// Copyright 2009, Andreas Biegert

#ifndef CS_STRIDE_ITER_H_
#define CS_STRIDE_ITER_H_

#include <iterator>

template<class Iter_T>
class stride_iter {
 public:
  // public typedefs
  typedef typename std::iterator_traits<Iter_T>::value_type value_type;
  typedef typename std::iterator_traits<Iter_T>::reference reference;
  typedef typename std::iterator_traits<Iter_T>::difference_type difference_type;
  typedef typename std::iterator_traits<Iter_T>::pointer pointer;
  typedef std::random_access_iterator_tag iterator_category;
  typedef stride_iter self;

  // constructors
  stride_iter() : m_(NULL), step_(0) {}
  stride_iter(const self& x) : m_(x.m_), step_(x.step_) {}
  stride_iter(Iter_T x, difference_type n) : m_(x), step_(n) {}

  // operators
  self& operator++() {
    m_ += step_;
    return *this;
  }
  self operator++(int) {
    self tmp(*this);
    m_ += step_;
    return tmp;
  }
  self& operator+=(difference_type x) {
    m_ += x * step_;
    return *this;
  }
  self& operator--() {
    m_ -= step_;
    return *this;
  }
  self operator--(int) {
    self tmp(*this);
    m_ -= step_;
    return tmp;
  }
  self& operator-=(difference_type x) {
    m_ -= x * step_;
    return *this;
  }
  reference operator[](difference_type n) { return m_[n * step_]; }
  reference operator*( ) { return *m_; }
  self operator+(difference_type y) const { return self(m_ + y*step_, step_); }
  self operator-(difference_type y) const { return self(m_ - y*step_, step_); }

  // friend operators
  friend bool operator==(const self& x, const self& y) {
    assert(x.step_ == y.step_);
    return x.m_ == y.m_;
  }
  friend bool operator!=(const self& x, const self& y) {
    assert(x.step_ == y.step_);
    return x.m_ != y.m_;
  }
  friend bool operator<(const self& x, const self& y) {
    assert(x.step_ == y.step_);
    return x.m_ < y.m_;
  }
  friend difference_type operator-(const self& x, const self& y) {
    assert(x.step_ == y.step_);
    return (x.m_ - y.m_) / x.step_;
  }

 private:
  Iter_T m_;
  difference_type step_;
};

#endif  // CS_STRIDE_ITER_H_