ColumnIterator.hpp

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#ifndef COLUMNITERATOR_H_
#define COLUMNITERATOR_H_

#include <vector>

namespace trase {

class ColumnIterator {
public:
  using pointer = float const *;
  using iterator_category = std::random_access_iterator_tag;
  using reference = float const &;
  using value_type = float const;
  using difference_type = std::ptrdiff_t;

  ColumnIterator() = default;

  ColumnIterator(const std::vector<float>::const_iterator &p, const int stride)
      : m_p(&(*p)), m_stride(stride) {}

  reference operator*() const { return dereference(); }

  reference operator->() const { return dereference(); }

  ColumnIterator &operator++() {
    increment();
    return *this;
  }

  const ColumnIterator operator++(int) {
    ColumnIterator tmp(*this);
    operator++();
    return tmp;
  }

  ColumnIterator operator+(int n) const {
    ColumnIterator tmp(*this);
    tmp.increment(n);
    return tmp;
  }

  reference operator[](const int i) const { return operator+(i).dereference(); }

  size_t operator-(const ColumnIterator &start) const {
    return (m_p - start.m_p) / m_stride;
  }

  inline bool operator==(const ColumnIterator &rhs) const { return equal(rhs); }

  inline bool operator!=(const ColumnIterator &rhs) const {
    return !operator==(rhs);
  }

private:
  bool equal(ColumnIterator const &other) const { return m_p == other.m_p; }

  reference dereference() const { return *m_p; }

  void increment() { std::advance(m_p, m_stride); }

  void increment(const int n) { std::advance(m_p, n * m_stride); }

  pointer m_p;
  int m_stride;
};

} // namespace trase

#endif // COLUMNITERATOR_H_