//  Boost next_prior.hpp header file  ---------------------------------------//

//  (C) Copyright Dave Abrahams and Daniel Walker 1999-2003. Distributed under the Boost

//  Software License, Version 1.0. (See accompanying file

//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

//  See http://www.boost.org/libs/utility for documentation.

//  Revision History

//  13 Dec 2003  Added next(x, n) and prior(x, n) (Daniel Walker)

#ifndef BOOST_NEXT_PRIOR_HPP_INCLUDED

#define BOOST_NEXT_PRIOR_HPP_INCLUDED

#include <iterator>

namespace boost {

//  Helper functions for classes like bidirectional iterators not supporting

//  operator+ and operator-

//

//  Usage:

//    const std::list<T>::iterator p = get_some_iterator();

//    const std::list<T>::iterator prev = boost::prior(p);

//    const std::list<T>::iterator next = boost::next(prev, 2);

//  Contributed by Dave Abrahams

template <class T>

inline T next(T x) { return ++x; }

template <class T, class Distance>

inline T next(T x, Distance n)

{

    std::advance(x, n);

    return x;

}

template <class T>

inline T prior(T x) { return --x; }

template <class T, class Distance>

inline T prior(T x, Distance n)

{

    std::advance(x, -n);

    return x;

}

} // namespace boost

#endif  // BOOST_NEXT_PRIOR_HPP_INCLUDED