Chris@16: //  Boost next_prior.hpp header file  ---------------------------------------//
Chris@16: 
Chris@16: //  (C) Copyright Dave Abrahams and Daniel Walker 1999-2003. Distributed under the Boost
Chris@16: //  Software License, Version 1.0. (See accompanying file
Chris@16: //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: //  See http://www.boost.org/libs/utility for documentation.
Chris@16: 
Chris@16: //  Revision History
Chris@16: //  13 Dec 2003  Added next(x, n) and prior(x, n) (Daniel Walker)
Chris@16: 
Chris@16: #ifndef BOOST_NEXT_PRIOR_HPP_INCLUDED
Chris@16: #define BOOST_NEXT_PRIOR_HPP_INCLUDED
Chris@16: 
Chris@16: #include <iterator>
Chris@16: 
Chris@16: namespace boost {
Chris@16: 
Chris@16: //  Helper functions for classes like bidirectional iterators not supporting
Chris@16: //  operator+ and operator-
Chris@16: //
Chris@16: //  Usage:
Chris@16: //    const std::list<T>::iterator p = get_some_iterator();
Chris@16: //    const std::list<T>::iterator prev = boost::prior(p);
Chris@16: //    const std::list<T>::iterator next = boost::next(prev, 2);
Chris@16: 
Chris@16: //  Contributed by Dave Abrahams
Chris@16: 
Chris@16: template <class T>
Chris@16: inline T next(T x) { return ++x; }
Chris@16: 
Chris@16: template <class T, class Distance>
Chris@16: inline T next(T x, Distance n)
Chris@16: {
Chris@16:     std::advance(x, n);
Chris@16:     return x;
Chris@16: }
Chris@16: 
Chris@16: template <class T>
Chris@16: inline T prior(T x) { return --x; }
Chris@16: 
Chris@16: template <class T, class Distance>
Chris@16: inline T prior(T x, Distance n)
Chris@16: {
Chris@16:     std::advance(x, -n);
Chris@16:     return x;
Chris@16: }
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #endif  // BOOST_NEXT_PRIOR_HPP_INCLUDED