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 

    17 namespace 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 

    29 template <class T>

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

    31 

    32 template <class T, class Distance>

    33 inline T next(T x, Distance n)

    34 {

    35     std::advance(x, n);

    36     return x;

    37 }

    38 

    39 template <class T>

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

    41 

    42 template <class T, class Distance>

    43 inline 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