CdaggerCdaggerCC_Iterator.h

#ifndef QNANO_NEW_CDAGGERCDAGGERCC_ITERATOR_DEFINED_H
#define QNANO_NEW_CDAGGERCDAGGERCC_ITERATOR_DEFINED_H

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


class CdaggerCdaggerCC_Iterator{
protected:
  CdaggerC_Iterator it_delta, it1, it2;
  int delta_counter, rank;

  int n1, n2, m1, m2, n_max;
  double sign;

public:

  bool done()const{
    return it2.done();
  }
  int get_n1()const{ return n1; }
  int get_n2()const{ return n2; }
  int get_m1()const{ return m1; }
  int get_m2()const{ return m2; }
  double get_sign()const{ return sign;  }

  const Fermion_Index& get_fi()const{
    if(delta_counter<rank)return it_delta.get_fi();
    return it1.get_fi();
  }


  //checks if current state make sense. If not, calls operator++
  CdaggerCdaggerCC_Iterator&  adjust(){
    if(delta_counter<rank){

        n2=m2=it_delta.get_fi()[delta_counter]; 
//std::cout<<"."<<it_delta.get_fi()<<" _n2: "<<n2<<std::endl;
        if(n2==it_delta.get_n())return operator++();
        sign=it_delta.get_sign();
        n1=it_delta.get_n();
        m1=it_delta.get_m();
    // c^dagger c c^dagger c part
    }else{
      n2=it2.get_n();
      m1=it2.get_m();
      if(it1.done()){
        ++it2;
        if(it2.done())return *this;
        it1.setup(it2.get_fi(),n_max);
        n2=it2.get_n();
        m1=it2.get_m();
      }
      n1=it1.get_n();
      m2=it1.get_m();
      sign=-it1.get_sign()*it2.get_sign();
      if(m2==n2)return operator++();
    }

    return *this;
  }

  CdaggerCdaggerCC_Iterator& operator++(){
    //first: treat special case where inner indices are the same
    if(delta_counter<rank){
      delta_counter++;
      if(delta_counter>=rank){
        ++it_delta;
        delta_counter=0;
        if(it_delta.done())delta_counter=rank;
      }
    }else{
      ++it1;
    }
    return adjust();
  }
  CdaggerCdaggerCC_Iterator& operator++(int){
    return operator++(); 
  }

  CdaggerCdaggerCC_Iterator(const Fermion_Index &fi, int n_max_) 
   :  n_max(n_max_){

    rank=fi.size();
    if(rank<2)n_max=0; 
    it_delta.setup(fi,n_max);
    it1.setup(fi,n_max);
    it2.setup(fi,n_max);

    if(rank<2)return;


    if(n_max<rank){
      std::cerr<<"CdaggerCdaggerCC_Iterator::constructor: n_max<rank"<<std::endl; 
      exit(1);
    }

    sign=it_delta.get_sign();
    n1=it_delta.get_n();
    m1=it_delta.get_m();
    delta_counter=0;
    n2=m2=0; //it_delta.get_fi()[0];
    adjust();
  }
};


#endif