// Demonstrating a counting iterator class
#include <iostream>
#include <algorithm>
#include <string>
using namespace std;

template <typename ForwardIterator>
class counting_iterator {
private:
  ForwardIterator current;
  int plus_count;
  string name;
  int version;
public:
  typedef counting_iterator<ForwardIterator> self;
  typedef typename iterator_traits<ForwardIterator>::value_type
            value_type;
  typedef typename iterator_traits<ForwardIterator>::reference
          reference;
  typedef typename iterator_traits<ForwardIterator>::pointer
          pointer;
  typedef typename
          iterator_traits<ForwardIterator>::difference_type 
          difference_type;
  typedef forward_iterator_tag iterator_category;
  counting_iterator()
    : current(0), plus_count(0), name("null"), version(1) {}
  counting_iterator(ForwardIterator first, const string& n)
    : current(first), plus_count(0), name(n), version(1) {}
  counting_iterator(const self& other) : current(other.current), 
    plus_count(other.plus_count), name(other.name), 
    version(other.version + 1) 
  { 
     cout << "copying " << name 
          << ", new version is "
          << version << endl;
  }
  reference operator*() 
    // dereference
  {
     return *current;
  }
  
  bool operator==(const self& other) const
    // test for equality
  {
    return current == other.current;
  }
  
  bool operator!=(const self& other) const
    // test for inequality
  {
    return current != other.current;
  }
  
  self& operator++() 
   // prefix ++
  {                            
    ++current;
    ++plus_count;
    return *this;
  }
  
  self operator++(int) 
    // postfix ++
  {   
    self tmp = *this;
    ++(*this);
    return tmp;
  }
  void report(ostream& o) const 
    // Display statistics on stream o
  {
    o << "Iterator " << name << ", version " << version 
      << ", reporting  " << plus_count 
      << "  ++ operations " << endl;
  }
};

int main()
{
    cout << "Demonstrating a counting iterator class." << endl;
    int x[] = {12, 4, 3, 7, 17, 9, 11, 6};
    counting_iterator<int*> i(&x[0], "Curly"), 
                            j(&x[0], "Moe"), 
                            end(&x[8], "Larry");
    cout << "Traversing array x\n"
         << "  from i (Curly) to end (Larry)\n";
    while (i != end) {
       cout << *i << endl;
       ++i;
    }
    cout << "After the traversal:\n";
    i.report(cout);
    end.report(cout);
    cout << "Assigning j (Moe) to i (Curly)."
         << endl;
    i = j;
    cout << "Searching the array\n"
         << "  from i (Moe) to end (Larry)\n"
         << "  using find\n";
    counting_iterator<int*> k = find(i, end, 9);
    cout << "After the find:\n";
    k.report(cout);
    i.report(cout);
    end.report(cout);
    return 0;
}