// ============================================================================
//
// Copyright (c) 1997, 1998, 1999, 2000 The CGAL Consortium
//
// This software and related documentation is part of an INTERNAL release
// of the Computational Geometry Algorithms Library (CGAL). It is not
// intended for general use.
//
// ----------------------------------------------------------------------------
//
// release       : $CGAL_Revision: $
// release_date  : $CGAL_Date: $
//
// file          : Counting_iterator.h
// chapter       : $CGAL_Chapter: STL Extensions for CGAL $
// package       : $CGAL_Package: STL_Extension $
// source        : stl_extension.fw
// revision      : $Revision$
// revision_date : $Date$
// author(s)     : Michael Hoffmann <hoffmann@inf.ethz.ch>
//                 Lutz Kettner <kettner@cs.unc.edu>
//
// maintainer    : Michael Hoffmann <hoffmann@inf.ethz.ch>
// coordinator   : ETH
//
// An iterator adaptor for the identity function.
// ============================================================================

#ifndef CGAL_COUNTING_ITERATOR_H
#define CGAL_COUNTING_ITERATOR_H 1
#include <CGAL/circulator.h>

CGAL_BEGIN_NAMESPACE

#if defined(CGAL_CFG_NO_ITERATOR_TRAITS) && \
!defined(CGAL_LIMITED_ITERATOR_TRAITS_SUPPORT)
template < class I, class Val>
#else
template < class I,
           class Val = typename std::iterator_traits<I>::value_type>
#endif
class Counting_iterator {
protected:
  I            nt;    // The internal iterator.
  std::size_t  d_i;   // The internal counter.
public:
  typedef I  Iterator;
  typedef Counting_iterator<I,Val> Self;

  typedef std::input_iterator_tag  iterator_category;
  typedef Val                      value_type;
  typedef std::ptrdiff_t           difference_type;
  typedef const value_type&        reference;
  typedef const value_type*        pointer;

  // CREATION
  // --------

  Counting_iterator( std::size_t i = 0)             : d_i(i) {}
  Counting_iterator( Iterator j, std::size_t i = 0) : nt(j), d_i(i) {}

  // OPERATIONS Forward Category
  // ---------------------------

  Iterator    current_iterator() const { return nt;}
  std::size_t current_counter()  const { return d_i;}

  bool operator==( const Self& i) const { return ( d_i == i.d_i); }
  bool operator!=( const Self& i) const { return !(*this == i);   }
  reference  operator*()  const { return *nt; }
  pointer    operator->() const { return nt.operator->(); }
  Self& operator++() {
    ++nt;
    ++d_i;
    return *this;
  }
  Self  operator++(int) {
    Self tmp = *this;
    ++*this;
    return tmp;
  }

#ifdef CGAL_CFG_NO_ITERATOR_TRAITS
#ifndef CGAL_LIMITED_ITERATOR_TRAITS_SUPPORT
  friend inline  value_type*
  value_type( const Self&) { return (value_type*)(0); }
  friend inline  iterator_category
  iterator_category( const Self&){ return iterator_category(); }
  friend inline  difference_type*
  distance_type( const Self&) { return (difference_type*)(0); }
  friend inline  Iterator_tag
  query_circulator_or_iterator( const Self&) { return Iterator_tag(); }
#endif // CGAL_LIMITED_ITERATOR_TRAITS_SUPPORT
#endif // CGAL_CFG_NO_ITERATOR_TRAITS //
};

CGAL_END_NAMESPACE
#endif // CGAL_COUNTING_ITERATOR_H //
// EOF //