cpp-useful-iterators/end_aware_iterator.hpp

//
//  end_aware_iterator.hpp
//  iterator
//
//  Created by Sam Jaffe on 2/7/17.
//

#pragma once

#include <iterator>

template <typename Iterator>
class end_aware_iterator {
public:
  using iter_type = Iterator;
  using value_type = typename std::iterator_traits<iter_type>::value_type;
  using reference = typename std::iterator_traits<iter_type>::reference;
  using pointer = typename std::iterator_traits<iter_type>::pointer;
  using difference_type = typename std::iterator_traits<iter_type>::difference_type;
  using iterator_category = std::forward_iterator_tag;
public:
  end_aware_iterator(iter_type it, iter_type end) : curr_(it), end_(end) {}
  
  template <typename I>
  end_aware_iterator( end_aware_iterator<I> const & other )
  : curr_(other.current()), end_(other.end()) {
    
  }
  
  end_aware_iterator & operator++() {
    if ( !done() ) { ++curr_; }
    return *this;
  }
  
  end_aware_iterator operator++(int) {
    end_aware_iterator tmp{*this};
    operator++();
    return tmp;
  }

  reference operator*() { return *curr_; }
  pointer operator->() { return std::addressof(*curr_); }
  
  bool done() const { return curr_ == end_; }
  bool operator==(end_aware_iterator const & other) const {
    return curr_ == other.curr_ && end_ == other.end_;
  }
  
  bool operator!=(end_aware_iterator const & other) {
    return !(operator==(other));
  }
  
  iter_type current() const { return curr_; }
  iter_type end() const { return end_; }
private:
  iter_type curr_, end_;
};