sl@0: //  Boost next_prior.hpp header file  ---------------------------------------//
sl@0: 
sl@0: //  (C) Copyright Dave Abrahams and Daniel Walker 1999-2003. Distributed under the Boost
sl@0: //  Software License, Version 1.0. (See accompanying file
sl@0: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
sl@0: 
sl@0: //  See http://www.boost.org/libs/utility for documentation.
sl@0: 
sl@0: //  Revision History
sl@0: //  13 Dec 2003  Added next(x, n) and prior(x, n) (Daniel Walker)
sl@0: 
sl@0: #ifndef BOOST_NEXT_PRIOR_HPP_INCLUDED
sl@0: #define BOOST_NEXT_PRIOR_HPP_INCLUDED
sl@0: 
sl@0: #include <iterator>
sl@0: 
sl@0: namespace boost {
sl@0: 
sl@0: //  Helper functions for classes like bidirectional iterators not supporting
sl@0: //  operator+ and operator-
sl@0: //
sl@0: //  Usage:
sl@0: //    const std::list<T>::iterator p = get_some_iterator();
sl@0: //    const std::list<T>::iterator prev = boost::prior(p);
sl@0: //    const std::list<T>::iterator next = boost::next(prev, 2);
sl@0: 
sl@0: //  Contributed by Dave Abrahams
sl@0: 
sl@0: template <class T>
sl@0: inline T next(T x) { return ++x; }
sl@0: 
sl@0: template <class T, class Distance>
sl@0: inline T next(T x, Distance n)
sl@0: {
sl@0:     std::advance(x, n);
sl@0:     return x;
sl@0: }
sl@0: 
sl@0: template <class T>
sl@0: inline T prior(T x) { return --x; }
sl@0: 
sl@0: template <class T, class Distance>
sl@0: inline T prior(T x, Distance n)
sl@0: {
sl@0:     std::advance(x, -n);
sl@0:     return x;
sl@0: }
sl@0: 
sl@0: } // namespace boost
sl@0: 
sl@0: #endif  // BOOST_NEXT_PRIOR_HPP_INCLUDED