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Cslice_iter.h

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#ifndef ATLFAST_CSLICEITER_H
#define ATLFAST_CSLICEITER_H
#include <valarray>
#include <cstddef>
//=================================================
//
// Cslice_iter
//
//  from Sjoustrup's "the C++ programming language" ch 22.4.6
//


namespace Atlfast {
  using std::valarray;
  using std::slice;

  template<class T> class Cslice_iter{
    valarray<T>* v;
    slice s;
    size_t curr;   //index of current element
    T& ref(size_t i) const {return (*v)[s.start()+i*s.stride()];}
  public:
    Cslice_iter(valarray<T>* vv, slice ss): v(vv), s(ss), curr(0){}
    Cslice_iter end() const{
      Cslice_iter t = *this;
      t.curr=s.size();
      return t;
    }
    const Cslice_iter& operator++(){curr++; return *this;}
    Cslice_iter  operator++(int){Cslice_iter t=*this; curr++; return t;}
    
    const T& operator[] (size_t i) const  {return ref(i); }//C style subscript  
    const T& operator() (size_t i) const {return ref(i); }    //Fortran style subsc  
    const T& operator*()           const {return ref(curr); } //current element

    friend
      bool operator == (const Cslice_iter<T>& p, const Cslice_iter<T>& q){
      //      bool operator ==<> (const Cslice_iter<T>& p, const Cslice_iter<T>& q){
      return 
        p.curr==q.curr && 
        p.s.stride()==q.s.stride() && 
        p.s.start() == q.s.start();
    }
    
    friend 
      //      bool operator !=<> (const Cslice_iter& p, const Cslice_iter& q){
      bool operator != (const Cslice_iter& p, const Cslice_iter& q){
      return  (!p==q);
    }
 
    friend
      bool operator < (const Cslice_iter& p, const Cslice_iter& q){
      //      bool operator < <>(const Cslice_iter& p, const Cslice_iter& q){
      return 
        p.curr<q.curr && 
        p.s.stride() == q.s.stride() && 
        p.s.start()  == q.s.start();
    }
    
  };
}//namespace
#endif

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