1// Boost next_prior.hpp header file ---------------------------------------// 2 3// (C) Copyright Dave Abrahams and Daniel Walker 1999-2003. Distributed under the Boost 4// Software License, Version 1.0. (See accompanying file 5// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 6 7// See http://www.boost.org/libs/utility for documentation. 8 9// Revision History 10// 13 Dec 2003 Added next(x, n) and prior(x, n) (Daniel Walker) 11 12#ifndef BOOST_NEXT_PRIOR_HPP_INCLUDED 13#define BOOST_NEXT_PRIOR_HPP_INCLUDED 14 15#include <iterator> 16 17namespace boost { 18 19// Helper functions for classes like bidirectional iterators not supporting 20// operator+ and operator- 21// 22// Usage: 23// const std::list<T>::iterator p = get_some_iterator(); 24// const std::list<T>::iterator prev = boost::prior(p); 25// const std::list<T>::iterator next = boost::next(prev, 2); 26 27// Contributed by Dave Abrahams 28 29template <class T> 30inline T next(T x) { return ++x; } 31 32template <class T, class Distance> 33inline T next(T x, Distance n) 34{ 35 std::advance(x, n); 36 return x; 37} 38 39template <class T> 40inline T prior(T x) { return --x; } 41 42template <class T, class Distance> 43inline T prior(T x, Distance n) 44{ 45 std::advance(x, -n); 46 return x; 47} 48 49} // namespace boost 50 51#endif // BOOST_NEXT_PRIOR_HPP_INCLUDED 52