boost/iterator/iterator_traits.hpp

// Copyright David Abrahams 2003. Permission to copy, use,
// modify, sell and distribute this software is granted provided this
// copyright notice appears in all copies. This software is provided
// "as is" without express or implied warranty, and with no claim as
// to its suitability for any purpose.
#ifndef ITERATOR_TRAITS_DWA200347_HPP
# define ITERATOR_TRAITS_DWA200347_HPP

# include <boost/detail/iterator.hpp>
# include <boost/detail/workaround.hpp>

namespace boost { 

// Unfortunately, g++ 2.95.x chokes when we define a class template
// iterator_category which has the same name as its
// std::iterator_category() function, probably due in part to the
// "std:: is visible globally" hack it uses.  Use
// BOOST_ITERATOR_CATEGORY to write code that's portable to older
// GCCs.

# if BOOST_WORKAROUND(__GNUC__, <= 2)
#  define BOOST_ITERATOR_CATEGORY iterator_category_
# else
#  define BOOST_ITERATOR_CATEGORY iterator_category
# endif


template <class Iterator>
struct iterator_value
{
    typedef typename detail::iterator_traits<Iterator>::value_type type;
};
  
template <class Iterator>
struct iterator_reference
{
    typedef typename detail::iterator_traits<Iterator>::reference type;
};
  
  
template <class Iterator>
struct iterator_pointer
{
    typedef typename detail::iterator_traits<Iterator>::pointer type;
};
  
template <class Iterator>
struct iterator_difference
{
    typedef typename detail::iterator_traits<Iterator>::difference_type type;
};

template <class Iterator>
struct BOOST_ITERATOR_CATEGORY
{
    typedef typename detail::iterator_traits<Iterator>::iterator_category type;
};

# if BOOST_WORKAROUND(BOOST_MSVC, <= 1200)
template <>
struct iterator_value<int>
{
    typedef void type;
};
  
template <>
struct iterator_reference<int>
{
    typedef void type;
};

template <>
struct iterator_pointer<int>
{
    typedef void type;
};
  
template <>
struct iterator_difference<int>
{
    typedef void type;
};
  
template <>
struct BOOST_ITERATOR_CATEGORY<int>
{
    typedef void type;
};
# endif

} // namespace boost::iterator

#endif // ITERATOR_TRAITS_DWA200347_HPP

Boost C++ Libraries

boost/iterator/iterator_traits.hpp