI{
protected:
  //Reference Fermion_Index
  //Fermion_Index fi_ref;
  //Current Fermion_Index
  Fermion_Index fi_cur;
  
  //index of destroyed Fermion
  int c_index; 
  //current position of cdagger index:
  int cur_index;
  //Current and maxmimal number of single-particle states
  int n_cur, n_max;
  int m_old;
  //current sign;
  double sign;

public:
  void adjust_fi();
  void calculate_next();


  bool done()const{
    return n_cur>=n_max;
  }
  int get_n()const{
    return n_cur;
  }
  int get_m()const{
    return m_old;
  }
  double get_sign()const{
    return sign;
  }
  const Fermion_Index& get_fi()const{
    return fi_cur;
  }

  CdaggerC_Iterator_SingleI& operator++(){
    calculate_next();
    return *this;
  }

  void setup(const Fermion_Index &fi, int c_index_, int n_max_){
    fi_cur=fi;
    c_index=c_index_;
    n_max=n_max_;

    //Handle vacuum:
    if(fi.size()<1){
      n_max=0; 
      n_cur=0;
      return;
    }

    if(c_index>=(int)fi.size()){
      std::cerr<<"CdaggerC_Iterator::constructor: c_index>=fi.size()"<<std::endl; 
      exit(1);
    }
    if(n_max<(int)fi.size()){
      std::cerr<<"CdaggerC_Iterator::constructor: n_max<fi.size()"<<std::endl; 
      exit(1);
    }
 
    m_old=fi[c_index];

    n_cur=0;
    cur_index=0;
    for(int i=c_index-1; i>=0; i--){
      //std::cout<<i+1<<"<-"<<i<<": "<<fi_cur[i]<<std::endl;
      fi_cur[i+1]=fi_cur[i];
    }
    if(fi_cur.size()>0)fi_cur[0]=0;
    sign=1.;
    if(c_index%2==1)sign=-1.;

    adjust_fi();
  }

  CdaggerC_Iterator_SingleI(){
    setup(Fermion_Index(), 0, 0);
  }
  CdaggerC_Iterator_SingleI(const Fermion_Index &fi, int c_index_, int n_max_){
    setup(fi, c_index_, n_max_);
  }

};


#endif